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Thread: New fuel pump, now new problem. 51 Commander

  1. #1
    President Member lelshaddai's Avatar
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    New fuel pump, now new problem. 51 Commander

    My 51 Commander V8 fuel pump was having problems leaking and needed to be be rebuilt. I purchased a rebuilt original pump. Swapped them out and now I have new problems. It stutters and backfires now upon acceleration. If it is in low you can floor it no problem with no hesitation. In drive it kicks and screams, it even popped and died. The pump is working and giving accurate pressure. I even have an electric backup to push the gas through if needed. It stutters even with that pump on. The carb is rebuilt. I thought maybe something passed through and lodge in the carb. I took the top off, cleaned it up, blew carb cleaner through the needle and jets and reinstalled. If anything it made it worse. Do I need to readjust the mixture and retiming? I would not think so. It was running pretty good before. Also parked in the garage it has a large gas smell. Do not see any leak. When I removed the carb top there was plenty of gas in the areas of the floats. When I disconnected the fuel line from the pump that leads to the carb the fuel sprayed out under pressure. Stumped here.
    Jim
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  2. #2
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    Did you put a fuel pressure gauge on it to check the pressure. Sounds like it is getting flooded.

  3. #3
    President Member lelshaddai's Avatar
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    Yes, I agree. I may change out the fuel pumps to see if it goes back.
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  4. #4
    President Member Dwain G.'s Avatar
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    Check the oil level to make sure it is not overfull and smells of gasoline.

  5. #5
    President Member Silverplate's Avatar
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    Had a similar issue with a Packard, to much fuel pressure after installing a rebuilt fuel pump. Installed an inline fuel pressure regulator and at a three pound setting runs awesome.
    Mike
    Fort Worth, TX


    1964 Avanti R2 #R-4986

  6. #6
    Golden Hawk Member StudeRich's Avatar
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    You could need to Richen the Choke setting, is the butterfly almost Closed when Cold?
    StudeRich
    Second Generation Stude Driver,
    Proud '54 Starliner Owner




  7. #7
    President Member lelshaddai's Avatar
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    Yes, butterfly is closed when it is cold. Could coil or coil wire be weak and it just came to light with the change of more fuel pressure.
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  8. #8
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    Quote Originally Posted by lelshaddai View Post
    Yes, butterfly is closed when it is cold. Could coil or coil wire be weak and it just came to light with the change of more fuel pressure.
    Very, very unlikely or related.

    EDIT: 1) How old is the fuel that you are trying to operate with?
    2) Have you checked for fuel in the oil, as suggested by Dwain. This could cause fuel smells.
    3) Perhaps you have a small air leak in a fuel line that may have been caused in the process of changing the fuel pump. This could cause operational problems and fuel smells.
    Gary L.
    Wappinger, NY

    SDC member since 1968
    Studebaker enthusiast much longer

  9. #9
    Golden Hawk Member 8E45E's Avatar
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    Do you have a VENTED fuel cap?

    Craig

  10. #10
    President Member lelshaddai's Avatar
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    1. No I do not have a vented cap.
    2. Fuel is 12 hours old
    3. When at idle no bubbles are in the clear bowl.
    4. Checked oil earlier and it was a little low. Did not smell like gas.
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  11. #11
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    Quote Originally Posted by lelshaddai View Post
    1. No I do not have a vented cap.
    2. Fuel is 12 hours old
    3. When at idle no bubbles are in the clear bowl.
    4. Checked oil earlier and it was a little low. Did not smell like gas.
    ALL Studebakers use vented gas caps!!!!!!

  12. #12
    Golden Hawk Member 8E45E's Avatar
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    Quote Originally Posted by lelshaddai View Post
    1. No I do not have a vented cap.
    That perhaps that may be your reason. There is no external fuel tank vent on a '51, and the cap should be vented, or you will experience fuel starvation.

    Craig

  13. #13
    Golden Hawk Member 8E45E's Avatar
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    Quote Originally Posted by rbisacca View Post
    ALL Studebakers use vented gas caps!!!!!!
    That is incorrect. 1962 & newer Lark/Lark types had an independent vent off the fuel filler neck and directed through the trunk floor.

    Craig

  14. #14
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    Quote Originally Posted by 8E45E View Post
    That is incorrect. 1962 & newer Lark/Lark types had an independent vent off the fuel filler neck and directed through the trunk floor.

    Craig
    You're correct. It's been a long time since I sold my '63. Guess I forgot.

  15. #15
    President Member lelshaddai's Avatar
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    I may be wrong on the cap. However the car ran fine before/

    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  16. #16
    Golden Hawk Member StudeRich's Avatar
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    It could be unvented. but the Gasket looks missing so it should not be sealed anymore, you do need a New Cap but maybe not the problem.

  17. #17
    President Member lelshaddai's Avatar
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    I don’t think the caps the problem or would’ve happened with the other pump.

  18. #18
    President Member Kurt's Avatar
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    Garbage in the needle and seat. I bet a little crud was introduced when the fuel pump was swapped. The popping and dying sounds like a lean condition to me. Or if crud is holding needle open a little you are flooding the engine out.
    1962 Champ

    51 Commander 4 door

  19. #19
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    If the gas cap is the problem it should run fine without the cap. Easy check.

  20. #20
    President Member lelshaddai's Avatar
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    Already took the top of the carb off and clean it. Blew out the needle area. I thought that something got into the needle area also. There is gas in the bowls.
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  21. #21
    Golden Hawk Member
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    Quote Originally Posted by StudeRich View Post
    It could be unvented. but the Gasket looks missing so it should not be sealed anymore, you do need a New Cap but maybe not the problem.
    To me, it looks like the gasket is there, but not in great shape. There also appears to be a small rust hole in the cap with fuel stains around it. Perhaps, depending on cap placement, sometimes it gets some venting and sometimes it doesn't have any venting.

    Try running the car without the cap and/or get a correct/proper cap.

    EDIT: Rich, you may be correct. Looking at the picture again, it is hard to tell if there is a gasket there or not. What I wrote above still applies.
    Gary L.
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    SDC member since 1968
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  22. #22
    President Member (S)'s Avatar
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    Was the pump an old one or fresh rebuild?. Is the filter good? remove it and test drive it. It comes out easy enough to check it......

  23. #23
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    Bingo! Kurt has my vote, dirt under the needle valve. I bet it belches black smoke out the exhaust too.

  24. #24
    President Member lelshaddai's Avatar
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    I tested the new pump it is at 5 pounds, The electric backup is at 4 1/2 pounds. The new fuel filter is clean and not stopping the flow. I cleaned out the needle area but could do it again. The fuel pump is NOS with new insides. Rubber inside is flexible and new. I guess I pull the carb top off again. No votes for possible weak spark or coil?
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  25. #25
    President Member lelshaddai's Avatar
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    Change coil wire and that did not make a difference. Looked in carb and Excelerator pump is working great. Plenty of fuel is being put in the barrels. Still need to check the coil for weak spark. Just cannot figure this out. This fuel pump is better than what I had but has caused more problems.

  26. #26
    Silver Hawk Member studeclunker's Avatar
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    My '56 had a tiny vent above the fuel bowl and gas would squirt out of it. This was because a tiny piece of rubber had found it's way onto the needle seat. Since they were both black, it was to all practical purposes invisible. Thoroughly squirted the seat and needle with carb cleaner and the problem was solved. Took several tries to get the little bugger dislodged though. Now everything works perfectly.

    It could be that you have a similar issue and in this case, your engine is being drowned.

    But then, mechanically speaking, I'm a mechanical ignoramus and any advice given by me should be taken with a grain of salt.
    Home of the famous Mr. Ed!
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  27. #27
    President Member lelshaddai's Avatar
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    OK, I think problem is solved. After checking and implementing all the fuel suggestions I went to the ignition system. About 6 months ago I found the breaker plate to be sticking. Got it freed up and lubricated. It appears it got stuck again and would not move. Tested it with the vacuum pump and was able to get it to move. Relubed it and the car runs without hiccups. Also sanded the points a bit for better contact. It ran well around the block. I will give it a better tests Monday. Thanks for the help again.
    51 Studebaker Starlight State Commander Coupe
    53 Studebaker Starlight Regal Commander Coupe
    62 Volvo PV544 Sport



  28. #28
    President Member Kurt's Avatar
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    Glad you got it figured out.

    Happy motoring!!
    1962 Champ

    51 Commander 4 door

  29. #29
    President Member lelshaddai's Avatar
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    So I drove her to a show this morning and she still hicup under a load. However at 75 miles an hour on the freeway not a blip at all.

  30. #30
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    Quote Originally Posted by lelshaddai View Post
    So I drove her to a show this morning and she still hicup under a load. However at 75 miles an hour on the freeway not a blip at all.
    Having driven the freeways in Phoenix and Mesa, 75MPH you were lucky you weren't run over.

    Bob Miles
    Pacific Southwest Zone Coordinator

  31. #31
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    Reminds me of the old mechanic telling me - you think you have a fuel problem...90% of the time it is ignition related.

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