Leaking injector or regulator?

jdlatil · 01-10-2003, 12:09 AM

Trying to find out if I possibly have leaking injector or bad fuel regulator? Fuel pressure only hold up for a short time after I shut the motor off, about 3 mintues and it starts to slowly drop down.
Can not find any fuel leaks have been from front to back. Do have strong smell of fuel in garage, but I been told it most likely the braid fuel lines.
Any suggestion on how to check?

cyberstang5.0 · 01-10-2003, 08:07 AM

The fuel pressure is suppose to drop down to zero when you shut the car down. It is just equalizing the pressure within the system. As far as the smell of fuel goes, it might be your exhaust. When my car was running rich, I was able to smell the unbunt gas. I also don't have cats to burn up the extra fuel. Check to see if your running too rich, that might solve your problem...

PKRWUD · 01-10-2003, 08:20 AM

Actually, that's not quite right. The fuel pressure shouldn't drop at all for at least 10 minutes. In fact, it shouldn't have dropped more than 10 psi over night. In order for fuel injection to work, the fuel has to be pressurized, and most people wouldn't understand the idea of waiting a few seconds for the pressure to build up when they start it, so the plan is to keep the lines pressurized all the time. When the pressure starts to drop after only 3 minutes, you do have a problem. It could be either of your suggestions, or the pump itself. For that matter, it could also be a crack in the rubber portion of the pick-up.

If you remove the vacuum line to the regulator, and it has no fuel in it, then the regulator is most likely fine. The method I use for determining if it's the injectors or the pump is a home made tool. I took an old fuel filter, and cut off the inlet and outlet tubes, and inserted an piece of rubber fuel injection hose in between them. To check for where the pressure dropping is coming from, I install this tool inline where the filter normally goes, turn on the pump, and then crimp the rubber with a pair of vise grips, and then turn the key off. If the pressure continues to drop as it did before, that I know there is a leaky injector. If the pressure now remains steady, I know the problem is in the tank.

Good luck!

Take care,
~Chris

01-10-2003, 12:09 AM	#1
jdlatil Registered Member Join Date: Jan 2002 Location: Gulfport MS Posts: 12	Leaking injector or regulator? Trying to find out if I possibly have leaking injector or bad fuel regulator? Fuel pressure only hold up for a short time after I shut the motor off, about 3 mintues and it starts to slowly drop down. Can not find any fuel leaks have been from front to back. Do have strong smell of fuel in garage, but I been told it most likely the braid fuel lines. Any suggestion on how to check? __________________ Jack 91 GT TFS TW heads, Edelbrock RPM, B31 cam, TRS RR, power pipe, Pro M 80, 42#inj, 70 TB, S-Trimed, 255lph FP, Kirby FPR, MSD 6AL BTM, 373 gears, shorty headers, mega bite jr. lower and adjustable uppers,sub frame, no cats, 2 1/2" with Flowmasters, billet Hurst, JMS Chip, Nitto 555r's, Under construction

01-10-2003, 08:20 AM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	Actually, that's not quite right. The fuel pressure shouldn't drop at all for at least 10 minutes. In fact, it shouldn't have dropped more than 10 psi over night. In order for fuel injection to work, the fuel has to be pressurized, and most people wouldn't understand the idea of waiting a few seconds for the pressure to build up when they start it, so the plan is to keep the lines pressurized all the time. When the pressure starts to drop after only 3 minutes, you do have a problem. It could be either of your suggestions, or the pump itself. For that matter, it could also be a crack in the rubber portion of the pick-up. If you remove the vacuum line to the regulator, and it has no fuel in it, then the regulator is most likely fine. The method I use for determining if it's the injectors or the pump is a home made tool. I took an old fuel filter, and cut off the inlet and outlet tubes, and inserted an piece of rubber fuel injection hose in between them. To check for where the pressure dropping is coming from, I install this tool inline where the filter normally goes, turn on the pump, and then crimp the rubber with a pair of vise grips, and then turn the key off. If the pressure continues to drop as it did before, that I know there is a leaky injector. If the pressure now remains steady, I know the problem is in the tank. Good luck! Take care, ~Chris __________________ Webmaster: Rice Haters Club Jim Porter Racing Peckerwoods Pit Stop Support Your Local RED & WHITE!

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01-10-2003, 08:07 AM	#2
cyberstang5.0 347ci of HORSE POWER!!! Join Date: Jul 2001 Location: Houston, TX Posts: 1,416	The fuel pressure is suppose to drop down to zero when you shut the car down. It is just equalizing the pressure within the system. As far as the smell of fuel goes, it might be your exhaust. When my car was running rich, I was able to smell the unbunt gas. I also don't have cats to burn up the extra fuel. Check to see if your running too rich, that might solve your problem...