73 F750 Sputtering?
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73 F750 Sputtering?
Hi all. Got an issue with my dump truck. Was hoping for some help. First of all it has a 391 FT with a 5 speed When I shift into 5th gear it starts spitting and sputtering and hesitating real bad. I can pull the choke out all the way and it levels out. Once it accelerates a little bit I push the choke back in and it runs smooth every time. Only does this when I first shift into 5th gear. All other gears are smooth and very strong. Can't figure it out. I put a brand new carb on it. New plugs, wires, cap and rotor. Used dry gas. Running 93 in it. Nothing helps. It was running great then one day started this problem. Any help would be great! Thank you
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WAG alert: Power valve in carb is wrong size or damaged. Older Holley carbs are vulnerable to power valve damage if the engine backfires. Did you have a backfire issue after which it started running like this?
You may also be running out of fuel. Float level too low, or lack of fuel pressure could starve you after a run through the gears and then the initial load in 5th.
Vacuum leak could do it too.
You may also be running out of fuel. Float level too low, or lack of fuel pressure could starve you after a run through the gears and then the initial load in 5th.
Vacuum leak could do it too.
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Freshman User
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WAG alert: Power valve in carb is wrong size or damaged. Older Holley carbs are vulnerable to power valve damage if the engine backfires. Did you have a backfire issue after which it started running like this?
You may also be running out of fuel. Float level too low, or lack of fuel pressure could starve you after a run through the gears and then the initial load in 5th.
Vacuum leak could do it too.
You may also be running out of fuel. Float level too low, or lack of fuel pressure could starve you after a run through the gears and then the initial load in 5th.
Vacuum leak could do it too.
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It had a 4160 on it before this started and it ran great. So I replaced it with a 4160. I'll have the float levels checked. Thank you!
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Frustrated
Im at a complete loss and frustrated as hell. I had to carb adjusted. Replaced fuel pump and filter. Pump has great pressure. Used dry gas. Replaced plugs wires and cap AGAIN. Put a new air filter on it. Still the same. No change whatsoever. It will run great for a few miles then spit and sputter when you give it gas. Gotta drop all the way down to third to have any power. Then all of a sudden it'll be fine again. I just dont get it. I could really use some help. Thanks
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Woohoo!
Finally! Problem is fixed. Oil breather/separator was bad. Had a hole in it. Was letting oil get into the carb. Replaced the breather and plugs and she runs like a top!!
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