Installed Fuel pump, gauge, AFPR, injectors = no pressure

[HuebyStang94]

Hey all,

I have installed Heads, Intake, Blower, etc. with a new intake fuel pump (walbro 255), injectors (42#), adjustable fuel pressure regulator (used kirban), and a electrical fuel pressure gauge. I have everything back together and when I go to prime the pump/lines I read no fuel pressure.

Now, assuming I installed the gauge right, what could be going on? I have tried priming it 6+ times in a row, but no build up of pressure. I would think this would be plenty to get some pressure back in the lines!! If it does move at all, it moves just a hair.

The pump turns on for a few seconds just fine. The AFPR is used, and I don't know where is was set at. I have turned the adjustment screw left and right some, but nothing still.

I can't turn it completely over yet, I'm just trying to get the fuel all setup. Thanks for any help, tips!!!

 

[Daggar]

Put your stock regulator back in and try it again. IF it still doesn't work, at least you'll have eliminted the AFPR as the culprit. Then you can start looking around and try to eliminate your new fuel guage/sending unit. If you can hear the pump priming but are actually not getting pressure, then you can be reasonably certain that the pump is lealking internally. A direct pressure guage that you can screw onto the fuel line for the purpose of troubleshooting would be a great help!

 

[DMAN302]

Check the schrader valve for pressure..if pump primes and no pressure check the cut off located in the trunk and see if it's been triped...may need to be reset. Also the gauge itself may be bad or installed wrong.

 

[HuebyStang94]

K, thanks for the ideas guys. The schrader valve is gone now - I have my fuel pressure sending unit there now.

I hope it's not an internal leak in the pump, it is brand new! I'll double check all those items. Thanks so far!

Also, how will I know if the cut off located in the trunk has been tripped? I'm guessing it's just an on/off switch...

 

[Daggar]

If the cutoff in the back of the car is tripped then you will not hear the pump prime.

 

[DMAN302]

That's right..my bad.

 

[Saleen0679]

How much did you adjust the regulator? Out of the box my Kirban took quite a few turns before I had enough pressure to start the car. I went back and forth a few times between adjusting the regulator and checking the pressure.

 

[HuebyStang94]

How much did you adjust the regulator? Out of the box my Kirban took quite a few turns before I had enough pressure to start the car. I went back and forth a few times between adjusting the regulator and checking the pressure.

I made a couple of turns each way. I have no idea where it is set now.. and turning which directions increases/decreases pressure... I was just playing with it to see.... maybe that's half my problem!

 

[Saleen0679]

Clockwise should increase pressure.
Reminder: remove vacuum line when adjusting.

 

[HuebyStang94]

Clockwise should increase pressure.
Reminder: remove vacuum line when adjusting.

Thanks for the info... I was adjusting it WITH the vacuum line on. It's getting fuel in the rails, I started to take off my pressure gauge sending unit and gas started to come out. I double checked my connections for the gauge, and them seem fine.

Only conern is maybe it's not getting enough volts??? I just found a wire by the fuse box that had power when the ignition was on... I didn't check how much was going through it.

I'm going to pick up a mechanical fuel pressure gauge tomorrow to mount on the fuel rail right fast.......... thanks for the help.

 

[HuebyStang94]

Well, the mechanical fuel pressure gauge worked fine. I got it set to 40 psi now. As soon as I hook my electric gauge back up .. NOTHING. SO it's a problem with the gauge.

I've tripled check my wiring.. tried a couple different power sources, and grounds. No luck.......

I'm beginning to wonder if I fried the gauge. I originally had it hooked up to the AC-heater blower motor fuse wire that goes through a 30 amp fuse. Could this of been more than 12v and fried my gauge maybe?? I need some ideas on why my gauge isn't working.

 

[Daggar]

You probably managed to hook it up backwards at some point or the sending unit for the guage is bad.

 

[HuebyStang94]

You probably managed to hook it up backwards at some point or the sending unit for the guage is bad.

Well, I honestly do not see how I could get it backwards because everything is pre-wired, and you just plug the one connecter into the gauge, and the other connecter in the sending unit. Then you have your red wire for power, black for ground. (excluding the lighting wires, which work fine)

Maybe it is the sending unit then............

 

[Saleen0679]

I would also suspect the sending unit may be bad. Hooking any precision instrument inline with a motor is never good. The circuit is always going to be exposed to surges, spikes, and noise just from the normal operation of the motor. Harmless for the motor, but not good for instruments.

 

[HuebyStang94]

FYI, i called autometer - this is how you test the sending unit.

There is a grey, black, and violet wire. The black is a common ground. The grey is the power source and should have 5v. The violet sends the PSI reading to the gauge and will vary from 0 to 5v. 1v = 20 psi .....

 

[HuebyStang94]

Okay, I tested the sending unit..... I've never used a multi-meter before and the power suppy was at 6.8 mV with the meter on V-DC, and at .005 v with the meter on A-DC. Can anyone explain further what is what?