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Okay well a while back I thought I got rid of the little dead spot that was occurring right off idle. Well it’s back and it’s right off idle, if I ease into the throttle it’s seamless, but push it a little bit and it goes lean and wants to die, but catches back on if I let off.
what’s been checked:
vacuum leaks- none found
vacuum advance canister- held vacuum great
coil - great
points- great
Here’s what’s odd to me and I cant seem to find a solution. When trying to rev up from using gas pedal it stumbles and has the dead spot, and same if I move it by hand under the hood.
HOWEVER if I go under the hood and move the accelerator pump and throttle butterfly by hand at the same time it revs up fine. And there is no stumble.
Yes I have adjusted the linkage so that it should move as soon You hit the gas, but it moves slow. Seems like the spring on the side of the carb doesn’t have enough power to move the arm as fast as it needs to.
This may not be the problem but it is an easy one to check.
One thing that can contribute to that off idle stumble is having the idle mixture screws in too much. (to lean). That will cause the transition circuit to be lean and when it runs out of the pump squirt it will stumble. That usually happens a low rpm before the main circuit is suppling enough fuel to keep things humming.
Okay well I can of course try and set those later today, I’ll just have to look up how I do that. It’s been a bit since I’ve done it. When carb was rebuilt I just put them back in the number of turns I took them out
Okay well I can of course try and set those later today, I’ll just have to look up how I do that. It’s been a bit since I’ve done it. When carb was rebuilt I just put them back in the number of turns I took them out
Without getting out a shop manual the general recommendation is to gently bottom them out then open them up 1 1/2 turns. After that you need a vacuum gage to fine tune the idle. Just make sure your ignition system is all good before you fine tune the carb. But at 1 1/2 turns out it should be close.
Okay well I can of course try and set those later today, I’ll just have to look up how I do that. It’s been a bit since I’ve done it. When carb was rebuilt I just put them back in the number of turns I took them out
The 1.5 turns on the idle mix screws is just a base to get the engine to idle. Adjusting is done with a vacuum gauge and you adjust the screws to just achieve maximum manifold vacuum.
If you do not have a vacuum gauge you can do it by adjusting to maximum engine rpm although not as accurate it is better than nothing.
A pic of your carb linkage showing the accel pump rod would also help us diagnose the issue.
Looks like you have a ground wire that is not connected to engine (right red circle) - May have nothing to do with your problem, but there should be a ground from engine to firewall.
regarding the red circle to the left - that linkage has two possible install locations on the pump arm. Obviously each position is used with certain applications, I don’t know which is correct for you, but maybe someone with access to a shop manual can check.
I had a problem once with the accelerator pump diaphragm getting brittle from the ethanol in the gasoline. It had to be forced to move. You said that you had replaced it recently, there are still some out there that are being sold that are not resistant to ethanol gas.
Ok a couple things right off the bat This looks to be an FE given the casting number on the intake. That does not look like a 2100 but a 2150 so not sure this is even the right carb.
What displacement is the engine?
Also given the pool of half evaporated gasoline under the throttle shaft seem to excessively worn. This may be your problem. As the when you are using the pedal the shaft will be sitting in it's bore as this is the wear pattern and when you actuate it by hand you are not shifting it as the load will not be on the direction of wear.
At this point I would say you need a new carb. If you give us the year and engine displacement I can link you to a good rebuilt unit.
1. The ground strap I took off a while back to get rust off a bracket and didn’t see it until you pointed it out. Thank you!
2. The linkage is in the closer because I moved it. Asked in an F100 Facebook group and one guy said try it. Seems to help.
3. I doubt that the diaphragm is dried out yet because it did this since the rebuild. I would be surprised if it got dried that fast but you never know
4. it is an FE 352 (1966)
5. I have the tag on the carb which I can get the numbers off of later to identify possibly.
6. It’s actually not gasoline, it’s a degreased which now contains grease. I had not cleaned it off yet. I checked when I rebuilt to see if the shaft was word and it seemed to be all good.
about the diaphragm; where do I get one to be sure it’s resistant?
1. The ground strap I took off a while back to get rust off a bracket and didn’t see it until you pointed it out. Thank you!
2. The linkage is in the closer because I moved it. Asked in an F100 Facebook group and one guy said try it. Seems to help.
3. I doubt that the diaphragm is dried out yet because it did this since the rebuild. I would be surprised if it got dried that fast but you never know
4. it is an FE 352 (1966)
5. I have the tag on the carb which I can get the numbers off of later to identify possibly.
6. It’s actually not gasoline, it’s a degreased which now contains grease. I had not cleaned it off yet. I checked when I rebuilt to see if the shaft was word and it seemed to be all good.
about the diaphragm; where do I get one to be sure it’s resistant?
carb tag:
C6TF T
F 6FB
Regardless what the tag says, that is definitely not the original carb, and appears to be a late model 2100 or early model 2150,
Also the venturi size on that carb is wrong for the 352 (undersized) and it has an auto trans kick down I assume your truck has a manual, or it's missing the kick down rod.
I was wanting to keep this truck as stock as possible, including the carburetor. Not looking to upgrade the engine whatsoever so I’m fine with the carb that it originally would have had, or as close as possible. Is there a way I could make this carb work at least for a few years? Is there a Venturi I can buy that would be correct?
i also do not understand the differences between a 2100 for a standard gearbox vs. an automatic. I would appreciate it if someone could clear this up!! Thanks everyone has been a big help so far
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