idle problem when first turning over?
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Junior User
Joined: Dec 2007
Posts: 61
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From: Harpswell
idle problem when first turning over?
first off, New to the forums so hey to all. bought my first vehicle a few months ago (78 f250) absolutly love it even though shes got a few problems. not very mechanical at all so hopeing to learn alot with this baby.
truck info:
78 f-250
2w drive
automatic trans
i was told it has a 351 cleveland but i read somewhere that they stopped putting them in trucks in 74, so i dont know if its been switched out over the years or if i was given false info
Question:
sometimes when i turn the truck on she sounds like she wants to die, like its idling at a low rpm(i think? again dont know much about this stuff hah) kinda like a vrooom.....vroom....vrooom. shes only actually died once while doing this in the 2-3 months i have had her though. if i let her sit there she'll stop doing it after about 5 min and run normally or if i just turn it on and go itll clear up a within a few hundred feet. however she doesnt always do it sometimes shell turn over and be 'full force' right away. any ideas on how to clear this up?
truck info:
78 f-250
2w drive
automatic trans
i was told it has a 351 cleveland but i read somewhere that they stopped putting them in trucks in 74, so i dont know if its been switched out over the years or if i was given false info
Question:
sometimes when i turn the truck on she sounds like she wants to die, like its idling at a low rpm(i think? again dont know much about this stuff hah) kinda like a vrooom.....vroom....vrooom. shes only actually died once while doing this in the 2-3 months i have had her though. if i let her sit there she'll stop doing it after about 5 min and run normally or if i just turn it on and go itll clear up a within a few hundred feet. however she doesnt always do it sometimes shell turn over and be 'full force' right away. any ideas on how to clear this up?
Laughing Gas
Joined: Dec 2000
Posts: 781
Likes: 18
From: East Texas
The engine in the truck, if original, is a 351M. Fourth digit of the VIN will indicate the original engine (H = 351M, S = 400 if I'm not mistaken). The 351M and 400 are visually identical on the outside (only difference between the two is crankshaft and pistons).
When the engine is cold and you push the accelerator pedal to the floor and release it, two things happen:
Automatic choke (if so equipped, either climatic or electric) closes throttle plate to the preset setting, and the throttle moves up on the fast idle cam. When those two things occur correctly, all other things being equal, the engine should start and idle up to ~ 1,200 - 1,500 rpm. The choke and idle settings can be found on the valve cover sticker. Mil1ion can assist with the calibration info should the underhood stickers be missing. The carburetor on my 77 is still not exactly right, so I am apparently not sure how to get it exactly right.
One of the best investments for your truck is the original shop service manual on CD-ROM which is still available from a company called Detroit Iron. That and taking advantage of the great wealth of knowledge available on this site.
When the engine is cold and you push the accelerator pedal to the floor and release it, two things happen:
Automatic choke (if so equipped, either climatic or electric) closes throttle plate to the preset setting, and the throttle moves up on the fast idle cam. When those two things occur correctly, all other things being equal, the engine should start and idle up to ~ 1,200 - 1,500 rpm. The choke and idle settings can be found on the valve cover sticker. Mil1ion can assist with the calibration info should the underhood stickers be missing. The carburetor on my 77 is still not exactly right, so I am apparently not sure how to get it exactly right.
One of the best investments for your truck is the original shop service manual on CD-ROM which is still available from a company called Detroit Iron. That and taking advantage of the great wealth of knowledge available on this site.
Last edited by firstonraceday; Dec 27, 2007 at 07:22 AM.
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Originally Posted by guitar_demon
first off, New to the forums so hey to all. bought my first vehicle a few months ago (78 f250) absolutly love it even though shes got a few problems. not very mechanical at all so hopeing to learn alot with this baby.
truck info:
78 f-250
2w drive
automatic trans
i was told it has a 351 cleveland but i read somewhere that they stopped putting them in trucks in 74, so i dont know if its been switched out over the years or if i was given false info
truck info:
78 f-250
2w drive
automatic trans
i was told it has a 351 cleveland but i read somewhere that they stopped putting them in trucks in 74, so i dont know if its been switched out over the years or if i was given false info
False info.
No 351C engines were ever installed in F Series trucks, Bronco's or Econolines.
Passenger cars only.
Question: After the truck warms up, does it bog down under acceleration?
If so = Replace the accelerator pump diaphragm and check valve.
C4AZ-9576-A .. Acc. Pump Check Valve (Motorcraft CM-825)
D5AZ-9B559-A .. Acc. Pump Diaphragm (Motorcraft CM-2092)
Also: Check the fast idle cam = your problem may be there. It's made of plastic (it's white in color) and over time, it'll snap in half.
The fast idle cam is mounted on the drivers side of the engine, between the choke and the carb.
D5AZ-9597-A .. Fast Idle Cam (Motorcraft CM-2105)
Shop manuals: Originals in printed form: helminc.com / faxonautolit.com
Faxon has reprinted originals and used shop manuals, sales brochures, owners manuals and Ford Data Books.
Firstonraceday is correct on the 351M/400 engine VIN codes.
Last edited by NumberDummy; Dec 27, 2007 at 07:27 AM.
Thread Starter
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Junior User
Joined: Dec 2007
Posts: 61
Likes: 0
From: Harpswell
Originally Posted by NumberDummy
Welcome to FTE
Question: After the truck warms up, does it bog down under acceleration?
Question: After the truck warms up, does it bog down under acceleration?
thanks to all
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 787
From: Simi Valley, CA
Originally Posted by guitar_demon
not sure what you mean by that.
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