AEM Fuel rail/ Aeromotive FPR install, Now car is hard to start// HELP

[gsxboost20g]

I just installed a new AEM fuel rail and an Aeromotive Fuel Fuel Pressure Regulator on my 98 GSX. I also just rewired my fuel pump with a relay and larger wiring. My car runs just fine. But if I try to start it after the car has been sitting for a while; even like 30mins, it has to crank over a couple of times before it fires.
Before these recent mods, the car would start on like the first or second crank. I would greatly appreciate any true insite on the possible correction of this issue.

 

[awdtalontsi1992]

Doesn't really sound like that much of an issue. You might be chasing ghosts. My only exsplination would be to check what the base pressure of your fpr is set at. Maybe it is not correct and could be causing an "issue".

 

[gsxboost20g]

Yo, thanks for the response. I did refer to the OEM shop manual, and it says something about the fuel pressure dropping right after the car is shut off is an issue and offers some troubleshooting recommendations. Like checking injectors, and a fuel pump check valve. My issue is; this started after installing the fuel rail and the FPR, and the fuel pump re wire.
Has any one else had this issue, or experienced this? thanks

 

[dsmpokolm]

The same thing happened to my car and it ended up being a little fuel leak.

 

[playitlouddsm]

FPR are known for loseing pressure after sitting for a while, my car does the exact same thing. What you could do is hook an inline power switch to the fuel pump to prime it before start up. The reason it takes a few cranks is the fuel system needs to pressurise up again after its been sitting, due to the fpr. Not a big deal, just annoying to some people.

 

[CarBizIndio]

prime the pump a few times before you start it and see if that helps, check for fuel pressure and leaks, use some Teflon tape on the fuel line fitings to keep them sealed better if you need to.

 

[oldman]

The only time an AFPR loses pressure immediately is fuel leaks at the front (pump or-ring) or rear (defective AFPR) of the fuel system. A properly setup fuel system (pump to AFPR) with the Aremotive unit should bleed off slowly in matter of hours, not immediately.

 

[FORMONTOYA]

The only time an AFPR loses pressure immediately is fuel leaks at the front (pump or-ring) or rear (defective AFPR) of the fuel system. A properly setup fuel system (pump to AFPR) with the Aremotive unit should bleed off slowly in matter of hours, not immediately.

+100%

I can attest to the fact that it's a lot easier to twist the o-ring in the fuel pump "hat" than most people think (even if oiled/greased), and that would be the first place I would look at with this particular issue.

 

[just2asian]

my buddies 1g had that same issue when we did the 190 fuel pump install. it ended up being that his fuel pump didn't seat right and it was slightly tilted at a angle when we dropped it back into the tank, so therefore it had a slight gap between the line and the pump. I'd check the fuel pump and make sure it's sitting straight up.

 

[MILITISINVICTUS]

In the meantime, he has a free pre-start oiling of the engine.. a bonus??

 

[oldman]

In the meantime, he has a free pre-start oiling of the engine.. a bonus??

Not needed at unless it's a first startup on new engine or head/turbo install. What he really need to worry about, If in fact it's pump o-ring, pump spacer or defective AFPR, is maintaining 1:1 rise rate especially at higher boost and RPM levels.

 

[playitlouddsm]

I run the aeromotive unit and it will hold pressure for about 3 hours. If the car sits longer then that i have to prime the system again.

 

[oldman]

I run the aeromotive unit and it will hold pressure for about 3 hours. If the car sits longer then that i have to prime the system again.

3-6 cranks instead of 2 when stock isn't exactly priming the sytem

 

[MILITISINVICTUS]

Not needed at unless it's a first startup on new engine or head/turbo install. What he really need to worry about, If in fact it's pump o-ring, pump spacer or defective AFPR, is maintaining 1:1 rise rate especially at higher boost and RPM levels.

I hear you. Coming from the perspective of having a dsm that's deadlined for long periods of time, spreading a bit of oil before firing up sounds like a good idea. But that's just my garage.

 

[MILITISINVICTUS]

Not needed at unless it's a first startup on new engine or head/turbo install. What he really need to worry about, If in fact it's pump o-ring, pump spacer or defective AFPR, is maintaining 1:1 rise rate especially at higher boost and RPM levels.

Oldman, can you go into the o-ring/pump spacer check/fix in a little detail? My car already had the 255 installed, so I'm not hands-on aware of the assembly characteristics. My AFPR gauge shows a quickly declining pressure, and I believe the issue predates the AFPR installation.

 

[FORMONTOYA]

If it was there before you installed the AFPR, then the issue more than likely has to be at the fuel pump end (o-ring).

When you remove the fuel pump assembly, you'll see a screw that holds the FP bracket on to the "cage". Once removed the FP "stem" will come out of the "cage hat" with an o-ring as the sealing mechanism. Under the o-ring (on the stem) will be a spacer to help hold the o-ring in place. If you find an o-ring that is fairly snug on the fuel pump stem (but not too tight), and fairly snug in the "cage hat" it will seal properly and not leak down as fast, thus improving the starting characteristics (also assures that you have the correct 1:1 rise). Using di-electric silicone grease helps a lot in replacing the fuel pump back into the "cage".

Sorry I couldn't scrounge up some picture, but that should give you an idea.

 

[oldman]

Oldman, can you go into the o-ring/pump spacer check/fix in a little detail?

Here you go.

When you remove the fuel pump assembly, you'll see a screw that holds the FP bracket on to the "cage". Once removed the FP "stem" will come out of the "cage hat" with an o-ring as the sealing mechanism. Under the o-ring (on the stem) will be a spacer to help hold the o-ring in place. If you find an o-ring that is fairly snug on the fuel pump stem (but not too tight), and fairly snug in the "cage hat" it will seal properly and not leak down as fast, thus improving the starting characteristics (also assures that you have the correct 1:1 rise). Using di-electric silicone grease helps a lot in replacing the fuel pump back into the "cage".

There are also pictures in this article.