I've been having a strange issue on my car lately that I have absolutely no idea how to fix and no amount of searching has turned up anything useful so far. I decided a while ago to swap out my intake manifold and carb for an edelbrock performer RPM and a holley (along with a new distributor) but have had nothing but problems related to the carb. I got everything on fine and hooked up properly (checked by my neighbor who's been a mechanic for 20+ years) but the carb will not stop dumping a ton of fuel in no matter what I do. The carb is not new, my friend had it on his 84 camaro when he got it and rebuilt it in an attempt to fix this problem but ended up getting a new carb before he could use it. I bought it from him for the price of a rebuild kit since we figured that would solve the problem. Clearly though, it didn't. The car ran rich no matter where the mixture screws were set and the floats were properly set. It also had a slow fuel leak on the outside by the rod going into the vacuum actuator for the secondaries. I don't know much about cars/carbs but it just doesn't seem like fuel should even be able to get in that part of the carb, let alone leak from there.

My neighbor looked at it and said that sometimes a part gets cracked or something and a carb will develop this sort of a leak which can't be fixed. That made sense to me, given the situation and my lack of experience, but I tried another similar rebuilt holley from my friend that was working on a previous car and I have the same problem. It may actually leak even more now. I didn't even get to adjust it because the car wouldn't start and I stopped trying when I noticed the fuel leak was still there. I've searched this forum and elsewhere online and have not found anybody else with this issue nor have I seen any mention of something like this happening. After looking through the holley manuals and examining the parts diagrams I can't even see how the fuel can get in there but it's quite possible that I'm missing something. Any ideas? Suggestions? The car ran fine before the swap so it must have something to do with the new parts.

84 trans am
stock LG4
edelbrock performer RPM intake manifold
holley 4 barrel carb with vacuum secondaries & electric choke (not sure of exact model)
summit HEI vacuum advance distributor

I'm completely stumped and without my own vehicle right now so any suggestions or ideas are welcome, I'd like to drive my car again asap. Thanks.

 

Try lowering the float level bit by bit & see if it stops leaking. I know a bad power valve can cause it to be rich but the kit shoulda had one in it. Could the floats be mounted upside down?

 

It sounds like you may have used the wrong gasket between the throttle plate and main body.

 

I'll try checking out the floats but I doubt they're in upside down. If the weather is nice then I'll be able to do it tomorrow and I'll let you know what I find. As for the gasket, would that cause it to leak from the vacuum actuator? It leaks from the actuator itself and drips down the rod, THEN onto the intake manifold. Seems like there shouldn't be any gas in there under any circumstances and I don't know how it would even get there. I may be able to at least put up some pictures to make it easier to troubleshoot.

 

There is absolutely no way gas should be anywhere near there. You either have a crack or a wrong gasket. It sounds like you are going to have to tear it down and inspect the casting very closely.

 

DO YOU HAVE A MECHANICAL OR AN ELECTRIC FUEL PUMP? IF ELECTRIC, YOU MAY BE PUSHING TOO MUCH FUEL PRESSURE.

 

I'm assuming it's mechanical because if I turn the ignition to on I don't hear any hum or other sounds indicating that a pump is active. I also have to pump the gas pedal a bit if the car has been sitting for a while in order for it to start up quickly. Just talked to my friend who rebuilt the carb and said he changed gaskets, float valves, power valve, and o-rings. All of that is brand new. He also said it doesn't even seem possible to mount the floats upside-down. As for fuel pressure, the car was carbed before so I would assume the fuel pressure is the same as it was before the swap and thus not a problem. Is there any reason that changing to a non-CC carb would affect fuel pressure? I meant to get some pictures on Sunday but it was raining. I should be able to get a few pictures up this weekend when I'm back from school.

EDIT: Did a little more research and I have to agree with TylerP that is sounds like a power valve issue even though there was a brand new one in the rebuild kit. Holley carbs after 92 had a check valve or something to protect the power valve but I'm not sure how old this carb is so it's possible that this one didn't have that. The car did backfire multiple times with the first carb so, if it didn't have this protection, it's possible that the power valve was blown as a result. The power valve should be fine and likely isn't the problem but I'm going to test it out anyway. As far as I know, the old power valve on the second carb was working before the rebuild so we'll try swapping that back on and see if that improves anything. Hopefully the solution to my problem will be that simple, I can't afford a new carb right now.

 

Ok, got a slight update on my issue. It still has not been resolved but I finally got some pictures. I got it to run with the second carb on but for some reason the throttle sticks open so it nearly redlines at idle unless I close the throttle myself. Not sure why it does that but my primary concern right now is still the fuel leak as I'm sure a little lube will fix the sticky throttle. Anyway, I took a look at the original carb while I was taking pictures of it and now that it's off the motor I got a better look at the main body gasket where I think the problem may be. Originally it seemed like the leak occurred near the diaphragm for the secondaries even though that shouldn't be possible. I think what was actually happening was that fuel was spraying from somewhere else onto that rod making it seem as if the leak was over there when it really wasn't. I found a spot nearby where it seems that the head of a screw is pushing the gasket away from the surface of the carb and that could very well be causing the spray that I just mentioned. Does that screw look to you guys like it might be problematic? I don't know how anything is supposed to look really but common sense tells me that it's probably preventing a proper seal in that area. You can see it best in the last picture, circled in red. I also circled in the first picture where it seems most of the fuel leaks out. The first carb I used is the black and gold one that is currently off the engine and the second carb is the purple one that is currently installed. Let me know what you think. If you need better pictures of certain things let me know and I'll put them up. I really want to get this car back on the road.

 

By the time the fuel gets to the fuel bowls, it is no longer under pressure. So, it can't spray from the base gasket.

Did you use gasket sealer on the carb mount gasket? If you did, that's a no-no, and could be what's causing your throttle to stick.

I would never put a painted carb on my engine. Way too much of a possibility for it to flake off and cause problems, and that is clearly flaking off.

 

Check your fuel pressure.
Make sure the needles are seating properly in each bowl.

 

Ok, I guess that rules out spraying but do you think that screw could still be causing a leak or is that how it normallly looks? Also, the carb is only painted on the outside so the flakes shouldn't be able to get into it. As far as I know, there was no gasket sealer used on the carbs but I'll verify that with my friend next time I talk to him. Since the fuel pump is mechanical and I made no changes to the fuel system other than the carb, is it possible to have excessive fuel pressure? I definitely plan on having my neighbor pop the carb open and checking out the floats and whatnot though, I'll have to grab him when he gets out of work sometime this week. Thanks for the suggestions, let me know if you think of anything else.

 

Been thinking about this over the last few days and now I'm wondering if this could be the result of a vacuum leak. I'm fairly certain that my vacuum lines are hooked up properly (initially the PCV and distributor were not but I fixed that) but I did change the intake manifold and we had some trouble lining it up at first. I'm not sure how likely it is that there is a leak there but if the seal was crummy over there, what would my symptoms be? I would think that would make the fuel mixture crazy lean. Initially I ruled it out as a possibility because of that but as I'm reading through some Holley carb manuals, it says that turning the mixture screws clockwise richens the mixture and my car wouldn't even start unless I turned them all the way in. Of course I do have a slight fuel leak so maybe that's why I have to richen it but if there is a hardcore vacuum leak then that could cause some mixture issues too. I think I read that you'd probably hear some kind of whistle if the seal was bad on the intake manifold but I don't recall ever hearing a whistling sound after the swap. I'll have to try to get outside and take a look at it. What do you guys think?

EDIT: You know what, I think I might just pop this thing open myself and attempt my own rebuild. Summit has rebuild kits for the Holley 4160 for just over $20 and it would be a good learning experience. I believe the kit comes with instructions. I've never done it before and I don't know a whole lot about carbs, do you think it's simple enough that I could do it properly with the Holley guide and some common sense? I was avoiding this because it seems like there are a lot of parts and a tiny mistake can have a big effect but my curiosity and desire to drive my car again are really eating away at me. I tend to be good at fixing things so I think I might be able to do it. Any tips/hints/suggestions? Also, there were like 3 different rebuild kits on summit but it looked like most of them had the same parts despite a $10-20 difference between each. I'm not familiar with the parts in the pictures and the descriptions are too vague so can any of you help me out with the reason behind this price difference? Here are the kits I was looking at:

I plan to get this one, this is $10 more, this is even more expensive

Also, if you look in the pictures of my carb that I linked to before, you can see that the throttle return spring, throttle cable, and TV cable are hooked up kind of weird. Does holley sell a bracket(s) specifically for 3rd-gens? I'm especially worried about the TV cable because it's barely hanging on and from the little bit that I've read about it, it seems that if it is not hooked up properly it will cause the trans to kill itself which I absolutely can not afford to deal with any time soon. Is there an aftermarket solution to that or can I transfer the old linkage onto this carb?

 

I took the carb apart to inspect it and found no signs of damage and all seals looked to be in great shape. Floats were moving freely and everything looked fine internally. The only thing I noticed was that the screw and washer that hold the rod onto the carb near the vacuum diaphragm were missing. I had those on the other carb which did not leak from that area and put them on the first carb, hoping that would fix my problem. I swapped carbs again today and the problem is still there. I still have a slow drip of fuel at the bottom of that rod and I can't seem to figure out why or how it occurs. The gaskets are all fine, everything is tight, and all parts are there so what could possibly be causing this?

Assuming I can't figure this out tomorrow or next weekend, I'll have to try getting a new carb all together. I need my car back on the road and this has gone on far too long. I will probably get this Holley 80450 from summit but I also found this summit brand carb that looks pretty nice (and it's cheaper). Would it be a bad idea to try my luck on the summit carb or should I go for it (assuming I can't get one of my current ones working)?

 

Is there any particular reason you're looking a vacuum secondary carbs?

Are you using the same fuel line, nuts, etc. between the two carbs? Or, am I mistaken that both carbs are dripping from the same place?

 

I like the idea of vacuum secondaries because my car is mostly stock right now and has very modest fuel requirements but I have a 327 that I would like to drop in when I have the money to clean it up and make it nice, at which point my fuel requirements will increase. From my understanding of carbs, vacuum secondaries are ideal for this situation since the carb will only feed as much fuel as the engine demands. This car is also meant to be more of a daily driver and might see the track in a few years (out of curiosity) but my goal is basically just to make it a street car with some *****. Would I be better off with something else?

The fuel line is different because the old carb was the stock quadrajet and when I changed intake manifolds I needed a square-bore carb so I went with a holley. I replaced the old fuel line with rubber hose (3/8" I believe) and an inline fuel filter. You can see it in this pic:



Between the two holley's, yes, I use the same fuel line, filter, and fitting. There is no leak or other noticeable issue in that area. Both carbs are leaking in similar areas but I'm not sure it's for the same reason. There was leakage near the base of the purple carb, near the back passenger side but the black/gold one leaks near the rod that opens the secondaries. I was trying to figure out the exact origin of the leak but it's hard to tell. I changed the gasket between the carb and intake to rule that out and it seems that it seals fine there. However, I still have a slow drip of fuel off that rod coming from the vacuum diaphragm and I'm unsure where it originates. I thought maybe fuel was leaking through that screw hole that I mentioned in the last post but putting the screw in didn't help and the other carb didn't have that problem. I'm quite stumped.

My neighbor did say that these carbs tend to do this after a while and they generally can't be fixed when they do but that just doesn't make sense to me. All gaskets seemed to be in great shape and I didn't see any signs of cracked or warped components. I did notice, however, that there is something odd about one of the mounting studs for my carb. The front driver's side stud seems to want to unscrew from the intake manifold before allowing me to tighten the nut down. It's a real pain to work with and I can't get it as tight as the other 3. I figured having the other 3 tight would compensate for that but could this be causing an issue? I mean, there is no sign of leakage in that area (fuel or vacuum) but is it possible that something as seemingly insignificant as that could be causing my problem?

 

Okay, I had a brain fart and forgot this was a single feed carb.

The only thing that is wet is the fuel bowl. A leak from there is the only thing that makes any sense.

IMO, vacuum secondaries are over-rated. I'll take a double pumper any day, even for a daily driver. But, that isn't why you're having a problem.