bwolfZ28

iTrader: (40)

hey guys im in the process in starting up my turbo 408 and im having some issues with my fuel pressure. I want to get this handled so I can break in the motor. its idled for a few minutes total but im puzzled on what is up with the fuel pressure.

My setup is a -8 feed, -6 return, aeromotive boost referenced regulator. Dual walbro 255 pumps; 1 pump is on the stock harness and the 2nd is wired on a hobbs switch.

My regulator is setup after the rails so that all injectors have the same pressure. On prime it will spike to about 35 psi and then drop almost instantly. when I started the car it will go to about 35 psi and no matter how much you crank up the regulator it will not go past 35-38psi. I can lower the pressure a little bit but it cannot go up. I have tried a brand new fuel pressure gauge as well.

Any input would be greatly appreciated as since I want to be able to break in my new motor and not have to deal with these issues.

ss performance

iTrader: (17)

If you turn on the second pump do you see any change?

Can you swap which pump is on the hobs switch? if you do is there any change?

Sounds like your pump isn't putting out enough pressure.

Check the voltage at the pump. If voltage is low the pump won't work properly.

Good luck.

bwolfZ28

iTrader: (40)

I was having some issues with my ground in the back of the car. My batter is in the rear and I'm trying to find the best spot to ground it out. My second pump is not fully wired in yet since I'm just getting it all together so I cant turn that one on as of now. I will check the voltage at the pump and see where it is at.

ss performance

iTrader: (17)

A good ground is critical to the proper functioning of your fuel pumps. A bad ground would have the same effect as low voltage to the pump. Try and take your voltage reading across the ground & 12v supply, then from the 12v supply to the battery negative terminal this will give you an idea if you ground is any good. Remember that even though a continuity test might so a ground as good it might not be able to take the load.

Good luck

S10xGN

iTrader: (11)

I'd be looking at the regulator, it's either plumbed wrong or the diaphragm is holed. Even with low volts and/or crappy ground, you should be able to achieve close to max deadhead pressure at idle when > 95% of the fuel is being returned...

ss performance

iTrader: (17)

If the diaphragm had a hole in it I would think you would have fuel coming out thru the adjustment screw or some where else. Since the OP didn't mention this I suggested he investigate the fuel pumps. But I could be wrong.

jrpimp00

iTrader: (17)

What's the part number on the regulator? IS it new?

bwolfZ28

iTrader: (40)

It's 13101 and it was used and I got it from a friend. I put a brand new diaphragm in it yesterday and saw no change. The regulator is plumbed after the rails and mounted on the strut tower. My return comes out of the bottom of the regulator and goes back to the tank.

Old Geezer

iTrader: (3)

Connection is leaking in the tank....

bwolfZ28

iTrader: (40)

Thanks guys! I'll check the voltage and the in tank connection to make sure everything is tight.

bwolfZ28

iTrader: (40)

So I checked everything and solved the issue. My secondary pump didn't have a bleed off valve in it and when the main pump would turn on it would push and most of the pressure would go through the secondary pump and back into the tank. I would switch the in tank connection to the secondary and check key on pressure and I would get full pressure. After thinking about everything and double checking all the in tank connections the valve was the problem. So now all is well and were ready to go. Thanks for all the help guys.

forcd ind

iTrader: (7)

curious what pressure you saw out of the A1000-i never ck'ed full pressure on mine