Carb pourining fuel out onto intake manifold need help ASAP!!! - Third Generation F-Body Message Boards

THETANK · 10-03-2009, 02:44 PM

I just had a new engine built and installed. About 1/2 way home the engine started to bog down heavily when I pushed on the throttle at all and didn't seem to want to go over 55 mph. I got home finally and could smell the odor of raw fuel. I popped my hood and and saw that fuel was leaking from the carb onto my intake manifold. The carb spacer was wet. I went to re start it and had a backfire through the carb. I am assuming something is causing it to flood.

The car has an AFPR return style ( Mallaroy) and the fuel pressure is at between 6 -7 PSI which the enigne buider set it at. I know very little about carbs. The carb is an eldelbrock 600cfm model 1406 electric choke. I watched the car idle for about 10 minutes at his shop and it was not leaking. He drove it a little and I did not notice a leak. The problem started about 5miles from the shop. He will take care of it I am sure but i need to be able to get it back there and he is closed unti Monday. Any ideas what the problem is or what I can do so it's not pouring fuel out?

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t-top havoc · 10-03-2009, 05:39 PM

Is the fuel fitting on the carb tight?
Also,if there's a nylon washer at the fitting,from the feed line to the carb,over tightening will squeeze it out of shape & leak.
Check the fuel feed line clamp for cracks & that it's tight enough.

radical82 · 10-03-2009, 06:03 PM

Possibly the float levels are too high, maybe the needle and seat got some trash in it and is sticking....

IMO, unless it's some kind of killer engine the fuel pressure is plenty high!! Edelbrock's work fine with 4 or 5 PSI of pressure

regal301 · 10-03-2009, 07:52 PM

7 is too high

THETANK · 10-03-2009, 08:13 PM

Motor is not any killer combo (CR 9.1:1) 380 Hp 430 TQ 355cu inch w/ xr 276 cam and dart s/s heads. Carb is a brand new Edelbrock 1406 ( I Know most aren't fans of edelbrock). Also when I tried to strat the car back up I got a small backfire through the carb and a little smoke from the carb as well.

The motor is literally a brand new motor with all new parts.

I'll double check the fittings but I don't think that is the problem considering the backfire.

IROCZ28KevinZ · 10-04-2009, 03:06 PM

There isn't many places on an Edelbrock for fuel leaks to develop. I know its a new carb, but you may have a bad float owl cover gasket. If you look at the top of the carb, you should see a bunch of torx screws going around the top. You remove those, unhook some linkages, and BAM the top cover comes off. Could be a manufacturing flaw where a machining flaw is making a tiny hole between the cover and gasket, causing a leak.

But I would look at what others have suggested first; since it didn't happen right away, this may not be your issue. If that gasket leaked, it would probably leak right from the start, and you said it didn't.

Another possibility is the gasket between the carb and spacer is bad, or the carb wasn't secured tigh enough so the nuts worked themselves loose after a little driving.

THETANK · 10-04-2009, 05:10 PM

Well I tried to start it today and it's bubbling out of the Bowl vents ( I think thats what they are called ) like a fountain. I was going to attempt to fix it today but I discovered some other issues with an improperly installed and tied TV cable. I paid this mechanic to do a professional job and that is not what I got. I am going to let him worry about correcting this problem, I could see if it happended a month or so after he completed the work but it was literally 5 miles from his shop when the problems started. That said I believe it is the fuel pressure.

I tried to point out the area where I saw the fuel bubbling out from in the attached pic.

naf · 10-04-2009, 05:51 PM

DO NOT attempt to start the engine until this is resolved. You do not want to wash down your fresh cylinders with raw fuel.

For it to be coming out of the top of the carb, the needle and seat must not be closing to shut off fuel correctly. This could be a hung float, bad float level, trash clogging the needle or too high fuel pressure. Have the shop tow it in and fix it.

THETANK · 10-06-2009, 02:49 AM

Car has been towed in by the shop, after a lot of discussion by myself and the owner, the owner was trying to tell me that I or my AFPR caused the problem, even though I only had it in my possesion for about 10 minutes after he "fixed worked on it". I checked the pressure on my AFPR and the gauge didn't peg so I ruled that out. He then said maybe he got some debris in it from the hose he installed.

He is supposed to take care of this as well as a problem with my TV cable . I'll keep you all posted

five7kid · 10-06-2009, 03:50 PM

On another note, unless that breather cap on the passenger side has a PCV valve contained within it, you need to get a PCV valve in that line.

THETANK · 10-08-2009, 06:39 AM

It has PCV.

3rd gen Will · 10-08-2009, 12:00 PM

That area you highlight is where your secondary metering rods and vacuum springs are.

If fuel is coming out of there I would suspect that your fuel pressure is/was to high. I used to run my Edelbrock 600 at 5.5 psi.

five7kid · 10-08-2009, 02:25 PM

Quote:

Originally Posted by THETANK

It has PCV.

Right, but does it have a valve in there?

As to the flooding, it's about a 99% chance that some crud got in the needle/seats. 7 psi is a little higher than Edelbrock recommends, but not so high that fuel should be pouring out of the bowl vents.

THETANK · 10-09-2009, 09:03 PM

I think I nailed down the problem ( at least one of them), the fuel pump had died so he had replaced that while doing the engine. The replacement fuel pump used was a TPI pump not the original TBI pump, which has significantly less pressure, than the TBI pump. The other issue he told me that was causing eratic fuel pressure was a bad relay ( the one on the driver's side firewall) which I had just replaced within the last few months because my old pump was not priming.

He told me that the relay had a bad ground ( I think that was the problem) or had some sort of malfunction. He also told me that the pump was a pulsating/pulsining pump ( I think that's what he said it was called). What he did to make it run was run the pump so that the oil sending unit controled it.

He wired the pump to a keyed ignition source ( said he bypassed the computer which I didn't think had any bearing on the pump but according to the wiring diagram he showed me it appears to.), so now when my keys in the on position my pump is running which I know will work but is probabbly not the best way. I will take pictures tommorow of the set up. Would this set up cause more stress on the fuel system or have any negative effects that you could think of?