Fuel Pump grounding out

[wordy1]

What else would cause the fuel pump to ground out besides the pump itself?
The car had an aftermarket Walbro fuel pump and the car just died on the road. I installed a stock 87 GN pump for the time being just so I had something to drive as the Walbro pump would have taken a couple days to get here. The car just died out again and I replaced the relay and still nothing. I got the car to start by bypassing the 2-5 switch on the relay completely and jumping the #2 wire directly to the pump. The car does not have a fuel return as far as I can tell. Being new to the GN's, I am not sure if it is supposed to or not. Also, the procedure for replacing a pump says to replace the schrader valve, what exactly is a schrader valve and what does it do? I just put back what I took out. I drove the car about 1000 miles till this happened, but I have a feeling that whatever caused the first pump to go bad will eventually make this pump go bad as well.

I want to put the Walbro pump that I took out back in as well. How do I tell what pump it is, there are no numbers or any type of markings on it and it looks the same as the stock GN pump. I am in desperate need of getting this solved, I drive this car daily and don't want to worry about being stranded again. Thanks guys!

 

[Quick6'n'-K.C.]

Hey daily driver bud, i know the feeling

Well, the 340 will have the numbers 340m stamped on the pump if that is exactly what it is.
My guess, is after a few days of driving, your relay is going to crap.

Depending on relays and your hotwire setup, i would check the pump you pulled out most likely its fine. Easy to test, once its stranded on the road, test the voltage at the pump and see if its gettin power and ground.


Also depending on fuel hot wire kits, it may reuse the stock relay on the pass fender to power the feed to power the new relay.

It does have a return fuel pressure line, right below the fuel pressure regulator.,,

BW

 

[Ormand]

The schraeder valve is in the end of the fuel rail, just ahead of the fuel pressure regulator. It's like the valves in the valve stems for the tires. It will hold pressure in, until you depress the little plunger in the middle. There is a screw-on cap covering the one in the fuel rail. It screws in, and you can remove it, using one of the little tools used for the tire valves.

 

[wordy1]

Could a stuck schrader valve be causing the pump to ground out/>

 

[57loboy]

Nope, a stuck schraeder valve (without a cap on it) that was stuck open would spray fuel all over the engine...the cap might contain it.

 

[Quick6'n'-K.C.]

Could a stuck schrader valve be causing the pump to ground out/>

The schrader valve is a test port. Ormand should have pointed that out

BW

 

[wordy1]

I bought a new relay and the same thing, how can I test if the relay is bad? If the realy is good, would I then need to replace the harness?

 

[wordy1]

When I jump the relay and run the #5 wire, (the power wire going from th relay to the pump.) to the #2 wire where the input of the relay starts, the pump works as it should. What I am asking, is there any way to check to see if the relay is working correctly? Or if the pump itself is again grounding out. I honestly doubt both pumps just went bad by themselves. There is an inline fuse as well as the relay and the fuses will blow if there is any problem, so I can't see how the pumps would have been damaged, but something is definitely wrong. I need to correct the problem or I will keep losing fuel pumps.

 

[urhstry]

Is there any chance that the wiring at the pump or the relay is bad or grounding itself to something? maybe inside the relay socket?

 

[wordy1]

I don't think so, but how do I know if the relay is bad? I tested the wiring and it only grounds out when the pump is attached, it could be on the top of the tank, but I honestly doubt it. I will drop the tank and check, I am getting a walbro pump anyways.

 

[SloGN]

does the car have a hot wire kit to the fuel pump.

if it does there should be a relay located AT the back of the tank where the stock harness is. check that relay.

also check the stock fuel pump relay it's located beside the map sensor on the pass side inner fender.

then also check to see if the oil sending unit wires are grounding out. the oil sending unit is located down below the turbo on the side of the block. or the oil sending unit itself might be grounding out. try unpligging it a drive to see it the fuel pump quits.

it also could be a bad driver in the ECM and tell the fuel pump relay when to activate. try another ecm for a day or too. the driver could be getting hot and shorting out.

HTH

 

[wordy1]

AS far as I can tell its just a stock 87 GN setup with an additional inline fuse . The fuel pump works when I bypass the relay by jumping the 5 wire to the 2 wire leading into the relay. I tested the wires all the way to the pump and it does not ground out until the pump is hooked up. The pump works when I bypass the relay and the car runs fine. Could the "new" pump just be failing? I am just concerned that once I get the Walbro pump it will die on me again. It seems like too much of a coincidence that the second pump went out so quickly, after the previous pump worked problem free for 15 years. This "new" pump has only 1000 miles or so of use.

 

[SloGN]

AS far as I can tell its just a stock 87 GN setup with an additional inline fuse . The fuel pump works when I bypass the relay by jumping the 5 wire to the 2 wire leading into the relay. I tested the wires all the way to the pump and it does not ground out until the pump is hooked up. The pump works when I bypass the relay and the car runs fine. Could the "new" pump just be failing? I am just concerned that once I get the Walbro pump it will die on me again. It seems like too much of a coincidence that the second pump went out so quickly, after the previous pump worked problem free for 15 years. This "new" pump has only 1000 miles or so of use.

this relay that your talking about where is it located? the factory fuel pump relay is located on the pass side inner fender beside the map sensor.

 

[Quick6'n'-K.C.]

AS far as I can tell its just a stock 87 GN setup with an additional inline fuse . The fuel pump works when I bypass the relay by jumping the 5 wire to the 2 wire leading into the relay. I tested the wires all the way to the pump and it does not ground out until the pump is hooked up. The pump works when I bypass the relay and the car runs fine. Could the "new" pump just be failing? I am just concerned that once I get the Walbro pump it will die on me again. It seems like too much of a coincidence that the second pump went out so quickly, after the previous pump worked problem free for 15 years. This "new" pump has only 1000 miles or so of use.

Depending on how the hotwire setup is used, it could RELY on the fuel pump RELAY from the factory on the pass side.

If you jump it like you say, then its not grounding out, if the positive wire grounds out, it would pop a fuse once it shorts to ground.

So, what your saying is, if you jump the "relay" that isnt factory it works and the car runs fine.

Either the relay doesnt have a b+ once key is on ( relay on pass side) or the b+ behind alternator grey wire with black lead isnt triggering the relay

The AFTERMARKET relay is not properly grounded (find new ground)

Bad realy (find new relay)

If the power wire leading to the back of the car is not covered and shorts to ground it will blow a fuse.

BW

 

[wordy1]

It is a stock setup with an additional fuse to the positive battery side in case something does ground out. I guess in theory I can run the car without it. All the wiring checks out fine up until the pump connection,. Bypassing the relay just keeps the fuse from blowing and allows the pump to turn on., I am getting a NEW relay tomorrow to see if the pump still grounds out with a new relay, I am assuming that it will, but for $12 its worth a shot. If all else fails I guess I can just "hot wire" the pump the way I have seen a lot of these cars.

 

[wordy1]

So, what your saying is, if you jump the "relay" that isnt factory it works and the car runs fine.

When I jump the relay it will not blow the fuse and the pump functions as it should. Which means it should be the relay. However, I have already bought 2 relays and the fuse still pops.

What is puzzling me is when I test the wire from the relay to to the pump, it does not give a ground until I connect the pump. Is this supposed to happen? Meaning does this wire ground to the pumps' ground or is it the pump itself?. If the pump is grounding itself, it should not operate at all correct?

If this is true, it would have to be the relay harness not allowing the relay to function properly and if that doesn't solve the problem, how can I test the relay to see if its any good so I can rule it out and start checking the other suggestions mentioned?

 

[Quick6'n'-K.C.]

After reading your posts, i gather that its a stock relay on the passenger fenderwell and it blows ONLY if the relay is installed.

Well, why is there a fuse inline to the factory relay?

Man its been so long since ive dealt with the factory wiring to the pump,.....

Go to the trunk, find the terminal strip located on the floor on the drivers sideinner wheel well, i believe that has the tan with white stripe wire that is actually the power wire for 12v+ and is in the taillight harness terminal strip hidden in the trunk.


Open the trunk, see if that terminal strip has some busted rivets.

I gather that your feed wire from the relay to the pump might be grounding out since its giving you a ground signal only when the pump is connected.

I am confused right now.

I would hot wire the fuel pump with a external relay, this is what 110% of the community does to supply good voltage to the fuel pump.

Try a quick search on how to hotwire the fuel pump using a separate relay, if you cant find it, i will write it down here how to do it.
Let us know what year your working on
BW

 

[wordy1]

The car is a 1984 Monte Carlo SS with a 1987 GN drivetrain. If I can't get the pump to work reasonably well, I will be hot wiring it as I don't want to deal with buring out a pump. Thanks SO much!

 

[wordy1]

What advantages would there be to run a hot wire set-up?

 

[wordy1]

Should the car run if I remove the relay completely?