89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
I could use some help troubleshooting a problem with my '89 S10 4.3 with model 220 throttle body injection. Engine has been running a little lean for the last year, idles a little funny. Suddenly started running very poorly, but no trouble codes. Rebuilt the TBI. It ran a lot better, but would stall suddently, or not want to start after being run. Several hours later, it starts right up, like it was flooded, but there is no strong gas smell. At idle, there is enough gas being sprayed to coat the butterfly valves, does not look like a lot to me. What does a normal spray pattern look like at idle?
Just replaced the fuel filter (gas looked clean). It's still not running right. Idles too fast, 2000 rpm when started cold, revs go up and down for awhile, then down to 1500 for awhile, then 1000, and finally 750, but is not idling smoothly. Followed Step 10 in "Troubleshooting your TBI Fuel Injection System" (http://www.73-87chevytrucks.com/tech...TBISystems.pdf) for when engine is revving up and down. I don't hear any sucking sounds, no loose vacuum lines. Again, no trouble codes. With key on, I hear a "clacking sound that I don't remember ever hearing before. When I pull the Idle Air Control (IAC) plug, the clacking stops, so it was the IAC (is that normal?). Then remove the jumper from ALDL connector (key still on), turn off for at least 15 seconds, and restart the engine. The engine refused to start. I sort of got it started by pumping the gas pedal, but it would not run. Not sure what to make of this. Plugged IAC back in, but engine still won't start/run. Again, no strong gas smell, but acts like it's flooded. Another weird thing that started happening today is the oil pressure reading is very low at idle. The "oil can" even started flashing for a bit. Engine has a fresh oil/filter change and is topped up. This truck has the digital dash with the led bar readouts, and has been replaced once. Sometimes it acts up a little, but turning off and back on makes it work right again. This oil pressure thing kept up for numerous on/off while testing. The only other thing is one of the rubber insulator things that go between the injector and the plug is missing, pretty sure it was missing when I got the truck, does not seem to affect running. Not sure what to do next. Suggestions? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Check out these threads. Then post your thoughts.
I would check for problems in the order I posted the links. I would think you replaced the base gasket under the TBI when you rebuilt the TBI, but if you didn’t you should of, it is a common spot for a vacuum leak. High idle thread: http://67-72chevytrucks.com/vboard/s...d.php?t=439984 Coolant sensor testing specifications and instructions: http://67-72chevytrucks.com/vboard/s...d.php?t=379142 Fuel pump testing information; truck had split hose in tank- http://67-72chevytrucks.com/vboard/s...d.php?t=375132 |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Thanks for the suggestions and links (had already read the IAC thread).
Yes, I did a full rebuild on the TBI using a kit for Rochester model 100, 200, 220 and 295 TBIs. Kit included new gaskets, injector filters and o-rings, and new pressure regulator. Kit did not include a new regulator dust seal. I tested the injectors using a D-cell battery (good). The kit diagram and instructions did NOT mention the idle air control (IAC)! IIRC, I removed it before cleaning the throttle body and installed a new paper gasket. The symptom before I rebuilt the TBI was that at idle, the left bore was dry, and the right bore had a film of gas. When I tore it down, the only sign of dirt/debris was what looked like engine oil in the fuel meter body. I assumed this was oil vented from the crankcase. Now, the IAC is making clicking sounds when ignition is turned on (engine not running and running). Does this sound like a dirty IAC? The brakes work fine, so pretty sure brake booster diaphragm is not leaking. Also tested the fan clutch recently (good), but it is engaged for cold starts and most of the time in general, only rarely disengages. Coolant sensor: The temp reading has always stayed right on the normal mark, and still does, so i think it's good. Do you agree? Fuel pump: After rebuilding the TBI, truck ran great on the test runs, great throttle response, and made good power (better than before). Just went out and tried starting the engine again, and it fired right up, ran to 1800 rpm for 20-30 seconds, then down to 1200. The fact that it starts right up after sitting and today's very low oil pressure sounds to me like it's flooding. Do you agree? Quote:
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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As trucker stated there is a separate sensor for the gauge and a different sensor for the coolant temp reading that the computer uses. Quote:
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After the engine is shut off, and before it is started, the IAC should open somewhat. This makes noise. The IAC is a stepper motor and uses short pulses of electricity on the wires to move its position. If the IAC does not open at all, the engine will usually “load up” or “flood”. When you replace, remove and clean an IAC, or unplugged the IAC with the key on, the ECM may need to relearn the IAC position. This will not happen without driving the truck and meeting specific conditions or taking other steps the cause it to relearn the idle. Quote:
The most noticeable symptom of low fuel pressure on TBI trucks is poor idle quality. The most common comment from an owner after a fuel pressure problem is fixed is "it has so much more power now". |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Not being familiar with non-vortec 4.3's I have to ask if the FPR may be leaking? The vortec ones are notorious for that. Gives you poor performance and bad idle quality and it can effect the oil.
Does the oil smell like fuel or did it ever before? Fuel contaminated oil would also give you the intermittent "oil can" light you spoke of earlier. But again back to what someone said earlier to check the fuel pressure is the key to several questions. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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This is what it looks like Fuel On one side, Spring pressure and Vacuum on the other http://www.jegs.com/images/photos/500/561/561-61511.jpg |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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==> Can anyone tell me if I should be able to see gas in the throttle bores at idle? If not, it's flooding, but I don't know WHY. The pressure regulator does not leak gas when engine is not running. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Two of us (at least) think it could be a temperature sensor problem and that is why we mentioned it.
It is very common for the temp sensor to read the wrong resistance. You should test it. When the engine is running there should always be fuel getting sprayed in the throttle bores. It should look equal on both sides. No fuel should drip out the injectors once the engine is turned off. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
I'd like to thank all who have offered me help so far!!!
Just confirmed that the oil is contaminated with gas. I could actually SEE gas on the dipstick, too! Dang, just changed the oil and filter a couple weeks ago. Since my problem is still not fixed, I don't want to change the oil/filter until I fix the cause (fingers crossed). I installed a new FPR when I rebuilt the TBI. When I turn the key on, I hear the fuel pump cycle the normal amount, then total silence. When I replaced the fuel filter, there was still a TON of pressure in the lines. So the FPR is probably not leaking, right? So, I guess testing the coolant temp sensor that feeds the computer is my next task. Problem: Don't have a shop manual for this truck! So, here come the dumb questions... Where is the sensor on this engine (4.3 Vortec with non-Vortec intake)? Can I test it without removing it? If I have to remove it, do I need to drain the system first? How do I test it? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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I posted a link. Quote:
http://67-72chevytrucks.com/vboard/s...25&postcount=7 You could also search my username and coolant sensor. Quote:
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The instructions are in the links posted. Does anyone look at the links I post??????? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Thanks, ChevyTech! Yes, I read the links. I'm just clueless, lol! ;-}
But seriously, hot weather and the worst allergies I've ever had are making it real hard to think/concentrate. I found the post where you list the temp sensor approximate resistance for various temps. It's noon and 76 degrees F outside. I went out and found the temp sensor on the right cylinder head. Set my DVM to the 20000 ohm range and got .004. This looks to be about right, given the ambient temperature and using the closest two resistance value from your list: 332 ohms @ 176 deg. F. or 80 deg. C. 467 ohms @ 158 deg. F. or 70 deg. C. There is no sign of corrosion or leaking on/around the sensor. Then I turned the ignition on and checked for leaks and found none. The entire area in and around the TBI is totally dry and no sounds to indicate a leak inside. What should I do next? I don't want to run the engine if I don't have to. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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That is not the sensor you should be testing!!!!! Quote:
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
According to my phone, it's 76 degrees F outside. The engine is COLD. My DVM is set to the 20k ohm range. The sensor on front of intake (for ECM) reads 005. For comparison, the OTHER sensor (for temp guage) reads 004.
What's the verdict? Is my ECT sensor BAD? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Please ignore my last post and read this one (ran out of time to edit it)! I had the DVOM set to the wrong setting. Here are the CORRECT readings for both sensors (to see if they agree), both with outside temp of 76 degrees F:
ECT sensor: 3900 ohms GUAGE sensor: 3670 ohms The actual readouts were 3.90 and 3.67. I did the conversion to ohms on a scientific calculator by entering the readout value (3.90), then pressing the "Exp" button followed by the "3" button. Your list of approximate sensor resistance specs says I should get 2796 ohms at 77 degrees F: 2796 ohms @ 77 deg. F. or 25 deg. C. I'm not sure what this means. Are BOTH sensors bad? Did I do something wrong? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The engine will not warn up as quickly as the air does during the day.
The sensor readings look close enough. Another test you can do is run the engine up to operating temperature (195), shut it off, and see what the resistance is when warm. My guess is, the sensor is not the problem. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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I would test the sensor with the engine at operating temp, but I have a crankcase full of gasoline. If I change the oil/filter now (so I can get it up to operating temp), it's just going to dump more gas in the sump. I don't have a thermometer or temp tester, or I would remove the sensor and test it in a pot of hot water on the stove. What would you do now if you were in my shoes? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The sensor is showing a resistance that is not far off. The engine should start and run they way it is supposed to with the reading you got from the sensor.
If the crankcase is getting fuel in it, there is another problem. Could the fuel have gotten into the crankcase before you did the TBI work and maybe you already fixed the problem like fuel leaking from the TBI? The sensor can be good, but if the wiring to it is bad, the computer will get bad data. Resistance on the wire, or wire connections, will cause the computer to think it is colder, so more fuel gets injected. If the ground wires have resistance the same thing can happen. The most important grounds are the ground wires at the front of the intake near the thermostat or manifold studs. The TBI trucks don't leak fuel into the oil like the central port injected trucks do. I would change the oil, because if that much fuel is getting in the oil, it should be obvious if you look at the TBI with it running. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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After rebuilding the TBI, it started right up and ran GREAT. I was on the way to get gas, and it died about a mile down the road. Thought it was empty, but when I added 2 gallons of gas, it would not start. Came back next morning and it fired right up, but died again as I was backing into my parking spot at home. I didn't even smell gas until I went to warm it up to run tests. This is when the crankcase started filling with gas, and the oil pressure dropped WAY down. I was worried, about that, but let it run for awhile, trying to get it up to operating temp. Quote:
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I replaced the starter and the battery right after rebuilding the TBI, because I couldn't get it to start and the battery tested "good" (but it was bad), so I replaced the starter first (it was an old rebuilt and was rusty anyway). I also removed and cleaned the battery ground wire at the engine (it was fine). Quote:
Yes, you would think it would be obvious, but it's not and I don't know why! This is why I asked how much gas I should be seeing with engine idling. BEFORE I rebuilt the TBI, I could see a thin coating of gas on one butterfly, and the other one looked DRY. At that time, the truck was running too lean and never flooded, EVER. After rebuilding the TBI, there was a thin coating of gas on the bores and butterfly valves, but I could not see the injectors actually SPRAY gas while engine was idling. Note I said "idling". Did not check for spray at higher RPM because all hell broke loose before I could get to that. Thanks for not giving up on me yet! I really need this truck back on the road. My other driver got wrecked last month (not my fault). Would it help to take pictures and post them? Should I test the Idle Air Control? Is it time to dismantle the TBI again? Should I get the injectors tested by a qualified shop? Seems like the ONLY possibilities are a) Injectors are dumping too much gas in the engine (reason still TBD), or b) Gas is LEAKING into the engine from somewhere (besides the injectors). When I replaced the fuel filter, I didn't cycle the fuel pump to relieve the pressure. First I disconnected the fuel hose between tank and filter. Then I disconnected the incoming fuel line from the TBI, and not much more gas dribbled out. Then I started disconnecting the outgoing fuel line (return line for when there's too much pressure), and it just kept on leaking and leaking gas. I finally gave up and tightened it back up again. Does this tell you anything? Is there any way that a plugged up return line could result in gas being dumped into the engine? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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If the fuel return line, FROM THE TBI TO THE FUEL TANK, gets plugged, the fuel pressure will go to high, unless there is another problem, like a weak pump or split hose in the fuel tank. This problem does happen, but is not common. Removing the fuel filters that GM put under the vehicle is a messy job. Often fuel will keep running out until the new filter is installed and tightened. Keep trouble lights away from the vehicle for safety reasons. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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After rebuilting the TBI, it would start right up and had great throttle response at all engine RPMs. But the first time I drove it, it died less than a mile down the road. It did this a couple more times. No smell of gas though! I wanted to drop the tank, inspect/flush the tank and the fuel lines and replace the fuel filter, but when I disconnected the fuel lines, the gas that ran out was clean. So I decided to just replace the fuel filter. Note that in the photos, there is a short rubber line with two clamps on each end between the tank and the fuel filter. It was like that when I got the truck. I checked all of the rubber hoses, and all are in excellent condition. I disconnected that short rubber line first and plugged it off and let the gas run out of the filter end of the line (only a constant dribble, not a stream). When I loosened the SECOND fuel line fitting to TBI body (the one on the LEFT side), there was a lot of pressure, and gas kept leaking out onto the back of the intake manifold, and down onto the ground. I used rags to soak up the gas, but it kept on coming, so I tightened the fitting again to stop the flow. I'm starting to wonder if the gas that leaked out of the fitting could have worked its way into the crankcase? The only thing on that end of the intake manifold that I think could have let the gas in is the DISTRIBUTOR, which of course leads to the crankcase. Could this be how the gas got into the crankcase? Before the gas leaked out at the TBI body/fitting, the engine was acting like it was flooded (would stall, then would not start until I let it sit for a few hours), BUT, there was no smell of gas, and the injectors were not visible SQUIRTING gas. So, maybe it was not flooding, but something else at that time. Quote:
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The only unusual thing I notice with your photos, other then the rubber injector grommets on the wire connectors are missing, is they are upside down.
Your truck has a “Port EGR Valve/ System” and you may want to make note of this for future reference. If you ever want to buy an EGR valve they will most likely try to sell you the wrong type. The return line is smaller diameter and is to the passenger side of the supply line. Test the fuel pressure. If the pressure is good with the engine running then the return line should be open. The rubber hose and clamps on the fuel supply line between the tank and the fuel filter are NOT factory. Lifting the bed is the method I prefer, rather than dropping the tank. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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The left grommet is missing. AFAIK, it was gone when I got the truck. Napa will sell me a whole new plug with wires and grommet (for $$$), but not just the grommet. How important is the grommet? Quote:
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The missing grommet is not important. I would just grab one at the U-Pull-It or run without it.
The rubber hose added to your truck would be an easy place to test fuel pressure. In a shop setting, a guy on each corner works well to lift the box and move it back. I have seen photos of people using a cherry picker to lift the whole box off. I don't like 2x4s and things that can fall. If you have a strong garage, some rope up to the rafters works well for removing toppers and boxes. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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I also know that it holds the pressure for a long time after shutoff, because when I replaced the fuel filter, it had been sitting overnight and still had (lots of) pressure when I loosened the supply line. What should I do next? Flush the supply line? OR... Quote:
Since the gas from the lines looks clean, do you think I need to drop the tank for inspection? |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The fuel pressure regulator is in the TBI unit and testing the pressure must be done with the gauge installed on a T fitting, engine running.
You are just guessing at the pressure because your gauge does not go that high, but 18 PSI is easily reached with a good strong pump when the gauge is on the end of the line, or the return line flow is stopped. My guess is there is no problem in the tank. If the hose in the tank was split it would not hold pressure after the pump stops. The test you did does not show that the pump is good for sure, but the test leads me to believe the pump is good. You were in the TBI unit already so you would have seen if the fuel regulator spring is broken. On ODB1 system and these TBU trucks it is a process of elimination, especially working over the internet when I am note using my senses to see how it is running. So far we have not definitively ruled out much. I suggest you change the oil and get truck on the road to give it some run time after the changes you have made, so it can relearn the IAC position and fuel tables. This will also give it a chance to clean up soot off sparks plugs and the oxygen sensor. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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Notes: I figured a static pressure test was inadequate, but hoped it would do for now. Would like to rig up a permanent test fitting (schrader valve?) so I can do a proper test anytime after I change the oil and filter. The auto parts store did not have anything like that, so I had to settle for an assortment of vacuum fittings with two different sizes on each end. I used two of them, a piece of hose and 3 hose clamps to connect the hose on the guage to the piece of hose added to the fuel lines by somebody else. Any suggestions? IMO, the (static) reading of 16 PSI was within +/- .5 PSI, because I measured it using an item that is the same width as each 1 PSI gradiation, using the outer/vacuum gradiations to mark each point on a blown-up photo on the computer. The engine would not even start with the IAC disconnected, but that may be because the crankcase was full of gas by then. After I change the oil/filter, if still having problems (like stalling), I will try the "relearn" procedure again. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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http://www.toolsource.com/fitting-01...y-p-95304.html You don't have a good gauge so you should buy one like in these links, that comes with the adaptor: http://www.actron.com/product_detail.php?pid=16175 http://www.autozone.com/autozone/acc...er=232719_0_0_ http://www.toolsource.com/fuel-press...sh0lcunug0t5v7 |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Thanks for the links! Current status:
Changed the oil/filter last night (5W-30 synthetic blend, Purolator PureOne filter). Pulled the coil wire. Went to crank the engine to circulate the new oil and nothing. Brand new made in USA Exide battery was DEAD. Put it on the charger overnight. This morning, put the freshly charged battery in, cranked engine for 15-20 seconds, put coil wire back on and engine fired right it up, went straight to 1750 RPMs and stayed there for about 1 minute. The oil pressure went straight to 60 PSI and stayed there for the 2-3 minutes I ran it. RPMs dropped to 1500 for the next minute or more, oil pressure remained at 60. Checked oil and added half a quart. Questions: How long should the ECM take to "relearn" and adjust the idle speed down? Any suggestions on what to do next? I will not be driving it anywhere until I know I can trust it to keep running and not burn up. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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If I remember correctly one of the conditions for a self learn of the IAC position is a 45 MPH threashold must be met. You can try this and see if it gets closer. Using a watch or timer to make sure you hit the times on step 3 and 4: 1) Disconnect battery for at least ten seconds. (with the Key OFF) 2) Reconnect the battery. 3) Start engine letting it run for five seconds. 4) Turn key off for ten seconds. 5) Then start it and see how it idles. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Thanks, I'll give that a try!
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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UPDATE: Looks like I have a bad Idle Air Control (IAC).
I found a paper gasket for the IAC in the remains of the TBI rebuild kit, which proves that I did NOT remove the IAC when I cleaned and rebuilt the TBI. As I mentioned before, the kit instructions and exploded view OMITTED the IAC entirely, though it did say to remove all electrical parts before cleaning (thought I had). I removed the IAC and measured how far the pintle is extended (just over 1-1/16"), then carefully cleaned it per the instructions in the "IAC maybe?" thread. Then put it back in with the new paper gasket and looked to see if I could see the tip of the pintle sticking through the hole into the TBI. NOPE. Then turn the key on (no sound) and checked again. Still not sticking out at all. Conclusion: I wrecked the IAC when I cleaned the TBI using carb cleaner. Will buy a new one and see if that cures my fast idle problem. Hope this helps someone else avoid ruining their IAC! |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Carburetor cleaner can damage the IAC in a hurry.
They are a high failure part anyway. They wear. Drive it a bit to get a self relearn after the new IAC is installed. Make sure the tip is not out too far when you install the new IAC. The tip of the pintle must not extend more than 28mm which is 1.10 inches from the shoulder toward the electrical connector, by the threads. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The new Idle Air Control Valve did the trick. Runs great now! The idle settled down to 750 before I made it to the freeway, but I took on the freeway anyway just in case. Thanks for all the help!
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
You’re welcome, and thank you for letting us know what fixed it.
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Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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UH-OH! Had a date last night and took the S10. Idle started at 1500, which I think is a bit high for warm weather. Shouldn't it be closer to 1200? It shudders and stalls when in gear and not moving. OK if not in gear. Had to keep my foot on the gas to keep it running. Accelerates fine and runs smooth in non-idle. AND, the TEMP GUAGE has a ZERO readout (see photo) the entire time. Made a stop on the way, and it didn't want to start back up, had to open the throttle and keep cranking it. Same problem starting back up after my date. Once going, it ran fine, except for the idle thing. The idle RPMs were the correct 750. Got gas on the way home, will drive it today and see if it's still acting up. The combination of no temp reading and wanting to stall out at idle is interesting. Bad ECT sensor?
BTW, I checked the ground on the firewall (black plastic thing that has several wires on it), and it was nice and clean (all copper connectors). Didn't find any other grounds for the engine wiring. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
The sensor for the computer is separate from the sensor for the gauge.
Like I said early in the thread. Test the fuel pressure. To correctly test the fuel pressure, test it with the engine it RUNNING. Until you cross that off the list, we are wasting time, because it sure sounds like a low fuel pressure problem. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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And what about the zero temp reading? That can't possibly have anything to do with a failing fuel pump. IIRC, I got that once before, but it started working after I turned it off, then back on again. Records show the digital dash was repaired once, and replace with new (or reman) later on. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
Re: The dash gauge reading wrong.
The display like in your truck where a problem before those truck even got old. They look nice. They are a high failure item. If the sender resistance reads even close to where it should, then suspect the instrument panel as the problem part. Quote:
At idle the injector pulse is so short that when the pressure is low, TBI systems go very lean. At high rpms & loads the injector has much longer pulses, spending more time open, and they do better with low pressure then at idle. That's the way it is. Do a search on my threads and see if you think I know what I am talking about. I am giving you my honest opinion. I have no reason to steer you wrong. I know nobody that knows the TBI trucks better then I do. This is not a carbureted engine you are working on. You are thinking about fuel supply like it is carbureted. |
Re: 89 S10 4.3 Need help troubleshooting TBI/IAC Idle issue
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