I performed a 255lph fuel pump transplant on my 1990 GT. I have done this operation once before on this same car (with a stock replacement pump) as well as once on my old Aerostar with good results. However this time I have a problem I am hoping someone with be able to help me with. After replacing the pump, my fuel pressure gauge showed slightly more fuel pressure (from 40 to 43 psi), so I adjusted the Kirban regulator. At first the fuel pressure dropped as expected, then the gauge needle jumped and began fluctuating between 44 and 50 psi with no adjustability. This condition caused a high idle (1000 vs 750 rpm). I checked the fuel return line for kinks and found none. The next day, the regulator worked perfectly and I was able to set the fuel pressure. I took my car out for a spin and when I returned, the fuel pressure again was erratic and the idle higher than normal. That is my problem. I hope someone can throw me a bone. Thanks in advance.

 

vac line to regulator is junk?

 

with the kirban you can just run it static. plug the regulator line if you still have it.

 

Thank you for your answers. The vacuum line is good. I think I'll pop the stock regulator back on and see what it does.

 

I think what he is saying is, leave the vacum line off and see how it reacts

 

Yea i would try that sounds like the regulator didn't like the new pump for some reason.

 

Does you have a manual f/p gauge on it? If so is it holding pressure on the rail after you shut the car of or does it drop f/p rapidly?

 

Thanks for your answer. I do have a gauge and the fuel line keeps pressure. My car runs well but a little rich running the Kirban statically (without vacuum). I performed a vacuum check on the regulator today and it bleeds down completely in about 1 to 1-1/2 minutes, so I am assuming the diaphram is gone.

 

Might not be regulator, hows the o-ring where it attaches to the rail?
Have you put a noid light on iinjectors to see if you have on that might
be outta whack?
I chased this problem on my GN ended up sending injectors out to be cleaned and flowed. This was after 2 new fuel pumps, had a newer Kirban but car sat so I bought new Accufab reg.
Had trash in a couple of them, wasnt letting them seat internally.

 

Fuel injection FTL