Selector valve\Fuel pump
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Selector valve\Fuel pump
Hey guys, I got a problem. To make a long story short my 92 F150 with 5.0 L. motor stumbles bad on acceleration sometimes. I checked fuel pressure on each tank and front tank starts out around 32 psi and builds pressure when i engage throtle. Rear tank starts out at 32 psi but momentarily looses pressure on acceleration and then slowly builds pressure.(runs ok on front tank, like crap on back tank) THEN while running front tank the dogone back tank somehow gradually fills back up and I have to drive the truck around sputtering to run $2.85 gas out of the back tank. Is the problem my fuel pump, fuel sock, or selector valve? Or something else altogether?
Thanks,
Charlie from SC
Thanks,
Charlie from SC
Junior User
Joined: Feb 2007
Posts: 85
Likes: 1
From: Eastern Washington
There are a lot of posts in this section from people with similar problems. give this one a read, I think they address the problems you are experiencing,
https://www.ford-trucks.com/forums/6...nk+gam+mileage
Hope this helps, but if it doesn't, type your symptoms in the search feature and give it a look-see.
Steve
p.s. that thread I linked is a bit lengthy, and some of it won't apply to your situation, but I believe it eventually addresses the issue of one tank filling the other and what the compnents are that cause it.
https://www.ford-trucks.com/forums/6...nk+gam+mileage
Hope this helps, but if it doesn't, type your symptoms in the search feature and give it a look-see.
Steve
p.s. that thread I linked is a bit lengthy, and some of it won't apply to your situation, but I believe it eventually addresses the issue of one tank filling the other and what the compnents are that cause it.
Last edited by S_Bruce; Jul 20, 2007 at 06:04 AM.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
You have a bad Fuel Delivery Module inside your rear tank.
The fuel pump is inside the Fuel Delivery Module (FDM) along with three valves one of the valves is bad and maybe the fuel pump also.
The FDM with valves and pump all comes as one unit.
You do not have a selector valve on your truck.
It is normal to start out at 32 PSI and it should jump to about 42 PSI at WOT (near zero vacuum on the fuel pressure regulator).
The bad valve in the rear FDM allows the fuel to enter the rear tank while running on the front.
Not sure why the pressure drops when you switch to the rear unless the valve in the front is sticking open for a short time or the rear pump starts up slow.
Here is a link to a diagram of your fuel system.
http://i54.photobucket.com/albums/g91/subford/Fuel/FielSystem.jpg
Here is a link to a diagram of the FDM.
http://i54.photobucket.com/albums/g9...yAssembly2.gif
The fuel pump is inside the Fuel Delivery Module (FDM) along with three valves one of the valves is bad and maybe the fuel pump also.
The FDM with valves and pump all comes as one unit.
You do not have a selector valve on your truck.
It is normal to start out at 32 PSI and it should jump to about 42 PSI at WOT (near zero vacuum on the fuel pressure regulator).
The bad valve in the rear FDM allows the fuel to enter the rear tank while running on the front.
Not sure why the pressure drops when you switch to the rear unless the valve in the front is sticking open for a short time or the rear pump starts up slow.
Here is a link to a diagram of your fuel system.
http://i54.photobucket.com/albums/g91/subford/Fuel/FielSystem.jpg
Here is a link to a diagram of the FDM.
http://i54.photobucket.com/albums/g9...yAssembly2.gif
Last edited by subford; Jul 20, 2007 at 07:02 AM.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
Likes: 301
From: Easton,Ks
Originally Posted by Cruss
Can I ask for this as a unit at the parts store?
Charlie
Charlie
I have heard that some part stores will jut try to sell you the pump and it next to impossible to get it apart to put one inside of the FDM.
Here is one from Advance Auto Parts.
