Fuel pressure drop
Thread Starter
Pro
Joined: Dec 2000
Posts: 534
Likes: 32
From: Farmington NY
Fuel pressure drop
When I turn on the switch in my 85 with the fuel pressure gauge attached, the pressure goes up to 42 then after about 2 seconds I hear a click and the pressure begins to drop to 20 then is back to zero within 10 minutes. I have a set of ACCEL injectors in it that have about 50k miles on them. Should I consider replacing them? Would this drop in pressure be a leaking injector? Thanks for whatever help you can offer.
Team Owner
Joined: Jan 2003
Posts: 20,316
Likes: 246
From: Summerland B.C. Canada
Diagnose where the pressure loss is before you do anything.
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Mine was the pulse damper .
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Mine was the pulse damper .
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
There could be a few different places to loose pressure. leaky fuel injectors, bad FPR diaphram, leak in the gas lines/connections, fuel pump pulsator/dampner, check valve in fuel pump.
Try this test: remove the gas lid and rubber boot. You will see three lines from the fuel pump assembly. Turn the key "on" to pressurize the system and quickly pinch off the feed line (top right line). Watch the fuel pressure.
If it still drops off then the leak is not in the tank. Pull the vac line off the FPR and look for signs of gas. Look under the car and at the fuel filter connections and fuel rail connections for leaks. Then pull the spark plugs and look for wetness.
If it holds good the leak is in the tank. You will have to remove the fuel pump assembly. You can remove the pulsator/damper and use a rubber hose in it's place with hose clamps. Retry the test and see if the pressure holds. If it does then you fixed the leak. If not suspect the check valve to be faulty.
Try this test: remove the gas lid and rubber boot. You will see three lines from the fuel pump assembly. Turn the key "on" to pressurize the system and quickly pinch off the feed line (top right line). Watch the fuel pressure.
If it still drops off then the leak is not in the tank. Pull the vac line off the FPR and look for signs of gas. Look under the car and at the fuel filter connections and fuel rail connections for leaks. Then pull the spark plugs and look for wetness.
If it holds good the leak is in the tank. You will have to remove the fuel pump assembly. You can remove the pulsator/damper and use a rubber hose in it's place with hose clamps. Retry the test and see if the pressure holds. If it does then you fixed the leak. If not suspect the check valve to be faulty.
