no fuel
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Joined: Dec 2002
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no fuel
'95 351, won't start (at times).
I can hear the fuel pump run for a couple seconds like it's supposed to, but it doesn't build up pressure. This started happeneing a week ago. If I turn the ignition a dozen times, or so, eventually it builds up pressure and the thing runs fine. since it runs smooth, I don't suspet the fuel filter, or it would bog and sputter on the freeway. Also the pump must be working or I'd run out of power at high rpms, so is it possible that the pressure relief valve for the fuel injector is sticking open.
It seems to be more than typical vapor lock.
Most of the time this thing starts right up.
Any other ideas?
I can hear the fuel pump run for a couple seconds like it's supposed to, but it doesn't build up pressure. This started happeneing a week ago. If I turn the ignition a dozen times, or so, eventually it builds up pressure and the thing runs fine. since it runs smooth, I don't suspet the fuel filter, or it would bog and sputter on the freeway. Also the pump must be working or I'd run out of power at high rpms, so is it possible that the pressure relief valve for the fuel injector is sticking open.
It seems to be more than typical vapor lock.
Most of the time this thing starts right up.
Any other ideas?
Fleet Owner
Joined: Aug 2005
Posts: 23,668
Likes: 301
From: Easton,Ks
Sounds like you have an open Hi-Pressure check valve in the fuel delivery module (fuel pump). I do not know if you have one or two fuel tanks but if you have two the one that will fill when the others tanks pump is running is the bad one.
Normally when you shut off the truck the check valves are supposed to hold pressure for a little bit and then slowly drop to zero PSI overnight but not drain the fuel system. So when you first turn on the key one second is enough to pressurize the fuel system. However if the fuel system drains dry then you would have to turn on the key a number of times to charge the fuel system.
To check this, put a fuel pressure gauge on the test point of the fuel manifold and ground pin #6 of the test connector with the key on. If you have an eight it should build up to 45 PSI. When you take the ground off, the pressure should hold and then drop very slowly. If the pressure drops fast then you have a bad check valve in a fuel delivery module.
I think your fuel pressure regulator (FPR) is more than likely good but if the pressure goes somewhat above 45 PSI or if you pull off the vacuum hose and you get fuel out of the FPR then its bad.
Here is a diagram of the test connector:
http://i54.photobucket.com/albums/g91/subford/Fuel/DataLinkConn88.gif
Normally when you shut off the truck the check valves are supposed to hold pressure for a little bit and then slowly drop to zero PSI overnight but not drain the fuel system. So when you first turn on the key one second is enough to pressurize the fuel system. However if the fuel system drains dry then you would have to turn on the key a number of times to charge the fuel system.
To check this, put a fuel pressure gauge on the test point of the fuel manifold and ground pin #6 of the test connector with the key on. If you have an eight it should build up to 45 PSI. When you take the ground off, the pressure should hold and then drop very slowly. If the pressure drops fast then you have a bad check valve in a fuel delivery module.
I think your fuel pressure regulator (FPR) is more than likely good but if the pressure goes somewhat above 45 PSI or if you pull off the vacuum hose and you get fuel out of the FPR then its bad.
Here is a diagram of the test connector:
http://i54.photobucket.com/albums/g91/subford/Fuel/DataLinkConn88.gif
Last edited by subford; Nov 22, 2006 at 02:48 PM.
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