I have been checking the forum for a long time and finally registered. I have a 1955 with a 351w in it that we built as a family project that started when i was 13. The truck has been finished for about 15 years and I have had it to some shows and cruise ins but me my wife and son would rather get out and cruise than to show i guess. I like to sit and talk to the guys at the shows but she would rather be on the move. My son and I drove the truck last night and it did something that is had never done before that I am assuming could be vapor lock. Living in East TN, the temp was about 90 yesterday with like 150 percent humidity. But I was driving and noticed under light acceleration i could feel the truck surge. I turned on our road and when i got back into the throttle it was missing a little more. Got in the driveway and it was missing pretty bad at idle. Pulled up to the garage and checked under the hood and found that the fuel filter was almost empty, filter is before pump on frame. I wiggled the line and filter some and it started to fill back with fuel. If i rev the engine it seems to rev fine and not miss. I went to pull it in garage and when i pulled it in gear it died. It started right back up though. It pulled in garage with a little throttle. I have just finished installing a new cold case fan and radiator and i switched the accessory drive to a serpentine set up off of a 93 f150. The old radiator was a griffin and it had developed a leak at one of the seams. But the engine has always ran perfectly fine no matter what the ambient temp was until yesterday. Does it seem like it could be vapor locking even though it fired right back up when shutting engine off? I did not go start it and see how it was doing after it cooled off last night. Anyway thank you all for your help and this forum has been a great help to me.

 

The missing at idle doesn't really fit the vapor lock scenario. Or was it generally rough? The ethanol laced fuel we use now is very volatile and might require a lower fuel level in the carb. See how it runs cold.

 

Welcome to FTE, the best Ford truck forum on the World wide Web! Show us some pictures of your truck when you have time.

Doesn't sound like vapor lock to me either. Could it be a loose clamp on your rubber fuel line somewhere? Maybe try ethonal free gas if you can find it. Or a higher octane gas.

 

Welcome to the forum! I would concur on the not vapor lock theory. I would check for obstructions in the fuel line first. Disconnect the line from the filter and gas tank, and if you have compressed air, blow backwards through the line and see what happens. You could have a deteriorated hose or hose collapse, junk in the fuel tank clogging the line, any number of scenarios. Heat and humidity does crazy things. Might even be as simple as your vented gas cap not venting correctly and a vacuum is created in the tank, not allowing the pump to pump. Just a few things to ponder and research. Let us know what you find.

 

I didnt think so either and it starts right back up. It was missing some at idle but when i went to pull it in garage and pulled it in gear it was really missing then died but fired right back up. I am going to try to start it tonight and see how it does.

 

 

Those pics are a little old the front end doesn't hardly sit that low anymore. I installed coil over shocks in the subframe.

 

Beautiful!
So yeah- drive it this evening and see how it starts and runs while its warming up. The idea is to see how it runs when engine and ambient temps are on the cooler side. If it still "misses" when cold/warmed up, then the conversation will shift from fuel deivery.

 

Welcome to the forum. Nice looking truck. I would go back and read 52 Merc's post above. Do you have a vented gas cap?

 

First, nice truck. Number one check for obstruction in the fuel line, number two do you have a suction type filter installed?

You states filter is before the pump, so you need a suction filter installed there or you will have problems.

 

Hey Case,
I like Wayne's suggestion above... a fuel venting problem. You've entered the hottest time of the year...
We live in Texas - just really hot here too. Our engine would feel starved for fuel & there was an odd whistling coming from
the tank under acceleration. We had a vented cap but it just didn't vent enough for the system to work right.
We added a rollover vent to our '70 Mustang under bed gas tank venting to an after market charcoal cannister... we've never had a problem since.

Do you feel or hear anything when you take the gas cap off?
Looking good over there in Tennessee.

Ben in Austin
351W/AOD

 

The only thing I will add at this time, the fuel filter should not be on the suction side of a mechanical fuel pump. This won't fix your issue, but the filter should be between the pump and carb. If there is no sock filter in the tank, then maybe a 100 micron filter on the suction side to catch big stuff, then a 40 micron filter between the pump and the carb.

 

Why between the pump the carb? I have seen it done both that way and before the pump.

 

Ideally, you want the filter as close to the carb as practical, to catch any 'last minute' crud that may be in the gas or line before going into the carburetor and causing a problem. I like the 56_F100 suggestion about having a large filter before the pump, and the smaller one after.

 

A filter before the pump can cause vapor lock by creating a pressure drop. A '55 with gas being drawn up to the top of the tank is already at a disadvantage compared to the in-cab tanks that have gravity helping at least part of the way to the pump.