I have an '87 Comanche with the 4.0L, well it's a renix electrical, 2000 intake, 96 block and head and new 24lb/hr injectors. Every time I prime the fuel system with the key it promptly goes right to zero. It doesn't even get to 40psi, it gets to around 20 and stops.

I have a Hesco adjustable fuel pressure regulator and a return system via the renix. Should I replace the fuel pump? Is the check valve in the pump for sure? I thought it was my old Ford injectors so I bought some 4 hole re manufactured ones on the bay that were flow tested etc.

Please give me some advice and a part number for the pump would be fantastic!!! I have heard horror stories about how hard it is to find a pump.

 

Are you talking about the oil pressure gauge? That's the one that moves when you accelerate.

 

No, fuel pressure. I have a gauge connected to the schrader valve on the rail.

 

Ooohh my bad. Can't help you there

 

So an update, installed a Carter replacement pump to the Bosch and now I get zero pressure period. The needle doesn't move at all! The one the parts store ordered was wrong when I compared my pump to theirs. They had the cross in stock, but I installed it and it makes noise but no pressure. Awesome worse than when I started...

 

Back up again, Replaced Carter pump with a Bosch from Amazon. I can prime the system with the key probably 4 times before I get 20psi on the fuel rail. It takes probably 6 seconds of cranking to start. I can hear the pressure bleeding off through the return at the Hesco adjustable fuel pressure regulator. This leads me to believe the fuel is just getting by the regulator back to the return instead of draining back through the pump.


So I have changed the o-rings on the regulator, replaced the fuel pump twice. I can't use a stock fuel pressure regulator, but I have one from a '95 I could try to see if the fuel rail holds pressure. I really don't like the chance that the new Bosch pump is bad out of the box.


Thoughts? The one thing I haven't done is pinch the lines to see which way the fuel is leaking back.

 

Update way to late...


It was indeed the Hesco adjustable fuel pressure regulator. The check valve failed in it so I bought 21lb/hr injectors and used a '95 stock regulator. Problem fixed.

 

Thanks for posting back.

I'm leary of any fuel pump other than Bosch.