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Fuel issues

Hi I’m new to the forum and own a 1992 F250 with a 5.8 motor 65000 miles

The front tank works fine, but when I switch to the rear tank after a period of minutes or longer, the engine appears to struggle for power as if there’s no fuel in a line from the rear tank

I had a fuel pump replaced, the tank cleaned out and the problem still exist.

The problem eradicates itself and when I switch the fuel tank switch from rear to front and than back again to the rear tank.

It’s at the shop again trying to be diagnosed, having the shop look at ground wires and they suggest replacing the fuse link for the rear tank which o am having done

Any ideas?
 

Fellro

Moderator
Staff member
The switching valve is known to have issues on these trucks. It is a passive valve that is supposed to switch back and forth like a check valve when each pump is powered. They can fail to do so and then return the fuel to the previous tank. It can also restrict fuel from getting to the motor. It is the fuel filter looking thing that has multiple lines going to and from it.
 
The switching valve is known to have issues on these trucks. It is a passive valve that is supposed to switch back and forth like a check valve when each pump is powered. They can fail to do so and then return the fuel to the previous tank. It can also restrict fuel from getting to the motor. It is the fuel filter looking thing that has multiple lines going to and from it.
It also looks pretty simple to install. Am I correct on this assumption
 

Fellro

Moderator
Staff member
Largely, yes. 2 bolts and 6 lines.
 
The switching valve is known to have issues on these trucks. It is a passive valve that is supposed to switch back and forth like a check valve when each pump is powered. They can fail to do so and then return the fuel to the previous tank. It can also restrict fuel from getting to the motor. It is the fuel filter looking thing that has multiple lines going to and from it.

I do not have a fuel restriction issue in my opinion. When I’m driving on the rear tank the , at times I have no issues which means it shouldn’t be a fuel line restriction issue.

I replaced or the shop replace the fuse link, the rear tank is almost new the pump is brand new.

So unless someone has another idea oh – that switching valve they, the shop couldn’t find it they don’t think I have it on this truck it only came with diesel?

What I’m thinking of doing is that I believe the pump is pumping at a constant rate and the injectors allow less one more fuel into the truck. I’m thinking of just rewiring the rear pump and bypass the current wiring to the rear tank switch in the dash
 
The last visit I took the truck to the shop replaced a fuse link. That didn’t help

now,I just replaced the fuel switch itself for the. F and R tank

will keep everyone Posted
 
There were some models the selector valve was hidden behind the tank itself. You would pretty much have to drop the tanks to find it. From what i read it was mainly the gassers that had them hidden there. The diesels had the larger ones under the driver side floor boards.

7AFF0523-1EAE-44B4-84CD-7CDBCB204082.jpeg
 

Fellro

Moderator
Staff member
1646999680268.png
This is the passive valve, the one Sparky showed is more for diesels, and electrically controlled.
 
There were some models the selector valve was hidden behind the tank itself. You would pretty much have to drop the tanks to find it. From what i read it was mainly the gassers that had them hidden there. The diesels had the larger ones under the driver side floor boards.

View attachment 35497

my Shop said it didn’t have one. And your saying that I do have a switching valve .

planning on taking the truck back to the shop and as close to the tank as they can, to splice into the ground and find the closest point to the chassis and reground the pump
 

Fellro

Moderator
Staff member
They are largely correct, 92 did drop the switching valves and relied on the fuel pumps to do it as they also eliminated the front high pressure pump. There may be a check valve at the fuel pump as well. Sorry I overlooked the year in the post...
 
They are largely correct, 92 did drop the switching valves and relied on the fuel pumps to do it as they also eliminated the front high pressure pump. There may be a check valve at the fuel pump as well. Sorry I overlooked the year in the post..

no issues, the latest on the truck is this. This current recent visit I had them tie into the ground cable as close to the tank as possible and ground it to the chassis to take away the ground issue causing the problem.

I have replaced the fuel switch backwards forwards on the dash, I replace the fuse link for that rear tank, replace the fuel pump, and the tank is relatively new and cleaned out.

So far I’m having no issues with the tank by re-grounding it to the chassis. I’ll keep my fingers crossed and keep everybody posted.

I suspect this will work but if it doesn’t I’m going to rewire the hot ground into the switch on the dash and coming out of the switch to the fuel pump and go that route if needed


don
 
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Fellro

Moderator
Staff member
Grounding issues will definitely cause problems..
 
Grounding issues will definitely cause problems..

so I Really thought I had the issue resolved. With 3/4 of the rear tank gone no issues in the engine ran better than it ever has on the rear tank. However the problem did raise its ugly head at about a quarter full of gas and then same situation happened again.

The engine starving for gas and about to stall, I turned the switch of the fuel tank to the front and it immediately started running perfectly switched it to the rear again and it ran fine which is the way it normally works when the problem arises.

The only thing that I have not done, is fully rewire the hot and ground wires to the fuel pump for the rear, starting from a new positive lead wire from the battery to the front back switch on the dash and then on the other side of the front back switch leading a wire to the fuel pump itself obviously using a fuse link for safety
 
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