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  1. #1

    Default Low power and backfire

    I have a 2002 VIP 2102 with a volvo penta 5.0 gl. It back fires under load seems like a lean condition. What controls the fuel pump output?

  2. #2
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,474

    Default Re: Low power and backfire

    the relay normally controls the pump's operation...there is no control that 'throttles its output'....

  3. #3

    Default Re: Low power and backfire

    How does the relay meter the pump i cant find a regulator?

  4. #4
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,474

    Default Re: Low power and backfire

    No regulator... Relay: Fuel Pump ON/ Pump OFF (@ no oil pressure, usually) You have a 2bbl carb, all fuel flow metering is done in the carb. Only control of fuel flow into the carb is the carb float valve, which again is ON/OFF depending on fuel level in the bowl,
    Last edited by sandkicker; 08-09-2020 at 08:15 PM.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  5. #5

    Default Re: Low power and backfire

    Hmm. I seem to have something different. The pump does not engage in run while engine is not running. It pumps while cranking. I hotwired the pump to remain on when key is turned to run and the pump overflowed the float and flooded.

  6. #6
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,474

    Default Re: Low power and backfire

    No....Fuel pumps while cranking is the correct setup... engine starts, oil pressure builds, oil pressure sense switch closes, energizes the fuel pump via relay. Engine stops ( no oil) fuel pump stops.... While you hot wired the system and the pump kept running, the carb float apparently did not stop the fuel flow into the carb.... Possible incorrect fuel float level adjustment AND a defective/dirty needle seat.
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

  7. #7

    Default Re: Low power and backfire

    A weak float would cause it to run rich i would think. But it isnt flooding at idle. Could the holly power valve cause a problem like this?

  8. #8
    Join Date
    Jun 2006
    Location
    Spotswood, NJ, USA
    Posts
    5,263

    Default Re: Low power and backfire

    what does the spin on filter say? maybe a clogged carb

  9. #9

    Default Re: Low power and backfire

    Its a volvo penta filter replaced it last week. Disassembled carb and cleaned float bowl (was very clean inside). Sprayed carb cleaner thru jets. Also disconnected fuel line and activated fuel pump to check flow. Pumped about a gallon in 2 min. Pump rated at 25 gal per hr

  10. #10
    Join Date
    Sep 2008
    Location
    Maryland - USA
    Posts
    8,474

    Default Re: Low power and backfire

    I'm reading two issues....

    1) you haven't said anything about the oil pressure controlled switch (for the fuel pump) being checked out...it appears to be failed based on your earlier posts....

    2) Posts #5 & #7 contradict each other...the carb is flooding or it isn't....did you check the float while the carb was apart? did you verify the needle and seat assembly is functioning?

  11. #11

    Default Re: Low power and backfire

    Carb isnt flooding unless i hotwire fuel pump. The oil switch is a good idea. I didnt know how the fuel pump was "controlled

  12. #12

    Default Re: Low power and backfire

    The float is copper or brass. Seems ok. Needle valve isnt stuck. Ill check the oil pressure switch first. Is it on the back of the intake near the distributor?

  13. #13
    Join Date
    Jun 2008
    Location
    Island Heights, NJ,
    Posts
    3,474

    Default Re: Low power and backfire

    On a SBC, its normally on the port side of the engine, aft and low on block...
    Capt Bob
    1969 23ft ChrisCraft Lancer
    Merc 5.7L 260HP/ Volvo 280

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