carb leaking, and running rich

[tab a]

I had the feeling my '72s 350 with stock carb, was running rich, at least when idling--starts easily, runs better the colder the weather, restarts require pedal to the floor, when warm, idle gets progressively worse then dies--but to be sure used a colortune to check it.

When I removed the air filter I've found that with the truck running, there is a hint of fuel leaking from the base towards the front of the left side of the carb, near a horizontal screw (throttle stop?). When I shut the truck off, it leaks considerably more, soaking much of the left base of the carb.

Is this likely to be just a gasket --I'll confess I did remove the carb and clean it/check float, etc. a year or two ago WITHOUT replacing the gasket? I've read about leaking fuel wells--can they do this? Or are there other possibilities I've not thought of?

I'd appreciate any thoughts you might have, before I start taking things apart! Thanks.

[Wrenchbender Ret]

You have a bad needle & seat or a bad float. Often those plastic floats get soaked up with gas & are too heavy.

[NoNeck]

You didn't mention what kind of carb you have. Holley, Edelbrock, QJet, GM, two barrel or four barrel.

If it's a Holley 4 barrel, it sounds like the accelerator pump gasket. That vertical screw you mentioned would be for adjusting the pump "shot" (quicker, slower) to the carb when you are accerlerating from a standing stop. It gives the engine an extra shot of fuel to get the truck moving.

If that is the case, I would purchase a new accelerator pump. I would never reuse one after removing it from the carb because most of the time they tear at the corners. When installing a new one, it helps to coat the gasket surface with a little petroleum jelly. This helps the new pump gasket slide in place when you tighten the 4 mounting screws. Make sure you reinstall the little spring between the pump and carb housing.

Maybe this will help.

NoNeck

[ole dollor]

i don't know for sure, but i have had two different pickups with this problem, i ended up putting a three line fuel pump on and sending gas back to the tank to fix the flooding problem i had, yours could very well be the float level form a bad float or needle and seat. for some reason the newer carbs one the older motors have these problems. like i said i tried every thing i could think of to fix the flooding problems, and even a new carb did not fix the problem, tap the tank up high, and run the return line back to the tank. it worked for me, after checking the other float and needle and seat to see if they are good, you might try the three line fuel pump. this will relieve the pressure going to the needle and seat, hopes this helps.....

[tab a]

The carb is a stock (I presume) Qjet.

Are you guys talking about 2 separate problems? The needle/seat or float causing the rich conditions vs. something else causing the carb leak? Or are you saying they're likely both from the same cause? I understand the reasoning behind the former, but wouldn't have guessed a bad needle/seat would cause an exterior leak at the base of the carb.

Thanks again!

[Wrenchbender Ret]

A bad float or needle & seat cause the same symtoms. The fuel bowl fills up with gas & o-flows into the throat of the carb. If the throttles are closed it leaks out the throttle shaft or any small gasket leak. If the throttles are open it runs into the manifold & floods it causeing hard starting.

[Sport/Truck]

You should check your fuel pressure, if it's too high it will cause similar problems.

[Fogline69]

Hi,

Wondering if you got this figured out as I am having a similar problem. I have fuel leaking out by the throttle control. Not sure what kind of carb it is as I just got the truck and honestly don't know how to tell much other than it is 4 bbl on a 350.

Any help is appreciated.

Thanks

[geezer#99]

Take a pic Fogline and start a new thread over in the Engine section of the forum.

[Fogline69]

Originally Posted by geezer#99

Take a pic Fogline and start a new thread over in the Engine section of the forum.

OK. I will. I feel like this issue has been posted before a few times, so not sure if it makes sense to post again, but I will.