Really need some fuel pump help. I can't take this anymore!!!!!

[DeanS]

Please someone help!!!
94 mustang gt 5.0. I have replaced the fuel pump in the tank now five times. Everytime the pump works and the car will run. No driving, just in garage and yard. Starts a couple times ok. Let it sit overnight or couple days and try again and pump will not run. Remove pump and hook up 12 volts and nothing. Got tired of replacing the in tank pump so ordered an external pump and remounted everything yesterday. Hooked up 12 V and pump ran and primed. Connected veh wiring and pump runs for the few seconds it should when key on and then car starts. Let it run to warm up a few times. Today went out and pump will not run. Hooked up direct 12V and nothing. Put a scope on the wires and get 12v for seconds when key on and then shuts off and 12V when cranking. With key off 0V.
This makes a total of five pumps that only last a day and will not run the next day.
Someone please tell me what can be going on. Its not like I new to this, I was a ASE mechanic when it was called NIASE.
Nothing else burns out in car except fuel pump.

 

[Noobz347]

Where do these pumps come from?

Do you recall the brand names?

 

[Bullitt347]

What would burn out a pump, any pump?
Resistance, high resistance.
Question is, why is the pump burning out but not the wiring, relay or fuse?
There is more going on here than what is posted.

 

[DeanS]

Where do these pumps come from?

Do you recall the brand names?

Four were from Oreilles Auto and external was from amazon

 

[DeanS]

What would burn out a pump, any pump?
Resistance, high resistance.
Question is, why is the pump burning out but not the wiring, relay or fuse?
There is more going on here than what is posted.

Yes agreed but nothing makes sense. Scope shows 12V when relay comes on and 0V when off. Got another pump coming today and gonna run it off external 12V and start car and look at the voltage on the line that feeds the pump. It feeds off the CCRM but thats just a relay controlled from the computer. If there was something wrong with it there would not be 12V at the pump. And it works fine the first day until it is shut off and then the next day its bad.
The pumps are brushless motors so something must be damaging the circuitry in the pump somehow.

 

[Noobz347]

Scope shows 12V

What "scope"? Do you mean multi-meter?

Brushless motors? I don't think so. They are 12V brushed motors with just two wires (one if you don't count chassis ground):

 

[DeanS]

Well I don't think anyone would sink a brushed motor that sparks on the rotor in a tank of gasoline. A motor can be brushless and two wire if the control is in the motor. And that is what I suspect is burning out in these. Just don't know how or why. If I go in the output tube of the in tank pump I can turn the impellor a little with tweesers and when I put 12V on it it will turn just a little like it burnt out one of the pole driver. I will cut the last one open and make sure.

 

[Bullitt347]

China
Made in China.

 

[Noobz347]

Looking forward to images of your brushless in-tank pump complete with ESC and heat sink.

This one, for example, runs for about $1700 online:

This one has an external controller for a retrofit (like on our cars if we decided to add one).

 

[DeanS]

I just cut it open and will admitit is brushed but that makes this so much worse. There is almost nothing that can damage a brush motor so This is very puzzling now. I'm gonna clean the armature and see if I can get this one to work. The only thing I can think of now is there is sonething in the gas that is screwing with the brushes and insulating the armature. That night be why it works for the first day and not after it sits for a while. Hummm. Should have cuy it open before.
When I put a meter on the bad motors there is no resistance on wires (open).

 

[Noobz347]

Yeah, see @Bullitt347 's post about El-Cheapo Chinese rebuilds and knock-offs.


At this point, if it were me, I would go onto a reputable site and order a Walbro 190L in-tank pump.

Try:

CJ Pony Parts
Late Model Restoration

 

[Noobz347]

If you have power adder mods in your future, go BIGGER (255L High Pressure for boost)...

 

[Noobz347]

A couple of things to keep in mind when trying to determine the type of pump motor:


We have a return style fuel system. Yeah, you can do a brushless setup but that's kind of redundant.

Age of the car: An ESC and heatsink for a brushless motor that would have been created in 1979 would be roughly the size of a small toaster or riding mower battery.

 

[DeanS]

The motor was gumed up on the comutator so the brushes did not make contact. The only thing that could do that is there is something in the gas doing it.
I'm going to flush the whole system next. It might explain the hard starting problem also.

 

[Noobz347]

The motor was gumed up on the comutator so the brushes did not make contact. The only thing that could do that is there is something in the gas doing it.
I'm going to flush the whole system next. It might explain the hard starting problem also.

That's a good idea. I'm now curious as to how old this gas might be?

 

[Noobz347]

--And--

This might be a [great time] to clean and rebuild the injectors if the gas was bad.

I cannot beat the podium hard or loud enough about this part.

 

[Mcmahst]

Yea, I agree with the two old guys posts. I would do an end to end cleaning before I send another pump to its death. For me, I’ve had good results with Spectra pumps.

 

[weendoggy]

As much time as you've spent replacing pumps, you could've spent time doing a "test by-pass" of the system and test it. No need for the ECU to run the pump because you'd be doing that. Also agree on cleaning the fuel system if it's a mess.