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Thread: I'm going crazy. Help!!!

  1. #1
    stashtrey
    Many of you have probably read some of my threads lately. I've been having one thing after another go wrong on me.
    After replacing my carb with a brand new one... new Pertronix ignition conversion, all new igntion wiring, new fuel lines, new fuel filter, good gas, new plugs etc..... I'm still having problems.
    Basically.... my boat starts up fairly easy. Once I get it going it sounds great... rev's great, idles just fine etc. My plugs are bright white and the engine sounds great.
    Here's where the problem begins. I can give the engine a good push of the throttle and it sounds amazing. I can get the boat up to about 4,000 rpms roughly and once it get's to 4,000 rpm's the boat just bogs out.... sounds like the engine is not getting fuel. If I keep it around 3800 or so it runs fairly well and I can stay on plane.
    Is this screaming 'fuel pump'???
    Can a fuel pump be bad but still allow the engine to start, run great when not under a big load, feed the engine but still cause problems in the higher rpm's??
    I'm just freaking confused here because the engine honestly runs great at idle... the timing is right on.... good plugs, good ignition that was just rewired, brand new carb that seems to be operating properly.
    It's just when I give it a lot of throttle and try to get the boat up on plane.... the thing just cuts out. The engine does die.... it just sounds like it's choking.
    Help me!!

  2. #2
    stashtrey
    CORRECTION:
    The engine does NOT die. It continues to run when I back off the throttle. If I bury the throttle it just totally bogs out. No backfiring.... no popping etc. Just absolutely no power when I really get into it and even at the lower rpms it's just doesn't have a lot of power at all.

  3. #3
    Senior Member
    Join Date
    Feb 2009
    Posts
    1,820
    how old is the gas? and yes you can have a weak pump.

  4. #4
    stashtrey
    The gas is new this year... about 15 gallons brand new in each 20 gallon tank I'd estimate. However... it sat all winter oustside and I didn't top the tanks off. I used a container of Stablize in each tank.
    Could bad gas only show it's face at high rpm's yet still allow the motor to run great at idle and at low rpms?

  5. #5
    Senior Member
    Join Date
    Feb 2009
    Posts
    1,820
    2 years ago at tower park a guy had gas that was about 6 months to a year old and some how got water in it. run great on the trailer but in the water no go. drained all the gas and put in new and it ran great the rest of the
    weekend. bad gas does funny things. have you check your fuel filter also? what fuel pressure do you have?

  6. #6
    stashtrey
    I just replaced the fuel lines and put a wix filter in.
    It's really odd... at times when I'm cruising along at 3500 rpms or whatever and the engine sounds decent..... I'll feel the engine come to life for a split second and pull a little... then it bogs out.
    The only two things I can think of at this point is the fuel pump is failing but still good enough to feed the engine at low rpm's.
    OR
    My gas tanks are full of something and it's clogging the pickup?? These are original tanks out of a '77 Spectra. I don't believe they've ever been touched.
    I did notice one thing recently when filling one of the tanks. It almost seemed like there was something inside the tank.... I tried to look down the hole but couldnt' see anything. I use a yard stick to check my fuel level and one of the tanks seems to have something inside that interfered with that stick.
    Could the tank be coming apart from the inside????
    I have no fuel leaks in the boat. It's always dry and no smell of gas.

  7. #7
    El Prosecutor
    Your fuel pressure is highest at idle and lowest at WOT - I would slap a guage on it after the fuel pump and see what the pressure is at WOT. Look at the spec sheet for your carb and see what it needs. My Edelbrock says it should be 5.5 - 6 at idle, and should never drop below 2 lbs at WOT. A simple guage is cheap and easy to get at Pep Boys or whatever and you can be sure before you spend the bucks and time on a fuel pump.

  8. #8
    Moneypitt
    [QUOTE=stashtrey]
    Basically.... my boat starts up fairly easy. Once I get it going it sounds great... rev's great, idles just fine etc. My plugs are bright white and the engine sounds great.
    There is the key, white plugs = lean.......Yes your fuel pump is dying, but put a pressure gauge on the line after the filter, just to be sure. You should have a fuel pressure gauge anyway, so do it now. It could also be a delivery problem associated with the tanks and/or plumbing, so you have to start to get some good info somewhere, and the fuel pressure is where to start. If you feel it is tank/plumbing associated, use an outboard type tank to test, hooked straight to the pump. If the problem goes away you know where to look, if it doesn't, you know where not to look. It is a process of elimination. MP

  9. #9
    rerfert
    Well at least your on the water I'll hopefully be shaking my project down next week.
    Seriously other than the fuel pump not holding fuel pressure??
    I have an inline clear plastic fuel filter so I can see the fuel headed to the carb from the fuel pump.
    After you rule out fuel pressure....check total advance and then how old is the timing chain?
    White plugs you say.....You did mention that you had some junk in the fuel lines already right?? Did you possibly get some junk into the secondaries on the carb?
    Maybe you just need to open up the mixture screws?
    I'm about out of suggestions,so good luck and let us know when you find the gremlins.

  10. #10
    stashtrey
    Thanks, guys.
    I really appreciate it... as always. I don't know where I'd be without this board.
    I'll pick up a fuel pressure gauge tomorrow.
    What is the key sign that I have fuel pressure/pump issues when looking at the fuel pressure gauge?

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