John Deere 755 Glow Plug problem

[Marty6645]

I have just purchased a JD 755 with loader that has been neglected by previous owner and needs a great deal of tlc. The tractor is very hard to start when its cold but starts fine when it is warm. I put test light on old glow plugs and they were getting positive voltage for about 7 to 8 seconds when key was turned in on position and you could hear a buzzing sound. So I figured bad glowplugs. I changed them all and still have same problem. My question is since there was positive voltage at the glow plug that would eliminate the glow plug relay correct??Any info greatly appreciated and also is there anywhere besides jd dealer to get fuel shutoff solenoid?

 

[bg71361]

The answer may sound wacky, but I basically had the same problem. I could heat and re-heat the glow plugs and she would not start. I put in new glow plugs, then a new battery. I was starting to suspect the injector pump; it would not start for anything. Then I asked a buddy of mine to take a look at it. He told me he did not think the engine was turning over fast enough. I told him it sounds like it was turning over fast enough to me, and sounded the same as it always was. I had the starter rebuilt, put it back in and she fired right up. It just was not turning over fast enough. My tractor is a Ford 1910 diesel. Maybe this will help.

Good luck!
Bill

 

[Fishguy]

Are you sure the glowplug is operated in the "on" position? The reason I ask is on my massey, you have to turn the key to the left and hold it there for the plugs to warm. The buzzing you are hearing could be the electric fuel pump. Just a thought!

Steve

 

[dfkrug]

I have just purchased a JD 755 with loader that has been neglected by previous owner and needs a great deal of tlc. The tractor is very hard to start when its cold but starts fine when it is warm. I put test light on old glow plugs and they were getting positive voltage for about 7 to 8 seconds when key was turned in on position and you could hear a buzzing sound. So I figured bad glowplugs. I changed them all and still have same problem. My question is since there was positive voltage at the glow plug that would eliminate the glow plug relay correct??Any info greatly appreciated and also is there anywhere besides jd dealer to get fuel shutoff solenoid?

Don't buy a new solenoid unless you are sure it is bad. JD is only
source and it is hundreds, I will bet. My bet is you have a bad ground.
Check them all. If the engine cranks fast, then it not the braided
one near the engine mount. My 955s have given me similar trouble
with grounds, but they do not use glow plugs. Good luck.

 

[RalphVa]

Does your 755 have a glow plug indicator light?

If it's like the more recent JDs, it doesn't. The glow plugs on most of them are only on when the switch is between "on" and "start", but without a glow plug indicator light, it's very difficult to know exactly where you are with the switch. The way most of us run our glow plugs is to either keep the shift indicator in gear (in HST, in L or H) or PTO on and turn the switch all the way to "start". Hold for a count of 4 if very cold, only about 2 if warm. Could be a count of 6 to 10, like on my 23 year old Benz; not sure how the 755 glow plugs are. Then put gearshift into N or turn PTO off. Should start immediately, even my 23 year old Benz does (until 2 of its glow plugs burned out just recently).

Ralph

 

[bg71361]

Marty,

Did you ever figure out the problem? Give us an update.
Bill

 

[workinallthetime]

a light spray of brake clean twodrs the air intake goes along way, lol
we had this problem on a 455 duno if its anywhere near what you have but the thing seems to have battery issues about once every 2 years, i have also replaced fuel transfer pumps on john deere units (looks like and electric fuel filter) but that was a lawn and garden 318 i think. I might be wrong but 7 volts to a glow plug sounds pretty low, i think it should be closer to b+ voltage.
good luck

 

[bkosienski]

What was the solution to starting a cold JD 755?? I am having a similiar problem, glow plugs get power 5 seconds then you hear a click and they turn off, also I hear the fuel pump operating correctly. The engine seems to be turining over correctly with a full charge. The jd 755 have no glow plug light indicator and the position before the start position engages the glow plugs but the following description below does not seem feasible since 2-4 seconds to heat a glow plug seems to quick , my kubota takes 10 -25 seconds in cold weather ... referring to reply below:
The glow plugs on most of them are only on when the switch is between "on" and "start", but without a glow plug indicator light, it's very difficult to know exactly where you are with the switch. The way most of us run our glow plugs is to either keep the shift indicator in gear (in HST, in L or H) or PTO on and turn the switch all the way to "start". Hold for a count of 4 if very cold, only about 2 if warm. Could be a count of 6 to 10, like on my 23 year old Benz; not sure how the 755 glow plugs are.
Any help much appreciated

 

[Wayne_H]

The answer may sound wacky, but I basically had the same problem. I could heat and re-heat the glow plugs and she would not start. I put in new glow plugs, then a new battery. I was starting to suspect the injector pump; it would not start for anything. Then I asked a buddy of mine to take a look at it. He told me he did not think the engine was turning over fast enough. I told him it sounds like it was turning over fast enough to me, and sounded the same as it always was. I had the starter rebuilt, put it back in and she fired right up. It just was not turning over fast enough. My tractor is a Ford 1910 diesel. Maybe this will help.

Good luck!
Bill

Bill here has a good point. If you are sure the GP's are working, and it runs fine when running, look at how fast it is cranking. Cranking speed is critical on a diesel unlike a gas engine. If it does not crank fast enough, it won't generate enough heat in the cylinders to fire off. I chased a similar problem on my 88 Ford truck for over a year. Put a new starter in, it spun over very enthusiastically, and cranked right up even when it is 10 degrees outside now.

Wayne

 

[RoyJackson]

Bill here has a good point. If you are sure the GP's are working, and it runs fine when running, look at how fast it is cranking. Cranking speed is critical on a diesel unlike a gas engine. If it does not crank fast enough, it won't generate enough heat in the cylinders to fire off.
Wayne

That's why I always respond to a thread like this and suggest jumping off a known good battery first and see what happens. Always do the least intrusive fixes first.
In the case of a bad starter, it might give it enough juice to turn quicker.

After all, it's a b!tch to replace (figure $300) or rebuild (figure $100-$150) a starter and find out it's not the root cause. And that's not counting labor time and costs.