This thing is driving me nuts. Replaced the relay and that's not the problem. Happens every now and then and kills the battery.

Anyone got any ideas????

 

Stays on.....intermittently?

 

 

I thought it would be obvious that it stays on after the car is shut off by my saying it kills the battery. And it does it intermittently. Meaning every now and then.

How much clearer can I get?

 

 

Oil pressure sending unit makes a direct connection between battery and fuel pump - when oil pressure is sensed the fuel pump will run - they can go bad and thus 'think' they are getting pressure when they are not. Might need to replace.

Meantime, everytime you leave the car for more than an hour, pop the hood, located the fuse between the battery and the fender (it's in a weatherpack), and remove it - that is the fuse for that circuit between battery and oil pressure sending unit.

 

I just replaced the sending unit by the oil filter a few days ago. Dang thing went bad after one year and we almost lost the engine cause it puked out 4 quarts of oil in 20 miles when my fiancee was driving he car.

As I recall I remember reading about another sending unit by the distributor. I'll see if I can find it.

 

Fuel pumps themselves can die slowly & run off & on for a short time, before they die entirely. Mine did that a few years back.

Hitting the floor above the pump when it wouldn't come in would usually get it running. I obviously just went ahead & replaced the pump that week instead of pushing the chance of getting stuck on the road.

 

When I bought the car in December 2009 it had a bad fuel pump. Got the car fro $600 and a new fuel pump and a battery and I had an 89 IROC-Z with a 350TPI, 4 wheel disks. Great car, in very nice shape. Since then the fuel pump problem has come up about 5 times and killed the battery. The oil pressure sending unit went bad and no oil pressure on the gauge, so replaced the sending unit in December also

The sending unit went bad and started gushing oil last week big time. So I replaced it and the pump still stays on now and then. Did the same with the old sending unit that leaked. The fuel pump relay was also replaced and still does this.

I've been doing more reading and I'm not sure if an 89 has the secondary oil pressure switch. The one I replaced has 3 wires on it.

If this is the case, with the sending unit replaced and a new relay on it, not sure where to check for the problem now.

 

The one you replaced is the faulty one - the one with 3 wires replaced the one by the distributor - so you should not have one there at all. The older cars had a single wire unit at the distributor for the guage, and if they had a intank fuel pump there was a second 2-wire sender above the oil filter - later they combined into one 3-wire unit at the oil filter when they stopped producing carbed cars.

If you got an Advance/AZ/Oreilly etc. part, it may not be quite "up to par" - might want to try a different (ie better) brand, like a NAPA part or CARQUEST part. Some of the "cheap" parts are fine, others are junk - just depends. I had a AZ unit that was fine for years, and the next one I got was junk (same manufacturer, same part #, but obviously a different production run). Most things I don't want to have to deal with again, I go to NAPA or CARQUEST for.

 

Well they must both be faulty. Both the one that leaked and the new one have done the same thing to me.

The sending unit was a Borg Warner part. I thought these were pretty good quality pieces.

 

I've went through about 5 OPSU's now They don't last long. The all go bad and keep the fuel pump running. I've verified it is the OPSU that doing it. I can remove the fuel pump relay and the pump stays running, disconnect the OPSU connector and the pump shuts off.

It seems to me that 5 sensors can't be bad, something is making the contacts apparently stick or weld themselves together. Not sure why...........but can't think of any other reason they go bad so quickly.

I'm thinking of using a relay kind of like was suggested in another thread, but using the OPSU to turn the relay on and off and the relay supplies the power to the pump taking the current load off the OPSU. This would retain the safety part of the sender.

The pump was new in Dec of 09. I really don't think it would go bad in this length of time and pull too much current to fuse the contacts together.