How do you check for fuel system leaks?

01-04-2001, 11:53 AM

I have a serious leak in my fuel system somewhere. I cannot see gas physically leaking and it does not have gas in the oil. I am pretty sure the fpr is bad, but how do you check for leaking injectors? Why do they leak, extra o-ring not letting the injector seat in the fuel rail, bad o-ring? Any help is appreciated.

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88GT stock shortblock, ported GT-40 iron heads, ported Edlebrock Performer intake, 24# inj, Pro-M 75mm Bullet MAM, 3.73, hurst short throw, F-303, electric fan, alum rad, FMS HD clutch, R134a ac conversion, 70mm TB , and some other stuff I probably forgot, best run so far on ET streets is 13.02@106 with a 1.87 60ft (Full body weight GT, full tank of gas, and sway bars connected, gonna disconnect sway bars and dip into the twelves).

JamGtStang · 01-04-2001, 02:58 PM

light a match

JamGtStang · 01-04-2001, 03:09 PM

j/k i think smell is the key to succes

LX XLR8R · 01-05-2001, 03:00 PM

well put a FP gauge on the rail and see what happens..if you see no diffrence(or decrese) in FP at idle and WOT then the regulator is bad and it is going right back to the tank..if when you turn the car off and the FP drops real low real fast then you got a leak somewhere..i guess just prime it and look and smell for leaks

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1987 black notch(ex 4 banger)
DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

fixer · 01-06-2001, 03:05 PM

if the evap canister is saturated it will smell. this condition can be caused by a canister purge solenoid not working; this allows vapor pressure and even(in serious cases)liquid gas to be forced into the canister.

is there a smell or a pressure drop?

Darkside · 01-07-2001, 11:07 AM

To check your fuel systems for leaks is fairly simple.

1 Get fuel pressure guage connect to fuel rail fitting. Prime system by turning ingnition on. Should be a 3 sec. prime. Pressure should hold.
2 If not plug return line to tank easiest place is a regulator connection if it holds regulator is notleaking to tank. If it drops disconnect vacumn hose to see if fuel is leaking through it to intake, if not the leak is not at the regulator. To further check regulator operation start engine observe pressure should 39 to 45 with engine running disconnect vacumn hose presure should increase 6 to 8 ILBs with factory regulator.
Injectors can leak into port due to binding pintle in injector due to wear or carbon deposits, some cleaners will work on the carbonized injectors but won't fix worn out injectors.
I have also found that Ford injectors orginal and FMS replacement in jectors do not like excessive pressures, and will heat up causing them to cause engine miss at times. Ford injectors have pintle design and are prone to this condition Bosch style with disc instead pintle design are far superior in design and reliabilty.

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89 Notchback 347 Trick flow heads and intake bbk full length headers 3.73 Pro Charger with 3 row intercooler and much much more

01-04-2001, 11:53 AM	#1
88GT5.013.02 Guest Posts: n/a	How do you check for fuel system leaks? I have a serious leak in my fuel system somewhere. I cannot see gas physically leaking and it does not have gas in the oil. I am pretty sure the fpr is bad, but how do you check for leaking injectors? Why do they leak, extra o-ring not letting the injector seat in the fuel rail, bad o-ring? Any help is appreciated. ------------------ 88GT stock shortblock, ported GT-40 iron heads, ported Edlebrock Performer intake, 24# inj, Pro-M 75mm Bullet MAM, 3.73, hurst short throw, F-303, electric fan, alum rad, FMS HD clutch, R134a ac conversion, 70mm TB , and some other stuff I probably forgot, best run so far on ET streets is 13.02@106 with a 1.87 60ft (Full body weight GT, full tank of gas, and sway bars connected, gonna disconnect sway bars and dip into the twelves).

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01-04-2001, 02:58 PM	#2
JamGtStang Registered Member Join Date: Dec 2000 Location: Miami, Fl Posts: 58	light a match

01-04-2001, 03:09 PM	#3
JamGtStang Registered Member Join Date: Dec 2000 Location: Miami, Fl Posts: 58	j/k i think smell is the key to succes

01-05-2001, 03:00 PM	#4
LX XLR8R Dirk Diggler Join Date: Feb 1999 Location: SLOATSBURG, NY Posts: 1,931	well put a FP gauge on the rail and see what happens..if you see no diffrence(or decrese) in FP at idle and WOT then the regulator is bad and it is going right back to the tank..if when you turn the car off and the FP drops real low real fast then you got a leak somewhere..i guess just prime it and look and smell for leaks ------------------ 1987 black notch(ex 4 banger) DSS 306 w/ main support...Elderbrock 6028 heads..gt-40 intake..24# injectors...70 mm tb..77 pro-m...accel 300+..mac full legnth..tremec w/ pro5oh...full MAC exhaust,off road h-pipe,long tubes, catback...ron davis radiator..subframes, control arms...CFDF II..o yea holley FPR sucks..dont buy one..

01-06-2001, 03:05 PM	#5
fixer Registered Member Join Date: Aug 1999 Location: mesa,az,usa Posts: 457	if the evap canister is saturated it will smell. this condition can be caused by a canister purge solenoid not working; this allows vapor pressure and even(in serious cases)liquid gas to be forced into the canister. is there a smell or a pressure drop?

01-07-2001, 11:07 AM	#6
Darkside Registered Member Join Date: Sep 2000 Location: East Alton Ill. USA!!! Posts: 26	To check your fuel systems for leaks is fairly simple. 1 Get fuel pressure guage connect to fuel rail fitting. Prime system by turning ingnition on. Should be a 3 sec. prime. Pressure should hold. 2 If not plug return line to tank easiest place is a regulator connection if it holds regulator is notleaking to tank. If it drops disconnect vacumn hose to see if fuel is leaking through it to intake, if not the leak is not at the regulator. To further check regulator operation start engine observe pressure should 39 to 45 with engine running disconnect vacumn hose presure should increase 6 to 8 ILBs with factory regulator. Injectors can leak into port due to binding pintle in injector due to wear or carbon deposits, some cleaners will work on the carbonized injectors but won't fix worn out injectors. I have also found that Ford injectors orginal and FMS replacement in jectors do not like excessive pressures, and will heat up causing them to cause engine miss at times. Ford injectors have pintle design and are prone to this condition Bosch style with disc instead pintle design are far superior in design and reliabilty. ------------------ 89 Notchback 347 Trick flow heads and intake bbk full length headers 3.73 Pro Charger with 3 row intercooler and much much more