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FUEL PUMP

3

3b a runnin

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Some of you may remember that I've had trouble with mechanical fuel pumps on my 360 AMC in my cj5. https://earlycj5.com/index.php?threads/159398/
I've been running a couple different electric fuel pumps just to be able to run the jeep.
1 of them is similar to this from Summit with the regulator, https://www.summitracing.com/parts/sum-g3136-2 REALLY loud, too loud
The other is just a generic cheap pump similar to this, https://www.summitracing.com/parts/edl-17301 Not really cheap. I'm concerned about quality long term
The 1st is way too loud and the 2nd, smaller pump I'm concerned about long term quality.
Since I'm runnin a carburetor, I need a low pressure pump.
My question for you guys is, Does anybody make/sell an in-tank pump usable with a carburetor? I would like to use a fuel pump relay that would shut it down in case of an accident, but would like to settle on a good, quiet pump first.
Any help appreciated!
 
I just bought one from the flaps that looks just like a gm intank pump but with hose fittings on each end . Was wondering if it could go in tank? the fuel runs through the center of the pump so in theory it would work Im just a little leery of trying it.
 
Thanks guys.
I'm not satisfied with my current arrangement. Framerail space is premium on a cj5, so that and noise is why I was thinking internal pump.`
I'll come up with something.
 
colojeepguy said:
Is the impetus for the electric pump the poor quality of replacement mechanical pumps?
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Yes
I have put 10 mechanical pumps on this jeep. Some got 0 miles, some got 100 or so miles. None more than that.
I tore down the front of the engine to check the fuel pump eccentric, no problem found. All the pumps fail in the same manner, ruptured diaphragm.
Maybe eventually I will opt for an aftermarket EFI. Didn't really want to do that now.
 
3b a runnin said:
I have put 10 mechanical pumps on this jeep.
Click to expand...

“Once is happenstance. Twice is coincidence. Three times is enemy action”
― Ian Fleming, Goldfinger

I have to think there is hidden factor here, as yet undiagnosed. Ten new "bad pumps" in sequence would mean thousands of other buyers would have had a similar experience.

Whereas most of us typically run a mechanical pump for several decades without failure.
 
PeteL said:
I have to think there is hidden factor here, as yet undiagnosed.
Click to expand...
Totally agree. I checked the pump eccentric and it seemed perfect. I rebuilt the engine and used the same eccentric.
What else is there?
Please help if you have other ideas.
The only pump that lasted for more time, probably 6mo., was an old one that member Jon B had laying around. Not sure how old it was. It never busted the diaphragm, but simply wore out to the point that a long hard uphill pull would run out of gas.
 
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scoutpilot said:
"Ten failed pumps in a row" is not a pump problem. It is a supply problem. Is the fuel tank cap vented? Are all of your line connections tight? Rubber or steel lines? A better description, preferably with photos, would help immensely.
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I don't have pictures but most of the line is steel, with rubber at specific points. Rubber at tank connection, pump connection and carb connection.
Cap is original so I'm guessing not vented on a 73. I'm not using a charcoal canister but I am using the original rollover/vent valve.
Since all the pump trouble started, I have made several alterations to the fuel system.
I cut a hole in the jeep bed so I could change the sending unit and sock on the pickup.
I now have an electric pump near the tank, so some more rubber line there now. Similar to this https://www.amazon.com/Electric-Universal-Pressure-Transfer-Carburetor/dp/B08PY7V2MM/?_encoding I also have another electric pump w/regulator mounted low on the left fender. I'm running a return line to tank by using a 3port filter near the carb. That line is mostly steel. Line connections are tight, and anywhere that rubber connects to steel there was a bubble created with flaring tool to create a lip for the worm clamp to rest against. No leaks under pressure.
My current system is an evolution of sorts, with a couple valves and 2 different carb feed lines, 1 from each pump, but all created after several mechanical pump failures.
 
Maybe this is an issue - maybe not.
How did you remove the vapor canister?
Plugging the line nominally makes vacuum rise in the gas tank.
Old car - the system may be leaky enough that you won't see vacuum in the tank.
A '73 does not have a "rollover valve" as such.
Not sure how it would behave in a rollover.
It's intended as a liquid check valve that keeps liquid gas out of the canister, protecting the charcoal bed.
Without the canister, kinda think there's no point in keeping the original valve.
Likely doesn't hurt anything to leave it there.
You could run a vent line up to the high spot of the cowl and cap it with a fuel filter open to the are.
Keeps bugs and dirt out.
Or, since you have most of the sytem, you could run a canister.
Not difficult to fit available parts, discussed quite a lot previously.
 
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timgr said:
Maybe this is an issue - maybe not.
How did you remove the vapor canister?
Plugging the line nominally makes vacuum rise in the gas tank.
Old car - the system may be leaky enough that you won't see vacuum in the tank.
A '73 does not have a "rollover valve" as such.
Not sure how it would behave in a rollover.
It's intended as a liquid check valve that keeps liquid gas out of the canister, protecting the charcoal bed.
Without the canister, kinda think there's no point in keeping the original valve.
Likely doesn't hurt anything to leave it there.
You could run a vent line up to the high spot of the cowl and cap it with a fuel filter open to the are.
Keeps bugs and dirt out.
Or, since you have most of the sytem, you could run a canister.
Not difficult to fit available parts, discussed quite a lot previously.
Click to expand...
That valve is in the same location as original. The port that originally went to the canister is now vented with a short piece of line and a breather similar to a transmission breather, in the highest part of the rear wheelwell.

Please keep hitting me with these questions guys. I need all the help I can get!
 
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