Will not stay running?

SHANNON M SULLIVAN-HERWEHE

MEMBER
1979 LINCOLN MARK IV
7.5L
V8
2WD
AUTOMATIC
150,000 MILES

I have replaced the fuel pump, fuel filter, and fuel lines. When it first starts it runs fine but after it warms up it starts chugging, shuts off and won't start again. If I pour fuel in carburetor, it starts and runs until the fuel has burned out, then shuts off again. I had it running at the gas station and as soon as I took the gas cap off it shut off and didn't want to start again. What am I overlooking? A couple people have said there is a really small sock filter in the carburetor, but I haven't ever heard of that before and not sure where on the carburetor to look? I'm at a standstill as to where to go and what to check from here I've been working on it for like 2 years and haven't made any head way it has me perplexed and frustrated beyond belief. Any help would be very appreciated. Thank you!

Tuesday, February 7th, 2023 AT 12:42 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,055 POSTS

Hi,

I totally understand your frustration. Hang in there, we can get it fixed.

First, there is no sock in the carburetor. On some vehicles with an electric fuel pump, there is one in the fuel tank to help filter the fuel before it enters the pump.

Next, since it starts if you feed it fuel, we know it is fuel related. There are a couple of things that need to be checked. First, make sure there is nothing restricting the fuel bowl vent. If air can't escape, fuel can't enter. See pic below

Next, you indicated the fuel pump is new. When it stalls and won't start, disconnect the fuel line at the carburetor and confirm there is fuel available when cranking the engine. Place the fuel line into an appropriate container so as not to spill it.

If you have fuel, then we need to suspect the needle and seat are not allowing fuel to enter the carb. Take the plastic side of a screwdriver and tap on the side of the carburetor where the fuel supply is located to see if that makes a difference.

Let me know what you find.

Joe

See pic below.

Image (Click to make bigger)