1981 F-100 running issues.
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1981 F-100 running issues.
Hey,
I have a 1981 F-100 4.9L 6 cyl.I just bought a new carb and installed it.Now the truck idles erratically(it revs up one second and barely runs at all the next)and when I turn it off it tries to stay running,I even have to let the clutch release in gear to turn it of sometimes.I appreciate all the help I can get.Thanks
I have a 1981 F-100 4.9L 6 cyl.I just bought a new carb and installed it.Now the truck idles erratically(it revs up one second and barely runs at all the next)and when I turn it off it tries to stay running,I even have to let the clutch release in gear to turn it of sometimes.I appreciate all the help I can get.Thanks
Senior User
Joined: Jun 2002
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From: Chandler,Arizona - USA
The erratic idle could be that maybe the vacuum lines are not connected properly, and you have a vacuum leak as a result. The run on after shut-off sounds like your idle is set too high. Re-check those vacuum lines, and your linkage. Good luck.
Post Fiend
Joined: Jul 2004
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From: Northern California
Do you have a MCU controlled carb, YFA or just a regular YF carb?
If you got the wrong carb, I.E. the wrong calibration, it will cause that problem.
With a MCU controlled carb, you have to get the EXACT replacement carb. Some Carb remanufactures lump several of them together, but they will not interchange, and cause the problems you describe.
PLEASE, tell me you still have the old carb.
. And it's got a Part Number on it.
If you got the wrong carb, I.E. the wrong calibration, it will cause that problem.
With a MCU controlled carb, you have to get the EXACT replacement carb. Some Carb remanufactures lump several of them together, but they will not interchange, and cause the problems you describe.
PLEASE, tell me you still have the old carb.
. And it's got a Part Number on it.
Post Fiend
Joined: Jul 2004
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From: Northern California
Originally Posted by sierraben
81-F-150-Explorer, I think he's from GA., so he may not have the same carb as you.
Why, you need a part number off of the tag on the carb?
Why, you need a part number off of the tag on the carb?
Well, that's why I asked him the question.
It could be a california import or something. I hope not! Anything is possible though. 
It could still be a calibration issue though, egr, distributor, Carb, etc.. all have to be calibrated for one another, and is critical for the MCU controlled ones.
The part number off the tag of the carb is to insure he gets an exact replacement. A carb with the number E1TE-DA will not replace a carb with a number of E1TE-GC as an example, even though they may look identical on the outside. The vaccuum ports will be calibrated differently, and "suck" a different amount of vacuum than the other carb.
A different calibrated carb, than the one that's called for may open the EGR too soon, or at idle, or cause the vacuum advance to advance the timing at the wrong times, or it may meter fuel at the wrong rate etc...
It's something that needs to be checked into at anyrate, even if in the future it turns out not to be a problem after all. Although it might be. If you understand. Leave no rock unturned.
Post Fiend
Joined: Mar 2004
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From: San Francisco, Ca.
81-F-150-Explorer, just thought you needed carb codes from a Ca. emissions carb.
You'd be surprise how many people just toss away I.D. tags off of their trucks.
I wrote down every tag/label number I could find and kept that info in my wallet; just in case a parts dude asked for it.
You never know.
You'd be surprise how many people just toss away I.D. tags off of their trucks.
I wrote down every tag/label number I could find and kept that info in my wallet; just in case a parts dude asked for it.
You never know.
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Post Fiend
Joined: Jul 2004
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From: Northern California
Well, that makes it a lot harder, but it's still not impossible yet.
There should be a calibration number on the radiator support, on the emission lable. You need to take that code to the local Ford dealer and if they are nice, and you tell them your situation, they should be able to tell you what carb is compatible with that calibration number. I bet there is only one or two at the most. You then cross reference that number with the aftermarket part number, and they should be able to tell if you got the wrong one installed.
It also might be a mislabled carb too. Just like the one you turned in for the core is most likely going to become mislabled to another unsuspecting customer, if they just rebuild the thing and read the part number off the box, and not the carb, if they are mismatched etc...
Never return anything for a core charge until the vehicle is running right, or that you know you got everything you need off the old part. First rule of thumb my autoshop teacher taught me in high school.
Good luck with your truck.
yet. There should be a calibration number on the radiator support, on the emission lable. You need to take that code to the local Ford dealer and if they are nice, and you tell them your situation, they should be able to tell you what carb is compatible with that calibration number. I bet there is only one or two at the most. You then cross reference that number with the aftermarket part number, and they should be able to tell if you got the wrong one installed.
It also might be a mislabled carb too. Just like the one you turned in for the core is most likely going to become mislabled to another unsuspecting customer, if they just rebuild the thing and read the part number off the box, and not the carb, if they are mismatched etc...
Never return anything for a core charge until the vehicle is running right, or that you know you got everything you need off the old part. First rule of thumb my autoshop teacher taught me in high school.
Good luck with your truck.
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Senior User
Joined: Sep 2005
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From: Milltown, NJ USA
Needle valve clean? Choke high speed linkage set up correctly? Also check the linkage rod and make sure it has the correct bend.
Just went through the whole set up process with my 1bbl Carter also. It was a real pain until it got straightened out. NOW it 's a blast to drive!
Just went through the whole set up process with my 1bbl Carter also. It was a real pain until it got straightened out. NOW it 's a blast to drive!
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