Truck running rough!
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Freshman User
Joined: Oct 2009
Posts: 47
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From: Hartsville, TN
Truck running rough!
Hello I recently bought a 77 ford f150 with a 351 W in it and Im having some problems. The truck was parked for 8 months and it fired rite up and idles fine, but when you give it some gas it bog's down real bad and acts like it's starving for fuel. I put a new in line filter on it this morning thinking that would fix it but it didnt work. When I drive it down the road it cuts out real bad and backfires in the Carb? Im ok with turning wrenches and dont have the money to take it anywhere to get it looked at so just wandering if anyone has any ideas? I have used some Carb cleaner on it but no luck with that either. Any help would be great. Its a 2 barrel carb!
New User
Joined: May 2009
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Following off what Montana_highboy said check fuel flow. I had the same thing on my 351m and it was clogged jets. I rebuilt the carb (kinda drastic to do in your case) and it runs like a champ now. With it sitting as long as it did its possible there is something in there no allowing a good flow. What you could do before buying parts is to take off the carb and blow out the jets with low pressure air.
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Freshman User
Joined: Oct 2009
Posts: 47
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From: Hartsville, TN
Ok I checked the fuel streams when i worked the throttle with the truck off and they looks good. 2 good healthy streams. So what next? yank it off and rebuild it or do ya thinks the problem is somewhere else?
Laughing Gas
Joined: Jan 2005
Posts: 1,011
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My old 360 did this and it turned out to be a pluged fuel filter. If it sat for a while it would fire up till it ran the gas out of the hose. There were two filters on my truck 73 f250 4x4. I think there is one on the carb too. That would make three. LOL Now I am not sure but does your truck have the ford dura spark? If so it could be the modual. Good luck
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Are you getting any fuel flow from the pump when you crank the motor over?
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Freshman User
Joined: Oct 2009
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From: Hartsville, TN
Well when I start it it will idle and run fine at low rpm's for as long as i want it to but when I get itno the higher rpm's it just bog's down. So I think the pump is working fine. I only changed one filter (the one in line before the carb) could it be a different fuel filter? I feel silly but it's been a long time since i worked on anything so may be a filter somewhere I don't know about.
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Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Check for other fuel filters, often there's 2 or 3 between fuel tank and carb, check your float level too, if set too low your float bowl won't fill completely and could be causing a fuel starvation issue at higher rpm's.
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Thread Starter
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Freshman User
Joined: Oct 2009
Posts: 47
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From: Hartsville, TN
The filter at the carb is see through and I am getting fuel to the carb. I will check the other filters tomorrow. Im not sure if the carb is the stock Autolite or not so I guess I will have to ID the Carb before I go into checking the float. Im not real good with Carbs lol. Thanks for the Ideas I will check it out.
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Backfiring through the exhaust is indicative of a too rich condition, backfiring through the carb is indicative of a too lean condition.
Senior User
Joined: Aug 2004
Posts: 463
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From: Arkansas
I've got what I think is a sticky valve and can hear a pop every now and then on decel. When the engine is cold I have to pat the gas a bit taking off or it will choke out and pop through the carb. Runs fine once warm.
Zombie Survivalist
Joined: Feb 2009
Posts: 14,809
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From: Rock Springs, WY, USA
reed. i would suggest you check your timing/ignition system as a precaution. i know that my 76 has some timing issues. had to advance the crap out of it to get it to run worth ten cents. at the point it ran good at idle, i had so much advance that it backfired through the carb when i get on it hard untill it got warm. then the thing is just a runnin monster. mine is an FE 360 or 390, not sure which.
Post Fiend
Joined: Apr 2008
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From: Big Sky Country
Is your choke opening and closing completely? a vacuum gauge will tell you if you have a valve sticking.