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Technical Ongoing fuel problems

Discussion in 'The Hokey Ass Message Board' started by '50_SEDAted, Mar 5, 2021.

  1. Fabulous50's
    Joined: Nov 18, 2017
    Posts: 354

    from Maine

    Without knowing running pressure, and a good volume test we are all just guessing.

    You can fill a bottle right in the garage. See if the fuel has any bubbles and what kind of volume you get.

    With that information we can point you in the direction to look.

    Generally it's either a restriction or sucking air from somewhere before the pump.

    For what it's worth, an electric fuel pump has several advantages over an engine mounted mechanical pump:
    1. It primes the carb before the starter does anything.
    2. It allows for fuel lines to be run anywhere, especially where its cooler away from the engine block or exhaust manifolds/headers.
    3. (MOST IMPORTANT) You can empty the gas tank with it....without sucking on a hose for a siphon! :D

    Some may not consider an electric pump...ummmmm....traditional. I like reliability and short cranking times better than "traditional".
    jaracer likes this.
  2. :D

    In 1960 my 1953 Vicky had an Electric pump on it. What year does Traditional start? Yep, it was Flathead powered still.
    firstinsteele and Fabulous50's like this.
  3. David Gersic
    Joined: Feb 15, 2015
    Posts: 2,457

    David Gersic
    from DeKalb, IL

    Checking at the other end of things, a stand alone AFR meter and O2 sensor mounted in an exhaust bung would tell you whether you’re running lean, rich, or ok.

    Sent from my iPad using The H.A.M.B. mobile app
    HalleysRevenge likes this.
  4. In the first post it states you have a new fuel tank .
    Then in post 14 you say you blew air into it to knock loose any crud,,,,,it’s new,,,,,there shouldn’t be any crud inside .
    Or is it just another old tank to replace the other old tank ?

    I could be wrong,,,,,,,but I would start at the beginning,,,,,,check the fuel sending unit .
    Or at least unhook the fuel line and run some fuel into a jug,,,,, that pump should fill a gallon jug up fast if the line is ok with no blockage .

    I ha a similar problem a few years ago,,,,,,,I even removed the sending unit and looked at the sock,,,,it was perfect and clear as a bell .
    After several more days and many more dollars,,,,,I decided to remove the unit again .
    This time I removed the sock and even looked up in the tube,,,,,,bingo,,,,there it was .
    Even though the sock was clean and clear,,,,,the tube had become clogged from evaporated fuel sediment up in the tube .
    Actually it was dried residue from octane booster I had used many years before .
    Only had a little opening to squirt a slight amount of fuel through .
    I went to work on it,,,,,,,removed the blockage and it was like new again,,,,,my old blue pump would shoot a geyser out again .
    Anyway,,,,,it is just something to consider .

  5. Has a similar problem with an OT car. Few things, where a rubber hose goes on to a hard line it is possible to carve out a flap of rubber that acts like a valve. Is there a hidden filter in the carb? Had this with an SU that wasn't supposed to have an internal filter - but it did and it was packed with detritus from the fibreglass tank. Are you running one of those glass and chrome inline filters? The gauze can pack with dirt that cannot be seen but won't allow flow

    Sent from my moto g(8) using The H.A.M.B. mobile app
    Desoto291Hemi likes this.
  6. If it was my Car I would put the original Carb. on the car.
    When I had the original Flathead Engine I Raced it ( drag racing )
    I Set a Record with my Car back in the Day (1963 )
    I did 16 Seconds in the Quarter mile which it took somebody
    10 years to break it.!
    The Car was all Stock, I would fill the Tires up with a lot Air
    Reget the Carb Play with the Timming.!
    and that did it for me.
    What I am Trying to SAY is Run n a Stock Carb & It should be Fine

    Just my 3.5 cents

    Live Learn & Die a Fool
  7. Okay, the car came to you with a problem. You've thrown a lot of parts at it and it's still there. The issue probably isn't with 2 electric pumps but someone before you tried to cure it with one. I understand your trying to get to the Real issue here. Your going to get a Ton of "Try this" and I was part of that. Bottom line is you only think you know what you have. You probably don't even know if you have a Healthy Motor. Give it a Physical and know that it will run if it get's solid fuel. You gotta start with the Basics and not assume because it runs it will run hard. How many guys do total ign changes and step into fuel to find out they have a Timing chain going away? (You don't have that issue it's gear driven) If the front door to your house stopped closing right would you trim the edge off so it would or go to the Foundation and shore it up to correct the alignment? Same theory here, the foundation needs to be healthy before any kind of fuel can do it's job.
    Blues4U and Truck64 like this.
  8. Mr T body
    Joined: Nov 2, 2005
    Posts: 2,194

    Mr T body
    Alliance Vendor
    from SoCal

    Didn't read that you checked the float level. If it's low you'll have a starvation issue during high demand.
  9. '50_SEDAted
    Joined: May 4, 2019
    Posts: 46


    Appreciate all the advice, folks.
    So I started this thread last Friday morning. Friday afternoon when I got home from work, I fired her up and took her on a drive. 35 miles. Car ran great other than the bog/lean issue (or whatever it is). Running at a steady RPM on level ground is no problem, but going up hills, giving additional throttle (as if I were going to pass someone -- HA!), or anything over light to moderate acceleration thru the gears from a stop is when she acts up. First, I'll address a few comments:
    The carb is a 1404, so 500 CFM. So, yes, twice as big as I need. Dumb-dumb. (...just had to have the shiny vintage intake...)
    I don't like to arbitrarily replace parts to try to fix a problem, either. Adding the 452 and 1404 went against my own belief in solving any particular problem before adding unknown variables, but I did it anyway. Mainly because I was going to have to rebuild the Holley, and since I'd gotten the manifold, I might as well just get a different carb to fit it. Which I really don't need. And the carb is really too big for the engine, so dumb-dumb X2.
    My descriptions may seem like I'm giving this old gal the spurs, riding her hard and putting her up wet. That's not the case. When I speak of putting my foot into it or heavy acceleration, I don't mean punching to the floor. I mean, being able to get out of the way of oncoming traffic or getting up a hill. The engine is tired; compression readings are fairly even across all cylinders and average out in the low 90's. She smokes a little (although I think that may have been a stuck ring -- since my trip on Friday, she seems to have cut back on her smoking habit). She runs a steady temp and has good oil pressure. She's got one lifter that ticks, but that also quieted down after our Friday trip. To be clear, I'm not trying to hot-rod a tired old flathead. I would like to rebuild either the engine that's in her now or find another Merc flattie to rebuild as I get the time and money. The addition of the new intake and carb belie my words, but I just got ahead of myself, and who hasn't.
    It is a new -- brand new -- tank. I blew air thru the outlet on the off chance that something made its way into the tank and was blocking the pickup tube/sock. I can see some particulate in the bottom of the tank; I'm thinking it's from the filler tube.
    I did; floats are set correctly.
    At least part of my problem may be of my own doing -- I went against my better judgement and replaced parts (out of vanity) before running the original issue to ground. It could be that the original fuel problem has been replaced with another. In any case, I plan on checking fuel pump volume this week and see what I come up with. As I said above, I can see that there is some particulate matter in the bottom of the tank, and I believe it is rust flakes coming off of the filler tube. Need to replace the filler neck and it could be that rust flakes have dammed up the works. I'll keep you posted.
    Thanks again for the help.
  10. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 8,128


    Does it still have the original distributor,I think those only have vacumn advance only like on the Y blocks and they only seem to work right with the original carb. You might not be getting any advance when you need it causing a bog.
    jimmy six likes this.
  11. coupe man
    Joined: Sep 1, 2007
    Posts: 264

    coupe man

    You replaced the tank,fuel pump and carb.Did you replace the fuel line between the tank and the carb?What is the dia. of the fuel line?Is it all metal except for connections to tank,fuel pump and carp?
    210superair likes this.
  12. The stock chassis line will be plenty big enough for his stock motor. The stock metal line has a line nut that connects the steel line directly to the Tank. There is a Bradded Flex line from Firewall to fuel pump and another metal line direct to the Carb in stock form. OP may have used a section of rubber with new carb but I bet it was new stuff.
    In reading the new information of it's actions sounds like a timing issue or bad accelerator pump. Might sound silly here but you have checked point gap, right?
    210superair likes this.
  13. 210superair
    Joined: Jun 23, 2020
    Posts: 1,092

    from Michigan

    Heck yeah, a good tuneup is always a good thing.

    Is it just me or isn't that carb too much for a stock flathead? Could it be falling on its face because it's dumping too much fuel in there? I have a hly390 that does great, my motor is slightly built. 500 seems like a lot to me...
  14. '50_SEDAted
    Joined: May 4, 2019
    Posts: 46


    No, I'm running a modified SBC dizzy, vacuum over centrifugal. Built by Charlie Schwindler here on the HAMB.
    Yes; set at .017 per the builders spec.
    It's not just you, I'm beginning to think the same thing...
    AND, if that be the case, what carbs did they set atop 452 Eddys "back in the day"?
    Pist-n-Broke and 210superair like this.
  15. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,414


    Holley 390 or a Autolite 4100 with 1.08 throttle bore for a 289. The Autolite is a very under rated carb.
    It is incredibly simple to rebuild and will be ok on your Flathead.
    I ran one on a 51 Merc with an adapter way back in the day when I had no money. That's funny ! I am 71 and still don't have enough money to do all the things I would like to do to my 65 Comet.
    210superair likes this.
  16. I am 86 & Still looking for enough Money to do certain Thing's
    For my Merc, so I Drive it Like it is & Enjoy it.

    Just my 3.5 cents

    Live Learn & Die a Fool
    rusty valley likes this.
  17. HalleysRevenge
    Joined: Apr 25, 2019
    Posts: 19


    I think the carb just needs to be tuned like in the video/instruction booklet. Tune for power or tune for cruising.
  18. You could confirm fuel delivery by installing a fuel air ratio meter and monitor it when you drive it's a good thing to have anyway
  19. '50_SEDAted
    Joined: May 4, 2019
    Posts: 46


    I appreciate everyone's input. I'll bump into the answer one of these days. In the meantime, it's just gratifying to hear her grunt twice and then kick off -- hot or cold -- tying every little bundle, and then ooze on down the road, smooth as glass.
  20. HalleysRevenge
    Joined: Apr 25, 2019
    Posts: 19


    Bump to see if ya got it figured out?
  21. jimmy six
    Joined: Mar 21, 2006
    Posts: 10,255

    jimmy six

    Without the adapter a small base Carter WCFB, Rochester 4GC, or Holley 4000 will bolt on and run fine on a 255 flathead Merc. Many car manufacturers used these up to the middle 50’s and folks say the around 375cfm. The are getting more expensive today. I use 2 Carter’s from a 53 Olds on a stock 292 Y-Block and they are perfect. My fuel pressure is 4 psi and the fuel line is 5/16”. At wide open throttle running 100 mph I don’t run out of fuel.
  22. '50_SEDAted
    Joined: May 4, 2019
    Posts: 46


    I'm still trying to decide what to do. I've decided that the carb is too big, so I'm either going to rebuild the old leaky Holley 94 and put the stock manifold back on, or get a Holley 390 cfm to mount on the Eddy 471 that's on the car. However, those small Holley 4bbls are EXPENSIVE, as are any good, rebuildable WCFB, 4GC or Autolites I've run across. Gone are the days when a fellow could pick one up at the junkyard for $10 bucks. If anyone has a good small square bore 4bbl for sale that won't cost me a limb, let me know...
  23. '50_SEDAted
    Joined: May 4, 2019
    Posts: 46


    I'm also going to get rid of the electric fuel pump and go back with a mechanical -- I'd like to get my wipers working at some point, so I'm in the market for a good or rebuildable dual-action fuel pump as well.
  24. TA DAD
    Joined: Mar 2, 2014
    Posts: 534

    TA DAD
    from NC

    If you are still using the 70 year old metal fuel line I would replace it. I have had more than one car with similar symptoms and between corrosion and a kink or two you don't have enough volume.
    Nicholas Coe likes this.
  25. speedshifter
    Joined: Mar 3, 2008
    Posts: 306


    Lots of good suggestions here. In my 60 plus years of mechanics I have never seen a lack of fuel going to the carb cause a bog under acceleration or heavy load condition. My experience has been when the carb bowl runs dry the engine just plain quits, maybe just for an instant or until the fuel supply "catches up". I do realize that as the fuel level drops the fuel air mixture becomes slightly leaner but I have never observed this condition causing a bog. Just my 2 cents worth.
  26. 51 mercules
    Joined: Nov 29, 2008
    Posts: 3,350

    51 mercules

    I'm having the same problem. 51 merc new gas tank from Tanks Inc, new fuel pump, pickup , sock and fuel lines, vented cap. Tried mechanical fuel pump and electric and it has the same symptoms as yours. Except I'm running 12volts and a 331 hemi.
  27. jaracer
    Joined: Oct 4, 2008
    Posts: 1,306


    Don't know if this is your problem, but I had something similar on a 88 Bronco. I took the Bronco in trade on a pickup I sold. It ran okay, but would die out on acceleration; let up a little and it would run fine. At the time I worked with a guy who had been a trainer for Ford. He said it was the fuel pump because they were problematic on this model. He even went for a ride with me and said for sure it was a fuel starvation problem. Replaced the pump and no change in the symptoms. It got progressively worse until it finally quit on me. Good fuel pressure and volume, I had spark and the compression was good. While testing it would occasionally start up, run a bit and then die if you tried to give it any throttle. It had everything it needed to run, but it wouldn't.

    This wasn't my daily driver, so it sat in my shop for about a month. An off-hand remark by a co-worker about a bad coil got me thinking about the ignition system. I had a scope attached to the engine and I could see a blip during cranking so I assumed that I had "sufficient" spark (I could have tested it, but I didn't). The coil for this model was cheap, so I picked one up from NAPA. Bolted it on and the engine fired instantly with no bog on acceleration. Since I have an old Sun coil scope, I decided to compare the old coil to the new one. The old coil put out about 8K volts while the new one was off the 30K scale. All the time the problem was a weak coil.
    ottoman, Desoto291Hemi and kfien5354 like this.
  28. 52HardTop
    Joined: Jun 21, 2007
    Posts: 969


    I've read this complete post and the last post from jaracer as simple as it sounds, might be something to consider? I had an old S-10 pickup with a V6 that did the same thing. It was the coil. It ran fine until under load. Go up a hill and it would fall flat on its face. Watching the coil at night and it was easy to see the arcing. Changed the coil and it was fine.
    ottoman and Desoto291Hemi like this.

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