I am on my last step to starting up the car and I am trying to build fuel pressure on my aftermarket fuel system with FPR. We have everything hooked up and when we turn the car to accessories, the FPR only shows about 10psi. No leaks by the injectors or the hardlines by the firewall.

Any ideas on what to look for/to do to fix this? Trying to get to 43.5psi.

 

when checking, did you jumper the F/P and GND terminals in the diagnostic box? You are using an aftermarket FPR I presume?

 

I did not do the jumped F/P and GND terminals in the diagnostic box. What does this do and is it necessary?

Yes aftermarket FPR, sorry.

 

It energizes the fuel pump relay so that the fuel pump will run continously. It allows you to check for leaks and set fuel pressure. I wouldn't trust a fuel pressure "blip" from the short priming action alone.

I have that exact FPR and I run that exact fuel pressure. Jumper the terminals. Put the key in the ON position, engine off. The fuel pump should be running continuously. First inspect for leaks. Then loosen the lock nut on top of the threaded rod of the FPR. Take a hex key and turn the the threaded rod until the needle is just before the 44psi mark (if you have marks every 2psi). Now disconnect the jumper wire. Fuel pressure may drop quickly. Some aftermarket FPR's seem to hold fuel pressure with the pump off but some don't. I haven't personally had any problems with aftermarket FPR's that don't as long as everything else in the system is ok.

 

edit** arghx has you coverd

 

arghx: First of all thank you for all of your help through my process of trying to get my car running. You've helped out a lot.

So I got home from work and did the GND to F/P jump and turned the car on. Fuel pressure on the FPR shows 10psi. I check for leaks and there was a slight leak on the lines going into the FPR. Tighten them and retry again. No leaks. Start screwing down the screw on top and the highest I can get the fuel pressure is around 30psi. I can keep screwing it down but it just doesn't move from 30psi.



Double checked for leaks, checked for any kinks in my fuel lines, etc and they all looked good and I saw no drips/puddles of fuel.

 

What is your fuel setup again?

 

It's possible you could have the fuel feed/return lines backwards.

Dale

 

Wonder if fuel is getting past the bottom injector o-rings since you mentioned a similar issue in one of your many other threads.

 

The fuel setup was stock rails with 550/1300 and supra pump

I now have KG parts primary and secondary rails with Image Dynamic 725/2000 and the same supra pump.

Dale: Please confirm that my lines are correct. When looking at the hard lines on the firewall, from "left to right" I have VENT which is open to atmosphere, then the RETURN line then the FEED line.

DJ7: What do you mean by wondering if the fuel is getting past the bottom injector O-rings?

Thanks for all the help guys

 

Bump for suggestions

 

Yes, vent, return, feed. Vent has the yellow dot.

 

bad fuel gauge???

 

bad fuel gauge? Or do you mean bad FPR?

 

your lines are correct as you describe them.

while you could check pressure w another gauge, most probable is that there is something wrong w the FPR. it is improbable that a fuel injector could leak down 20 psi of fuel pressure... your engine would be filled w gas. it is improbable your battery would power the fuel pump to 30 but not 50 psi (remember you have had the adjuster turned all the way in which is capable of reading 50+ pounds...

it is possible that there could be a leak from the fuel pump in the tank. it is possible that the pump is defective.... though not probable.

so my vote is FPR or leaky output fitting at the pump in the tank. did you run the pump w your previous motor? did you install it recently?

hc

 

^I agree with Howard. If the output fitting of the pump isn't solid, fuel will be coming out there and back into the tank, dropping the pressure.

Dale

 

All the mods are the same mods on the car since I bought the car from the old motor. The ONLY difference between from when I last shut down to when I'm about to start up the car hopefully soon is the fuel system.

He originally had a 550/1300 injector setup all stock rails with a Supra pump. The car ran and drove fine even with hot start problems. As stated, I've switched the fuel system with aftermarket KG fuel rails and ID 725/2000 injectors.

The FPR at this moment is screwed down all the way and showing only 30psi at most. I can test the battery by having my Dad's truck jumped to my car when I turn it to accessories. Although it's not likely the problem, we can start with eliminating the simple things.

I do not have my fuel pump "re-wired" like I'm seeing a lot of people say to get done so sooner or later I may take a look at that. Dale, I know you started the thread but the link is dead. Do you have another hyperlink for it?

There isn't any damage that I can do by testing for fuel pressure correct? Howard, you mentioned that the engine would be filled with gas?

 

I would check the voltage at the pump, check pump connections as well, it could be the regulator but I rarely see new ones fail rate out of the box. (though it has happened). The secondary rail is not a KG rail just so it's clear, keith's are smaller diameter. I do use keith's primary, though as it is just easier for me time frame wise at times.

~S~

 

Thanks Sean, I will check the voltage and connections.

What should the usual voltage be for the pump?

 

I'd pull the regulator and T in a guage to confirm your low reading.

 

Is it ok to try to just start the car without correct fuel pressure set? Wouldn't be driving, just want to see if it will fire up for the first time and sit idle.

 

You can turn the car ON at 30 psi of fuel pressure but i wouldn't drive it around or rev the car..

I was driving my car around one day and my wide band gauge kept leaning out and my car would buck, i drove it all the way home and when i popped the hood my fuel gauge was reading 32psi...................come to find out i forgot to set the the adjustment screw and forgot to hook up the vacuum line but to make a long story short Yess you can idle your car at 30psi. maybe for some weird reason the FPR will start working properly once the air is out the fuel system.

 

I'm experiencing this problem right now and slowly eliminating things. Let me know if you figure out the cause. Although after reading this thread I think it might be my fuel pump attachment to the hanger.

 

with the fuel pump running (diagnostic connector jumpered) disconnect the FPR vacuum line from its vacuum/pressure source. connect it to some kind of pump or source of pressurized air. Verify that fuel pressure increases as pressurized air is applied. Also try hooking a vacuum pump to the FPR. Verify that fuel pressure decreases as vacuum is applied. These two tests mimic the engine in boost and in vacuum.

If the fuel pressure doesn't respond to vacuum and pressure, you probably have a bad FPR (assuming the gauge is good).

 

Could I have hooked up the vacuum hose going into the FPR to the wrong source? Is the vacuum hose what drives the pressure of the FPR? Wouldn't it just be the fuel lines?

Anyway, I have the FPR vacuum hose hooked up to one of the connectors right before the throttle body on the UIM. Is that alright?

EDIT: Well wish me luck, I'm going to attempt to start the car... I'm recording it just in case it blows up.