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BillD

Electric Fuel Pump for AC720 or Powermax

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BillD

Hello, all. I just rebuilt the fuel pump on my onan cckb on a Montgomery Ward Twin 20 (same thing as a powermax), and it ran for about 1/2 hour and started failing. Diagnosed by pulling the return line, and no flow, either while motor was running (barely), or when pumped with the manual lever. Worked great when I first put it in. Would spurt fuel when hand pumped.

So, I went to the auto parts store, and got a Mr. Gasked 42S electronic fuel pump. It is 2-3.5 PSI @ 42 GPH. It started, and ran for about 30 seconds, and then died. Fuel was coming from the carb bowl. What pump should I be using? What am I doing wrong?

Help please!

Bill

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midnightpumpkin

Bill,

That pump should be fine. Do you have the return line connected with the factory setup? (ie a T connector with a small orfice that limits the fuel pressure going to the needle valve in the carb)

Sounds like you may need to put a kit in the carb, you should then be set to go.

John U

BTW I have a similar electric fuel pump on all 3 of my Powermax's.

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BillD

John, thanks for the reply. Yes, it does have a return line. I have it connected as gas tank > pump inlet > pump outlet > carb inlet > return line to tank. It has a tee fitting which was on the tractor fro the beginning. I have put a carb kit in it. Not sure why it is overflowing. Maybe float needs to be set differently?

Ideas from all, please!

Bill

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BillD

Well, it is fixed. Pulled the carb and fuel pump. Fuel pump worked fine off the tractor. Remounted, and discovered I couldn't even blow through the filter! It has rust in it. This tractor had sat for 7 years. Put a much larger filter on it, and I am back in business. If this one clogs, I'll pull the tank and use muriatic acid to clean it out.

Mounted the tiller on it, and the PTO works great! It has a 4' PTO driven tiller, 4' Woods M4 brush hog, 5' blade, plow, disc, and a platform that works off the 3 point. I got this running for my nephew, as he and his wife just bought 10 acres and moved to South Dakota.

Hopefully, no other issues! I'll send the electric pump with the tractor in case the onan pump ever goes bad.

Bill

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isetta

Awesome Bill, congrats. Lots of crap wants to find it's way to your carb bowl and float. Sounds like you have the deluxe package with all those attachments. What a great Uncle!

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Bird76Mojo

Where are you guys tying in to for 12v+ ??? I know it has to be an ignition only 12v supply, but I'm not sure where to tie mine in..

I read on here that people were hooking it to the coil positive wire, which I don't really like the sound of. Taking any voltage away from the coil is never a good thing on any ignition system.

I guess I'll keep probing wires with the meter, but I still hate to splice in to anything. It would be nice if there was an ignition-on junction block.

Edited by Bird76Mojo

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midnightpumpkin
11 hours ago, Bird76Mojo said:

Where are you guys tying in to for 12v+ ??? I know it has to be an ignition only 12v supply, but I'm not sure where to tie mine in..

I read on here that people were hooking it to the coil positive wire, which I don't really like the sound of. Taking any voltage away from the coil is never a good thing on any ignition system.

I guess I'll keep probing wires with the meter, but I still hate to splice in to anything. It would be nice if there was an ignition-on junction block.

I understand your concern in theory, however I have never had any issues with connecting the electric fuel pump to the + terminal on the coil.

John U

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Bird76Mojo

I guess I'll go that route then. It'll probably get electronic ignition next spring as well.

I got a little carried away last night, taking off the hydro cooler and the heat shrouding, because the shrouding is 100% surface rust. I'm taking the shields in to work to blast and paint them since it wasn't that much extra work to go ahead and remove them. The tractor may be ugly overall, but this will be a small improvement..

Thanks Midnightpumpkin 


GB :)

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Talntedmrgreen

I always pop the dash and find the terminals that go hot with the key “on”.  Then I tag in there. 

I once used the hot lead to the light switch, which is only hot with the key on.  However, the pulsation of the pump working made my lights flicker! 🤦‍♂️

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Bird76Mojo

Anyone else have their electric fuel pump mounted up high? Higher than the level of fuel in the tank? Mine is mounted directly in front of the tank, and when fuel in the tank gets to the same level as the pump, the tractor starts to starve out on fuel. The pump has plenty of flow. I'm thinking the pump is just old and weak, and can't push fuel uphill..

Thoughts?

Edited by Bird76Mojo

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rockfangd

What you described screamed restriction. I went through it with my 4211 last year. Fuel would flow when it sat, but once the engine used up that fuel there was too much restriction to flow what it needed.

Tractor would run for about 30 seconds when first started but choke itself.

Mine was caused by the nipple at the gas tank. It had rusted nearly shut. Between debris and its own rust. Was not an easy fix because it was impossible to get to the bottom of the tank on that one. 

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s_stephen
13 hours ago, Bird76Mojo said:

Anyone else have their electric fuel pump mounted up high? Higher than the level of fuel in the tank? Mine is mounted directly in front of the tank, and when fuel in the tank gets to the same level as the pump, the tractor starts to starve out on fuel. The pump has plenty of flow. I'm thinking the pump is just old and weak, and can't push fuel uphill..

Thoughts?

if you have a pin hole in the pickup tube in the tank it will suck more air then fuel

Edited by s_stephen
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Bird76Mojo

I believe the pump to be weak because it ran fine when low on fuel when the pump was mounted on the side of the engine tins. I moved it under the hood to protect it and to make the tractor look better. I'll be installing a new pump soon and I'll try to report back here with my results.

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