88 Suburban wont idle - The 1947 - Present Chevrolet & GMC Truck Message Board Network

88SuburbanMONSTER · 08-07-2011, 07:08 PM

88 Suburban wont idle. Going down the highway, let off the throttle and it died. Timing was off and warped some intake valves. (found while trouble shooting.) Replaced all pistons, all intake valves, TPS, AIC, MAP, EGR, egr solenoid, coil, pick up coil, ignition control module, plugs and wires. Checked for vac leaks, checked fuel pressure (13#) I think that is good for this TBI. Rebuilt fuel regulator and TBI gaskets. Injectors seem ok, good spray. As you can see tons of money already. Any ideas?

scotts62 · 08-08-2011, 08:30 PM

has to be either vacuum leak or fuel. have you put a vacuum gauge on it and see if the needle bounces around?

ChevyTech · 08-08-2011, 09:08 PM

Did you unplug the set timing connector when you set the timing?

Welcome to the board!

88SuburbanMONSTER · 08-09-2011, 12:04 AM

No Scott, I haven't put a vac gauge on it; but that sounds like a good idea. may take a day or so ; but I'll try that. As far as the timing advance wire, It seems to be close just by initial time, at least enough to keep it running. I just can't run it long enough to fine tune it yet. Thanks for your replies and I hope to get more ideas in case this doesn't resolve it.

ChevyTech · 08-09-2011, 10:11 AM

Unplug the hose to the EGR and see if it helps.

The next thing that comes to mind is that it may have valves (rockers) adjusted to tight.

If you used the method in the manual that tells you to spin the pushrod in your fingers when you were adjusting the valves, you could easily have them adjusted to tight.

If the parts are smooth, and you use good lube on reassembly, it is very hard to feel the point your reach zero lash when spinning the push rod. I only use the wiggle the push rod method when adjusting valves.

88SuburbanMONSTER · 08-09-2011, 06:25 PM

Rockers too tight may be a possibility and I will check that too on Thursday; but before I put the new intake valves in, It was running ok. Then one day after going down the interstate (8 miles) I lost the ability to idle once I let go of the throttle on the deceleration ramp. Has not idled since. Also puchased a vacuum gauge, fuel gauge, and OBD1 scan tool today; which I will try Thursday.

08-07-2011, 07:08 PM	#1
88SuburbanMONSTER Registered User Join Date: Aug 2011 Location: Lake City, Florida Posts: 4	88 Suburban wont idle 88 Suburban wont idle. Going down the highway, let off the throttle and it died. Timing was off and warped some intake valves. (found while trouble shooting.) Replaced all pistons, all intake valves, TPS, AIC, MAP, EGR, egr solenoid, coil, pick up coil, ignition control module, plugs and wires. Checked for vac leaks, checked fuel pressure (13#) I think that is good for this TBI. Rebuilt fuel regulator and TBI gaskets. Injectors seem ok, good spray. As you can see tons of money already. Any ideas?

08-08-2011, 08:30 PM	#2
scotts62 One day... Join Date: Apr 2008 Location: Tuttle, Ok Posts: 9,240	Re: 88 Suburban wont idle has to be either vacuum leak or fuel. have you put a vacuum gauge on it and see if the needle bounces around? __________________ Scott 93 crew cab build Project 62

08-08-2011, 09:08 PM	#3
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,620	Re: 88 Suburban wont idle Did you unplug the set timing connector when you set the timing? Welcome to the board! __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

08-09-2011, 12:04 AM	#4
88SuburbanMONSTER Registered User Join Date: Aug 2011 Location: Lake City, Florida Posts: 4	Re: 88 Suburban wont idle No Scott, I haven't put a vac gauge on it; but that sounds like a good idea. may take a day or so ; but I'll try that. As far as the timing advance wire, It seems to be close just by initial time, at least enough to keep it running. I just can't run it long enough to fine tune it yet. Thanks for your replies and I hope to get more ideas in case this doesn't resolve it.

08-09-2011, 10:11 AM	#5
ChevyTech Registered User Join Date: May 2004 Location: Minnesota Posts: 4,620	Re: 88 Suburban wont idle Unplug the hose to the EGR and see if it helps. The next thing that comes to mind is that it may have valves (rockers) adjusted to tight. If you used the method in the manual that tells you to spin the pushrod in your fingers when you were adjusting the valves, you could easily have them adjusted to tight. If the parts are smooth, and you use good lube on reassembly, it is very hard to feel the point your reach zero lash when spinning the push rod. I only use the wiggle the push rod method when adjusting valves. __________________ For those of you that are wondering why you are not getting replies to your thread: Did you give the model, year, engine, fuel system type, and transmission information? If it is modified from what came stock from the factory, let us know that too.

08-09-2011, 06:25 PM	#6
88SuburbanMONSTER Registered User Join Date: Aug 2011 Location: Lake City, Florida Posts: 4	Re: 88 Suburban wont idle Rockers too tight may be a possibility and I will check that too on Thursday; but before I put the new intake valves in, It was running ok. Then one day after going down the interstate (8 miles) I lost the ability to idle once I let go of the throttle on the deceleration ramp. Has not idled since. Also puchased a vacuum gauge, fuel gauge, and OBD1 scan tool today; which I will try Thursday.



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