I need help fixing the carburetor in my FB. I am running WAY rich, and was told that if I were to replace the float that it should fix the problem. Only problem is that I have never replaced a float, and I am not too familiar with the carburetion, I only know about efi. ANY help would be greatly appreciated!

James

 

Not sure where your advice came from, but the only reason to replace a float is, generally, if it is leaking. In my sig line is a link to the online FSMs and the carb manual.

 

How do you know you're running way rich? at what section of the rpm band?

 

I am unable to keep the car running. At one point the car was idling so high and unstable it was backfiring and shooting fireballs from the exhaust. As of last night, the car will kinda start and then idle at around 300 rpms, and studder a lot. I know the spark plugs are probably fouled out now, but before yesterday, it was a fairly steady idle at 2000 to 2500 depending on the day.

James

 

Ok let me see if I can translate what you're saying. So you're saying the floats are not operating properly and therefore the fuel bowls are overflowing gas down the carb venturis, making the car run too rich?

 

I've seen two carbs just DUMP fuel out the jets. Both recent rebuilds, both by "professionals"...

I'm going to have mine "professionally" rebuilt...

By putting quotes around professional, I mean that sarcastically. In italics, it's where someone who was SUPPOSED to be a pro was paid to do it... in Bold, that means I will be doing it myself, having no prior clue as to what I'm supposed to be doing, but in the end knowing exactly what's up...

Hey.. it works for household repairs...

I suggest that your needle valves are clogged...

My basic understanding of a carb is this:

Fuel gets pumped from the tank... It goes to the bowls... When the bowls get full, there's a floater connected to a needle valve to turn off the flow. (Open the back of your toilet tank to see an example.)

The float bowls are not actually under any sort of pressure. The engine vacuum and air rushing through the venturis sucks fuel out of the bowls through the jets. The jets make a fine mist or vapor of the fuel.

The problem is that either A.) some dirt has jammed into the needle valve so it won't shut all the way. or B.) The floater has filled with fuel. It is now a sinker. Needle valve stays open.

Both result in the bowls getting fuel pressure and filling all the way up. Hence fuel drips out of the jets rather than being sucked out.

 

Thank you for understanding what I was trying to explain. I believe my float has become a sink and I was trying to find someone that has directions on how to repair, replace the float. I looked in the carb manual posted above this, but I was unable to find the directions on how to replace just the float.

James

 

Are you sure you don't have any vacumm leaks? Have you checked to make sure its only the carb?

 

Replacing the floats is pretty straight forward. You take the top hat off of the carb and the floats will come with it. The floats are held in by a pin shaft. Slide the pin out and the float comes out, along with the needle valve that is held to it with a spring clip. It is a very simple swap, do one float at a time, using the other one as a guide for reassembly.

If you have an aftermarket fuel pump that puts out more psi than the stock pump, and no fpr, it will produce the same symptoms you have now. If you are still running the stock pump, debris may be binding the needles in the sleeves they ride in, same results.

A small piece of debris at the needle and seat can prevent the needle from shutting off the fuel flow and raising the fuel level in the fuel bowls too.

 

Well, after further diag, I have kinda determined that I have an issue with debris in the needles. Is there an easy way to clean them out, or is this a rebuild thing?

James