QuestionQUESTION: I have a 95 firebird with the 3.8 V6 and 4L60E trans.
occasionally when trying to start the car when I get to the run position on the key, the fuel pump relay (under left foot corner panel) makes a vibrating/low buzz noise and the pump doesnt run and of course the car wont start. turning the key back and forth a few times fixes it and off you go. but occasionally the car will just die while driving too (did it 4 times on an hour and a half highway drive yesterday). Not sure if its related. not sure why the relay would buzz like that. I can try just replacing it for starters but is there anything else you can think of? the pump and filter were changed about 1 year ago so they should be fine. I have a meter and know electric quite well.
thanks.
ANSWER: Hi mark:
a few things to think about. the 3800 is noted for crankshaft position sensors going bad That aside the relay buzzing issue you have going on makes me think more of a power/ground issue you have going on. Make sure the battery terminals are clean and tight no corrosion on them and look at the gound wires on the engine and on the body On those older one they were on the body by the strut towers same with the battey junction block if anyting is loose or corroded clean and or replace that and start there. I think the relay is buzzing because it's lost ground or is lacking power.
Good luck :-)
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QUESTION: thanks. yeah it definitely seems like a bad connection somewhere. or just a completely bad computer? the thing has a mind of its own. it also now has no power when flooring it (it revs but doesn’t go anywhere).fuel pressure is fine though. also once when it stalled ALL the gauges went to zero and "check gauges" appeared on the cluster (no check engine or security light).
also the oil pressure gauge occasionally jumps all over the place flipping out so much you can hear it clicking against the sides. the torque converter is also flipping out locking and unlocking over and over while driving on flat ground/maintaining speed. (TPS sensor check out good though)
I found a ground that goes from the battery to the engine and its tight. there must be one from the engine to the body though right? cant find that one. all connections I did find are tight and clean though.
help! :-)
ANSWER: follor the ground cable and you will see where is splits off to the engine and then to the body. It more then likely need an oil pressure sensor for the guage if only that gauge is acting up. I would take a look at the brake light switch to make sure that is adjusted propelry that will cut out the Torque converter clutch if the engine computer see any kind of brak input.
When was the last time this had a fuel filter replaced in it? you may want to look into that and also a bottle of chevron techron fuel system cleaner in the gas tank follow the bottle for dosage to the amount of fuel in the tank. Wal* mart sells it CHEAP.
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QUESTION: sorry to be a pain. hope you dont mind.
so the buzzing relay is actually being FED a buzzing signal (used an O-Scope)
also I put a multimeter across the relay's inputs and drove around while glancing at the meter. apparently this relay is driven off the ECM's 12 volt regulator becuase I get +14 at the battery and alternator but I get anywhere from +12.2 to +13.2 across the coil of the relay.
I also checked the voltage at the MAF which I understand should be a VERY steady +12.0 (+/- <5%)off the ECM and I'm getting 13.4 at idle (batt is at +14).
I'm thinkng the 12v regulator (in the ECM?) is shot which would certainly account for all the crazyness. now the question is how to find/fix that.
Answerthat voltage flucuation may be normal depending on the loads on the eletrical system lights/blower motor rear defogger etc.. Have you had the charging system on this checked? meaning load test the battery and the alternator output checked? If no look there. On those old ones I'm not sure the ECM controls the alternator field or not. My online service info only goes back to 1998 and there is a big difference in those cars over 3 years. if indeed the ECM does control the alternator field then I would back track and check all the grounds again especially the ones that feed the ecm. Also you may want to do a volatge drop across both battery cables and the power and grounds to the Ecm it's self. Good luck :-)
