Issue with rear tank
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Issue with rear tank
I am having issues with a loss of power when I switch to my rear tank. The tank is full and I can still drive somewhat but it seems almost like not enough fuel is getting through. Unless each tank has its own filter I don't think it's the fuel filter because everything is fine with the front tank. My only other thought is a clogged line; but I wanted to get a few opinions before I start taking anything apart. Any help and advice is welcome and appreciated.
My truck is a 1992 Ford f250 with the 460 engine.
My truck is a 1992 Ford f250 with the 460 engine.
Last edited by kgrice09; Mar 14, 2018 at 12:31 PM. Reason: Missing information
Fleet Owner
Joined: Oct 2005
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From: Kentucky
Welcome to FTE!
Each gas tank has it's own internal high pressure fuel pump. You can rent a fuel pressure tester to measure the pressure with each tank selected.
It's not uncommon for one or both to go bad. Sometimes they just quit. Other times it's low output just like you are experiencing.
Have you noticed if the front tank is mysteriously filling up when running on the rear tank? This cross-flow issue is another another common problem....with similar symptoms.
Each gas tank has it's own internal high pressure fuel pump. You can rent a fuel pressure tester to measure the pressure with each tank selected.
It's not uncommon for one or both to go bad. Sometimes they just quit. Other times it's low output just like you are experiencing.
Have you noticed if the front tank is mysteriously filling up when running on the rear tank? This cross-flow issue is another another common problem....with similar symptoms.
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I forgot to mention that the front tanks gauge is bad so I have no reading of the amount of fuel within. This is an issue I plan on fixing when money allows. I had been relying on the rear tank because I can actually see how much gas I have.
I'm gonna go the route of testing fuel pressure first to see if the pump is the issue and I'll go from there. Thanks for the help!
OH and thanks for the welcome!
I'm gonna go the route of testing fuel pressure first to see if the pump is the issue and I'll go from there. Thanks for the help!
OH and thanks for the welcome!
Last edited by kgrice09; Mar 14, 2018 at 08:11 PM. Reason: Bad spelling
Senior User
Joined: May 2014
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From: Cedar Lake, IN
I forgot to mention that the front tanks gauge is bad so I have no reading of the amount of fuel within. This is an issue I plan on fixing when money allows. I had been relying on the rear tank because I can actually see how much gas I have.
I'm gonna go the route of testing fuel pressure first to see if the pump is the issue and I'll go from there. Thanks for the help!
OH and thanks for the welcome!
I'm gonna go the route of testing fuel pressure first to see if the pump is the issue and I'll go from there. Thanks for the help!
OH and thanks for the welcome!
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That is actually usually what I do with the front tank and it does work pretty well. As for the rear tank issue, I think I may have the culprit and it had been hinted to earlier. I believe it may be the tank selector. Many seem to have the same issue and after either cleaning it or replacing it, the issues disappear. I'm going to try cleaning it first and replacing the fuel filter and we will see if that does the trick.
Last edited by kgrice09; Mar 15, 2018 at 09:45 AM. Reason: Spelling
Fleet Owner
Joined: Oct 2005
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From: Kentucky
There is no frame mounted "tank selector" on your 1992 with a gas engine. Ford changed the fuel system design starting in 1990. Your truck has a high pressure pump in each tank. The only fuel selector on your truck is the switch on the dash.
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Junior User
Joined: Jul 2014
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I bought an old farm truck two weeks ago, a 1993 F150 with a 4.9L and a 5spd. I AM HAVING THE SAME ISSUES AS YOU!!!!
My front tank’s sending unit doesn’t work, so it always shows empty. The rear tank works best out on the open road, but will sputter some at stop and go driving, and acts like it floods the truck when I shut it off. It also appears to route the return fuel to the front tank.
Right now, I use the tripometer to tell how far I can drive, or switch to the rear tank when the front runs out. That gets me to a gas station, where I can refuel the front.
I bought a fuel pressure gauge at Harbor Freight for $20, and plan to check both tanks. I anticipate having to pull the bed off and swap out both fuel pump/sending units soon. I already replaced the fuel filter.
I hope you figure out exactly what’s going on. Sounds like we are two peas in a pod...
My front tank’s sending unit doesn’t work, so it always shows empty. The rear tank works best out on the open road, but will sputter some at stop and go driving, and acts like it floods the truck when I shut it off. It also appears to route the return fuel to the front tank.
Right now, I use the tripometer to tell how far I can drive, or switch to the rear tank when the front runs out. That gets me to a gas station, where I can refuel the front.
I bought a fuel pressure gauge at Harbor Freight for $20, and plan to check both tanks. I anticipate having to pull the bed off and swap out both fuel pump/sending units soon. I already replaced the fuel filter.
I hope you figure out exactly what’s going on. Sounds like we are two peas in a pod...
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New User
Joined: Feb 2018
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From: Florida Panhandle
Hey!!, that's my problem!! How come you have it too? Just kidding, but I am having the same problem. When I first bought my truck about a month ago the front gauge doesn't work but the pump does great, now the rear is a different story. When I first got it, the yard where I bought it put gas (only a couple of gallons) in both tanks, so I thought. Turns out that the rear was just empty. So I put $15 in it and wow the gauge works too! Well today the rear pump is acting up. I can start it and it will idle and rev fine until I put it in gear (AOD automatic w/ 5.0 efi), then idle is ok but it won't rev at all, it spits and boggs and stutters etc. Hit the switch to the rear and it'll take off just fine. So back to the front tank and watching the trip meter again. I also have noticed that when left overnight or longer that I need to cycle the key a couple of times or it won't start right up. Truck has new battery in it from the car lot but it's about big enough for a medium to small sized lawn mower. New battery is on the list too.
Boy howdy, is that list getting long!!
Geoff
p.s. what kind of pressures should we be looking for?
Boy howdy, is that list getting long!!
Geoff
p.s. what kind of pressures should we be looking for?
Last edited by Geoff Adams; Mar 20, 2018 at 05:05 PM. Reason: add question
Mountain Pass
Joined: Sep 2009
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I had a cold start issue with my '90. Both tanks completely full. Would start fine when warm, and run fine. Pulled the codes, replaced the air and coolant sensors, still no good. Ordered a fuel pressure tester, and while waiting for it, I happened to switch to the front tank for some reason. Started right up in real cold weather.
Fuel pressure tester arrives, something like 20# on the rear tank when key is first turned on. Multiple cycles only increased it slightly. Front tank was near spec on pressure.
Since I had both tanks full, while plowing I noticed that as soon as I put a load on it, it would start to sputter when on the rear tank.
So, I'd bet you have a weak pump.
Fuel pressure tester arrives, something like 20# on the rear tank when key is first turned on. Multiple cycles only increased it slightly. Front tank was near spec on pressure.
Since I had both tanks full, while plowing I noticed that as soon as I put a load on it, it would start to sputter when on the rear tank.
So, I'd bet you have a weak pump.
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Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
A bad valve in the front pumping unit (FDM) will make it run bad and sputter while running on the back pumping unit.
The reason being the with the bad valve in the front the fuel pressure will be much lower while on the rear pump.
Attachment 280308
Attachment 281295
Where the fuel lines are "T"ed:
/
The reason being the with the bad valve in the front the fuel pressure will be much lower while on the rear pump.
Attachment 280308
Attachment 281295
Where the fuel lines are "T"ed:
/
1st Gear
Joined: Aug 2022
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Help rear tank issue
I got a 1992 f250 7.5l v8 and I put a new fuel pump in the rear tank. The problem I'm having is the truck will run fine on the front tank but if I switch to the rear tank it's will run at idle and up to 30mph but will start to acted like it's not getting fuel pumped to the motor under the load of the truck what could cause this to happen