Engine Misfire - "About Last Night"

Terry Stapley · #1 (**permalink**) 04-10-2008, 07:53 AM

I got home after 3 hours in the dentist chair and after soup for dinner I head to the garage to start the engne to see if it is still running ok!
I start it and it starts easily but it is immediately apparent that it is missing again. I only let it run for a 30 seconds or so and shut if off! I spray water on the headers and #1 and # 8 are cooler than the other 6 cylinders again. So I take the air cleaner off and look inside the carb and fuel is dripping onto the very front of th throttle plate on the passenger side front primary! Not good! I take out the front fuel bowl sight plug and NO fuel spills out so the float level does not seem high, it continues to drip.
I pull the # 1 and # 8 spark plugs and they are WET with fuel. It continues to drip. I pull the rest of the plugs and they are dry, but black and sooty! It continues to drip!
I then remove the bottom bolt of the fuel bowl to let the fuel drain and the dripping stops!
I looked closely but with the choke in the way I could not see from where it was dripping.
I then held the throttle plates wide open and turned on the fuel pump with the sight plug still out and no dripping inside or outside the carb!
It is a 750 Holley DP and do not have a clue as to why it would be dripping if the fuel bowl level is at normal level or where the fuel is dripping from. I have 6 lbs of pressure at the fuel regulator.
Anybody have any suggestions as to where to look to fix this issue!!
At least I think I have the problem narrowed down to the carb!!

jhv48 · #2 (**permalink**) 04-10-2008, 08:13 AM

Did you buy the carb new?

If so, did you take it apart and blow out all jets and orifices before installing?

If not, these carbs are noted for arriving dirty (BG too) from the manufacturer.

Take it apart and check for metal shavings. Mine had them everywhere.

Terry Stapley · #3 (**permalink**) 04-10-2008, 08:25 AM

The carb is not new!! I purchased it new but that was 4 years and 12K + miles ago!!

DAVID GAGNARD · #4 (**permalink**) 04-10-2008, 08:29 AM

Terry;
Something is out of whack in your carb, could be a piece of trash floating around in there or no telling what....pull the carb off, take it apart and run a small wire thru all the holes you can see and then used compressed air in every hole, carefully re-assemble with those nice blue gaskets and you should be good to go.....

I seem to have to do this about once every other year on my car........

David

RedBarchetta · #5 (**permalink**) 04-10-2008, 08:53 AM

Quote:

Originally Posted by DAVID GAGNARD

Terry;
Something is out of whack in your carb, could be a piece of trash floating around in there...
David

Yup. I would pull the needle and seat and check there first. If you replace them, get the viton tipped ones. The fact that you didn't have fuel spilling out of the float level sight plug tells me it's probably the needle and seat assembly hanging open. Even the smallest piece of gunk will flood a carb in no time.

-Dean

undy · #6 (**permalink**) 04-10-2008, 09:03 AM

I'd just buy an overhaul kit and just go through the carb from scratch, less than and hour to do it..

Silverback51 · #7 (**permalink**) 04-10-2008, 05:24 PM

Quote:

Originally Posted by RedBarchetta

Yup. I would pull the needle and seat and check there first. If you replace them, get the viton tipped ones. The fact that you didn't have fuel spilling out of the float level sight plug tells me it's probably the needle and seat assembly hanging open. Even the smallest piece of gunk will flood a carb in no time.

-Dean

If the needle was hanging open, then fuel would be running out the site plug, and if it was in place it would run out of the vent tubes.

You may have a ruptured power valve. Take a look at it. What ever it is, it's allowing fuel to run into the carburator from somewhere.

blykins · #8 (**permalink**) 04-10-2008, 08:35 AM

Terry, the easiest solution is to bolt that pretty new carburetor on...

Rick Parker · #9 (**permalink**) 04-10-2008, 08:55 AM

Try lowering the fuel level considerably, and then bringing it back to normal, if it then continues to drip from one booster you have an internal leak that will require the metering block gasket to be replaced.

DonC · #10 (**permalink**) 04-10-2008, 07:20 PM

Terry:
Jus 3 little words, EFI :-)
Just kidding. You coming over to Portland this summer?
DonC

Terry Stapley · #11 (**permalink**) 04-15-2008, 03:50 PM

Don, yes, I should be there next Month! I will give you a heads up to see what is happening!!

I was at the NHRA Event in Las Vegas over the weekend so I did not work on the Cobra! I will post again when I have the chance to delve into my issues some more!!