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Unread 09-29-2013, 04:03 PM   #1
willierat
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mech. fuel pump not pumping?

I have a 1980 CJ5 that I've been trying to get running. I put a new fuel pump on it and cleaned the carb. Drove it around the yard several times, sat and idled revved everything seemed great. Drove it next door to show my Uncle and it died. No fuel to the carb! Is there anything I could have done wrong while installing it(seemed simple enough) or did I just buy a BAD pump. Is there anything that could happen with the eccentric that operates the pump? Now I'm considering an electric pump. Yay or nay. If so what should I look for. I am not a troubleshooter but I can take stuff apart and put it back together, most of the time

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Unread 09-29-2013, 07:54 PM   #2
Spieg8
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It's possible that the eccentric is worn out, but not likely (you can inspect it through the hole when you remove the pump.. look for deep grooves). It could also be that you purchased a bad pump (again, unlikely, but possible). I would be looking for an obstruction in the fuel system somewhere. Could be a clogged filter, kinked line, plugged vent, or blockage at the pickup in the tank. An electronic pump is not a bad thing to have, but I would resolve the current problem before making modifications. Good luck
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Unread 09-29-2013, 11:48 PM   #3
BagusJeep
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It could be dry rotted / cracked / holed hose on top of the tank. There is a section from the fuel sender to the fuel line, about 2 foot long, that is prone to this.

Your pump may be working fine and just sucking air.

Have you tried connecting the pump inlet to a jam jar of gas?

Have you tried sucking petrol from the fuel line? Yuck.

PS I am not a fan of electric pumps, just one more thing to go wrong and another expense. The mechanical pump with the 3 way proper fuel filter and tank return work fine.
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Unread 09-30-2013, 07:50 AM   #4
Balvar24
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If you're tank is rotten, you could be getting rust in the pump and screwing it up. I've had it happen to mine before.
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Unread 09-30-2013, 08:53 AM   #5
keith460
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A 1980 Jeep now has a fuel system that is 33 years old if it is all original. Start from scratch and drop the tank and look for rust and other debris inside of tank. Check all the fuel lines for rust and corrosion and replace as necessary.

Your fuel system may need a complete overhaul. I know mine did!
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Unread 09-30-2013, 12:56 PM   #6
danielbuck
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I just had this issue on my 46, it was a loose fuel line connection inbetween the engine and the tank, it was just sucking air.
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Unread 09-30-2013, 02:43 PM   #7
LumpyGrits
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Check you fuel lines and clamps.
You either have a hard blockage in the main feed line. OR you are suc'n air because of poor lines/connections.
LG
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Unread 09-30-2013, 08:49 PM   #8
thantos858
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I would replace all the rubber lines, fuel filter and then try it all again.
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Unread 09-30-2013, 08:57 PM   #9
seabass1858
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I did the overhaul. with 500$ master rebuild and 600 in machining I opted out for new fuel system and I flushed the steel lines which were already in good shape.
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Unread 10-01-2013, 08:57 AM   #10
LumpyGrits
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Remove the gas cap and use compressed air to blow the main line out.
You should hear the bubbles in the tank, if the line is clear.
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Unread 10-01-2013, 09:32 AM   #11
Matt1981CJ7
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FYI, new (reman'd) mechanical fuel pumps can be bad right out of the box. I had to return 2 NAPA pumps before I got one that worked.

It's an easy test. Just disconnect the fuel line from the carb and stick it in a separate container. Then crank the engine and see if you get a steady stream of fuel from the line. If it comes out bubbly, then you have a leak somewhere upstream. If it doesn't flow at all, then the pump is probably bad, or you have a major obstruction. If it's the latter, you can further isolate the problem using Bagus' suggestion.

Good luck,

Matt
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Unread 10-01-2013, 10:04 AM   #12
willierat
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Thanks guys, I'm gonna try the container of gas today.
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Unread 10-01-2013, 05:44 PM   #13
willierat
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So I run a hose into a gas can, turn the engine over, nothing. Take the pump back off try it manually by pushing the lever by hand, gas to the sky! I can't see how I could be installing it wrong since it did work one time. I've reinstalled it like 20 times Made a block off plate so tomorrow the pump goes back and I'm buying a universal electric.
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Unread 10-01-2013, 06:29 PM   #14
BagusJeep
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When you install it the lever on the end is pushed down by the lobe on the camshaft. This means it is not a drop in and bolt up operation, it needs some pressure applied.

Do you feel that pressure when you install?

If not have you got a small mirror and flashlight to look into the hole and check out what you are seeing?
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1981 CJ7 258ci - Bagusjeep
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