DROPPING RPMs

Hi, Great forum folks!!!!!
Have an early 90s vintage JD455 with FEL, 935 Hrs.. Sometimes the RPMs drop and it sputters giving black smoke. Cough Cough. Replaced fuel pump and filters twice. Temporary fix. What's next??? Injectors and pump??? Would welcome any advice, as this machine is handier than my Bobcat when it runs well. Thank you in advance, Dennis

Hey Dennis, good to see you post.

Is your tractor gas or diesel?

Dennis Funk

Doc,
The 455 Deeres are 22Hp. Diesels. I emptied the tank and gave it fresh fuel a few times to assure it was not gelled or sour. Thank's for asking

That the fuel pump fixes it temporarily does indicate the next logical item would be the injectors, like you suggested. Purely a guess on my part also, as I have nothing to base it on other than my limited understanding of the diesels.
Before springing for the injectors I wonder if there is a way to test injectors to be sure you need them?

Symptoms: smoke and bogging down.

Looking at this from another angle - could there be something that suddenly throws a heavy load on the engine? Maybe a heavy counterweight box on the 3-point that sags then automatically is pushed back up?

Or something in a hydrostatic transmission?

I assume this sounds different from a misfire which would push unburned fuel out the exhaust.

When you said you changed filters does that include air filter ? I Just had the same problem with a mid 80,s Iseki Deisel . It would run a good 20 minutes or so then acted like it was going to die . I,d put it in Nuetral & it seemed to come back to life .

The longer I waited before trying to run it much the longer it would go . I thought for sure it was fuel , & had Blowed the air filter out . But putting a new air filter in it seemed to cure , I just ran it for over an hour this morning & all seems to be fine . Just a thought .

Many thank's for the input folks.
Tomarrow I plan to work on her and will advise of any progress.
In the meantime I want to share an article which may be of concern to many on this site. It cites legislation regarding age limits of farm equipment operators. It could spell hardship for many family farmers.
http://readingeagle.com/article.aspx?id=199872

Good information Dennis. You might want to re-post this in this forum. It would be good for all to read.

check your fuel cap, the vent might be plugged.when sputters, loosin the fuel cap

Dennis Funk said:

legislation regarding age limits of farm equipment operators. It could spell hardship for many family farmers.
http://readingeagle.com/article.aspx?id=199872

Click to expand...

Looks like this only applies to trucks (not tractors). From the PA Farm Bureau website: FARM VEHICLE REGULATION UPDATE BULLETIN – Feb. 22, 2010 During a February 19 information meeting convened by the Transportation Committees of the PA Senate and House of Representatives, offi cials of the Pennsylvania Department of Transportation (PennDOT) and U.S. Federal Motor Carrier Safety Administration (FMSCA) stated that the restrictions and requirements which have been proposed for drivers of agricultural vehicles in Pennsylvania will not apply to the drivers of farm tractors. Drivers of certain farm trucks will still be affected by the proposed regulations.

Click to expand...

Same source.

Does it bog then smoke or smoke then bog?

How long did it take after you did all the other work before it started running bad again?

I assume the governer is working freely?

Hi cj7 Motor bogs&smokes same time. After filter and pump change it ran well for many hours and acted like it was fixed, then problem returns exactly the same. Thought about air binding injector, but can find no leaks. Always blead air after any fuel line work and it starts right up. The engine handles loads like it should, but when it drops it is usually under load. Governer??? How check???? Thanks for input

I am not totally certain what the exact problem is but you can start with simple things first. Sometimes even if you think your ok when you go back over it you find the problem sometimes.

The black smoke should mean a rich condition. Usually because of lack of air. But when you put a load on the motor the pump will adjust and add more fuel to compensate for the load. So it may be possible that is the smoke you see also.

Eliminate the easy and cheap things first.

I would first check to make sure all the linkages at the injector pump are moving freely. If not then use some PB blaster to loosen them up.

Then make sure your air filter is still clean and air is able to pass into the filter and into the engine.

Then move to the fuel side. Good fuel? Is it cold where you are? Is it gelling the fuel? Fuel filter clogged due to gelling or dirt from the tank?

Are the fuel lines from the tank to the filter and to the pump free and clear? Are they leaking? It may be possible that some garbage is in the tank and sloshing around and sometimes closing the hole to the fuel line.

Check all the injector lines also.

I do not know this pump and fuel system on the deer but, did they possibly install an extra fuel screen someplace in the plumbing?


Does it start dying right as the load is applied? example. your driving up a long grade in a higher gear and as you near the top or it gets steeper you just loose rpms? If so your running out of fuel.

Eliminate the easy and cheap things first. Exactly. Start small. that 30¢ o-ring is going to fail before that $200 injector guaranteed. Also follow the fuel flow circuit. Start at the cap for the fuel tank and go from there. Buy a Manual and a real one not some Clymers or what ever but a real JD Shop/Repair manual. They are all over ebay and whatnot. I have the manual for nearly everything I own. JD manuals usually have some decent diagnostic flow charts in them. Best of luck. M.

Did you figure out the problem?????