Mechanical Fuel Pump Leak

[johnnyzoom]

Hey Fellas-

This is about my 3rd month with this Comet, thanks to everyone here things are going very well, she's running better than I thought she would by now.

BUT- Today I put on my 2nd new mechanical fuel pump, and it's leaking a little fuel below where it meets the block, just a little more than a weep, same exact place and amount as the last one. Could be two bad pumps in a row but I wonder if it's sign of something bigger. Have read all posts I can find on this and it doesn't look like there's much choice in pumps unless I convert to electric.

Car's behaviour lately-

-- Starts after about 2 tries cold, idles strong, during DAY (about 70 F outside) bogs down and sometimes stalls at stoplights, at NIGHT (about 60 F outside) wants to stall but doesn't. I've noticed the more gently I accelerate the better it responds. Symptoms are more likely coming off the freeway. And of course smell of fuel is present.

Timing is set 12 degrees, plugs gapped .25, tested TDC is accurate, dizzy is 2 months old and vacuum to autolite 1100 tested good, not been able to detect vacuum leaks anywhere, pro installed new exhaust manifold and I've bypassed heater hose at carb plate (suspected heat at carb may have been problem). Carb is new also (3 months ago) but admitedly I haven't dismantled it yet.

Long post I know but just trying to give as much info as I can, and I'd settle for help just on the leak!

Thanks a lot -- Johnny

64 Comet 404, 200ci, automatic

 

[JackFish]

You have replaced the fuel filter?

 

[johnnyzoom]

Replaced filter twice, it's the cylindrical cannister type seated above the pump as one piece. Would throwing a smaller "bottle" type filter inline before the pump help, maybe too much pressure trashing these pumps? Gas tank is relatively new, about 3 years old. No signs of damage to fuel line, have driven about 200 miles since I got it, would think that's enough to dispel dirty fuel?

Thanks- Johnny

 

[pedal2themetal45]

I wouldn't think two pumps would leak in the same spot... I'd look at all the fuel conections at the pump and at the filter and check the lines to make sure they arn't cracked??
Tim

 

[JackFish]

Um, didja use gasket sealer? I had a leak too, and that and a new gasket fixed it.
How about the carb and needle valve, is that stuff clean too?
Make sure your pcv valve is working OK too.

 

[pedal2themetal45]

This may sound stupid but
you did use clamps on the filter conections.
I say this as a guy I know put a filter on and didn't and he had a leak. I know its kind of a DUH thing.
tim

 

[jamyers]

If you've got fuel leaking out at the pump-to-block seam, you've also got fuel going into the crankcase - not good. The only way for that to happen is a leaking diaphragm, which can happen on a brand new pump. And the way they seem to put old car parts together anymore, it wouldn't suprise me at all to find 2 or 3 leaking "remanufactured" pumps.


Won't any of the 144-170-200-250 fuel pumps bolt right on? I thought they were all interchangeable, even though their mounting-flange shapes differ slightly.

 

[johnnyzoom]

Thanks for the tips. It's leaking out of the very bottom and to the back a little where the pump meets the block, nowhere near the lines. Both times pump installed with new gasket and proper gasket sealant. Torqued to specs (12-15lbs). Fuel lines are clamped and pump is absolutely dry everywhere else except that spot.

No leak, completely dry when installed after idling for about 10 minutes. Quick spin on the highway and leak was back.

Jamyers I read about your trouble before posting my problem, good idea, I'll investigate other compatible pumps. Probably going to dismantle both bad pumps and see if I can find anything, don't know what would rupture diaphragm. Then trace back to gas tank, hey, I wanted an education, what better way to get to know this thing intimately, right?

Will post when I've found a solution. Then will figure out how to treat the 200 after fuel's been in oil. Oh it's going to be a magical spring this year, haha!

Thanks- Johnny

 

[johnnyzoom]

OK - I think this is the final on this from me. I'm going to go ahead and embarrass myself so maybe someone in the future can benefit.


After closer inspection (utilizing a paper towel and my nose) I determined it was OIL leaking where the pump meets the block, not FUEL. There's a strong smell of fuel while driving (another problem altogether), so I figured that was where it was coming from. Understandable mistake, right?

New bolts to secure the pump weren't working out too well, with some valuable help from Addo, I hit the threads with a tap and that made a big difference in how the pump mounts. Just for grins I skipped the gasket and just used black RTZ, after running two days I don't see anything. Maybe temporary fix, will retry new gasket but may see how long this lasts.

I'm keeping one pump for backup, but I have a barely used mechanical fuel pump for a 6 cylinder 200 for the price of postage, if anyone's interested PM me.

Thanks for everyone's help-

Johnny

 

[Anonymous]

--

Starts after about 2 tries cold, idles strong, during DAY (about 70 F outside) bogs down and sometimes stalls at stoplights, at NIGHT (about 60 F outside) wants to stall but doesn't. I've noticed the more gently I accelerate the better it responds. Symptoms are more likely coming off the freeway. And of course smell of fuel is present.

I would regap the plugs to .035, maybe try leaning out the idle jet a little, up the idle speed a little, and check the vac advance diaphram on the dizzy.
Had a bad 1 that appeared to be working when i looked at it with a timing light--then i realized it was retarding not advanceing under accel. Vav adv diaphram was bad and timing was wandering under accel, looking like it was working but was actually going the wrong way due to return spring pressure coupled with centrifical pressure from rotor and vibration.

 

[johnnyzoom]

Thanks for the advice Dan, I've read a ton of threads on this and haven't seen what you described with the advance yet. Plugs are already gapped to .35, I miswrote .25.

I've got a lot of work and studying to do on these carb problems (autolite 1100 new rebuild from chain store). There is a constant smell of fuel when driving, cannot find a leak anywhere in the fuel-line. I have an intermittent fuel leak now over the manifold, think this is float valve sticking. Either the automatic choke spring is bad or I need to adjust the linkage. The carb didn't come with a fuel bowl vent rod or spring, it was covered up. Obviously this carb needs a rebuild but the general consensus is that I need to get one from Pony Carbs ($300). Ouch, that's almost what I paid for the Comet! Guess I'll keep at it for a while with this one, I'm sure I can learn a lot even if I can't get it tuned right.

 

[MustangSix]

I would look for a couple of things on the fuel smell. First is all the fuel connections. Filter, lines, clamps.

Then make sure the float level is correct. These old carbs are vented to the atmosphere, so any sloshing or bowl overfill will spill out the vent into the venturi (causing the engine to stall or sputter) and leaving a smell.

Finally, look at the throttle shaft. A worn carb body at the throttle shaft will leak fuel and cause poor running. Might even be temperature dependent.