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Technical Help gm 350 fuel pump

Discussion in 'The Hokey Ass Message Board' started by Kevinbosch711, May 16, 2019.

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  1. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    I have a gm 350 in my shoe box it has a mechanical fuel pump I started the car backed it out of the garage and washed it I tried starting it back up and it’s getting no gas to carb When I crank it over the feel filter is dry I blew in it ergo stool I think the pump ain’t working has anybody ever had a problem with this everything seemed fine it just wasn’t sending no gas out
     
  2. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    Photo of it
     

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  3. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,259

    David Gersic
    Member
    from DeKalb, IL

    When mine failed it leaked gas on the floor. I’ve heard of others failing and leaking gas in to the oil pan. Could be on yours it’s pumping but the diaphragm is bad.

    Take it off and see what’s going on with it.


    Sent from my iPad using The H.A.M.B. mobile app
     
    Rich S. and Mark Yac like this.

  4. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    My tank is full to max
     
    Johnny Gee likes this.
  5. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    I ordered a new one just was wondering if it’s common for them to just fail I have noticed the car was getting hard to start at times after I drove it and when idle it seemed like it wasn’t getting enough gas so prob all symptoms of it was going bad then it finally gave
     
  6. Rex_A_Lott
    Joined: Feb 5, 2007
    Posts: 1,018

    Rex_A_Lott
    ALLIANCE MEMBER

    Good rule of thumb, if it moves it can fail. Check the simple stuff first.Gas tank vent, fuel filter. Give it a little shot of ether , maybe it will run long enough to start pumping. Good luck
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 46,909

    squirrel
    Member

    yes, they fail. A few years ago the pump on the 350 in my brothers' old wagon quit working, the lever pivot pin worked loose...
     
    lothiandon1940 likes this.
  8. 29moonshine
    Joined: Dec 30, 2006
    Posts: 1,301

    29moonshine
    Member

    mine did the same thing running down the road it just quit pumping
     
  9. Not to difficult to diagnose, but I cant understand your lingo......? I get the general issue, but.......:eek:
     
    lothiandon1940 likes this.
  10. I changed a pump once per word of mouth. "Can you do a fuel pump for me?" It was a hot summer day along the curb where the vehicle stopped and where I worked on it. They failed to check the obvious and so did I. Apparently new pumps need fuel in the tank to work. ;)
     
  11. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,552

    Mr48chev
    ALLIANCE MEMBER

    It doesn't take much to kill a fuel pump including running out of gas and sucking the crud off the bottom of the tank, getting dirty due to a dirty gas jug, or driving without a gas cap for a few miles.
    If you just changed gas caps before this happened the cap you installed may not be properly vented. A full to the top tank won't have very much air to slow down the process of creating a vacuum that outdoes the suction of the pump.
     
  12. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,259

    David Gersic
    Member
    from DeKalb, IL

    Checked with a stick? Or gauge reads full?

    My dad once spent several days figuring out why mom’s car wouldn’t start. Gauge read 1/2 tank. Checked everything else, nothing wrong, still wouldn’t start. Put a stick down the filler tube, found the tank was empty. Gauge was bad.



    Sent from my iPad using The H.A.M.B. mobile app
     
    lothiandon1940 likes this.
  13. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    So just took off the old fuel pump new ones on way quick question my fuel sale is in the trunk gas tank is full ! When I took off the fuel line off the pump barely any fuel came out of the fuel line that comes from the gas tank I blew air with my compressor into the hose and it’s not clogged it was bubbling in the tank no prob , only question is shouldn’t fuel be coming out from the line just from the gravity pressure alone from the tank ? I mean it is all the way in the back of my ford shoebox , or does it least need a little bit of help from the (mechanical fuel pump )
     
  14. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    Gas tank
     

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  15. squirrel
    Joined: Sep 23, 2004
    Posts: 46,909

    squirrel
    Member

    no vent on the tank?
     
  16. anthony myrick
    Joined: Sep 4, 2009
    Posts: 6,218

    anthony myrick
    Member

    clogged filter between the rank and pump/crap in the fuel line
    worked on a diesel half a day once with a fuel issue until I discovered it sucked up a rag in the pickup tube from someone trying to steal fuel

    the last chain store pump I bought only made it about 12k miles
    I keep a replacement
     
    Last edited: May 22, 2019
  17. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,610

    1oldtimer
    ALLIANCE MEMBER

    Pull the rubber line off the pump to make sure gas is making it to the pump first (low fuel or clogged line), with the rubber line off, pinch off line to stop leaking, put your finger over the inlet side and have someone crank it. You should feel some suction or action, if not pull the pump.


    Now would be a good time to put out the cigarette and not check with a lighter.
     
  18. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    Yea with the line off no fuel is coming out but when I blow air threw it it makes it all way to the gas tank and I can see it coming out it’s odd
     
  19. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    It’s just a straight line from the tank to the pump no filter in between and I didn’t see a vent I’m guessing it’s in the cap
     
  20. Take the cap off of the gas tank and see if any gas comes out via gravity. By the way, gas is what our hot rods run on, fuel is what trucks run on (diesel).


    Sent from my iPhone using The H.A.M.B. mobile app
     
  21. ....that's in there backwards. The fittings on top are for a return system and a vent that goes forward and under the car (outside the trunk) . Where does the gas outlet go, assuming it's in the front?
    Seems to me you could look right at it with a flashlight. If there's foam in the way, that could be your problem.
     
  22. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711


    The gas outlet yes it’s in the front and I don’t see anything blocking the line like I said I can blow air from the end of the hose (disconnect it from my fuel pump ) and it goes to the tank no prob it’s odd should gas come back after I blow air kinda like Siphoning a tank
     
  23. You looked at the outlet from the inside?
    As Jim said, where's the vent? Fuel sales (cells) need an outside vent and an anti- rollover valve.
    The gas line goes up and over the frame, yes? Siphon may not work.
    If the outlet is clear, (visual inspection) then put the front hose in a bucket and apply SLIGHT air pressure through a rag at the tank.
    That pump is probably good. Take it off. Put one ear in a vise. put a socket and 6" extension on the arm and work it up and down. See if it sucks and blows .:eek::eek:
     
  24. Road Racer
    Joined: Jan 29, 2017
    Posts: 39

    Road Racer

    I have heard the " run the tank low and suck crud off the bottom of the tank" before, doesn't the pump always suck from the bottom of the tank on most systems?
     
  25. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    I’ll post some pictures tomorrow of cell and mounting see if you guys can help shed some light on what is going on I bought this ford like this so who knows how they did it I didn’t see a vent line
     
  26. squirrel
    Joined: Sep 23, 2004
    Posts: 46,909

    squirrel
    Member

    does fuel run out if you leave the cap off?
     
    Truckdoctor Andy likes this.
  27. 1oldtimer
    Joined: Aug 21, 2003
    Posts: 7,610

    1oldtimer
    ALLIANCE MEMBER

    Another semi quick test is to run some fuel hose into a gas can and then to the fuel pump inlet. If it runs on that the problem is in the tank or lines.
     
    lothiandon1940 likes this.
  28. B.A.KING
    Joined: Apr 6, 2005
    Posts: 3,641

    B.A.KING
    Member

    How much rubber line you got between tanks and pump?+Did you leave fuel i it for a while?Could have a hose that is acting like a one way flap.Todays fuel pretty much kills anything that is not designed for todays fuel. Should be able to look in fuel cell. check that,Start with rubber hoses if you have any, work
    forward to pump. I have a fuel pump that is screw together. Been on car a year.Has about 250 miles on it. Rubber gaskets are leaking.
     
  29. Kevinbosch711
    Joined: May 4, 2019
    Posts: 40

    Kevinbosch711

    So changed the pump still no go I can feel the pump working just the gas from the tank isn’t making it to the pump the line when unplugged off the pump doesn’t even have a drop coming out , it’s funky it goes from steel line to rubber but mostly steel line the hole way under the car I didn’t see any pinch in the line should I just switch it to a rubber line the hole way ? Like I said I blow air in the line to the tank and it doesn’t seem blocked ? And I had the gas cap off
     

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