Ok I am stumped. I am losing prime after sitting for 5 minutes. I have replaced the pump, fuel pressure regulator and removed and tested injectors. Still losing prime. There are no visible fuel leaks anywhere.

 

Do you mean you need a few extra cranks to start after sitting for 5 minutes? When you replaced the pump, did you replace the whole pump assembly or just the pump module? If you're certain there are no other leaks, it's likely a bad check valve

The check valve is built into the pump assembly to preserve fuel pressure. You can test it by using a fuel pressure tester on the test port. Turn the key on, you can start it if you want, and observe the fuel pressure. You should see 49psi (+/- 2psi). Then shut it down, key off. Then watch the fuel pressure. If it bleeds off quickly, the check valve is bad. You can get an inline one and install somewhere in the fuel line.

 

I replaced just the pump and fuel pressure regulator above the the pump. Replaced all the rubber fuel lines and pulled injectors and tested. Replaced fuel filter. If you cycle key 3 or 5 times it starts up fine. I have closed fuel line off at tank after priming and the problem seems to be in the tank.

 

It may be you have a build up of scum in the tank

I though the check valve is incorporated in the pump body, as I see no other parts in the '96 assembly, except the regulator

It is possible your new pumps check valve is faulty

Check the entire fuel line for any leak at all, I have had this twice!

If an inline check valve works, you may have to be satisfied with that

I have twice replaced '96 fuel pumps, and the pump body is a '95 and earlier, not the post '97 item

 

The tank is clean. I have put two pumps in so far and same problem. Thinking it’s time to just replace the whole unit and see what I get. Thanks for the input. Also note the check valve is located within the pump. I read another post stating that if wrong pressure regulator is installed or just bad it will do what mine is doing.

 

I had the idea to install an external pressure regulator to do away with the hard to obtain Crown unit, and lo & behold, I am reading Go Jeeps web page, and he has done it

You can buy adjustable external regulators for the same as the internal unit.

I see no reason why it would not work, does require some re plumbing

will see if i can find the link and edit it in

Adjustable Fuel Regulator (willyshotrod.com)

 

So update to this headache. I bought a brand new fuel pump assembly and installed today. Primed the jeep and it is still losing pressure when I key off after 5 minutes. I pulled the injectors again and connected fuel line and primed to make sure no leakage from them. I am replacing the seals once more and wondering what the heck is going on

 

I believe I have read where others have resorted to installing an external check valve, presumably in the rubber lines down near the fuel filter

That would be upcoming for me if nothing else works, as it should not only cure the symptoms, but also give strong clues on the nature of the problem

You would have little to lose, a few $ for a check valve and fuel lines, easily reverted to original

 

yes I have read that also but I feel like that would create an air pocket if the system is indeed bleeding out. I have also read that just because the pump is coming on doesn’t mean it is pumping. I will be replacing the fuel pump relay and all fuses associated with pump. I will update after doing all of that.

 

ok so update again. I have just discovered that fuel is not my issue here. When I turn key the on position my gen light and check engine light do not come on. If I pull the fuse to ECM and put back in it the lights come on and everything works like it should. Fuel pump primes and jeep starts right up. Any ideas would be helpful