I'm putting this one out there to see if you guys agree with me. Lately I've had some stumble/missing coming from my engine, but it doesn't feel like the usual ignition/fouled plugs type of stumble as it's very arbitrary. Sometimes the car runs fine, sometimes it runs like ****. Well, I've noticed lately that there is a lot of air in my fuel filter. It's usually only 50% full with fuel when the car is idle and drop down pretty low when at a moderate throttle. In fact, today I was out there holding the engine steady at 1500rpm and I noticed that the carb managed to suck all the fuel from the filter and began to suck air through the screen. Sound like a bad fuel pump to anybody? All the hoses and the filter are brand new and I haven't noticed any fuel leaking. Also, isn't the fuel pump now supposed to allow fuel to flow back through the pump from the fuel line? When I shut off the car I noticed that all the fuel runs back out of the filter.

 

Do you have a mechanical or electric fuel pump? Which brand/model?

Dave

 

Looks like it's prolly stock. Mechanical.

 

Update: Doesn't appear to be a fuel pump problem. I was out there playing with the car earlier and I noticed that the problem only occurs after the car gets warmed up. In order to isolate the problem, I took a can of gas and 6 feet of hose and plugged that directly into the intake on the fuel pump. I let the car run for at least 20 minutes like that and everything appeared to be fine. Even during engine revs the gas appeared to be fine. This leads me to believe that I'm sucking in air from somewhere. I am going to go hook the can of gas up to the rear side of my fuel hardline to see if that problem still occurs. Maybe it's the pickup in the gas tank?

 

It's possible your picking up air from the fuel tank for some reason. Without dropping the tank and taking a lok its hard to say what that problem might be. Looks like you are on the right track in diagnosing the problem, though.

 

Alright, I think I have the problem isolated to the hard line. Hooked the gas can up via hose to the back of the hard line and fired up the car. Looks like there could be a crack somewhere in the hard line where I'm getting the air from. I'm gonna jack the car up tommorrow and look to see if I can find any cracks or anything. Anybody know where I can pick up a new hard line for my car? NPD has them, but they're like $100. The car already isn't 100% original so I don't really have to worry about something as mundane as keeping the original hard line.