96 4.0 cranks but wont start

[scott25a]

if i am correct the fuel pump should come on for 2 or 3 seconds when turning the key. I hear pump come on but it does not turn off. I replaced the fuel pump relay and get the same result. I've had the same problem in the past a few times but just let the truck sit for a few and it would start up. It's been fine for the past few months and now it's doing it again. I'd be greatful for any input to help fix.

 

[BlackBII]

Question.

Are you not getting spark? Or, are you not getting fuel?

If you don't know, then spray some starting fluid in the intake, and then try to start it. IF it starts, even for a second, then we know that you are not getting fuel. IF it does NOT start with starting fluid, then we know its not getting spark, and we'll go from there.

Let us know.

 

[scott25a]

it's not getting fuel. A friend said something about not having pressure. I'm guessing that is what is making the pump run instead of shutting down after 2 or 3 seconds when turning the key. I checked to see if inertia switch was popped and it was not.

 

[BlackBII]

Ok, if the pump is running when you turn the key, it's probably fine.

I would find the schrader valve on the fuel rail and see if fuel sprays out. It not, remove the fuel filter and see if you have fuel there. If there is fuel at the filter, but not at the fuel rail, I bet your fuel filter is clogged. If you remove the fuel filter and no fuel comes out of the pump side, your pump probably isnt pushing the fuel out of the tank

 

[feellnfroggy]

When you turn the key do you get all dashes across the odometer? When you have an issue with your pats system, it will allow everything to work, and the car/truck will turn over, but won't get fire. Just something to look at.

 

[scott25a]

We checked at schader valve and fuel came out. Do not know what the pressure was thou. Had the fuel filter replaced less than 1,000 miles ago. I don't think thats the problem. I have a manual odometer so nothing shows on dash.

 

[turboranger2.3]

the ECM is giant grouding box.

ECM ground the relay to complete the circuit to ground. follow

If the relay stays on. ___________ wire is grounded
ECM driver(tranister) is permantly closed.(broken)

My truck is like that(pump stays on. ) been like that for years.IT runs
HOW DO YOU KNOW, IT, NOT GETTING FUEL.
IS THERE SPARK ?

 

[TheTopher]

When you turn the key do you get all dashes across the odometer? When you have an issue with your pats system, it will allow everything to work, and the car/truck will turn over, but won't get fire. Just something to look at.

I don't think they started adding pats 'til 98



This is pretty simple, you're getting crank and you're getting fuel. Let the fuel that came out of the shrader valve evaporate and check for spark...several ways to do this. The easiest way is to just pull the wire boot off the ignition module and hold it a half inch away from where it's supposed to go and have someone try to start the car (Keep your fingers out of the way). The electricity SHOULD start visibly arcing and you'll hear an audible "clicking" as it does.

Check it on a few just to be sure.


If you're getting spark then I'd go rent a fuel pressure gauge from autozone and go from there.


If you aren't getting spark, then you have an ignition problem to diagnose.

 

[scott25a]

went out this morning and truck started up fine. could it be ecm?