Fuel Pressure Drop After shut off!

[DSM_ThuNDeR]

My car has had this issue for about a month for now.
-Takes 5-10 seconds to start (cold or warm)
-When it starts, it struggles really bad to stay alive
-Car struggles under boost.

Replaced:
-Fuel pump (Jay Racing)
-Fuel filter

I ruled out:
-kinked lines
-possible bad injectors(known good stock ones are on right now)
-leaks

I am running a Aeromotive AFPR. After I shut the car off, within 5 secs or less, the needle on my liquid filled gauge drops down to zero. I talked to a couple of local DSM'ers here, and they say it takes more than 20 mins to relieve all the fuel pressure in the system in their cars.

Im thinking my AFPR might be faulty but there is no fuel leak at the pressure source nipple.... Im wondering if anyone has come accross to this situation and if you guys found or read about a fix?

Any input will be greatly appreciated.

 

[hubz91talontsi]

How's the o-rings on the injectors?

 

[jpmxrider489]

Do you have the stock solinoid hooked up?

 

[9!'clipseDOHC]

I am running a Aeromotive AFPR. After I shut the car off, within 5 secs or less, the needle on my liquid filled gauge drops down to zero. I talked to a couple of local DSM'ers here, and they say it takes more than 20 mins to relieve all the fuel pressure in the system in their cars.

Im thinking my AFPR might be faulty but there is no fuel leak at the pressure source nipple.... Im wondering if anyone has come accross to this situation and if you guys found or read about a fix?

Any input will be greatly appreciated.

I have the same issue with losing pressure immediately after shutting off the engine. Mine takes about 10 seconds to start when cold, but fires up instantly when warm and runs great all the time (once it is stated).

It is possible that the AFPR diaphragm is damaged. You can buy rebuild kits for Aeromotive AFPR's, Aeromotive Fuel Pressure Regulator Rebuild Kits - SummitRacing.com. It might be something to consider. It wasn't the issue on mine though, my issue has yet to be resolved. I did write a tech article on changing the AFPR if you are interested: http://www.dsmtuners.com/forums/articles-engine-fuel/399037-replacing-diaphragm-your-afpr.html

 

[jpmxrider489]

I have heard if you don't have the solinoid hooked up, it could cause issues.

 

[turboglenn]

I've noticed on many cars and heard from others that the aeromotive AFPR won't hold pressure for crap anyway when the pumps aren't running as it isn'tmeant to.. mine may hold 10-20psi for a short bit but that's all, then it's gone, even after the pump prime.. but upon inspection the thing is in perfect shape (done this from day one)

And when it's running FP is perfect every time so i don't worry, a few more revolutions to get it started is no big deal tome i guess buti wouldn't worry either way

 

[9!'clipseDOHC]

I have heard if you don't have the solinoid hooked up, it could cause issues.

All the fuel pressure solenoid does is increase the fuel pressure on hot starts. That is it.

 

[DSM_ThuNDeR]

How's the o-rings on the injectors?

Top and bottom injector seals are in good condition. No leaks there.

 

[bryzenga]

My Aero does it too. Just takes a couple more cranks to get her running.

 

[RBehne2]

This has been a common problem. It's the seat the ball sits on inside the regulator. Take it apart, look inside, see if the seating surface is not completely round. That most likely is the issue.

 

[dalesocks]

Is the fuel pump priming the system prior to cranking?

 

[TSITurbo95]

Double check the o rings on the fuel pump? My car will not drop pressure to about 20psi, but within 10 seconds, its down to 0. It is normal for it to happen, as everything is in excellent condition in my car, as well as all my other dsm brotherins, and theirs do the same thing. I used to have your issue though, found out it was the hat looking thing that goes on the fuel pump before the o ring, and it caused the o ring to not seat properly.

 

[9!'clipseDOHC]

Is the fuel pump priming the system prior to cranking?

Its a DSM; the fuel pump doesn't get power until the engine is cranking.

 

[dalesocks]

Its a DSM; the fuel pump doesn't get power until the engine is cranking.

haha no comment!

 

[9!'clipseDOHC]

haha no comment!

please comment.

http://www.dsmtuners.com/forums/bolt-tech/330793-fuel-pump-prime.html
http://www.dsmtuners.com/forums/bolt-tech/377041-how-prime-fuel-pump-2g.html

The fuel pump doesn't prime until you start cranking the starter. It's not intended to do it when you turn the key on.

That's completely normal on a 2G. It won't run the pump intil you're cranking the engine. Don't ask me why they did it this way though.

 

[954g63gst]

Is the fuel pump priming the system prior to cranking?

No our cars crank first then spark then the ecu will kick the pump on That’s why everyone with aeromotive afpr take an extra turn or two cause they return the fuel if pumps not on so it takes a moment for the electrical to get the pump pumping