MF255 Fuel Pump Timing Question.

[Jimmy Farm]

Hi,

I'm getting ready to change the fuel pump on my MF255, because it is leaking diesel. I've watched a few videos of people changing fuel pumps on MF tractors, not all of them being a 255. The MF255 video I found the guy swapped them out and it fired right up. No checking the timing of the pump to the fly wheel position. Other video I found of a MF135 require you to check the position of the pump to the fly wheel.

My question is, does the MF255 not require a pump to fly wheel position check once the pump is reconnected with the bolts and the etched line is lined up?

Pictures attached are my tractor(MF255) and two screenshots of someone timing the pump to fly wheel (MF135) as an example.

Thanks

 

[Dieseltech]

Hi,

I'm getting ready to change the fuel pump on my MF255, because it is leaking diesel. I've watched a few videos of people changing fuel pumps on MF tractors, not all of them being a 255. The MF255 video I found the guy swapped them out and it fired right up. No checking the timing of the pump to the fly wheel position. Other video I found of a MF135 require you to check the position of the pump to the fly wheel.

My question is, does the MF255 not require a pump to fly wheel position check once the pump is reconnected with the bolts and the etched line is lined up?

Pictures attached are my tractor(MF255) and two screenshots of someone timing the pump to fly wheel (MF135) as an example.

Thanks

No flywheel timing needed, just MAKE SURE the drive gear locating pin is in the drive hub when installing the pump. I've done it that way for years as an OLD MF mechanic, and diesel injection pump repair mechanic.

 

[Jimmy Farm]

No flywheel timing needed, just MAKE SURE the drive gear locating pin is in the drive hub when installing the pump. I've done it that way for years as an OLD MF mechanic, and diesel injection pump repair mechanic.

Awesome! thank you

 

[Jimmy Farm]

I finally replaced my fuel pump and fuel lifter pump. I primed at the fuel filter and got all the air out and then did the locations on the pump in order 1 then two. Those locations no longer had air or bubbles coming out of them. I went to turn over the tractor and it will not start. It just spins from the starter and doesn't sound like its trying to fire.

The pump can only go in one way to the oil filler housing because there is a pin that fits in the slot of the fuel pump. I did try rotating the position of the fuel pump to see if adjusting that would work, but no luck. I do get a strong stream of diesel from the pump when i full remove the top bleeder bolt and turn it over for a second, so fuel is pumping. I bought this fuel pump in 2021 and have been sitting on it since I got another tractor, so the listing is gone. Maybe it's the wrong fuel pump.

I did have to reuse the little cylinders arms (blue in picture) that connect to the fuel line because the ones that came with it were about 1/4in short.


Anyone have any thoughts? Thanks

 

[used red MN]

I finally replaced my fuel pump and fuel lifter pump. I primed at the fuel filter and got all the air out and then did the locations on the pump in order 1 then two. Those locations no longer had air or bubbles coming out of them. I went to turn over the tractor and it will not start. It just spins from the starter and doesn't sound like its trying to fire.

The pump can only go in one way to the oil filler housing because there is a pin that fits in the slot of the fuel pump. I did try rotating the position of the fuel pump to see if adjusting that would work, but no luck. I do get a strong stream of diesel from the pump when i full remove the top bleeder bolt and turn it over for a second, so fuel is pumping. I bought this fuel pump in 2021 and have been sitting on it since I got another tractor, so the listing is gone. Maybe it's the wrong fuel pump.

I did have to reuse the little cylinders arms (blue in picture) that connect to the fuel line because the ones that came with it were about 1/4in short.


Anyone have any thoughts? Thanks

You will probably need to bleed the injector lines as well. Loosen the nut that holds the line to the injector on the heads about a turn. Then give the line a sideways tap near the nut to make sure it unseats from the injector. Crank the engine about 10 seconds and see if fuel appears at the loose injector lines. If you see fuel snug down the line nuts an see if it starts. If no fuel after the first 10 second crank. Do it the 10 second crank again and look for fuel. If you see fuel at a couple seconds injectors snug those down and bring the others snug and back them off an 1/8 turn. They should bleed out eventually. When it starts on a couple well bled injectors shut it off and tighten them all, any air left will work out when the engine is running.

 

[Jimmy Farm]

You will probably need to bleed the injector lines as well. Loosen the nut that holds the line to the injector on the heads about a turn. Then give the line a sideways tap near the nut to make sure it unseats from the injector. Crank the engine about 10 seconds and see if fuel appears at the loose injector lines. If you see fuel snug down the line nuts an see if it starts. If no fuel after the first 10 second crank. Do it the 10 second crank again and look for fuel. If you see fuel at a couple seconds injectors snug those down and bring the others snug and back them off an 1/8 turn. They should bleed out eventually. When it starts on a couple well bled injectors shut it off and tighten them all, any air left will work out when the engine is running.

I will give that a try. Thank you

 

[Harry in Ky]

Good chance here you're beating a dead horse. While you probably did everything right (or close enough) in the installation, I think the key to problem is in this sentence. "I bought this pump in 2021 and have been sitting on it since". Therein lies the problem. At one time new and rebuilt pumps could sit on a shelf for months, be installed and would start right up. It was common practice at a dealership where I worked many years back. That just doesn't seem to work out any more. My guess is you need to free up some internals before it will run.

 

[Jimmy Farm]

Good chance here you're beating a dead horse. While you probably did everything right (or close enough) in the installation, I think the key to problem is in this sentence. "I bought this pump in 2021 and have been sitting on it since". Therein lies the problem. At one time new and rebuilt pumps could sit on a shelf for months, be installed and would start right up. It was common practice at a dealership where I worked many years back. That just doesn't seem to work out any more. My guess is you need to free up some internals before it will run.

You talking about the internals of the pump or the tractor itself? The tractor did run last week and would fire right up, before I replaced the leaking pump.

 

[Harry in Ky]

Just the pump.

 

[used red MN]

Good chance here you're beating a dead horse. While you probably did everything right (or close enough) in the installation, I think the key to problem is in this sentence. "I bought this pump in 2021 and have been sitting on it since". Therein lies the problem. At one time new and rebuilt pumps could sit on a shelf for months, be installed and would start right up. It was common practice at a dealership where I worked many years back. That just doesn't seem to work out any more. My guess is you need to free up some internals before it will run.

I bought this fuel pump in 2021 and have been sitting on it since I got another tractor,

Did you get it to pump fuel out of the injector lines? Probably not if you are not reporting it is running. So was it a rebuilt pump or a “good” used pump? A rebuilt sitting with test fluid in it all this time has a fair chance of being okay. A used pump sitting partially fully of diesel fuel has a minimal guarantee of working properly after setting that long.

 

[Dieseltech]

If it’s had diesel fuel in it I’ll bet some internal parts are stuck. If it’s had TEST OIL in it during storage there’s more chance of it working.

 

[Jimmy Farm]

If it’s had diesel fuel in it I’ll bet some internal parts are stuck. If it’s had TEST OIL in it during storage there’s more chance of it working.

How would i go about breaking the parts free? Do i need to take the whole thing apart? I assume its put together in a certain way that it's timed correctly. If i take it apart do the internal parts only fit back together one way or do i need to make sure they are lined up the same way they came out?

 

[Jimmy Farm]

***Fixed***

I bleed the fuel filter and the fuel pump again and it started right up this time. Must have been some more air stuck in there.

 

[used red MN]

***Fixed***

I bleed the fuel filter and the fuel pump again and it started right up this time. Must have been some more air stuck in there.

Glad it worked out, sometimes you get lucky!