I have a holley 4 barrel carb on my jeep that has been working great until yesterday. I went cruising around at the ranch and when I shut the jeep off I heard something dripping and sizzling on the exhaust. I raised the hood and noticed there was fuel dripping from the carb onto my exhaust manifold. I took off the air cleaner and noticed there was fuel flooding out onto the throttle valve. It appeared to be coming from the holes the throttle valve shaft runs through. The venturies weren't dripping and once it started it ran fine. Any ideas what would cause this?
Carb issue
- Thread starter kc jones
- Start date
slo-wrench44
New member
Could be that your throttle shaft bushings have worn out. This can happen if you run a heavy return spring or it's just old. You can replace them but you will have to get a rebuild kit.
Look into the possibility of the float level being set too high or debris has cause the needle to remain open.
After your next engine shut down open the bowl level viewing plugs, if fuel runs out there either of those will be the issue.
It should be set so that the fuel just reaches the hole but not in excess so that a drip runs.
As mentioned the throttle bores may be worn however that will show itself with symptoms of a nasty air leak.
Point is that fuel should not be available so to leak at the rod after shut down.
After your next engine shut down open the bowl level viewing plugs, if fuel runs out there either of those will be the issue.
It should be set so that the fuel just reaches the hole but not in excess so that a drip runs.
As mentioned the throttle bores may be worn however that will show itself with symptoms of a nasty air leak.
Point is that fuel should not be available so to leak at the rod after shut down.
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Thanks for the tips. I plan to pull the carb tonight and give it a good cleaning. It is less than a year old with little use in that year although I do run a fairlly heavy return spring. If the bushings are worn bad enough to leak like they apear to be, will there be a noticeable amount of play in the shaft or is it one of those things where you just replace the bushings and hope the problem is solved. As far as the float level goes holley decided not to put a level plug in this model carb so From what I understand I'll need to find a gauge that screws into the lower bowl screw hole.
A word of caution with using "a fairlly heavy return spring" when it is in excess of what is required is one of the two major causes of worn throttle rod bushings. The other being that anchoring the spring so that it is not in-line with the accelerator cable's draw of the rod or in other words it should be anchored at a point that is 90* from the axis of rotation of the rod, just the same as the accelerator cable.
Either will allow that pressure to cause the rod to wear into the bushing at one point instead of rotating smoothly in the center of the bushing.
At a year old you should not be experiencing any notable wear unless one of those conditions exist.
While the throttle plates are closed any excess fuel will leak there since there is no other place for it to exit aside from a extremely slow run between the plates and the bore. So naturally it occurs there.
As I said earlier if you have excessive wear it will be a major cause of concern since air passing by will cause you grief in maintaining a smooth idle, it causes hesitation and will often cause a lean pop in the carb.
That fuel leaking thru the bushing is not the issue, until it evaporates or drains by the plates it will run out at the point of least resistance, the rods.
It is a symptom of having residual fuel laying on the plates..
Either will allow that pressure to cause the rod to wear into the bushing at one point instead of rotating smoothly in the center of the bushing.
At a year old you should not be experiencing any notable wear unless one of those conditions exist.
While the throttle plates are closed any excess fuel will leak there since there is no other place for it to exit aside from a extremely slow run between the plates and the bore. So naturally it occurs there.
As I said earlier if you have excessive wear it will be a major cause of concern since air passing by will cause you grief in maintaining a smooth idle, it causes hesitation and will often cause a lean pop in the carb.
That fuel leaking thru the bushing is not the issue, until it evaporates or drains by the plates it will run out at the point of least resistance, the rods.
It is a symptom of having residual fuel laying on the plates..
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