1985 L44 V6 Vin9 Fuel Pump Shut Off

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chief1

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1985 GT Fiero fuel pump or regulator keeps running after ignition is turned off



Hi all,
Maddening problem with my 1985 Fiero GT V6 Vin 9. Quite a while ago I came out one morning and the battery was dead. I charged the battery and drove the car. Afew days later, when I went to start the car, Dead Battery. Charged battery and drove the car. Starting checking to see if a dome light or some other lamp or switch was energized and draining the battery, but found none. Upon returning home and shutting it down, I noticed that I could still hear either the fuel pump or the fuel regulator still running. I finally found the 10 amp fuse that feed power to the fuel pump and pulled it out. That solved that battery draining problem. I have the factory 1985 Fiero Field Service Manual, but after much studing, I havenot been able to fix the problem. I pulled the fuel pump relay and then plugged in the 10 amp fuse. The fuel pump system kicked right off, the car started and ran with no problem. Looking at the wiring diagram for the system, I am thinking that with the relay out of the curcuit, that maybe a shorted oil pressure switch would keep the pump running even with the ignition turned off, as it also gets its power from the always hot 10 amp fuse. Now for the foollish part. I haven't been able to locate the oil pressure switch. Although the manual diagram calls this item the "oil pressure switch" I havn't been able to find a reference anywhere else dealing with the 'oil pressure switch" Am I on the right track? Can anyone tell me if they have expierenced this problem or is familiar with a fix? Thanks to anyone in advance for an answer. Chief1
 
Someone with more Fiero experience may answer this but my guess is the ignition switch.
 
Yes it is most likely the oil pressure switch. On a V-6 with AC it is located just to the left of the battery and the line is bolted to the head next to the waterpump. About 2" round and 3" tall mounted on a steel line mounted vertically. If the car was not originally equipped with A/C it is then mounted towards the passenger side right next to the oil filter.

Here is a picture of the sensor. The electrical connector faces up when mounted on an A/C equipped Fiero.
oil%20pressure%20sensor%20switch%20for%20pontiac%20fiero%201986%20gt%202.8%20litres.JPG


To verify it is shorted, just pull the plug off the top and see if the fuel pump shuts off.
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Oreif, Thanks a bunch for your quick info and pix. I do have the 85 GT with factory installed AC, and I had just come to suspect that the item that you described was in fact the Oil Pressure Switch. The fact that it had a three wire connection and that the colors on the wires wern't really distinct had me questioninbg myself. Then I started looking for the signal source for the Oil Pressure Guage, figuring that it was a single wire from the sending unit. I finally last evening started to suspect that it might be a combo unit housing the Oil Pressure Switch and the Oil Pressure Sensor. Any recommendation as to a reliable source for the unit? The local Autozone only shows a listing for the 2.5 engine, two wire Oil Pressure Switch.
And again, thank you for your quick and accurate answer. chief1
 
Hey Oreif: Meant to get back to you a lot sooner, but for some reason I just couldn't get logged on. Anyway I pulled out the battery and the battery box and was able to see and get the proper wrenches on the top of the pipe and the bottom of the sending unit and replace it. Walla.....The sweetest sound of silence! since I had a little accident that cracked a couple of vertabre, I decided to let some one else do the brakes as the left front was grabbing fiercely. The motor was running rough so I pulled off most of the electrical connectors and sprayed them with an marine anti-corrosion product. It really smoothed things out. Then in the next few days, I had trouble getting it to keep running. I got it gassed up and though it was missing some, got it to the mechanic that was doing the break job for me. On the way there, it smoothed out again. Next day, when I went to pick it up, he told me that when he went to test drive it, it died outside his driveway and "nothing". Seems that my next priority, which was to inspect and if necessary replace the distributor cap and rotor, wasn't going to wait. He changed those out and it really smoothed out and no hesitation while starting.
One other issue that I might ask about. In '95, a week or so after hurricane Opel, I suddenly heard a clanking noise from the auto transmission. Had to have it rebuilt. All went great for two years. Then fairly suddenly, whenever I dropped it into gear, there was a whining sound coming from the transmission. Took it to the repair place and they couldn't tell me anything. It continued to shift into all gears with no problem. They told me that it was out of the warranty, and they only way to know what was causing it was to take it down completely again. That was in '97, and I am still driving it and it is still whining...until it gets into 4th gear. Mostly an annoyance, but I get a little concerned when I want to take out for a fairly long distance. Ever hear of this problem?
And again, thanks a million for your gracious help. Chief1
 
Glad to hear it is back up and running smooth. As for the trans, there is no "4th" gear. What you feel/hear is the torque converter lock-up. The trans locks the torque converter to the input shaft in third gear when cruising. If the whine goes away, Then it could be the torque converter itself or the input shaft pump making noise. Since it sounds like it's been that way for 15 years, I do not think it is a big issue.

If the trans ever goes, you could always swap in a 4t40. This is a 4-spd auto trans that swaps right in and works very well.
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