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My 1991 S10 Blazer died on free way.
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eddie13blue
New User
Sep 3, 2009, 8:09 PM
Post #1 of 3
(6072 views)
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My 1991 S10 Blazer died on free way.
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I have a 1991 S10 Blazer 4 wheel drive with a 4.3L engine TBI (2 fuel injectors) automatic trans. Engine has 225803 miles. The problem started on the free way, all system where normal, when the motor just died. sprayed starting fluid in carb it fired up but would not stay on? I had just filled the tank 20 miles prior.I Could not hear fuel pump on freeway it was too noisy. I towed it home. It still would not start. Next day went to start it and started right up. Warmed up ran for about 30 minutes and died. Hooked up code reader but had no error codes . I took off air breather and ring fitting it sets on,to see in to the TBI. Let cool down and checked all fuses all was good . I started it after about 5 hours. Every thing was normal looked at injectors spray pattern all seemed good. Reved up motor all was good , then let idle for about 20 minutes then it died. Turned off key then turned on key I could here the fuel pump presserize. Tried starting but no fuel at injectors? checked fuses agian all good.Hooked up another code scanner but no error codes? The check engine light was never on but I thought I would try to scann for codes any way.(Engine light works when key is in on position so I know it works). Put every thing back together. Ordered the computer and puchased fuel pump relay. Installed both but nothing happend. rechecked fuses and ecm1 was blown . Read schamatic put a tracer on the ecm1 circuit and followed the pink /blk to every component . Opened every circuit till I found short. My mistake I pinched the the white lead to the fuel injector. Fixed then I put a 10 amp fuse in and started the engine. All was good for about 30 minutes then it died. I tried to start,I can hear the fuel pump and there is spark, But no fuel at injectors and no error codes on the ECM. Checked all connections but all seems good,I did change the fuel pump about ten years ago and its been a very reliable Blazer since then no leaks no problems. I know it runs a bit on the rich side and gets bad gas milage and has a slow pick up on the free way when floored. It sets most the summer and use this blazer for the winter but try to run motor every other week in the summer. Checked voltage at the injectors with just the key on it was red and white leads to ground 12 volts,red to blue lead 00.4volt,white to green lead 00.3volt. Resistance between prongs on injectors was 1.4 on each. Also reading the schamatic I see that the PCM runs the the the blue and green leads to fuel injectors. Could there be a bad sensor that sends info to the PCM to shut down fuel injectors? How about the coolant temp sensor? I did feel the new fuel relay a bit hot but did not think it would be an issue since it is a better rated relay. I am just hoping I find the answer to the problem. Any input would be helpful.
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DanD
Veteran
/ Moderator
Sep 3, 2009, 11:08 PM
Post #2 of 3
(6064 views)
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Re: My 1991 S10 Blazer died on free way.
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The throttle position sensor (TPS) if it were intermittently shorting to reference voltage; may put the ECM into clear flood mode and turn off injector pulse.
The next time the engine quits; check the TPS signal return voltage too the ECM at the ECM; connector C13.
Closed throttle Approx .5(1/2) volt, wide open throttle 4-5 volts.
I know you said that you can here the fuel pump running but that doesn’t mean its producing pressure. T in a pressure gauge and confirm that there is proper pressure. (9-13 psi)
Confirm whether the injectors are or are not being pulsed by the ECM. Do not connect a standard test light across the injector’s connector; it may draw more amperage then what the EMC’s injector driver (grounding switch) can handle and burn it out. Use a Noid light or a self powered test light.
A noid light is a very low amperage light that will plug right into the injector connector.
A self powered test light uses different colored LEDs that will light up depending on whether it senses power or ground. It also uses its own power source rather then power from the circuit you’re testing to run the LEDs.
With the engine cranking and the test light connected; there should be a constant blinking of the light.
The last thing I can think of that might be causing the stall and no restart, until it cools; is the ignition module. I know you said you have spark when it’s not starting; but a shorted ignition module can throw in some confusion into the ECM and I’ve seen injector pulse become affected.
Dan.
Canadian "EH"
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eddie13blue
New User
Sep 27, 2009, 10:17 PM
Post #3 of 3
(5989 views)
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Re: My 1991 S10 Blazer died on free way.
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Dan. I think I have solved the issue. I did the trouble shooting you recommended. I had .5volt on TPS even after shut down of motor. Had no voltage pulse at injectors, tested with clamp meter cranking over on dead motor. Had fuel pressure reading 12psi on running motor and 9-10psi on dead motor cranking over. Dead motor ignition key on had fuel pump pressurize to 10psi for two seconds then pressure is released. I replaced the ignition module and the distributor cap and rotor while I was in there.Started engine, ran for an hour with heavy reving at times, to heat up engine let idle and seemed to do well did not die.I have not taken it on a road test yet but seems to be ok. Thanks so much for your help Dan!
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