fuel pump leak

[Bill MC]

So I installed a new fuel pump.
Works great until the moment I shut the engine off. Then it drips. Hard to see where, but assuming the gas is leaking at one of the rubber gasket joints.
I added some torque to the screws, and still leaks the second I shut the engine off! Doesn't leak a lot...maybe five drips then leak stops.
doesn't seem to leak while running, or while sitting. Otherwise engine seems to get plenty of gas when running.
Is wierd...Any ideas?
Thanks-

[cad-kid]

You should really figure out where it's leaking. Where did you purchase it from?

[Jerry Whitt]

The term "assume" the leak is from the rubber seals. The assumption is the problem. The actual leak is solvable, but must be accurately identified.

Don't guess. Look more closely. It is something that can be identified, if you really put in some effort.

[azdave]

You might have a very tiny hole or porosity issue on the suction side of the pump internals. That would only leak a little after the engine was shut off but not while running or sitting parked.

If it were a big hole on the suction side the pump would only suck air instead of fuel. A really tiny hole (like I'm guessing you have) might not be enough to cause poor fuel draw except maybe when the tank is near empty.

[Jerry Whitt]

Have to disagree with azdave, about using certain terminology. "Suction" is a term than indicates the thought of a pulling process.

The process is not that of pulling. Physics tells us high pressure pushes toward low pressure. When trying to isolate a problem, the proper terminology will help with thought and reasoning to eventually isolate and correct the real problem.

In the fuel system, the high atmospheric pressure, around 15lbs per square inch at sea level, will push the fuel from the tank, toward the low pressure caused at the input side of the mechanical pump. Once the fuel arrives at the pump, pressure is applied to the fuel, usually around 3-4 lbs per square inch. Using this thinking, and then careful examination, the actual leak will more likely to be found.

[azdave]

Have to disagree with azdave, about using certain terminology.

Sorry you think my terminology "sucked" but at least I helped by described a very plausible solution using common terms understood by every single person who read it. Your best recommendation was to "Look more closely".

I'll bet 99 out of 100 people would say that when they suck on a straw a beverage gets pulled up the tube. They don't care that it was actually atmospheric pressure pushing the fluid up the straw. They just want a refreshing drink but if their straw has a small hole in it they might have trouble getting a sip.

[Jerry Whitt]

Great minds often disagree!

[azdave]

Great minds often disagree!

I'll agree with that! No wait...

Ha-ha!

[Carburetor]

I had a similar problem, but mine would drip when first started and then as it warmed up would stop. Using a mirror and flashlight I found it coming from a "hole" between two of the fuel pump castings (wish I had a pic) towards the rear of the car. I was able to stop this by tightening the screws while cold, again while hot, cold, etc. until it stopped. BTW - this was a Clark's replacement that I swapped the original spring and top cover on (I cracked the original bottom casting by getting a little too aggressive screwing in the nipple to the fuel line tee which also caused fuel to drip).