Question : Fuse/Relay for Fuel Pump.

[swalsh19]

I need to temporarily turn off the fuel pump as I want to run a can of fuel injector cleaner through the injectors. I have pulled the fuel pump relay from the fuse panel on the passenger side of the car. This is the only thing clearly marked fuel pump. When I pulled this the car continued to run as normal. I pushed the accelerator to hopefully use up the remaining fuel in the lines but I don't think the pump is turned off as the car ran for a good 5mins. the only other thing they claim for the fuel pump is the ECM fuse. I pull this and nothing works at all so that can't be the way to go. Is there something else I am missing???


I'm going to jack the car up tomorrow and see if I can get at the fuel pump plug easily. But if anyone has any ideas as to why the relay doesn't kill the car let me know. I have the relay pulled right now and the car runs like normal...

[3100 MPFI]

oil pressure sensor can let the car run. It is a backup thing.

What YEAR are you working on?

if you have the fuel pump relay and ecm batt fuse out, try unplugging your oil pressure sensor. It is right next to the oil filter.

[swalsh19]

Sorry, year and make would help. its a '95 Grand Prix GTP, 3.4L engine.

When you pull the ECM fuse the car is dead. I require the car to be able to run still just without the fuel pump as the injector cleaner is going into the car.

My fuel mileage has dropped off considerably although the car runs fine. I figured I would try cleaning the injectors.

[3100 MPFI]

leave the ECM BATT fuse, but remove the fuel pump relay, and the unplug the oil pressure sensor.

here you can see it right over the oil filter.



I don't know how the car will run without fuel, but doing those 2 things will ensure the pump does not turn on, but the injectors will.

[swalsh19]

Having the oil pressure sensor detached, along with fuel pump relay stops the fuel pump? Interesting...

[3100 MPFI]

yeah.

The fuel pump relay is a normal relay, but the oil pressure sensor one is to cut the fuel off in the event of a loss of oil pressure. I think it only works if the car gets rolled over or something.

Need me to scan the wiring diagram?

[swalsh19]

If you had it, I would love it!

Is there a fuse for the oil pres. sensor?

Whats the point of the relay then? The car runs without it.

[3100 MPFI]

It is like that as a sort of double redundency thing. The oil pressure sensor does not have it's own fuse.

Here ya go. This should help you out some.

[swalsh19]

Thanks!!!

[3100 MPFI]

any time

[3100 MPFI]

i forgot to add..... That wiring diagram is for the 1994 Cutlass Supreme 3.4 DOHC. It is almost identical to the 1995 setup. So far the only difference I have found (I just put a 1994 3.4 DOHC in my 1995 Cutlass Supreme), is the oil level sensor. All the fuel stuff is the same.

[pocket-rocket]

leave the ECM BATT fuse, but remove the fuel pump relay, and the unplug the oil pressure sensor.

here you can see it right over the oil filter.



I don't know how the car will run without fuel, but doing those 2 things will ensure the pump does not turn on, but the injectors will.

Please, Taylor, tell me that is your old BAD engine.....

[3100 MPFI]

yes. That is the engine I pulled out of my 1995. It has 4 bad mains. It spun the main bearings, and the oil pan was filled with something that looked like wheel bearing graphite grease.

Here are some pics from that engine. I took that pic right before I pulled off the oil pan to see why the engine had failed. I actually took that pic for the OIL LEVEL SENSOR, but since the oil PRESSURE sensor was so visible, I posted it for that.

This was the insides of that engine.









After I saw that, I didn't tear any more into it. I just stopped there, and decided to trash the engine.

[pocket-rocket]

And that, my friends is why we DON't USE FRAMS!

[3100 MPFI]

I thought it was more why we are SUPPOSE to do oil changes. It looks to me like the last oil change was done never years ago.