interesting observation: I got an actually fuel pressure gauge. Hooked it up to the port and did some testing. Here is what i did.

1. Plugged the gauge and, cranked the car. Started like normal even idled for a little bit and then just died. I was even convinced for a few seconds its all fixed itself. Go look at the fuel pressure gauge, it says zero. But i noticed some fuel leaking from it. So there was gas in the rail obviously.

2. Did the same thing but watched the gauge while cranking. Was stunned when i saw a soling 30+ psi when it was cranking, but then it just dropped to zero in no time and the car died again.

3. pulled the relay for the pump and cranked the car. It did not start at all but the pressure on the gauge went up to 30psi and i cranked for a while and it went up to like 35psi when i stopped cranking the pressure went down slowly.

So what the hell is going on?

 

Check voltage while cranking till it dies? Have you checked all your wiring, grounds? Get a wiring schematic, follow all your pump wiring, and all the wiring to and from the pump relays! I did read that in any vehicle, if the circuit for the fuel pump gets overloaded ( in the ecm ) it will shut it down, ecm could be taking a dump as the worst case scenario, try swapping it out with a junk yard ecm, if it still happens, then its wiring/component.

 

Kind of veering off the path you guys are on, but how is the condition of your battery?

 

When cranking i see 5v to the pump. There is not a single wire that havent been checked in this pos. I had terrible ignition issues that made me replace every single ground and make sure they are in top shape. battery is in a great shape.

I just dont understand why there is no pressure in the line as soon as it fires up. If it was an electrical issue and the pump did run for even a short time that it does to make the jeep start and idle for a few seconds that i does, there should be quite a bit of pressure left in the rail, but there is non. I tried pinching the line while the jeep is running for a few seconds that it does but the pressure still drops to zero in no time.

 

1. Where is the fuel leaking from? You must fix that ASAP. It could be the source of fuel pressure drop, along with it being a significant source for an engine fire. Tolerate no fuel leaks.

2. Then do some pressure testing again. This still sounds like a fuel pump to me. It is NOT unusual to see premature fail of fuel pumps. In fact, the fuel pump is one of the components that is most prone to this, especially like a lower price point mfg. like Airtex.

 

Good Morning,

This might not be any help, but, i was following your post, and well, maybe the fuel pump is wired backwards?
(yeah, it probably has modular connector which can't be wired bakwards)

but wanted to throw it out there.....

i do know also that even though you might have new fuel pump, they do fail even new.

I know this from my BMW fuel failure. Brand new fuel pump and it still didnt work, got another new one and it fired right up.
it happens sometimes.

good luck sir!

cpnwrench

 

The leak is from the pressure gauge, where the hose connects to the gauge itself, it's a cheap gauge, they always leak a little bit. That is for sure the least of my problems.
Pump is wired correctly there is absolutely no other way it can be wired it's a one way connector and how the hell would it just wire itself when I did not touch anything.

Can somebody tell me what power should the pump be getting at the harness? Is it 5v or that's too low?

 

bump

 

FIXED IT! Well, i'll be damned! It was a freaking fuel pump blast. how something stupid like that even breaks?