1959 John Deere 730 fuel problem...

A friend of mine has a 1959 JD 730 and we are having some problems with it. To start off with, it is low on power. It has about 35-40 HP on the dyno at rated rpm. It seems like it is getting way too much fuel. Has a fair amount of black smoke coming out when you load it down to 40 on the dyno. The most HP we could get out of it is about 45. In 6th gear you can just about kill it when you apply the brakes. And we left the fuel shut off in the off position by accident when we changed the fuel filters. When we started it, it ran for about 15 seconds and started to load up with fuel had a lot of black smoke and then died.... ???

So far we have replaced filters, cleaned out the intake and changed the oil in the oil bath. And we have also adjusted the rack to 13 according to the JD service manual we have. We also cleaned out the sediment bowl. Next we checked the transfer pump pressure... and this is were we got more confused. The pressure is supposed to be 12-24 psi, and when we checked ours we couldn't get a definite reading, the needle was all over the place at idle and when you went full throttle it got worse. What could be causing this? Any help or advise to our low power problem is greatly appreciated.

Could be some air trapped in the filters Those tractors are a total bear to bleed and get all the air out.Used to work on them and have some that I simply took the bleed screws out,set bucket under the tractor and maybe an hour later a couple bubbles of air would come out and I tried everything.I don't envy you at all.If the tractor is equipped with the later return fitting with the ball and spring, it sometimes helps to remove the check until you get it bled. Then put it back together. The check usually raised the horsepower a couple or three horses.

Msb, the tractor was low on power and smoked the same as it does now before we changed the filters... Could there have been air in it then too? There are no signs of leaks so I don't think its sucking air from anywhere.

First you need a damper to check transfer pressure as when each inj.pump pulls fuel there is a temporary drop in pressure. That said sounds like you may have blown delievery valve gaskets,Time to have inj.pumps and nozzles run. There is the possibility that the camshaft idler gear has gone out. Its under the left reduction cover . The bearings go out and can take the idler shaft out. Thats a big job. Good luck.

(quoted from post at 17:45:54 10/10/10) First you need a damper to check transfer pressure as when each inj.pump pulls fuel there is a temporary drop in pressure. That said sounds like you may have blown delievery valve gaskets,Time to have inj.pumps and nozzles run. There is the possibility that the camshaft idler gear has gone out. Its under the left reduction cover . The bearings go out and can take the idler shaft out. Thats a big job. Good luck.

Click to expand...

Ok so how do I check the delivery valve gaskets and the cam idler gear? What should I look for?

I think I would try removing the bottom cup from the air cleaner and try it again on the dino..
There may be something restricting intake air-flow.
It should not be blowing black smoke at 40 HP.... (unless the rack is set too high)...

Ron..

I think I would try removing the bottom cup from the air cleaner and try it again on the dino..
There may be something restricting intake air-flow.
It should not be blowing black smoke at 40 HP.... (unless the rack is set too high)...

Ron..

(quoted from post at 18:51:06 10/10/10)
I think I would try removing the bottom cup from the air cleaner and try it again on the dino..
There may be something restricting intake air-flow.
It should not be blowing black smoke at 40 HP.... (unless the rack is set too high)...

Ron..

Click to expand...

Ron,
We did try running it without the aircleaner cup, when we found the screen (tray) was laying in the bottom of the cup. When we did that the smoke cleared up some under load, especally when at idle and full throttle and no load. But HP didnt improve much. Could the intake be clogged somewhere else? We have checked, rechecked, and checked the rack setting again and its set at 13. When its under load we even tried to adjust it to see if we could get the smoke to clear up... to no avail.

thanks, Nick

(quoted from post at 21:58:47 10/10/10)

(quoted from post at 18:51:06 10/10/10)
I think I would try removing the bottom cup from the air cleaner and try it again on the dino..
There may be something restricting intake air-flow.
It should not be blowing black smoke at 40 HP.... (unless the rack is set too high)...

Ron..

Click to expand...

Ron,
We did try running it without the aircleaner cup, when we found the screen (tray) was laying in the bottom of the cup. When we did that the smoke cleared up some under load, especally when at idle and full throttle and no load. But HP didnt improve much. Could the intake be clogged somewhere else? We have checked, rechecked, and checked the rack setting again and its set at 13. When its under load we even tried to adjust it to see if we could get the smoke to clear up... to no avail.

thanks, Nick

Click to expand...

Pull the injectors and check the spray pressure and pattern.
Did you bleed from all three plugs as per the service manual?
Pull the entire intake system off and check for mud and crud from intake snorkel to intake valves. Then check the entire exhaust system for restrictions.

If you know for sure that you have no air restrictions I would check injection timing and supply fuel pump pressure.

You will need a liquid filled gauge to check fuel pressure. It should be making 55 PSI at rated speed. If not you will have to add shims to the bleed valve. Low fuel pressure will cause lots of black smoke and low power.

Fuel pressure can be checked at the filter housing. I screw my gauge into the bleed plug hole.

Be sure you drain the fuel tank most of the way out before removing the bleed valve line or else you will have a mess on the floor. You can leave some fuel in the tank to run the tractor since the bleed valve return has a straw that sticks up a few inches in the tank.

Can't say but might be worth dropping the air-cleaner and having a look...
Engine air is sucked up the OUTSIDE area..could the metal gauze be loaded with debris..??
Could be that is the restriction..

Ron.

If you are getting smoke, that means you are getting enough fuel. You either have air restriction in intake or exhaust, poor spray pattern, or bad timing. I have seen mufflers on diesel engines get plugged up. Pull the muffler just to be sure.

I think about now I would remove the flywheem cover and work through the timing of the pumps. Be sure to use the correct marks. #1 INJ, not #1 TDC, and #2 INJ, not #2 TDC. If the pump timing is off, it could be sending it in late, which equals lots of smoke and loss of power. Make sure the decomp lever isn't holding the valves slightly open.

As several said... check the injection timing.

I tinkered with my 70 D a few years back just to see if I could "tame the harshness" of the diesel knock by retarding the timing a bit. Others in the family thought it was surely off because it was so harsh.

Sure could. Didn't take much change in timing either! Was a LOT less harsh when set just a few degrees late. He also got smoky and his guts went away with the knock!

I set it back right away & told others to get used to it!

Looks like about all you've NOT checked is injector spray pattern and break pressure. Those are not nearly as easy to check as the timing.

Later.

PS.... Taking the cup off of the air cleaner will only help if the air cleaner's INLET pipe is where a clog is located. IE in the pre-cleaner stack (if so equipped) or in the top of the housing assembly or the center pipe. If the filter media are clogged with dirt, they're still in place and still restricting when the cup is removed. To be sure the air filter is not the problem you would have to open the passageway between the engine & the filter assembly.

I would have it run on a test stand. Sounds like the barrels and plunger could be worn out.Setting the rack on 13 won't help if that is what is wrong with it.There is a cranking speed test that will tell you the condition of the pumps if a visual inspection doesn't reveal any problems.

Here is an update on what we have checked.

1. Injection timing is right on, can't get any closer
2. Muffler is clean and unclogged
3. Valves were out of adjustment, adjusted to .20
4. Fuel pressure is at about 12 at idle and about 25 at full throttle

Haven't checked the air cleaner yet, but we did notice one big factor... when we were turning the engine over to check timing we noticed a hiss coming from the exhaust when timing cyl. #2. Didn't do it when timing #1. So.... seems like the valve is being held open by carbon?? Whats the best way to clear it out, short of taking it all apart? 30 hours ago we just put a new head and headgasket on it.

(quoted from post at 22:57:27 10/11/10) Here is an update on what we have checked.

1. Injection timing is right on, can't get any closer
2. Muffler is clean and unclogged
3. Valves were out of adjustment, adjusted to .20
4. Fuel pressure is at about 12 at idle and about 25 at full throttle

Haven't checked the air cleaner yet, but we did notice one big factor... when we were turning the engine over to check timing we noticed a hiss coming from the exhaust when timing cyl. #2. Didn't do it when timing #1. So.... seems like the valve is being held open by carbon?? Whats the best way to clear it out, short of taking it all apart? 30 hours ago we just put a new head and headgasket on it.

Click to expand...

When the head was off. Did anybody magniflux it looking for cracks?

(quoted from post at 16:17:14 10/12/10)

(quoted from post at 22:57:27 10/11/10) Here is an update on what we have checked.

1. Injection timing is right on, can't get any closer
2. Muffler is clean and unclogged
3. Valves were out of adjustment, adjusted to .20
4. Fuel pressure is at about 12 at idle and about 25 at full throttle

Haven't checked the air cleaner yet, but we did notice one big factor... when we were turning the engine over to check timing we noticed a hiss coming from the exhaust when timing cyl. #2. Didn't do it when timing #1. So.... seems like the valve is being held open by carbon?? Whats the best way to clear it out, short of taking it all apart? 30 hours ago we just put a new head and headgasket on it.

Click to expand...

When the head was off. Did anybody magniflux it looking for cracks?

Click to expand...

Yeah, it was magnifluxed with new valves put in it.