Go BottomFuel flow problem in JD755
 | Mark L
Join Date: Posts: 1 
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2002-07-28 40750
My JD 755 has a very odd problem. When the tank gets to 1/3rd full it starts misfiring. The sediment bowl is full of air so I guess it starts drawing in air from somewhere. I have had a look and I can see that there are two fuel lines going into the top of the fuel tank. My current theory is that the one of these that is the draw-off tube has been damaged part way down. Can anyone shed any more light on this and tell what the other pipe does? I figure my best bet now is to wait until the tank is part empty and unscrew the metal fitting on the top of the fuel tank and see what's in there.
I'd be grateful for any advice
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| TomG
Join Date: Feb 2002 Posts: 5406 Upper Ottawa Valley 
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2002-07-28 40757
It might be a venting problem. I don't know 755's. Many tanks are vented through the caps, but some may have vent tubes. One of the tubes on top of the tank may be a vent tube. The other tube likely is the injector pump return. I'd figure where the vent is and check it. It might be tempting to take off the cap to see if that cures the problem, and that would certainly diagnosis a venting problem but operating a tractor with the cap off would be a safety issue.
Most tanks have the fuel feed coming from the bottom of the tank are fitted with a shut-off valve. The tank is above the pump and gravity supplies adequate fuel flow. A few older tractors do have lift pumps in addition to injector pumps. In either case, it's a little hard to judge if fuel flow is adequate by looking at the filter bowl. Many tend appear nearly empty when the engine is running.
....
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 | Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-07-28 40758
My tractor is a newer 955. The tank on is is PE. There is a filter element on the end of the pick up line. The element is there to filter out large particles that might block the line.
If this is plugged than it will have trouble pulling the gas from the tank. The reason you see it when the tank is low is that the pump is essentually gravity feed. As with most pumps the suction end is critical. ....
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| Fitch
Join Date: Jul 2003 Posts: 23 Southern California High Desert
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2002-07-28 40764
I had the same problem with my 2600 Ford about 8 years ago right after I bought it. It turned out to be a clogged in tank strainer like Peters describes. The strainer is mounted on the fuel shut off valve that is inserted into the bottom of the tank. Removing the valve also removes the strainer from the tank.
I found it by loosening the fuel line where it entered the fuel filter - only drops came out. Blew back into the fuel line with the tank filler cap removed (Diesel tastes awful but there was no compressed air available where the problem happened) and cleared it - heard bubbles in the tank.
Of course it clogged up again a few hours later. I finally ran it till the fuel was really low (by repeatedly blowing it clear, unscrewed the valve from the bottom of the tank which left a sizable opening, and cleaned out the tank using compressed air through a short piece of copper tube to blow the crunk out the bottom. It had an amazing collection of crunk in it. Cleaned strainer one more time, reinstalled valve, changed fuel filter, been fine ever since.
Fitch ....
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| Bob in Ohio
Join Date: Posts: 1
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2002-07-29 40803
Mark, I had the same problem with my 755. There is a fuel strainer at the end of the fuel pickup tube, attached with a rubber (?) hose. The hose gets old & brittle, breaks and the strainer goes to the bottom of the tank leaving the pickup tube much shorter than it was. When the tank shows 2/3 full, you will run out of fuel (bummer). You must remove your tank, empty it, remove the gage/float assembly (top of tank), fish out the strainer and broken hose. Good time to get water and sludge from bottom of tank (trust me, it's there). Get new hose from JD, reverse the process. Not a hard job. Good luck! ....
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| Mark L
Join Date: Posts: 1
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2002-07-30 40815
Thanks to everyone for their replies. Bob I think you have hit the nail on the head because this starts at exactly the same point every fill.
I'll get out my spanners and let you know. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-08-03 40968
Murphies Law # 123
Think about a potential problem and then it will happen.
Now my 955 is acting the same as your 755. I guess I will need to take the sender unit out of the tsnk at the next fill. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-08-10 41139
Mark;
You must be the slowest wrench in the west. Mine was just dirt on the pick up screen. The line was OK. Cleaned the screen and everything is back to normal.
Peters ....
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| Mark L
Join Date: Posts: 1
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2002-08-10 41141
Hi,
No in actual fact I happend to get a call from the dealer who sold it to me quite recently (about something else) and I mentioned the problem. Despite no warranty agreement with them they've agreed to fix it for me. However we're mid harvest this side of the Atlantic and it's been in the shop for a week and a half!
Promise I'll let you know. ....
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| Peters
Join Date: Feb 2002 Posts: 3034 Northern AL
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2002-08-10 41142
I think it took me 20 minutes to repair, only because I had to hunt for the pliers. Wow, I don't think I could be with out my tractor that long.
Peters ....
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| Mark L
Join Date: Posts: 1
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2002-08-13 41209
Promised I'd finish the story. Tractor came back today with the draw off tube and filter replaced, fuel tank cleaned out and refilled. Also had a a minor hydraulic leak fixed, pressure wash and brush-up and no bill. I guess it was worth the wait. Seems my local JD dealer is a good one - I couldn't get that good a service with one of our cars last year! ....
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