Fuel Pressure Gremlins..low....really low FP

[Toby_Goodmk]

I installed a transducer onto my rail and am able to see now why I have a stumble in acceleration. I get 20 psi in the throttle.....so....back to the shop....at idle now I have 10 psi, where as last week had good 43psi numbers....so IDK....

In my diagnosis I have performed the following:

1. Make sure the transducer is the same as a mechanical...which it is.
2. Changed out to a plain jane bosch regulator
3. However I need to change the fuel filter first and see if the regulator will see better pressure
4. Vacuum at the regulator seems ok, no vacuum leaks apparent
5. Do not notice any fuel leaks at any lines, anywhere
6. Put my finger over the fuel feed line (pre filer) to see if pressure felt good at pump prime...it was quite difficult to hold back the raw fuel pump pressure

further ideas welcomed!!

 

[achalmersman]

You pulled the line off pre filter but didn't change the filter? You dead headed the pump and stopped flow with your finger? I've never tried that but I wouldn't think you could stop flow with your finger pre filter. Hopefully someone else will come in on that. Replace filter, test pressure. If no change I would look for a voltage drop, internal leak at the sending unit, or bad pump.

 

[bison]

Check the connections in the tank.


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[Toby_Goodmk]

yes, you can stop fuel pressure at the frame connection before flex hose. Pump puts out about 25psi or so I beleive...but dont quote.

I ended up changing the fuel filter to see the regular old bosch regulator and the new filter allow 38 psi of fuel pressure so it pays to check simplest things first. Ended up changing out the O rings to some fresh vinton style. Definitely keeping the fuel pressure readings into the PL helped see first off where the problem lies.

 

[TurboTnZ06]

Check the connections in the tank.

That is right, someone probably put a non-fuel safe hose on the fuel pump, broke, and is spraying fuel back into the tank.

 

[Toby_Goodmk]

THose are fine I changed them to originals that I had as well as using the supplied fuel hose with the new pump. The issue was with the fuel filter.