Hi Everyone,

I joined many years ago but had not inherited the 1985 F150 XLT Lariat truck yet. Well, now I have it and having some problems that has an expert mechanic stumped.
This is a dual tank truck and so it has 3 fuel pumps one for each tank and then a main one. The rear tank is not even being used just the front one.

One day the truck would not start and turns out that the mechanic determined it was the pump so he replaced it. I bring it home and 2 days later same problem.. Have it towed back and he replaced it pump again.
I bring it home and again have it towed back. He currently has had it for the 3rd time. This is what he told me today. Either the tank is bad but he checked it a year ago and he felt it was okay, the lines are bad, the gasoline is bad,
or there is the canister that says on it that should not be opened or removed. He had no clue what it is. I have no plans to ever sale the truck but will keep it in the family so over time I will upgrade it with more modern parts. So I have no problem
with putting in more modern parts in this case the pump.

Below is a snapshot of that pump and the truck. Which he has replaced already about 6 times with new ones each time. He is already getting in trouble with his supplier because he is claiming it a warranty replacement.
Anyways he is going to replace it and I am to come and pick it up and drive it home immediately because it if sits for a day or so the pump gets stuck.
He has told me he takes it off empties the gasoline out of the pump and puts a voltage to it and it starts working again. Either I take it to a mechanic that loves old truck and have him repair it or I will need to systematically tackle
what ever this mysterious canister is in case it has deteriorated inside, replace the gasoline/ replace the tank, or replace the fuel lines. He did say it does have clean 12 volt power going to the pump.

He is supposed to have the truck ready for me to pick up next Tuesday June 29th at which point I may just drive it until the tank is empty and eliminate bad gasoline problem.
The plan is to modernize the truck to make it very reliable so I can drive it.

Any suggestions and in what order I should try them would be greatly appreciated.

Thanks in advance.



Any suggestions and in what order I should try them would be greatly appreciated.

 

It sounds like the truck has serious sentimental value. I hope you get it running reliably.

 

Thanks.

Yes, it was my Father-In law's truck and he gave it to me about 9 months before he passed. In about 16 years I will pass it to one of my granddaughters but not before I upgrade it, make it reliable and use it myself.

 

We need to see ALL the truck's details & history in your signature (not in the body of the post, or in photos) so we can review them with each reply, as this page explains:

(click this text)


Put EVERY detail in it now (even those that seem insignificant) so you don't have to add any later for this or other questions. Post pics of each component in the fuel system so we can be sure which one your truck has:

(click this text)


Also post pics of the VECI label, engine, tanks, & anything else that might be relevant.

 

Hey guys,

Just to let you know I did not fall off of the planet. I had taken before the crazy freeze in Texas which protected it, finally got my truck back from the mechanic after he went through about 4 to 5 pumps. Remember after 3 days each pump would die.
My neighbor said to get the truck back and he would help my troubleshoot.it. After removing the canister which says on the outside, "Do Not Open", we did open it up and it housed a paper filter. So I got a replacement filter washed the canister with soap and water to get out any bad gas. We also emptied the rear tank and what a bad smell it had. The tank selector switch was on the front tank but I emptied the rear just to be sure to not contaminate the new fuel pump.

The engine did indeed start and would stay started but it ran very rough and several times would die at idle. While it sounded like it needed a tune, my neighbor suggested the fuel pressure regulator. We replaced it and it runs much better now.

Today I replaced the cruise control sensor (see below) that is connected to cable going to the speedometer and a 2nd cable going to the transmission. I know have my speedometer and odometer back. I did not check to see if cruise control works but that is for another day.
I will posting some more questions related to the air conditioner after I do some research in this forum. I look forward to meeting more of you here.

Thanks,

Cruise control sensor that goes between the cable going to the speedometer and transmission.


Jeremiah 29:11-13 - For I know the plans I have for you,” declares the Lord, “plans to prosper you and not to harm you, plans to give you hope and a future. 12 Then you will call on me and come and pray to me, and I will listen to you. 13 You will seek me and find me when you seek me with all your heart.

1985 F150 XLT Lariat

 

Did you replace the in-tank pump at the same time as the external pump? If yours is like mine-you have 2 internal pumps and 1 external which I think is what you have pictured.

 

I don't know if your problem has been resolved, but offering my two cents worth. I lso have a 86 F150 dual tank. I replaced both tanks and fuel pumps since it was obvious when I pulled the tanks what my problem was. What some folks dont realize is, there is a dual tank reservoir which feeds the main fuel pump. Mine was so clogged up it would not function. I cannot find a replacement for the 86 dual tank. They do have available a single tank reservoir which can be used with one tank. I replaced mine with a reservoir from a 1987, and since Ford re-designed their fuel delivery systems in 1987, the reservoir looks much like the 86 model, but has stronger internal spring systems which the fuel pumps for the 86 cannot overcome, causing the front tank to fill the back tank and vice versa. I drive for a while on one tank, then switch to the other tank to keep from overfilling the tanks. When I purchase fuel, I do not fill both tanks, leaving room in one tank to accept the overflow from the other tank.
However, if you are only using a single tank, I would offer that you purchase a single tank reservoir and only use the one tank. There is a fuel filter in the bottom of the reservoir, which is not listed on most parts breakdowns. The bottom of the reservoir unscrews to get access to the filter.

Hope this insight helps you. I am considering putting one way check valves in the supply lines to eliminate the fuel feedback, but have not yet done so.

 

cturk69, honestly I do not know because the original work was done by another mechanic. I know for sure he replaced the external one probably about 6 times and I finally just got it home and replaced that crazy filter that was the original problem because the paper filter inside had deteriorated was the real problem.

 

Hey bcassity,

Thanks for asking. I did replace the paper filter in the reservoir shown below, if that is the one you are talking about. That was the problem because that paper filter was so deteriorated since the truck is several decades old but only has 93K miles.
I changed out the $10.00 paper filter and then the fuel regulator. Now it runs so much better. I just need to work on it as the idle is rough when the engine is cold and on the first start of the day. Also I will probably investigate the rear tank to see if it needs replacement
and the the front tank which I run off of has a bad sender so I never know how much gasoline is in the tank. I have a friend who is going to help me remove the bad since we think that is the best way to work on the tanks. By the way that picture was taken before I replaced the filter.
FYI - previous mechanic never wanted to touch it because it said on the outside of the reservoir " Do not remove". Go figure.

 

Just yesterday, I got some profound information on the fuel system very few mechanics will know about. This man was a Ford mechanic for 50 years and is very knowledgeable about these vehicles. There was a safety recall on the fuel system. The fix was to install one way check valves in the supply lines to prevent back feed to the tanks.

I have purchased after market valves but am still trying to figure out the best way to install them. Will update when I do install them.

I guarantee you have a defective sending unit. Neither of mine worked until I replaced both tanks and fuel pumps with the sending units. Both my fuel pumps failed and there was enough sediment in the reservoir to warrant the tank replacement.