Just Purchased a 93' - B7100 HST Fuel Leak Help

   / Just Purchased a 93' - B7100 HST Fuel Leak Help #1  

NDTHAND1992

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Ford / New Holland 1920
I recently had the chance to purchase a 1993 B7100 HST with a 60" deck and its my first time owning a Kubota. The tractor and mower run great, but I discovered a fuel leak that appears to be coming from the injector pump where it is threaded going to the cylinders. I have attached couple of photos and was looking for anyone that has had a similar issue and what a good fix would be, is there an O-ring?

Thanks
 

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   / Just Purchased a 93' - B7100 HST Fuel Leak Help #2  
Clean it off and see which one is leaking and ordered a new injector line. No oring it has a ferrule made on the line and they crack sometimes. Make sure the lines are tight. They could be leaking from not being tight.
 
   / Just Purchased a 93' - B7100 HST Fuel Leak Help
  • Thread Starter
#3  
Thank you for the heads up, I will see what I can find this evening. If I unthread those ferrule will I need to then bleed the air out or since it is downstream of the injector pump it will feed?
 
   / Just Purchased a 93' - B7100 HST Fuel Leak Help #4  
Thank you for the heads up, I will see what I can find this evening. If I unthread those ferrule will I need to then bleed the air out or since it is downstream of the injector pump it will feed?
Maybe..... Probably..... At any rate, you are going to have to crank for awhile, so get a spare battery or jumper and BE SURE TO give it plenty of time for the starter to cool between tries. 15/20 minutes if the starter feels warm

What will happen is when you loosen the bottom ferrules, you can't help getting air into the high pressure lines, and that air is compressible. The problem is that until the air iin those downstream high pressure lines is forced or bled out at the injectors, you can't build enough pressure on each pump stroke to open the injector. And if the injector can't open then it can't get rid of the air by spitting it into the engine. So you know in advance you will certainly have to open the ferrule at the injector to give the air a path out. Although that does depend on how much air is in the line - which you can't know.

Still, it makes sense to figure that luck is on your side, so just turn off the valve on the fuel filter, and do what you have to to the high pressure lines. No point in going any farther until you find out if those connections are good at the pump. Assume that they are OK and were just loose, so here we go now.... Open the valve at the filter and crack the ferrules up at the injectors. You can now try to start it by first just bleeding it up at the injectors. Always try that first. But often it doesn't work... which means there is air hiding somewhere else.

How far back toward the filter or even the tank you will have to go to get rid of air that got in that way, depends on the wear in the pump and just where in the stroke that the pump piston stops. Sometimes you have to go all the way back to the input to the fuel filter and get a pure flow out of the filter onto the ground without any bubbles. You just cannot know.

So since just bleeding at the injectors didn't work, the next assumption is that that even though you turned off the valve at the filter, somehow air did get into the filter. So disconnect the filter-to-pump line and gravity bleed that line until pure fuel without bubbles is making it to the pump. It helps to start with a full tank of fuel.

Tighten both hoses at the filter, open the valve at the filter, tighten the hose where it inputs to the high pressure pump, and loosen the pump ferrules to the output lines. Now crank until it spits fuel out of the pump ferrules, stop cranking, tighten those ferrules on the pump, and loosen the ferrrules at the injectors. Now crank until all the bubbles are gone up at the injectors. Stop cranking, tighten down those upper injector ferrules and cross your fingers. Crank for awhile. Then repeat...

After it doesn't start, you can repeat the whole process....but before you do, just loosen the ferrules up at the injectors AGAIN and see if you can crank some more air out. If you are lucky, all the air has been forced up there to the top and you can get it all out at the injector ferrules. Crank, tighten down, and crank for a start... maybe repeat....

Eventually you will get one cylinder to fire and that will raise the RPM enough that you can quit with cranking on the starter. With luck it will continue running and as it builds RPM it will eventually run on all cylinders.
As you can see, there's a bit of luck involved.
rScotty
 
Last edited:
   / Just Purchased a 93' - B7100 HST Fuel Leak Help
  • Thread Starter
#5  
Maybe..... Probably..... At any rate, you are going to have to crank for awhile, so get a spare battery or jumper and BE SURE TO give it plenty of time for the starter to cool between tries. 15/20 minutes if the starter feels warm

What will happen is when you loosen the bottom ferrules, you can't help getting air into the high pressure lines, and that air is compressible. The problem is that until the air iin those downstream high pressure lines is forced or bled out at the injectors, you can't build enough pressure on each pump stroke to open the injector. And if the injector can't open then it can't get rid of the air by spitting it into the engine. So you know in advance you will certainly have to open the ferrule at the injector to give the air a path out. Although that does depend on how much air is in the line - which you can't know.

Still, it makes sense to figure that luck is on your side, so just turn off the valve on the fuel filter, and do what you have to to the high pressure lines. No point in going any farther until you find out if those connections are good at the pump. Assume that they are OK and were just loose, so here we go now.... Open the valve at the filter and crack the ferrules up at the injectors. You can now try to start it by first just bleeding it up at the injectors. Always try that first. But often it doesn't work... which means there is air hiding somewhere else.

How far back toward the filter or even the tank you will have to go to get rid of air that got in that way, depends on the wear in the pump and just where in the stroke that the pump piston stops. Sometimes you have to go all the way back to the input to the fuel filter and get a pure flow out of the filter onto the ground without any bubbles. You just cannot know.

So since just bleeding at the injectors didn't work, the next assumption is that that even though you turned off the valve at the filter, somehow air did get into the filter. So disconnect the filter-to-pump line and gravity bleed that line until pure fuel without bubbles is making it to the pump. It helps to start with a full tank of fuel.

Tighten both hoses at the filter, open the valve at the filter, tighten the hose where it inputs to the high pressure pump, and loosen the pump ferrules to the output lines. Now crank until it spits fuel out of the pump ferrules, stop cranking, tighten those ferrules on the pump, and loosen the ferrrules at the injectors. Now crank until all the bubbles are gone up at the injectors. Stop cranking, tighten down those upper injector ferrules and cross your fingers. Crank for awhile. Then repeat...

After it doesn't start, you can repeat the whole process....but before you do, just loosen the ferrules up at the injectors AGAIN and see if you can crank some more air out. If you are lucky, all the air has been forced up there to the top and you can get it all out at the injector ferrules. Crank, tighten down, and crank for a start... maybe repeat....

Eventually you will get one cylinder to fire and that will raise the RPM enough that you can quit with cranking on the starter. With luck it will continue running and as it builds RPM it will eventually run on all cylinders.
As you can see, there's a bit of luck involved.
rScotty
Thank you Rscotty for the detailed instructions , I am hoping the weather clears out today where I can get in there and see what I can find or do. I am hoping it is just the ferrule leaking.
 
 
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