Fuel leak!!

[dagassa]

Hey all!

I have a fairly significant problem with my 85 Fox. A week or so ago, I walked by my car and smelled gas. Did some looking around and I was leaking gas out of the bottom of my Mechanical Fuel Pump. I grabbed a new Holley unit and installed it and was good for a few days. Now it's leaking from two holes in the body of the pump up top??

When I took out the first pump, the feed line from the tank to the pump was spewing gas everywhere! Got it capped and got the pump changed! Took it to the gas station and when I unscrewed the gas cap, you would have thought that I was letting the air out of a Blimp! If the gas cap didn't have threads on it, it would have blown right out of the fill pipe! Tonight, I wanted to pull the feed line off the pump and cap it to stop the leak but before I did so, I loosened the gas cap and same as last time, there was an enormous amount of pressure that vented from the tank! When I pulled the feed line, I got zero gas out of the hose.

To me, it seems like the pressure that's building in the tank is causing the leaks. Any ideas? thanks!

[KevinK]

It’s typical for an external mechanical fuel pump to leak on failure. I would recheck the inlet and outlet positions.

The fuel tank is vented to the charcoal canister which is mounted up on the front frame rail by the sway bar. You could have a plugged line. An 85 5.0 with an external fuel pump would mean a carbureted car. EFI used an electric fuel pump.

[dagassa]

It’s typical for an external mechanical fuel pump to leak on failure. I would recheck the inlet and outlet positions.

The fuel tank is vented to the charcoal canister which is mounted up on the front frame rail by the sway bar. You could have a plugged line. An 85 5.0 with an external fuel pump would mean a carbureted car. EFI used an electric fuel pump.

It's a Carbed 351 with a mechanical pump. I found the canister up front near the bottom of the radiator on the passenger side and it smells like a gas station. Maybe it's supposed to? It seems like both pumps failed because of the pressure build up. Both pumps were literally weeping fuel! I'm not embellishing when I say there's a LOT of pressure coming out of the tank! When I crack the gas cap, it sounds like somebody pulled the plug on an inflatable mattress with somebody laying on it!

[erratic50]

Vented cap would help but you will lose fuel to evaporation.

Charcoal canister or the vent line going to it are plugged or the vacuum line going to the canister is plugged causing the canister to siphon full of gas.

[WilliamCapri]

Hi Da,

How is it running? Smell rich at all? If the floats are stuck or leaking, excess raw fuel will end up in the charcoal cannisters and then likely fill the lines back to the tank with the fuel pump happily pressurizing everything. Carb rebuild may be in your future. That's if all the vapor equipment is in place.

[dagassa]

Hi Da,

How is it running? Smell rich at all? If the floats are stuck or leaking, excess raw fuel will end up in the charcoal cannisters and then likely fill the lines back to the tank with the fuel pump happily pressurizing everything. Carb rebuild may be in your future. That's if all the vapor equipment is in place.

The car has been running fine since I bought it about 6 months ago. Never really noticed that it smelled like it was running rich. Literally, one day I noticed the smell and saw gas on the ground. Found it was leaking from the bottom of the pump. When I pulled the pump feed line, gas was shooting out like a fire hose! Put in a new pump and went to get gas and it blew dry my hair when I cracked the gas cap. Put in the new pump, and it seemed ok for a few days until I started smelling gas again and this time it was coming from the upper body of the pump. This time, I started at the gas cap. Cracked it and same thing, extreme pressure. When I got up to the feed line, there was no gas coming out. I guess because I relieved the pressure first.

I'm picking up a new Charcoal canister after work and I have the solenoid coming tomorrow.

[dagassa]

Here's the first leak at the bottom of the pump.

[dagassa]

And here's the one from last night. Notice the fuel is weeping from the pump body on the replacement Holley unit.