Strange LS fuel pressure issue.
Thread Starter
Teching In
Joined: Jul 2020
Posts: 9
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Strange LS fuel pressure issue. Hey All
I have a 2005 LM7 out Silverado. I have a returnless system. Electric fuel pump is brand new (in tank), fuel filter is brand new, lines are brand new, fuel rails are brand new. I have LS6 injectors. My question is why is my fuel pressure higher after starting the engine.? When I turn the ignition on I hear the fuel pump and the fuel pressure gauge reads about 57-58 psi and doesn't hold pressure for a long period of time. When I turn the engine on the fuel pressure goes up to about 61-62 psi. The car drives fine and no issues idling or with acceleration. I'm thinking I have a slow injector leak but I was curious if anyone else could shed some insight on this?
I have a 2005 LM7 out Silverado. I have a returnless system. Electric fuel pump is brand new (in tank), fuel filter is brand new, lines are brand new, fuel rails are brand new. I have LS6 injectors. My question is why is my fuel pressure higher after starting the engine.? When I turn the ignition on I hear the fuel pump and the fuel pressure gauge reads about 57-58 psi and doesn't hold pressure for a long period of time. When I turn the engine on the fuel pressure goes up to about 61-62 psi. The car drives fine and no issues idling or with acceleration. I'm thinking I have a slow injector leak but I was curious if anyone else could shed some insight on this?
TECH Enthusiast
Joined: Mar 2005
Posts: 663
Likes: 384
From: South Carolina
The leak down could also be in the fuel pumps check valve. I have a Walbro 255 drop in module pump and it doesn't hold pressure very long unless the engine is running. If you hold enough prime to get the engine started and of course you don't have a leaky injector, I wouldn't worry about it. In HP Tuners you can add more prime running time if necessary to fire off the engine.
