1985stang

I've been having a very strange problemaround the fuel pump lately. Please keep in mind this is a carbureted car, with a mechanical fuel pump. I'll start it up in the morning after i haven't driven it in a day or so, and it will start leaking fuel somewhere around the pump, presumably around the lines that connect to it. The problem is that it has only leaked in the morning,as I'm getting ready to go to school and it's cold and dark outside. I'll take a different car because it has just left a big puddle of gas underneath it, then I come home and start it up again. The strange part of this whole thing, it doesn't leak in the afternoon. This has happened a couple of times, and I'm stumped because how can a fuel leak only leak part of the time? If it was the lines, wouldn't it just leak all of the time? Any help would be great...

95greengt

wow im puzzled the only thing i can say is remove the lines and see if the threads are messed up it may be leaking in between the line and the nut or it could be the seals in the pump goin bad id replace the pump any way they arent that highanyway

mjr46

it's a simple principle of physics...as the day goes on air temp warms up and warms parts on car and metal expands as it warms= seals...cools overnight and metal contracts and leak opens up.... check it in the morning....if lines need tightening do so..if leak is at pump ..replace it....and or any rubber lines that may be dry rotted that are the suction lines that go into the pump from tank

projectresto83

Exactly what Mjr said. I bet if you let your car run and warm up you wouldn't have the problem. But try and tighten the hard line or get some thread tape and wrap the threads and put it back in and see what happens. You probably have a crack in the pump.

1985stang

But here's the problem mjr, one of the days this happened it was below freezing in the afternoon when i started it up again and it didn't leak. It was one of those days where it got colder as it went on, so i can't see how the car idling for 1 minute was enough to expand the seals enough to where it wouldn't leak later that day when it was even colder.

1985stang

I will try tightening the hard line. I'm just confused because the days it hasn't had any problems were just as cold as days it hadn't. Maybe it's just one of those things that happens at just the right conditions. It's also strange because it just started doing this about a week ago. No problems whatsoever before that, it just started doing this randomly. I'm almost positive it's not a cracked pump, but idk. How would it just crack all of a sudden?

mjr46

look for the trail/ gas stain.....the hard line that goes up to the pump is a self sealing flared end......the line that comes from the tank is a rubber hose held on by a clamp and on the 85 the mech stock pump had a return feature to and that line was rubber and held on by a clamp....check your clamps and hoses going into the pump...... the diapram may be dry rotted internally and when the arm extends the diaphram to just the right position it opens the leak up............think of it as like an accordioan opening and closing to create the suction/ pressure

projectresto83

Well you said it got below freezing. Maybe some water got into a small area and froze, expanded and cracked something. just go buy a new pump and see what happens.

1985stang

Yeah, the problem has been trying to find just where it's coming from because i also have a power steering pump leak, and it drips right onto the fuel pump making all of the lines wet. I know the fluid is red, but on mygreasy rubber lines it's hard to tell what i'm looking at. If i was to replace this stuff (hard line, rubber lines, fuel pump) what should i get and how hard is it to run the rubber lines all the way back to the tank? It's probably something that needs done anyway. Maybe holley fuel pump (model?), braided hose to replace hard line going to carb, etc...

mjr46

holley mech pump would be a good way to go...pending on the model you get.. you may need an adjustable regulator