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Truck Problem (please help) (update)

gun_runner
1976 Ford F-250


My truck has been at the shop for a week now. I got a new fuel pump installed 2 weeks ago and it looses pressure when the truck warms up and fizzles out and the truck wont run. Starts right up when cold though. They have gone through 2 more different brands including Napa with no success. Any ideas as to what could be going on??? The tank is right behind the cab so the distance the fuel has to travel is not far. This process takes 30-60 minutes to happen.

Whats the deal!
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Comments

32 comments

Date Votes
  • dlrjj
    I'm going to assume that you have changed the fuel filter, right?
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  • dheffley
    And, check the intake screen in the tank. Most likely it's trashed up and can't keep up with the flow needed to keep the truck running.
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  • catpealer111
    Sound to me like vapor lock. Check the routing of your fuel line. If its too close or touching the engine, it'll heat up the fuel causing it to vaporise. When the engine is cold, it'll run just fine, but as it heats up, power will fall off until it dies. Once things cool off it'll restart. It's been awhile since I've played with carburetors, but that's what it sounds like to me.
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  • dlrjj
    I'm guessing here, but if the truck has a tank behind the cab, it is likely of an age to still have a carburetor and not fuel injection. Is that correct? I don't remember that model for sure.

    If so, then that truck very well may have a sintered brass filter in the base of the carburetor. They have a habit of allowing just enough fuel through for an engine to get running, and then starve the thing out after it has run for just a few minutes, or less.

    Check to see if you have one where the fuel line enters the carburetor, if that's what you have. Disconnect the line, pull the sintered (crushed brass) filter out if so equipped, and try blowing through it. If you cannot blow air through it with almost no restriction, it needs to be replaced.
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  • victorlvlb
    When is the last time you had the catalitic converter,(sp), checked?
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  • gun_runner
    What catalytic converter?[:D] its got Flowmasters and they are new.quote:Originally posted by victorlvlb
    When is the last time you had the catalitic converter,(sp), checked?
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  • gun_runner
    Yesquote:Originally posted by dlrjj
    I'm going to assume that you have changed the fuel filter, right?
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  • gun_runner
    Thanks guys. Some good suggestions. I will collect them and present them in a humble way to my mechanic tomorrow.
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  • Colt Super
    All good procedures for troubleshooting your truck.

    You also might try removing fhe fuel line at the carb, turning the engine over and check to see if you have good fuel flow out of the line. The upside to this is, if you have full insurance coverage, and this corrective action torches your truck, youll need to get another.

    D.
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  • TexasVet
    All good suggestions here.

    I would check the sock in the fuel tank; sounds like it's collapsing or is full of trash and shutting down the fuel flow.
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  • br549
    i have owned a 1977 ford 150 since 1978 there are 2 things you need to keep as a spare. 1:a fuel filter and 2: an electronic egnition modgual(sp) when either has a problem you don't go anywhere. your problem sounds like the electronic egnition.
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  • Colt Super
    What rsr said may be correct.

    D.
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  • mark308
    Possible in the system there is an old fuel hose collapsing inside itself. When it runs out of pressure or out of fuel at the carb or inlet to pump?
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  • jabronij3
    quote:Originally posted by mark308
    Possible in the system there is an old fuel hose collapsing inside itself. When it runs out of pressure or out of fuel at the carb or inlet to pump?
    +1
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  • jabronij3
    quote:Originally posted by rsr1950
    i have owned a 1977 ford 150 since 1978 there are 2 things you need to keep as a spare. 1:a fuel filter and 2: an electronic egnition modgual(sp) when either has a problem you don't go anywhere. your problem sounds like the electronic egnition.
    +1
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  • dcon12
    There is a hose that connects under the cab from the tank to a metal fuel line. When it builds up pressure, this hose will collapse and then shuts off fuel. When it kills the motor, the hose will open back up and allow the motor to start again. Don
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  • Horse Plains Drifter
    Well, it's something in the fuel line or the line(rubber part) is collapsing or it's the sock on the end of the in tank pick up as already mentioned. OR it's the vent in the tank cap plugged. next time it does it quickly remove the cap and listrn for a sucking noise, then see if the truck will start with the cap off.
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  • ObiWan
    Check the choke.
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  • gun_runner
    It only does it when its warmed up and its actually ruining the fuel pumps. Blowing the seal etc. I will call today and get the report and let you know what Andy say's.

    Thanks for the brainstorm fella's,
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  • gun_runner
    They put an electric pump on the line to keep the fuel from getting hot before reaching the pump. The fuel kept on blowing the diaphragms in the pump.

    First for me, but at least its working now.
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  • Colt Super
    I think that that doesn't cure the problem. SOMETHING was making the high line pressure. You should keep digging to find out what.

    D.
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  • gun_runner
    I thought it was kinda wierd to but my mechanical inclination only goes so far. I dont have my shop yet either. I will tear it up this summer and get to the root of the problem. They said the line wasnt close to the engine and they checked the tank, filters, line and carberator. All were OK. They were unable to replace the pump with a factory one because Ford quit making them for the 76's so I think thats half the problem. We shall see I guess.

    Thanks for all the suggestions,
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  • minitruck83
    quote:Originally posted by MT357

    OR it's the vent in the tank cap plugged. next time it does it quickly remove the cap and listrn for a sucking noise, then see if the truck will start with the cap off.



    Thats what I was gonna suggest. Ex brother in law had a mid 70s ford truck that would quit on a hill. Spent $300 bucks with a mechanic and they couldn't find the problem. Ol drunk came by one day and took his gas cap off and told him to "try it now" Ran like a top!

    Might be some reason behind stuffing an old rag in it! [:D]








    Allen
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  • oldgunner
    This might not explain everything, but just for grins, drain some gas from the tank and check for water..
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  • 11echo
    You need to put a fuel pressure gage in-line near the carburetor. You should see about 6 p.s.i. at the carb. IF you see less then 3 p.s.i. than I'd be looking at the fuel pump. Inline filter is another thing to look at. With the air filter off look down the throat of the carb. and actuate the throttle, you should see 2 squirts of fuel into the throat (only when you first actuate the throttle and one on either side of the carb. at the same time). "IF" you have good pressure (even when cranking) and see the fuel when you actuate the throttle, I'd be looking at an electric problem! My $0.02 anyway, Good Luck!
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  • Colt Super
    Why are you looking for the carb at the dealership ??

    Check with auto parts stores, and also some Wal-Marts.

    D.
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  • dcloco
    You are losing the battery + or - to the fuel pump circuit - okay when cold, but dies after a bit. More than likely the wonderful fusible link that are on Fords. There are several coming off the battery.
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  • oldfordsnguns
    They covered most everything. Make sure its losing fuel not spark.Then check for cab pinching gas line (rusty or broken cab mounts)or I had one that did that, it had rust pinholes in gas line right by pump, not big enough to leak but would let pump suck air in, stop after about 1 mile.
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  • Horse Plains Drifter
    quote:Originally posted by dcloco
    You are losing the battery + or - to the fuel pump circuit - okay when cold, but dies after a bit. More than likely the wonderful fusible link that are on Fords. There are several coming off the battery.
    Mechanical fuel pump.
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  • jabronij3
    quote:Originally posted by gun_runner
    1976 Ford F-250


    My truck has been at the shop for a week now. I got a new fuel pump installed 2 weeks ago and it looses pressure when the truck warms up and fizzles out and the truck wont run. Starts right up when cold though. They have gone through 2 more different brands including Napa with no success. Any ideas as to what could be going on??? The tank is right behind the cab so the distance the fuel has to travel is not far. This process takes 30-60 minutes to happen.

    Whats the deal!
    ignition coil and not a fuel related problem?
    0

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