NCGumby

Check to see if that year has a crankshaft sensor or camshaft sensor. my 5.7 FI 97 hoe was doing the same thing. What fixed me was the crankshaft sensor.

Good luck!

medimg

Thanks for your help ..Problem found, I mounted an engine fuel pressure gauge and the reading was 6 psi engine running , pulled tank and found tube off pump partually. Replaced pump and tube w/delphi have 9-10 psi at the TBI and runs very good now considering 169k miles.

olds4554speed

I have a fully restored 1991 Chevy Suburban that has fresh engine transmission rear end paint interior and I have left nothing undone or unrefreshed.

About 3 months ago it quit running cold in Houston and had to have it towed back to Dallas.

For all parts below I acquired all parts thru O'Reillys Auto Parts.

Hereth begins the diagnostics, no CHECK ENGINE LIGHT was produced.

Similar issue occured 3 years ago on an older engine ,same truck. At that time it was a bad EGR VALVE. I had bypassed the vacuum source and it ran fine. So I replaced with AC DELCO EGR Valve and that fixed the issue. That was then this is now!!!!!!!!

So isolating the EGR did not fix it this time.
Symptoms are: starts, runs fine, until warmed up and then the engine will lose all power and act as if its starving for fuel.

Starting there the original tank had broken plastic windage tray baffles in it so I replaced the fuel tank with new tank and replaced with a new pump and hanger assy. No change.

Next, took the car to local Chevy Dealer that has several old school techs still working. After running their tests they figured the ECM was failing. So I purchased a reman'd unit thru O'Reillys Auto Parts. Swapped the CAL unit and reinstalled it. No change.

Forget the dealer, they were useless.

Next, read when MAP sensor can cause this similar condition, replaced MAP Sensor. No change.

Next, replaced EGR, EGR sensor. No change.

Next, replaced distributor. I had found traces of surface rust on reluctor on distributor shaft so pickup coil maybe effected. New distributor comes with new ESC electronic unit, pickup coil, cap & rotor, also. No change.

Next, read somewhere that the fuel pressure regulator diaphram if split could cause flooding. rebuilt throttle body unit, rebushed it and boiled it out and added rebuild kit and brand new Borg Warner injectors. No change.

Next, read somewhere that Engine Oil Pressure sender (behind and below the distributor) since it serves and oil pressure guage sender and fuel cutoff switch in case of loss of oil pressure, replace it with new to eliminate that. No change.

Next, read somewhere that bad ground wire on Thermostat housing can cause ECM issues. Checked it, cleaned it off, verfied that contact wanhers are all steel and attract a magnet, reinstall the ground wire. No change.



Next, read somewhere that Engine Coolant Temp Sensor if malfunctioning could cause the ECM to think the engine is at -40 deg F in dflt mode.
This would make the IAC Valve stay or go closed as if engine were in cold start mode. This would cause flooding since the injectors are receiving signals from the ECM that its a cold start so needs little air and lots of fuel.
Replace dhte driver side (left side) Coolant Temp Sensor (1 wire pigtail) unit. No change.
BUT BUT BUT, I forgot that there is a 2nd Temp Sensor (2 wire pigtail) unit mounted very front of intake manifold just to the front of the thermostat housing area. I pulled it and replaced it. BINGO!!!!! Problem resolved.

Now I know why ODBI only lasted a couple of years.

Its all about luck. Yes..... if I had started with the coolant temp sensor first I would have gotten off cheap. But all items replace can potentially cause this symptom.

olds4554speed

I have a fully restored 1991 Chevy Suburban that has fresh engine transmission rear end paint interior and I have left nothing undone or unrefreshed.

About 3 months ago it quit running cold in Houston and had to have it towed back to Dallas.

For all parts below I acquired all parts thru O'Reillys Auto Parts.

Hereth begins the diagnostics, no CHECK ENGINE LIGHT was produced.

Similar issue occured 3 years ago on an older engine ,same truck. At that time it was a bad EGR VALVE. I had bypassed the vacuum source and it ran fine. So I replaced with AC DELCO EGR Valve and that fixed the issue. That was then this is now!!!!!!!!

So isolating the EGR did not fix it this time.
Symptoms are: starts, runs fine, until warmed up and then the engine will lose all power and act as if its starving for fuel.

Starting there the original tank had broken plastic windage tray baffles in it so I replaced the fuel tank with new tank and replaced with a new pump and hanger assy. No change.

Next, took the car to local Chevy Dealer that has several old school techs still working. After running their tests they figured the ECM was failing. So I purchased a reman'd unit thru O'Reillys Auto Parts. Swapped the CAL unit and reinstalled it. No change.

Forget the dealer, they were useless.

Next, read when MAP sensor can cause this similar condition, replaced MAP Sensor. No change.

Next, replaced EGR, EGR sensor. No change.

Next, replaced distributor. I had found traces of surface rust on reluctor on distributor shaft so pickup coil maybe effected. New distributor comes with new ESC electronic unit, pickup coil, cap & rotor, also. No change.

Next, read somewhere that the fuel pressure regulator diaphram if split could cause flooding. rebuilt throttle body unit, rebushed it and boiled it out and added rebuild kit and brand new Borg Warner injectors. No change.

Next, read somewhere that Engine Oil Pressure sender (behind and below the distributor) since it serves and oil pressure guage sender and fuel cutoff switch in case of loss of oil pressure, replace it with new to eliminate that. No change.

Next, read somewhere that bad ground wire on Thermostat housing can cause ECM issues. Checked it, cleaned it off, verfied that contact wanhers are all steel and attract a magnet, reinstall the ground wire. No change.



Next, read somewhere that Engine Coolant Temp Sensor if malfunctioning could cause the ECM to think the engine is at -40 deg F in dflt mode.
This would make the IAC Valve stay or go closed as if ewngine were in cold start mode. This would cause flooding since the injectors are receiving signals from the ECM that its a cold start so needs little air and lots of fuel.
Replace dhte driver side (left side) Coolant Temp Sensor (1 wire pigtail) unit. No change.
BUT BUT BUT, I forgot that there is a 2nd Temp Sensor (2 wire pigtail) unit mounted very front of intake manifold just to the front of the thermostat housing area. I pulled it and replaced it. BINGO!!!!! Problem resolved.

Now I know why ODBI only lasted a couple of years.

Its all about luck. Yes..... if I had started with the coolant temp sensor first I would have gotten off cheap. But all items replace can potentially cause this symptom.

HvyKvy

Thanks olds4554speed! I've been plagued with the same issue and as the dash temp gauge was working I didn't look any further in that direction. Doh!!! There are 2 temp sensors! I get the genius award for that one. My 94 5-speed Blazer is running great now especially with all the parts I threw at it!

Anthony Wilson

I had a similar issue with my 04 2500HD 6.0L. Had sluggish performance and would enter limp mode on the highway. Turned off the engine and restarted usually fixed it for a short time. Turned out to be the cam position sensor goes bad in those models. Try checking that out as well maybe. Just a thought.

Amy McLaughlin

where is the 1 terminal temp sensor located on the 1992 Lumina???