funny fuel pressure

[svohoo]

I have a 190 lph fuel pump and a Kirban adjustable regulator. With a modified engine, I have the pressure set at 45 psi (without vacuum). The problem is that, as I pressurize the port on the regulator, the pressure climbs to 49, then drops back to 44. It does the same thing if I try turning up the pressure with the adjusting screw. I just put on a brand new regulator - same thing happens.

[SVOeric]

sounds like you may have a problem similar to what I had.

the pressure would get up to about 40 psi, and then drop off...

The problem I had was the clamp on the rubber hose of the fuel pump (in the tank) had come lose. could also be that the pump just isn't keeping up.. you should be able to adjust the fuel pressure regulator all the way up to 60 psi (not that you should run it there).. if you can't do that... there is something going on with the pump.

What year is your car, there is a ground wire issue with the 84-85 cars with the single pump conversion.

one other thing to check, is your return line.. this should only make the pressure go up if it was blocked.. but you should still check it

[svohoo]

Thanks for responding, Eric.

It's an 86. It looks like I'll have to check out the pump. I could see it not being able to keep up at full power, but at idle?

[svohoo]

I finally had a chance to revisit this issue & check the fuel pump. I made sure the clamps were tight, and it's still doing the same thing. If I apply pressure to the fpr, it goes up to about 50 psi, then drops down to about 45. When it does, the needle is a little bouncy. It settles out when I apply vacuum to it to bring the pressure back down.

[Wolf]

When you installed the pump, did you install a 2nd ground to the frame? The factory ground wire has a resistor in it so it limits the pump's output. Ground the pump to the frame and you'll get the full output.

[svohoo]

I forgot to mention - mine's an 86 & so doesn't have the resistor. Also, it just occured to me that, to the best of my poor memory, I might have been checking it each time with only about 1/8 of a tank of gas. I filled it all the way up this morning & will re-check. I thought of the filter, too, but it's fairly new. When I had the tank down (and I didn't even burn the car/house down!) it looked pretty clean inside.

[fengler]

When you installed the pump, did you install a 2nd ground to the frame? The factory ground wire has a resistor in it so it limits the pump's output. Ground the pump to the frame and you'll get the full output.

im interested in this concept. I have an 84 with dual pumps. So what your saying is that when i start upping the boost, i can just take the resistor out and ground the pump for more output?

[boostedbruiser]

DO a search........... i know i have personally done a write up on this subject concerning my 85 SVO.
Long story short, when you install a new pump(255 HIGH PRESSURE, don't waste your money/time on anything else) run a new ground wire and just don't use the one from the harness. My pump grounds to the chassis near the tank. The power wire is ok, just need a new ground

Also get a fuel filter out of a 90's ford ranger and pull the inline pump out of the car and replace it with the filter.
Don't ask for a PN on the filter i don't know , just go to autozone and ask for a fuel filter off a 93 ford ranger w/ 4.0 V6 in it.

Last thing Search is your friend

[fengler]

dude if you look at the thread starting date I DID IN FACT SEARCH! that is why i posted in this thread