Question about tbi to Rochester 2 barrel - The 1947 - Present Chevrolet & GMC Truck Message Board Network

byopp12789 · 10-21-2018, 10:16 PM

So I just bought a 1987 Chevrolet r10 with a tbi on it and the tbi is shot so what I was wondering was I have a Rochester 2 barrel laying around would it fit in place of the tbi and would it run right with all those sensors and everything not being hooked up to the carb.
Thanks, Bryson

MARKDTN · 10-22-2018, 03:20 PM

You have no mechanical fuel pump so you will have to deal with that (you can't use the electric in-tank pump with a carb). The block may or may not be machined for it. The electronic distributor won't work without the computer. But in simplistic terms an intake is an intake. If you can bolt on a carb leak-free and supply fuel and spark then yes it will run. If it were me, I would much rather make a TBI work than a 2-bbl carb. The TBI is a very simple system. You will also have issues if you have a 700R4 transmission with the TV cable and a 2-bbl.

**jayoldschool** · 10-22-2018, 05:54 PM

Define "shot" please. The TBI is easy to work on, cheap to service, and ultra reliable. I wouldn't downgrade to a carb.

byopp12789 · 10-23-2018, 05:18 AM

Quote:

Originally Posted by jayoldschool

Define "shot" please. The TBI is easy to work on, cheap to service, and ultra reliable. I wouldn't downgrade to a carb.

At idle it will not run to save its life and i was told by the guy I bought it from it needed injectors but after changing them that didn’t fix it so I would just rather give up to a carb because I know a little about them and I know nothing about the 87 tbi. Maybe you could help me? Give me more insight on what could be causing it to flood at idle? Thanks, Bryson

P.S. I pulled the plugs and all 8 are black. Could it be some sensor or something? If you can help let me know. Thanks again
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byopp12789 · 10-23-2018, 05:28 AM

Quote:

Originally Posted by MARKDTN

You have no mechanical fuel pump so you will have to deal with that (you can't use the electric in-tank pump with a carb). The block may or may not be machined for it. The electronic distributor won't work without the computer. But in simplistic terms an intake is an intake. If you can bolt on a carb leak-free and supply fuel and spark then yes it will run. If it were me, I would much rather make a TBI work than a 2-bbl carb. The TBI is a very simple system. You will also have issues if you have a 700R4 transmission with the TV cable and a 2-bbl.

Maybe you could tell me what could be causing it to flood at idle? I know nothing about these things the guy told me it needed injectors but after changing them no luck and I know a little about how to work on a carb that’s why I was ready to give up to one but if I can get this fixed I would rather go tbi route. Thanks, Bryson

P.S. I pulled the plugs and all 8 are black. Could it be some sensor or something? If you can help let me know. Thanks again
Posted via Mobile Device

**clay68c10** · 10-23-2018, 06:56 AM

Will it start and idle with the engine cold? Does it get worse as it warms up?
The injectors rarely go bad on these, as you found out.
Do you have a fuel pressure gauge?

rpmerf · 10-23-2018, 06:58 AM

Clean up the plugs. Run the codes. Disconnect the battery to reset the ECU. If it gets better after the ECU reset, then gets worse again, it'd blame a sensor. If it stays about the same, I'd look at non-sensor issues like fuel pressure. A good manual should have troubleshooting steps.

Found this with a little searching.
http://www.73-87chevytrucks.com/tech...TBISystems.pdf

roboticjunky · 10-23-2018, 06:34 PM

If you can found a good scanner that tells you what your sensors are reading, that will really help.

I had a truck that had TBI and ran rich and would die when you put in gear. MAP sensor wasn't reading right. Ended being the wire going from the MAP sensor to the ECM was bad. So that bad wire made the ECM think it at full throttle and ran really rich. Bad o2 sensor could also make it run rich. Bad coolant sensor would also make the motor run rich, because the ECM will think it's really cold when it's not.

You can check the MAP sensor by using a multimeter and checking to see if it's getting 5 volts from the ECM. Then you can check how much voltage is going back to the ECM should be around 4.90 volts or so. You can also check your coolant sensor, which is next to the thermostat housing, by unplugging the coolant sensor and setting your multimeter to ohms. Then check the resistance across the 2 prongs on the coolant sensor. Reading should be around 5670 if the motor temperature is 50 degrees F.

Also do a visible check like is everything plugged into the sensors and are there any broken or burnt wires.

10-21-2018, 10:16 PM	#1
byopp12789 Registered User Join Date: Oct 2018 Location: Gainesville Georgia Posts: 5	Question about tbi to Rochester 2 barrel So I just bought a 1987 Chevrolet r10 with a tbi on it and the tbi is shot so what I was wondering was I have a Rochester 2 barrel laying around would it fit in place of the tbi and would it run right with all those sensors and everything not being hooked up to the carb. Thanks, Bryson

10-22-2018, 03:20 PM	#2
MARKDTN Registered User Join Date: Jan 2011 Location: Chattanooga, TN Posts: 2,131	Re: Question about tbi to Rochester 2 barrel You have no mechanical fuel pump so you will have to deal with that (you can't use the electric in-tank pump with a carb). The block may or may not be machined for it. The electronic distributor won't work without the computer. But in simplistic terms an intake is an intake. If you can bolt on a carb leak-free and supply fuel and spark then yes it will run. If it were me, I would much rather make a TBI work than a 2-bbl carb. The TBI is a very simple system. You will also have issues if you have a 700R4 transmission with the TV cable and a 2-bbl. __________________ '83 K20-TPI '73 C10 '79 C10-ex-diesel(SOLD) '07 Tahoe(Son driving) '14 Suburban-DD '71 C10-current project

10-22-2018, 05:54 PM	#3
jayoldschool Moderator Join Date: Dec 2012 Location: ON, Canada Posts: 2,151	Re: Question about tbi to Rochester 2 barrel Define "shot" please. The TBI is easy to work on, cheap to service, and ultra reliable. I wouldn't downgrade to a carb.

10-23-2018, 06:56 AM	#6
clay68c10 Senior Member Join Date: Aug 2004 Location: Centennial, CO Posts: 2,882	Re: Question about tbi to Rochester 2 barrel Will it start and idle with the engine cold? Does it get worse as it warms up? The injectors rarely go bad on these, as you found out. Do you have a fuel pressure gauge? __________________ ClusterTruck: 68 C10 Bought in 89, wrecked in 03. Slow low $ rebuild started '17. 6.0 & TKO http://67-72chevytrucks.com/vboard/s...d.php?t=788602 93 K1500 Short Step, 350, NV4500, EBL flash ECU. Vortec heads & roller cam someday... 05 Jeep Wrangler Unlimited. 3” lift & 6-speed 02 E320 the insurance total “free car” 13 Tahoe LTZ

10-23-2018, 06:58 AM	#7
rpmerf Registered User Join Date: Feb 2011 Location: Parkville, MD Posts: 1,024	Re: Question about tbi to Rochester 2 barrel Clean up the plugs. Run the codes. Disconnect the battery to reset the ECU. If it gets better after the ECU reset, then gets worse again, it'd blame a sensor. If it stays about the same, I'd look at non-sensor issues like fuel pressure. A good manual should have troubleshooting steps. Found this with a little searching. http://www.73-87chevytrucks.com/tech...TBISystems.pdf __________________ 1970 C20 Custom Camper - 350, TH350 1997 GMC Suburban 1994 Acura Integra GSR 1987 Dodge Daytona Shelby Z

10-23-2018, 06:34 PM	#8
roboticjunky Registered User Join Date: Oct 2015 Location: IN Posts: 208	Re: Question about tbi to Rochester 2 barrel If you can found a good scanner that tells you what your sensors are reading, that will really help. I had a truck that had TBI and ran rich and would die when you put in gear. MAP sensor wasn't reading right. Ended being the wire going from the MAP sensor to the ECM was bad. So that bad wire made the ECM think it at full throttle and ran really rich. Bad o2 sensor could also make it run rich. Bad coolant sensor would also make the motor run rich, because the ECM will think it's really cold when it's not. You can check the MAP sensor by using a multimeter and checking to see if it's getting 5 volts from the ECM. Then you can check how much voltage is going back to the ECM should be around 4.90 volts or so. You can also check your coolant sensor, which is next to the thermostat housing, by unplugging the coolant sensor and setting your multimeter to ohms. Then check the resistance across the 2 prongs on the coolant sensor. Reading should be around 5670 if the motor temperature is 50 degrees F. Also do a visible check like is everything plugged into the sensors and are there any broken or burnt wires.



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