Fuel Pump Etc.

[stealth1942]

ok, i have the 94 mustang gt 5.0v8, and it started this thing where at random times ti just wont start, it just cranks over and over, and then it will randomly start...so i replaced the distributor cap, checked the spark plugs, cpark plug wires, and replaced the fuel filter...and also, it likes to now randomly stall at any time, like im turning off the ignition,...so is it 110% the fuel pump or is there something else i should check before i spend 200 on a new pump...?

 

[HGFireHazard]

I can't help you too much with your symptoms or diagnostic, but I can tell you that you can get a nice new Walbro fuel pump off ebay for about $100, better to upgrade now if the pump is the problem.

 

[HISSIN50]

When it cranks but wont start, check for spark. Then check for injector pulsing.

To test the FP, simply connect a FP gauge at times when it won't catch. See how pressure is doing. The FP would not be the first thing I'd suspect of being at fault.

You should also pull codes to see if something was stored.

Good luck.

 

['94ChickStang]

It's happened to me twice & both times it was the fuel pump

 

[GreenStangGT]

The fuel pump is a possible culprit, but it could also be your heads, intake manifold, exhaust, and/or rearend gearing. I suggest replacing and upgrading all of them to be sure....

 

[mo_dingo]

An easy way to check the fuel pump is to remove the gas cap, stick a screwdriver in the filler to open the check valve, and put your ear right next to the filler. When someone else turns the key to the acc position, the fuel pump should prime; you should hear a whirring sound.

That doesn't mean it's working 100%, but it does mean that power/ground is getting to the pump and it's less likely to be bad. I have seen them prime but not put enough pressure out before. A pressure gauge on the fuel rails is the only real way to test it.
Scott

 

['94ChickStang]

An easy way to check the fuel pump is to remove the gas cap, stick a screwdriver in the filler to open the check valve, and put your ear right next to the filler. When someone else turns the key to the acc position, the fuel pump should prime; you should hear a whirring sound.

That doesn't mean it's working 100%, but it does mean that power/ground is getting to the pump and it's less likely to be bad. I have seen them prime but not put enough pressure out before. A pressure gauge on the fuel rails is the only real way to test it.
Scott

true, but be careful because one of the two times for me it was still priming even though it wasn't working properly

 

[1TallMF]

A bad fuel pump wouldn't be my first guess, I'd say check for spark first, it could be as simple as a loose connection at the coil or a bad ground somewhere. If there is injector pulsing but no spark, then its likely the coil or TFI module. If there is no injector pulsing, you can almost guarantee its the PIP. And like the others said, check the fuel pressure when this happens.