Hi guys,
I recently purchased a 1976 F-150 4x4 with what I believe to be a 351m for $900. Obviously at that price the truck has a few problems . When I first got it home it was leaking a lot of oil. So I replaced the passenger side valve cover gasket and it helped a little. Next I hooked up the PCV valve to the base of the carburetor on the side closest to the cab and this really helped the leak. I'm now down to maybe 3 or 4 quarter sized drips after driving.

Question #1
I have a hesitation when hitting the accelerator from the start position. The truck starts up fine and idle's fine but when I first hit the accelerator the truck hesitates and maybe stalls but after that hesitation it runs fine. If I'm at speed and take my foot off the accelerator then hit it again I get the hesitation. I looked into the carburetor and I get 2 good squirts when hitting the accelerator. I replaced the accelerator pump diaphragm and this seemed to make the hesitation worse. I'm assuming my next step should be to rebuild the carb? I can't get a rebuild kit until this weekend or next weekend so is there anything else I should check?

Question #2
As I mentioned earlier I've hooked up the PCV valve to the carb and I'm getting good vacuum through the PCV. Next I started looking for vacuum leaks and the first thing I found was a hose coming from the TEE to hook up other things to the vacuum that wasn't plugged. Well I put my finger over the hose to check for vacuum and immediately it starts idleing rough, take my finger off and idle goes back to being fine. I know I should plug the hose but what should I do about idle?


Pics of the truck
http://i679.photobucket.com/albums/v.../IMG_00211.jpg
http://i679.photobucket.com/albums/v.../IMG_00191.jpg

Thanks in advance for any help.

Mark

 

What brand carb is it, Autolite, Edelbrock, Holley? if it's the original carb a rebuild certainly wouldn't hurt, they're cheap and easy to do, buy a can of Berryman's B-12 and give your carb a good soaking after disassembly.

Is your vacuum advance hooked up? if yes is it to ported or manifold vacuum? does your vacuum advance canister hold vacuum? these too can cause a hesitation off idle if not working.

 

I believe it's a Motorcraft 2150 which I think would be the original.

On the vacuum advance I'm not sure but will check this evening.

Thanks for your quick response.

 

The vacuum advance is hooked up but I'm not sure if the canister holds vacuum I'll check that this weekend. To add to the problem I started it up in the garage and wow it really smells like gas when it's running. Do you think the gas smell may be contributing to the problem?

 

It's most likely running too rich, at the very least i'd adjust the carb or better yet just rebuild it, if it's running too rich it can cause the engine to load up, stumble and bog, that may be the "hesitation" you're experiencing even though technically speaking hesitation refers to a lack of fuel the effects are somewhat similar.

 

the carb could be running too rich. i don't know carbs, but this could be a problem.

 

You may want to check that your choke is open at operating temperature. I had a problem with my engine stalling under load and found that to be my problem. I used the choke cap to adjust.

 

If that thing is a 2150 then it has an enrichment valve in it and they are pretty notorious for leaking. If it is leaking that could be where the smell is coming from. It could be running extremely rich and this as well could cause the hesitation.

 

Does anyone have any good diagrams of the 2150? I'm searching the site and can't find any.

 

Try here. Mine hesitates a little too, I always thought that was normal for this carb.

 

Thanks for the link I found one as well that has some adjustment instructions. The PDF is big but worth it as it comes with adjustment tables as well.

http://www.carbkitsource.com/tech/Fo...2050-547-2.pdf

 

So yeah I don't really know what I'm doing. Looking at the diagram and then the carb it looks like there is no choke. So should I just buy a new carb? Would a new carb come with the choke?

 

Can you post a picture of your carburetor? Then I can tell you what's missing. Don't buy a remanufactured carburetor; it's a wild goose chase. Carburetion is a science you need to spend a little time learning before you throw money at your truck.

 

I agree that I shouldn't just throw money at a problem without proper troubleshooting. So here are the pics.

Image hosting, free photo sharing & video sharing at Photobucket

Thanks again for all the help.

 

There's definetly no choke, that would explain you running rich, that carb is in dire need of a good cleaning, i'd certainly recommend rebuilding it if a new one isn't in the budget.