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Thread: Carb only starts after dumping fuel.

  1. #1
    1fastmofo Guest

    Default Carb only starts after dumping fuel.

    This is my first attempt at rebuilding a carb. Got the accelerator pump working when I pull off the bowl, but I'm not seeming to get fuel to squirt into the actual body of the carb. once I dump fuel in it it will idle at about 1300-1500 no lower. I am extremely agitated, any help is greatly appreciated. BTW, the carb is a 600 cfm electric choke. I purchased a complete rebuild kit cleaned the primary jets, set the float levels and replaced the gaskets. I'm not fully sure what the valve body on the front bowls job is. Any help is appreciated thanks.
    Last edited by 1fastmofo; 09-05-2012 at 06:30 PM.

  2. #2
    Ryan Guest

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    I know this is an old post but I was having similar problems with my 670 DF 4150 vacc secnd. I finally figured out after I rejetted it some how I jammed up the discharge nozzle weight/needle. This tiny weight is underneath the discharge nozzle/squirter. So I took very fine grit sand paper to it and rubbed all burs off and bingo my Stang would start again. As for the high idle I too am trying figured that out too. Mine not that bad though, only about 900 rpm and my car misses at idle and after accelerator pump then clears out.
    Last edited by Ryan; 12-16-2012 at 10:05 PM.

  3. #3
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,091

    Default

    Look for vacuum leaks and watch these videos that apply to your dilemma:
    http://www.youtube.com/playlist?list=PL353239D6A7D7BFF0
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

  4. #4
    Ryan Guest

    Default

    Make sure choke is working when key is on and you may have someone watch the choke plate as you attempt to start it. If choke is closed too much any attempt to start will fail due too lack of air. If choke is all the way open pump it one time to the floor and turn key. And if your accelerator pump most works and nozzle discharge squirt is strong it should light. If it is cold as heck outside than it will only stay running for a few seconds. So repeat until it stays. If this attempt doesn't work at all then your not getting enough fuel whether it be accelerator pump failure or fuel pressure problem. (Bad fuel pump or fuel line size or hole in line) It should light with choke all the way open and ONE full throttle press. If its warm outside this technique should yield a started car first try. Also, too advanced timing or too retarded timing will cause a similar issue. Also, by dumping fuel down venturis you are bypassing all idle circuits and fuel passages. So as a last resort if none of the above gives you results you may have to pull it back apart and checks all bowl gaskets make sure they are not blocking any fuel passages and and spray the heck out of every passage there is. There May be debris blocking something. When you reassembled use Chap Stick plain, yes I said Chap Stick, coat all bowl gaskets with this glorious product. This will allow you to reuse new bowl gaskets when you take it apart for tuning. That is unless you like throwing money away every time you pull it apart. Once again if that accelerator pump doesn't squirt strong you play heck getting a cold start out of it.
    Last edited by Ryan; 12-16-2012 at 11:39 PM.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
    Posts
    23,091

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    IF the electric choke thermostat is functioning properly and the fast idle cam (speed screw) is correctly adjusted, I'd check the choke pull-off (qualification) setting. Check that the choke 'pull-off piston' slightly opens the choke blade, immediately after the engine starts. The vacuum operated choke 'pull-off piston' (inside choke housing) is sealed to the carburetor body by a tiny round gasket. Also, check that the throttle linkage is on the fast idle cam when choke is closed and you depress the pedal once (before starting). Ensure you have actual 14 volts at the electric choke thermostat when running and rotate the indexed plastic cap to adjust the opening rate. If your choke pull-off (qualifying) needs to be adjusted, do so following these instructions on page 7: https://www.holley.com/document/199r10013rev1.pdf
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 160A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/2800 RPM converter, M4602G aluminum driveshaft, FRPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 tires.

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