Mowing Engine Misfires while mowing

[pathunt]

Would appreciate help from anyone who has suggestions for a Massey Ferguson 250 series (251) that misfires under load.

The motor starts well when cold. It warms up ok, but starts to misfire when throttle is applied. It misfires at 540 PTO and the rpm surges while in use.

The fuel looks clear in the filter.

The fuel is new, off-road diesel.

It just died coming up the road to the house.

What should I be looking at first?

I will post the results of trying any suggestions. Thanks.:confused2:

 

[Soundguy]

Misses or looses rpm?

 

[pathunt]

Misses or looses rpm?

Soundguy -

Engine misses at 540 pto. Sounds like it is struggling. It will take more throttle, but does not sound "right".

When set at mowing speed the rpm surges.

Thanks.

Starkiller Hollow

 

[George2615]

Two things come to my mind.
1) Water in the fuel.
2) Fuel filter needs to be changed.
A third thing could be the fuel pump but its rare that they fail.

I just had a similar problem with my gas powered generator / welder. I had just added 3 gallons of fresh gas (bought the day before) to the tank and fired it up for a welding job. Under load it started missing. I shut it down and stuck the tank with a dipstick coated with a paste that detects water. The paste is yellow but turns red if water is detected. It turned red so I siphoned out what I could, went and bought fresh gas at another station, tested that gas before putting it in, added a bottle of dry gas and fired it up again. After a few minutes it ran fine again. Now I test my gas and diesel for water before I fill the tank. I buy the tube of water detection paste at my local fuel supplier.

 

[Soundguy]

that sounds more like a bog down than a miss.

i'd suspect fuel delivery when a diesel won't make rpms or keep them, and not overloaded.

 

[murphy1244]

Two things come to my mind.
1) Water in the fuel.
2) Fuel filter needs to be changed.
A third thing could be the fuel pump but its rare that they fail.

I just had a similar problem with my gas powered generator / welder. I had just added 3 gallons of fresh gas (bought the day before) to the tank and fired it up for a welding job. Under load it started missing. I shut it down and stuck the tank with a dipstick coated with a paste that detects water. The paste is yellow but turns red if water is detected. It turned red so I siphoned out what I could, went and bought fresh gas at another station, tested that gas before putting it in, added a bottle of dry gas and fired it up again. After a few minutes it ran fine again. Now I test my gas and diesel for water before I fill the tank. I buy the tube of water detection paste at my local fuel supplier.

Try using a Mr.Funnel, water can not go thru it.

 

[pathunt]

Soundguy, George, and Murph:

Thanks for suggestions. Will try draining fuel, and changing the fuel filter. The Mr. Funnel sounds like something that should be in the shop anyway.

Next week....

Starkiller Hollow

 

[pathunt]

Hate to ask - but pictures in the Agco manual are so dark they are almost illegible. Having hard time locating fuel shutoff for tank and fuel lift to refill the bowl. Trying to locate all the key points before I try to fix it. Can get the fuel pump cartridge locally on Monday.

Have found a few videos, but none cover the 251 XE.

Signed,

Ignorance is not bliss.:laughing:

 

[pathunt]

All:

Called the Massey dealer. About 50 miles away. He was very helpful.

Found fuel lift pump, lever, and shutoff valve. Will get the filter from the dealer this week and replace it.

For newbies like me who may be reading the thread - Procedure runs something like this:

Take fuel filter
loosen nut at top
take filter and bowl off
clean bowl
replace O-ring on little nub inside the top of the housing
replace gasket in top of filter housing
replace gasket in bowl
screw the bolt almost tight
pump fuel until fuel comes out between the gaskets
tighten bolt snug
pump fuel until lever starts to feel pressure behind it
start tractor
if no start, pump lever four or five times and try starting again
should start, run rough for a little bit, and then smooth out.

Thanks to all -

Starkiller

 

[pathunt]

OKdokay -

Changed the fuel filter. Filled up the fuel bowl. Could not get it to start. Recharging battery. No joy. Will keep you posted. Appreciate any suggestions. Thanks.