I am getting ready to go on a cross country drive towing a trailer and have a small problem I would like to get fixed.

I have had this truck and done a total rebuild on it as I have posted over the past 2 years. Both in tank fuel pumps have been replaced as has the tank switch solenoid.

When I am driving, the motor will occassionaly starve for fuel but all I have to do is switch to the other tank and it goes away. I thought that the in tank pump had died again and was going to replace it but then the problem switched to to the other tank. A HA, I figured it had to be the solenoid so I bought a new one. Put it in and the problem is still there.

I can go weeks with both tanks working fine then all of a sudden, one tank or the other won't want to feed but it is never the same tank and the problem will fix itself in a few hours. I can never get it to do it when I am home and can check things out, it is only on the road where I can't troubleshoot it. I always make sure there is a 1/4 tank in both tanks just in case it does this to me so I can make it home or to a gas station so it hasn't been a big deal up until now.

I am moving from California to Florida soon and with my luck, I will be on empty on one tank and full on the other tank and the full tank will die in the middle of the desert with no gas stations around for hundreds of miles so now want to get this fixed and not get stranded. Any ideas on what this could be? I keep wondering if it could be excessive tank vacuum not allowing the pump to feed or a chaffing pump wire grounding out once in a while. Just hoping someone else has run into this and might know where to look.

FWIW - Sometimes I can switch to the other tank then go back to the "bad" tank and it will run fine again.

Thanks in advance,

Lee

 

Isn't there also a frame mounted 3rd pump on the 86 or is that just a filter ?

IIRC, we changed out a frame pump and filter on an 84 F150.

 

Sounds like the black plastic canister filter needs replacing....

 

Mi1lion - Yes, the tanks each have a low pressure pump then there is a 3rd high pressure pump on the frame by the driver's door. I don't think it is the high pump though as it is a total starvation issue and not low volume or low pressure issue. The truck will starve till it dies no matter if it is under load, accelerating or idling. My experience was usually a high pressure problem would idle but not accelerate but I guess it could be possible.

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Lockney - Do you mean the filter in the tank switch solenoid or the filter in the vapor canister?

I did put in a vapor canistor from the junk yard because my old one had a cracked fuel line fitting. I cleaned the junk yard one up pretty good but who knows, I guess something could be clogging it.

When I bought the new tank switch solenoid, I asked the Ford dealer if it came with a filter or I needed to buy one and he told me that they no longer had filters in them and we weren't supposed to open them up anymore. The solenoid is only about 6 months old as well. If he is right, then there is no filter in it at all unlike our original ones.

I did run some Sea Foam through the truck a few times so could have clogged something up but there shouldn't have been much in the fuel system. Both tanks were drained and cleaned when I replaced the in tank pumps about a year ago. The Sea Foam was mainly an attempt to clean the injectors and valves. I have two more cans I plan on running through it soon and then will change the fuel filter before my trip.

Who knows, I may just have to let this get worse until it will do it in my driveway with the bed off so I can test pressures at failure. If we had normal fuel lines, I would even consider putting in line gauges on it so I could see where the pressure drop was. -gggg-

Thanks for the ideas so far.

Lee