# New Holland TN 75 fuel problem



## JoelW (Jun 26, 2020)

I am a new member though I have followed for years looking at old tractors and getting advice. I followed the previous thread on a TN 75 fuel problem and I am having similar difficulties. Not long ago as I was mowing hills the tractor started to lose power. I managed to get back to the shop and checked the fuel filter for water. I put some more fuel in and that seemed to help but it happened again. Not what you want on a steep hill.

I have changed the fuel filter and bled the system. I drained all the fuel out and there was no contamination in the fuel. I put on a new transfer pump and went through the bleeding again (3 times now from filter to injectors). The new pump didn't work any better so I put the old pump back on. I even ran a new fuel line from the tank to the transfer pump. The tractor will run fine for about 5 minutes then begins to surge and lose power. Unloaded it runs a bit better but not much. As it surges it seems to "clear" out and then stumbles again. It doesn't want to idle and dies. I can pump the transfer pump and it will start again and runs pretty well unloaded but as soon as you put a load on it, it happens again. It acts like it is running out of fuel but I can't see why.

The tractor is an 2002 or 3 model New Holland TN 75 (Iveco 8035 3 cylinder) with only 1060 hours on it. I checked all the filters, changed the oil, and did a full service. Nothing has helped so far. It doesn't smoke like it did at first but it still loses power after a few minutes. Anyone have ideas as I am out of things to try?


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## Fedup (Feb 25, 2014)

It does indeed seem like a fuel supply problem. You've covered most of the problem areas with apparently little improvement? One notorious problem with the Iveco engine used in the TN series (and other models as well) is the banjo fitting and the banjo bolt itself where the supply line from the tank (which you have replaced) meets the lift pump. (Which you have also replaced) Both the fitting and the bolt are known to trap debris and restrict or even stop completely the flow into the lift pump. You haven't mentioned having closely inspected both for possible obstruction. 

Also some TN tractors were equipped with a single fuel tank mounted under the platform, others had an additional tank behind the seat, which when full or close to full supplied a strong fuel flow to the lift pump just from gravity. Which package does your tractor have? Probably only the single tank, which requires the pump to pull fuel up hill under any and all conditions. This makes even minor restrictions or other issues much more problematic.


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## JoelW (Jun 26, 2020)

Fedup said:


> It does indeed seem like a fuel supply problem. You've covered most of the problem areas with apparently little improvement? One notorious problem with the Iveco engine used in the TN series (and other models as well) is the banjo fitting and the banjo bolt itself where the supply line from the tank (which you have replaced) meets the lift pump. (Which you have also replaced) Both the fitting and the bolt are known to trap debris and restrict or even stop completely the flow into the lift pump. You haven't mentioned having closely inspected both for possible obstruction.
> 
> Also some TN tractors were equipped with a single fuel tank mounted under the platform, others had an additional tank behind the seat, which when full or close to full supplied a strong fuel flow to the lift pump just from gravity. Which package does your tractor have? Probably only the single tank, which requires the pump to pull fuel up hill under any and all conditions. This makes even minor restrictions or other issues much more problematic.


Thanks so much for the reply. I have a single tank model. Mine is the plain TN75. No options. I will check the banjo fitting. There was a very small number of pieces of black plastic in the fuel filter in the transfer pump but not enough to cause any restriction. The odd thing is that the tractor will run fine for a few minutes under load before it starts running poorly. I have replaced the transfer pump once before when it wouldn't start. After it dies now, I can reprime it with the pump. I have checked the bleed valve on the filter and I do get air out of it but I am not sure you can get 100% of the air out of it with the hand pump. It will sit and idle and run up with the foot feet fine but under load it starts to lose power but not immediately. The surging is puzzling as it will act like it is going to "clear up" but then loses power again. I'll check the banjo fitting and repost. Some people suspect the fuel injection pump but the injectors seem to be getting plenty of fuel and pressure.


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## HarveyW (Sep 15, 2014)

Plugged fuel cap vent?? Plugged fuel return line?? Plugged fuel screen in the tank?? Degenerated flexible hose?? Maybe the new lift pump is defective?? Is that a CAV injection pump.... the older models have a small screen in the inlet??
Is there a sediment bowl in the fuel line...if so, has a screen in it. There should be a screen at the inlet the the lift pump.


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## Fedup (Feb 25, 2014)

Restricted/insufficient supply is far more likely than an injection pump problem. Sometimes a little "jury rigging" is necessary. A jug of clean fuel and a length of fuel hose for a makeshift temporary fuel supply can help narrow down such problems. Sometimes I interject an electric pump temporarily at various places in the system. That has been effective in some cases. It can be a lot of trial and error, yes, but a $500+ repair bill on the pump would be a last resort and no guarantee to solve your problem. If you're just guessing, don't guess there first.


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## JoelW (Jun 26, 2020)

Fedup said:


> It does indeed seem like a fuel supply problem. You've covered most of the problem areas with apparently little improvement? One notorious problem with the Iveco engine used in the TN series (and other models as well) is the banjo fitting and the banjo bolt itself where the supply line from the tank (which you have replaced) meets the lift pump. (Which you have also replaced) Both the fitting and the bolt are known to trap debris and restrict or even stop completely the flow into the lift pump. You haven't mentioned having closely inspected both for possible obstruction.
> 
> Also some TN tractors were equipped with a single fuel tank mounted under the platform, others had an additional tank behind the seat, which when full or close to full supplied a strong fuel flow to the lift pump just from gravity. Which package does your tractor have? Probably only the single tank, which requires the pump to pull fuel up hill under any and all conditions. This makes even minor restrictions or other issues much more problematic.





Fedup said:


> Restricted/insufficient supply is far more likely than an injection pump problem. Sometimes a little "jury rigging" is necessary. A jug of clean fuel and a length of fuel hose for a makeshift temporary fuel supply can help narrow down such problems. Sometimes I interject an electric pump temporarily at various places in the system. That has been effective in some cases. It can be a lot of trial and error, yes, but a $500+ repair bill on the pump would be a last resort and no guarantee to solve your problem. If you're just guessing, don't guess there first.



I am not sure but Fedup may have been right. I did not find black plastic blocking the banjo fitting but some other trash that may have caused the problem. The bolt itself was clean but in the fitting there was some trash all the way around the indent. I cleaned it out and it sounded better. Unfortunately it is pouring rain right now so I can't take a run around the field to tell. Stay tuned - film at 11:00.

Thanks again to all who replied. I'm probably going to feel stupid but that's normal.


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## JoelW (Jun 26, 2020)

JoelW said:


> I am not sure but Fedup may have been right. I did not find black plastic blocking the banjo fitting but some other trash that may have caused the problem. The bolt itself was clean but in the fitting there was some trash all the way around the indent. I cleaned it out and it sounded better. Unfortunately it is pouring rain right now so I can't take a run around the field to tell. Stay tuned - film at 11:00.
> 
> Thanks again to all who replied. I'm probably going to feel stupid but that's normal.


The good news is that the tractor is running fine again. The rain clouds parted long enough for me to mow an acre and everything seems OK. Thanks to all who posted suggestions. I am thinking about putting an in-line filter in place to stop more trash from getting in the inlet of the transfer pump. Thanks again.


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## Dan Bayford (11 mo ago)

JoelW said:


> I am a new member though I have followed for years looking at old tractors and getting advice. I followed the previous thread on a TN 75 fuel problem and I am having similar difficulties. Not long ago as I was mowing hills the tractor started to lose power. I managed to get back to the shop and checked the fuel filter for water. I put some more fuel in and that seemed to help but it happened again. Not what you want on a steep hill.
> 
> I have changed the fuel filter and bled the system. I drained all the fuel out and there was no contamination in the fuel. I put on a new transfer pump and went through the bleeding again (3 times now from filter to injectors). The new pump didn't work any better so I put the old pump back on. I even ran a new fuel line from the tank to the transfer pump. The tractor will run fine for about 5 minutes then begins to surge and lose power. Unloaded it runs a bit better but not much. As it surges it seems to "clear" out and then stumbles again. It doesn't want to idle and dies. I can pump the transfer pump and it will start again and runs pretty well unloaded but as soon as you put a load on it, it happens again. It acts like it is running out of fuel but I can't see why.
> 
> The tractor is an 2002 or 3 model New Holland TN 75 (Iveco 8035 3 cylinder) with only 1060 hours on it. I checked all the filters, changed the oil, and did a full service. Nothing has helped so far. It doesn't smoke like it did at first but it still loses power after a few minutes. Anyone have ideas as I am out of things to try?


Hi there I went through the same type of issues. Emptied fuel tank changed fuel lines replaced lifter pump changed fuel filter and fuel filter housing and ended up being and electrical fitting that sends power to the solenoid on the injection pump hops this helps


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