Fuel draining back???
Thread Starter
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Posting Guru
Joined: Apr 2003
Posts: 1,153
Likes: 1
From: Venezuela
Fuel draining back???
Hi there, my F150, 1995, was in my home for 3 weeks an when I tried to start it was very difficult.
I notice this happen when the truck is off for more than 5 days. Trying to diagnose I notice the Fuel System is losing all pressure AND fuel is going somewhere because Fuel system get air.
After 5 days or more, before start; I just use a jumper at EEC Diagnose Connector to manual activate Fuel pump to Prime the whole Fuel System for about 10 seconds, after that truck star immediately.
There are no fuel leaks, 2 Brand New Fuel Pumps where installed, 6 brand new injectors also but still doing same. So...
Where is going the fuel? Why is air entering to fuel system? Any ideas will be appreciated.
I notice this happen when the truck is off for more than 5 days. Trying to diagnose I notice the Fuel System is losing all pressure AND fuel is going somewhere because Fuel system get air.
After 5 days or more, before start; I just use a jumper at EEC Diagnose Connector to manual activate Fuel pump to Prime the whole Fuel System for about 10 seconds, after that truck star immediately.
There are no fuel leaks, 2 Brand New Fuel Pumps where installed, 6 brand new injectors also but still doing same. So...
Where is going the fuel? Why is air entering to fuel system? Any ideas will be appreciated.
Post Fiend
Joined: Jan 2000
Posts: 5,860
Likes: 4
From: Metro Detroit (Redford)
I don't know much about it, but what about the fuel pressure regulator? Could it be leaking down? Easy to replace, two hex screws, it's just under the intake tubes, so some hand squeezing and finger gymnastics, but should be doable. Of course, it could be something else.
Freshman User
Joined: Dec 2007
Posts: 36
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Originally Posted by javi2001
Hi there, my F150, 1995, was in my home for 3 weeks an when I tried to start it was very difficult.
I notice this happen when the truck is off for more than 5 days. Trying to diagnose I notice the Fuel System is losing all pressure AND fuel is going somewhere because Fuel system get air.
After 5 days or more, before start; I just use a jumper at EEC Diagnose Connector to manual activate Fuel pump to Prime the whole Fuel System for about 10 seconds, after that truck star immediately.
There are no fuel leaks, 2 Brand New Fuel Pumps where installed, 6 brand new injectors also but still doing same. So...
Where is going the fuel? Why is air entering to fuel system? Any ideas will be appreciated.
I notice this happen when the truck is off for more than 5 days. Trying to diagnose I notice the Fuel System is losing all pressure AND fuel is going somewhere because Fuel system get air.
After 5 days or more, before start; I just use a jumper at EEC Diagnose Connector to manual activate Fuel pump to Prime the whole Fuel System for about 10 seconds, after that truck star immediately.
There are no fuel leaks, 2 Brand New Fuel Pumps where installed, 6 brand new injectors also but still doing same. So...
Where is going the fuel? Why is air entering to fuel system? Any ideas will be appreciated.
Post Fiend
Joined: Dec 2007
Posts: 8,521
Likes: 16
From: Lost
Kinda of a shot in the dark here, but....
Check your tank vent lines and charcoal canister. The tanks both vent thru the charcoal canister, and if the vent system is plugged somewhere, the pressure could be releasing, then as the tanks cool, they will have a vacuum-like effect, pulling the fuel back into them from the lines.
An easy way to check this, would be simply loosen the fuel cap(s) before allowing it to sit. Then, if it starts right away like it should, you've kinda isolated the issue.
Check your tank vent lines and charcoal canister. The tanks both vent thru the charcoal canister, and if the vent system is plugged somewhere, the pressure could be releasing, then as the tanks cool, they will have a vacuum-like effect, pulling the fuel back into them from the lines.
An easy way to check this, would be simply loosen the fuel cap(s) before allowing it to sit. Then, if it starts right away like it should, you've kinda isolated the issue.
Thread Starter
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Posting Guru
Joined: Apr 2003
Posts: 1,153
Likes: 1
From: Venezuela
Thanks to all for the input.
Problem appears on both fuel tanks. Venting lines where disconnected some weeks ago, no improvement. Also fuel tank caps remove, nothing...
I was considering check/replace fuel pressure regulator but as far as I know, once the fuel pumps are turned off, the return line to tanks is also closed, so no matter presure regulator is leaking the fuel shouldn't go back to tanks, isn't it?
The Fuel Delivery Module (FDM) has a closing valve at return line, it should open by the pressure developed by the same fuel pump, preventing return fuel to improper tank.
Could the pressure regulator still causing my problem???
Problem appears on both fuel tanks. Venting lines where disconnected some weeks ago, no improvement. Also fuel tank caps remove, nothing...
I was considering check/replace fuel pressure regulator but as far as I know, once the fuel pumps are turned off, the return line to tanks is also closed, so no matter presure regulator is leaking the fuel shouldn't go back to tanks, isn't it?
The Fuel Delivery Module (FDM) has a closing valve at return line, it should open by the pressure developed by the same fuel pump, preventing return fuel to improper tank.
Could the pressure regulator still causing my problem???
