Autolite carburetor problem

[yodabiri]

Ok i am having serious problems with my autolite 1100 carb. I recently took the carburetor apart and changed the jet size on it from a previous 64 to a 67. The car was stumbling and surging before. Now it got better and drives a bit smoother, but after it stands in traffic at a red light for a couple of minutes it starts shaking and choking, and then stalls. I have had to push it out of the way twice already because it wouldnt start back up. Apparently it is flooding the carburetor and fuel is coming out of the top vent tube that comes out at the top of the airhorn. What could be causing this? I am completely stumped!

Any and all comments are welcome!

Thank you!

 

[Anonymous]

That is a sticky float (or bad float needle/seat)

 

[CZLN6]

Howdy Yodi:

Linc's got the diagnosis. Now, what to do? Here's a list of things to look for that might cause a needle valve/float to not seat an function properly.
*Float set too high.
*Gasket interfering with float or lever function.
*Needle wire hanger, needle valve and seat misaligned.
*Seat not tightened.
*Leak in the float, allowing it to fill with gas and not float as high as needed.
*Too much fuel pressure.

Another item to check and recheck is the automatic choke. They frequently get crudded up and can stick and do other weird things.

It is possible you have several issues going on. Cleanliness is very important with 1100s and even in ideal circumstances, they need to be cleaned and rebuilt regularly. I doubt changing to a #67 main jet fixed anything. It probably just masked the problem. The surging and stumbling could be a vacuum leak or a malfunctioning SCV or vacuum cannister, or vacuum leak.

Report back on what you find.

Adios, David

 

[Anonymous]

David, you sure are an asset to these forums.

Yoda, since you had the carb apart recently to change the jet, I am suspect that there is something jarred with the float, and perhaps it didn't get installed properly when you did the reassembly. Also the float level will have changed if the float arm got bent by accident in any way.

 

[yodabiri]

I have tried changing the seat and needle, and also filed off a little bit of the hinge on which the float pivots so that it does not catch on anything and the flooding still occurs. The car is a 200cid mustang with a manual transmission.

I will try and replace the seat and needle with the old ones that i had before and see if that has any effect on the flooding.

I will post back with the results.

 

[Anonymous]

David, you sure are an asset to these forums..

'


aint that the truth

 

[Anonymous]

I recently bought a 67' mustang and rebuilt my autolite 1100. I used a Car Quest rebuild kit. Part #901. Best 23 bucks I've spent on my car yet. It comes with the needle valve that you need. (bunch of other good stuff to) hope i helped

 

[addo]

You definitely deserve a welcome - first post in, sharing carb experiences.

Cheers, Adam.

 

[Anonymous]

also, if your float is brass, if it has a tiny pinhole or crack t may have "taken on" some fuel and would be heavier. Same thing with the black Nitrophyl floats, sometimes they get pourous and soak up gas and get heavier.

 

[yodabiri]

The float does not have any holes, i checked. So it must be the needle or the seat. I was also wondering about the vanve that is on top of the carb. What is its function? Does it release vapors or something?
Thank you for the respeonses!

 

[yodabiri]

The float does not have any holes, i checked. So it must be the needle or the seat. I was also wondering about the vanve that is on top of the carb. What is its function? Does it release vapors or something?
Thank you for the respeonses!

 

[yodabiri]

The float does not have any holes, i checked. So it must be the needle or the seat. I was also wondering about the vanve that is on top of the carb. What is its function? Does it release vapors or something?
Thank you for the respeonses!

 

[kirkallen143]

How did you check your float? Visually, not good way unless the hole is giant. Did you submerge it in water to see if any bubbles come out, or shake it to hear fluid inside? Just a thought.

 

[yodabiri]

I put the float in water and shook it and no bubbles or sound of liquid. So i might have the float adjusted wrong though, i will check that tonight and see if it helps.

Thanks

 

[mkgcars]

CZLN6 nailed it.


I was in this same boat - same behavior.

I had a number of issues.

1. My fuel pump was putting out too much pressure 7-8 lbs (and it wasn't very old either - but had been sitting for a good year+). When I replaced the needle valve and seat, it would be okay for a month and then re-appear. The new needle valve would work okay for a while but then not be able to handle the pressure. I got an Airtex replacement pump that put out within the 4-6 lb spec. Certainly check the pressure on a replacement pump a well - don't assume that a new one will meet spec. I checked the pressure by putting in a T-fillting between the soft line going out of my carb. If you don't have a soft line you'll have to rig one up etc.

2. My original needle valve and seat did need to be replaced.

3. When I continued to see fuel on the exterior of the carb I thought the issue wasn't resolved (see below for more info), and so I lowered the float (raised it if you have it inverted) by 1/32 as the spec reads 1 3/32 +- 1/32 (if I recall correctly) - I haven't changed it back yet, but I plan to try it.

I continued to see some leaking, which turned out to only be on the exterior of the carb - and didn't see any wholesale fuel flooding the carb, and the carb was running well.
Additional leaking issues were resolved by:

- Replacing the fuel line going into the carb. I don't think the original line wasn't seating correctly, which caused a leak and or may have caused the fitting into the carb to become unscrewed.

- The fitting going into the carb kept loosening up. You could tighten it, go on a 40 mile drive, and when you stopped there was fuel on the exterior of the carb. Using some blue threadlocker on the fitting going into the carb. Note: You may actually want to try teflon tape first. Mechanic friend told me this isn't that uncommon - that the fitting vibrates lose.


These second issues visually can look like the issue where too much fuel is getting into the bowl -but you can tell the difference because the carb will run well but you see fuel on the exterior of the carb.

With the flooding issue going on it will be hard to know whether all kinds of settings aren't optimal, carb accel pump setting, timing, plugs, jet, float setting, advance - as the car will be running so crapola. So, don't get too sidetracked with other settings until you get the flooding issue fixed.

Good luck, let us know how it goes.
matt

 

[Anonymous]

Note: You may actually want to try teflon tape first. Mechanic friend told me this

NO! NO! NO! NEVER use teflon tape on anything fuel system related.

NSTEAD, use ONLY Permatex brand "liquid teflon thread sealant"
It is 1000% easier to use and little pieces of it won't end up in your carb, and it ACTUALLY seals!

 

[yodabiri]

Come to think of it there was fuel leaking from the carb and around the fitting leading the hard fuel line into the carb. I recently replaced that fitting by the way because i cracked the old one. Anyways i am also coming to the conclusion that there is a problem with the fuel pump. I will try and buy a fuel pressure guage and make a soft fuel line to test the pressure.

Thank you all for your great responses!