Newbie with carb problem
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Newbie with carb problem
I have a 1978 f-250 with a 351W and motorcraft 2150. I'm having problems with the engine bogging down when under load. The engine will run without load on it but when I ease the clutch out and start giving it gas it chugs and sputters. I've tried adjusting the float, starting at a dry measurement of 9/16" and no gain either higher or lower. What else could be wrong? IT was running kinda rough before I replaced the needle and seat, now it hardly runs at all. Any ideas?
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Now this is funny!!! My 77 has been doing the same thing lately. I think I finally might have, maybe did, quite possibly but not sure though, figured out the problem. OK now that thats outta my system, make sure the fuel tank is vented and make sure the fuel filter isnt plugged or full of water. Mine did the same thing yesterday but was fine today after putting on a new fuel filter and a new gas cap. Hope this helps!!!!
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From: Bethlehem, PA
when you say boggin down do you mean like a stutter?...kinda like it isnt getting enough gas?...the acelerater pump could be shot...that would cause a power loss of the start and stuttering type issues...def. check your fuel filter first...you might be better off just rebuilding the whole carb, a rebuild kit for those things is like 20 bucks...easy to do aslo...
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I just replaced the fuel filter when I replaced the needle and seat. I tried pushing the throttle linkage and the accelerator pump did inject gas into the carb intake. THe carb did sit for a year on another engine, do you guys think I would be best off just rebuilding the carb? What about vacuum leaks, could that be the cause of the problem.? The bog is a lot like a stutter. I thought at first it wasn't gettin enough gas so I started adjusting the float to allow more fuel in the bowl. Eventually it started over flowing and the stutter got worse, tried lowering the fuel level in the bowl and it didn't make a differnece. I can rev it up when the gear shift is in neutral but as soon as I apply a load it stutters.
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What is stutter? I have been working on cars for 40 years and I have never seen this stutter some people talk about. I have seen engines and vehicles shudder but never stutter. What is it? As far as I know it is only a speech problem not a car term.
Stutter: noun; A speech disorder involving hesitations and involuntary repetitions of certain sounds. Verb; Speak haltingly.
Or- Stuttering (commonly known as stammering and scientifically known as dysphemia) is a speech disorder in which the normal flow of speech is frequently disrupted by repetitions (sounds, syllables, words or phrases), pauses and prolongations that differ both in frequency and severity from those of normally fluent individuals. ...
Shudder: noun; An involuntary vibration. Verb: Shake or tremble convulsively.
Stutter: noun; A speech disorder involving hesitations and involuntary repetitions of certain sounds. Verb; Speak haltingly.
Or- Stuttering (commonly known as stammering and scientifically known as dysphemia) is a speech disorder in which the normal flow of speech is frequently disrupted by repetitions (sounds, syllables, words or phrases), pauses and prolongations that differ both in frequency and severity from those of normally fluent individuals. ...
Shudder: noun; An involuntary vibration. Verb: Shake or tremble convulsively.
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the best way I can describe what the truck is doing is that its like dropping the clutch and getting spring wrap occilations. Except its cause by the engine and not the moron attached to the clutch pedal. I just went and checked that carb mounting nuts and they were a little loose. I tightend them but didn't put the death grip on them. I'm gonna try tweaking the float level again and if that doesn't work I'm thinkin it might be time for a rebuild of the carburator.
Hotshot
Joined: Oct 2002
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From: The Big, Oregon
Have you checked the timing? Disconnect the vacuum advance line and plug it, then check the timing. It should be at 6-8ºBTDC at idle.
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I got it. The brake booster is leaking. Un hooked the vacuum line, folded it over and zip tied it. Runs like a champ, stopping is a another matter.....
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Posting Legend
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Ahhh, what you described is called surging...
There is a $2 seal inside that booster that leaks, unfortunately it is made of unobtainium and the entire booster will need to be replaced.
I usually replace the booster and MC as a unit instead of messing with the intermediate rod adjustment. The rebuilders know all the different combinations of parts that are found out there after all these years and usually set it right.
There is a $2 seal inside that booster that leaks, unfortunately it is made of unobtainium and the entire booster will need to be replaced.
I usually replace the booster and MC as a unit instead of messing with the intermediate rod adjustment. The rebuilders know all the different combinations of parts that are found out there after all these years and usually set it right.
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Sorry to drag topics up from the dead but I finally found the actual cause of the problem and maybe this knowledge would help someone else.
It wasn't the brake booster. Come to find out there was crap in the fuel tank that was small enough to get through the stock filter but large enough to float around the float bowl and block one of the main jets. Since my engine has a split intake, blocking a jet effectivly kills half the engine. I installed a paper filter before the fuel pump and haven't had the problem since.
It wasn't the brake booster. Come to find out there was crap in the fuel tank that was small enough to get through the stock filter but large enough to float around the float bowl and block one of the main jets. Since my engine has a split intake, blocking a jet effectivly kills half the engine. I installed a paper filter before the fuel pump and haven't had the problem since.
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