Question about 1983 Chevrolet Malibu

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Fuel delivery on carb 350 chevy marine engine

Bought in so. ca. last fall. ran great. brought to Colo.and ran bad when fired up this spring. suspected carb and had 650 holly double pumper rebuilt and jetted for altitude. Runs good now if you feather throttle and keep rpm above 1500 but dies in 20-30 seconds if you let idle. Fuel filter dry- large pint spin on getting fuel from 2 20 gal (40 total) side tanks. Fuel pump OK All fuel lines clear. Engine idles at 1000 rpm which is about right with carb, high riser manifold, electronic ignition,and cam. Float sticking closed at idle? This would allow engine to burn fuel in the bowls and then die but why is filter dry? Filter should be full at all times unless-----? No equalizer line between tanks but should draw from both although trucks with dual tanks have equalizer line (40 yr retired otr driver) I'm at a loss to fix!!!!

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  • oldies213 Jun 01, 2008

    Of course this isn't a malibu but no slot for marine engines. Engine was mfg somewhere between late 70's and 1986- marine engines numbered different. Don't even know if 2 bolt or 4 bolt. Great compression with max 8 lbs variation between cyls. This is a fun and ski boat 19 ft long and just flies when running right. Will run at 50mph all day long but this carb problem got me buffaloed. Any help greatly appreciated Thanks, Smitty

  • oldies213 Jun 01, 2008

    Is it possible for fuel pump to fail at idle but supply fuel at rpm? Smitty

  • oldies213 Jun 01, 2008

    Maklean: The web sites you referred me to just sell fuel pumps. No help to my question. Can a fuel pump fail at idle but supply fuel at higher rpm? Local napa dealer checked earlier today and said fuel pump good but suppose he could be wrong. Smitty

  • oldies213 Jun 01, 2008

    I don't need to be referred to sites that sell fuel pumps. I need an answer to question. Can a mechanical fuel pump fail at idle rpm but supply fuel at higher rpm's?

  • oldies213 Jun 01, 2008

    Thanks maklean. I'll pickup a new fuel pump tomorrow and install. Hope your right Smitty

  • oldies213 Jun 01, 2008

    Help! What do you mean by "altitude adjuster"? Carb was rebuilt and jetted to
    colo. altitude and timimg reset. Smitty

  • oldies213 Jun 01, 2008

    Maklean: Your diagnosis of bad fuel pump was correct. Both a Napa Parts and Checker checked pump and said OK but bought new one anyway and installed today. Engine running fine and idled down for 15 min with no problem. The pump replaced had no more than 8 hrs on it. A tip of the halo hat to you.


    Smitty

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From SoCal to Colorado. It's all about altitude. You'll need an altitude adjuster, no matter what they tell you.

Posted on Jun 01, 2008

  • Patrick Michaels
    Patrick Michaels Jun 01, 2008

    what I mean is that the settings at altitude are different for fuel to air mixture. Any local mechanic can tell you about this. The mix tends to run a little rich, to compensate for less oxygen at altitude. That's more likely what's causing this situation.

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Hi!
It seems your fuel pump fails at idle speed. I would first ensure that fuel pump is well fitted, no leaks, and good diaphragm condition.

Posted on Jun 01, 2008

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