My father and I have restored two JD sleds and will be taking them to West Yellowstone, MT in March for the 3rd Annual Vintage Round-Up. We have filled the tanks with 40:1 mixed gas, pressurized the tank a little and have been able to pull gas up to the carbs. It appears, however, that the engine wants to run on the return line and not the supply line.
Attached is a picture of the set-up, which when the supply line is connected to the bottom of the fuel pump as shown, the engine is starved for gas. Switch the supply and return, and it runs fine. Could the fuel pump be bad?
1972 and 1973 JD 500 carb issues
-
- Posts: 12
- Joined: Sat Jul 23, 2005 12:00 am
- Location: Layton, UT
1972 and 1973 JD 500 carb issues
1972 John Deere 500
Various Polaris sleds
Various Polaris sleds
- 400brian
- Posts: 5626
- Joined: Wed Jul 20, 2005 12:00 am
- Real Name: James T. Kirk
- Location: South Central Wisconsin
1972 and 1973 JD 500 carb issues
It appears to me you have this set up all wrong. First, the Walbros used on JDs have internal pumps, you do not need the separate pulse pump.
It appears you have the impluse fitting on the carb connected to the pulse pump, what have you got connected to the pulse fitting on the crankcase?
The center fitting on the bottom is the supply inlet, the one near it is the return, the fitting on the side of the carb body is the for pulse line to the case.
Try running it without the separate pump, if the diaphrams are good, it should work.
It appears you have the impluse fitting on the carb connected to the pulse pump, what have you got connected to the pulse fitting on the crankcase?
The center fitting on the bottom is the supply inlet, the one near it is the return, the fitting on the side of the carb body is the for pulse line to the case.
Try running it without the separate pump, if the diaphrams are good, it should work.
'09 Vintage Challenge Survivor, and I wasn't late for supper!
'10, '11, '12, '13,'14,'15,'16,'17, '18, 19, 20, 21, 22 Vintage Challenge Survivor !
72 400 restored, Father bought new in '71
73 X8 restored
'74 340 green machine
'74 X8 9 time VC finisher
'78 Spitfire in progress
2 '75 340S 1 running, one on deck
'78 LF 440 future CC clone
'73 Skiroule RTX 440, 500 mi.
-
- Posts: 12
- Joined: Sat Jul 23, 2005 12:00 am
- Location: Layton, UT
1972 and 1973 JD 500 carb issues
OK. This set up is the way we found it.
It does look wierd and we will remove the separate fuel pump and plug off one of the impulse lines. I guess one impulse line was added when the original owner added the separate filter. Thanks for the comments.
It does look wierd and we will remove the separate fuel pump and plug off one of the impulse lines. I guess one impulse line was added when the original owner added the separate filter. Thanks for the comments.
1972 John Deere 500
Various Polaris sleds
Various Polaris sleds
- 400brian
- Posts: 5626
- Joined: Wed Jul 20, 2005 12:00 am
- Real Name: James T. Kirk
- Location: South Central Wisconsin
1972 and 1973 JD 500 carb issues
Have you rebuilt the carb?
I would assume someone put the pump on because the internal one failed.
I honestly don't know if that would work right or not, possible. I've heard of this being done on Tillotsons, but things had to be removed in the carb to allow it. Best to return to the stock config I think.
I would assume someone put the pump on because the internal one failed.
I honestly don't know if that would work right or not, possible. I've heard of this being done on Tillotsons, but things had to be removed in the carb to allow it. Best to return to the stock config I think.
'09 Vintage Challenge Survivor, and I wasn't late for supper!
'10, '11, '12, '13,'14,'15,'16,'17, '18, 19, 20, 21, 22 Vintage Challenge Survivor !
72 400 restored, Father bought new in '71
73 X8 restored
'74 340 green machine
'74 X8 9 time VC finisher
'78 Spitfire in progress
2 '75 340S 1 running, one on deck
'78 LF 440 future CC clone
'73 Skiroule RTX 440, 500 mi.
1972 and 1973 JD 500 carb issues
like Brian said rebuild the carb if it wasnt done yet and get rid of the add on pump. It will run on the return because the add on pump is just pushing gas through the carb then but not on supply because there is nothing opening the inlet needle or it is stuck.
- 400brian
- Posts: 5626
- Joined: Wed Jul 20, 2005 12:00 am
- Real Name: James T. Kirk
- Location: South Central Wisconsin
1972 and 1973 JD 500 carb issues
Tell us a little more about this vintage ride out in Yellowstone.
This is something I would like to do before I'm too old to wipe my own arse.
:huh:
This is something I would like to do before I'm too old to wipe my own arse.
:huh:
'09 Vintage Challenge Survivor, and I wasn't late for supper!
'10, '11, '12, '13,'14,'15,'16,'17, '18, 19, 20, 21, 22 Vintage Challenge Survivor !
72 400 restored, Father bought new in '71
73 X8 restored
'74 340 green machine
'74 X8 9 time VC finisher
'78 Spitfire in progress
2 '75 340S 1 running, one on deck
'78 LF 440 future CC clone
'73 Skiroule RTX 440, 500 mi.
-
- Posts: 12
- Joined: Sat Jul 23, 2005 12:00 am
- Location: Layton, UT
1972 and 1973 JD 500 carb issues
The sleds fired up today. My dad had a JD tech manual which shows the additional fuel pump can be used. Our problems was air leaking in the top of the pickup line in the gas tank. The clamp was not on tight and air was getting in the intake line. It is running great.
For information on the vintage ride in West Yellowstone, MT on Saturday, March 18, 2006.. please visit www.pnwvsc.com and click on the Vintage Round-Up link. This year is the 3rd Annual Vintage Round-Up which is held the same weekend as SnoWest Magazines Expo. The vintage display is at the old airport strip right next to the SnoCross Track.
A vintage ride will be held Saturday afternoon after judging of the show. It is a great time!! Last year there were over 65 vintage sleds from the west there, the goal this year is over 80.
For information on the vintage ride in West Yellowstone, MT on Saturday, March 18, 2006.. please visit www.pnwvsc.com and click on the Vintage Round-Up link. This year is the 3rd Annual Vintage Round-Up which is held the same weekend as SnoWest Magazines Expo. The vintage display is at the old airport strip right next to the SnoCross Track.
A vintage ride will be held Saturday afternoon after judging of the show. It is a great time!! Last year there were over 65 vintage sleds from the west there, the goal this year is over 80.
1972 John Deere 500
Various Polaris sleds
Various Polaris sleds