# MF362 Air in fuel lines



## Wes F (4 mo ago)

Hello all,

I am trying to track down a fuel problem with my MF 362 diesel tractor. After running it for 30-45 minutes, the tractor dies and 8 have to bleed lots of air out of the injectors before it will start again. Takes 30 minutes at least of bleeding to get it going again. Tank was 2/3rds full when it died.

So far all I've done is change the fuel filter

What would you try next? My plan is to drain the tank, check for debris, and wash it out well. I also have a new lift pump coming next week in case there is an internal air leak in the pump. What else can I try of those don't resolve the issue? Or is there something different you would try first?

Thanks,

Wes


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## FredM (Nov 18, 2015)

Welcome to the forum Wes

Did you bleed from the fuel filter first when the tractor died or just from the injectors?, if you where to bleed from the fuel filter and you found air there, then you could narrow down the problem to between the tank and filter.

Not sure what fuel filter system is on your tractor, some types require the seal to be fitted up into the seal recess before fitting the filter.

Have you checked the vent hole in the fuel cap for blockage?, have you disconnected the fuel line at the filter and let the fuel run into a container to check for blockage at the tank outlet?.

If the lift pump is mechanical and driven from the engine camshaft, and the diaphram has a leak, then the fuel will leak into the engine sump, have you noticed the engine oil level rising at all?.


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## Wes F (4 mo ago)

Hi Fred,

I did bleed at the filter first and did not notice air bubbles come out prior to fuel coming out, whereas when I bled the injectors the air was quite obvious.

What are the possible causes between the filter and the injectors?

I have a bolt on fuel filter with a glass separator at the bottom. I just replaced the filter and its o-rings.

I also drained the tank today, and there did not seem to be any debris. The flow out of the line from the tank to the lift pump was constant the whole time it drained.

Re: oil level: The tractor is new enough to me that I haven't checked the oil enough times to see any major trends. When I checked three days ago, it read all the way full, maybe a tiny bit above full.


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## FredM (Nov 18, 2015)

Sorry Wes, I forgot to mention bleeding the injection pump after the filter and then to the injectors, and you should have had air at the filter when bleeding, you can't rush the bleeding of the system.

Did you check the vent hole in the cap?.

With the engine oil, if the diaphram is leaking, you will be able to smell the engine oil and diesel fuel on the dip stick if the leak was bad enough.


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## dvcochran (Nov 23, 2010)

Wes F said:


> Hello all,
> 
> I am trying to track down a fuel problem with my MF 362 diesel tractor. After running it for 30-45 minutes, the tractor dies and 8 have to bleed lots of air out of the injectors before it will start again. Takes 30 minutes at least of bleeding to get it going again. Tank was 2/3rds full when it died.
> 
> ...


On MF CAV injection pumps there is a fuel lift pump with a primer and upper and lower bleed screws on the injection pump, any of which could be a source of air (along with the more common ones mentioned). If you are positive the air is not coming from somewhere downstream (much more common) I would focus on these areas. Most often, air is being introduce from a bad flex hose, hose clamp, or bowl gasket/seal. 
The injection pump Pulls fuel in, so for it to have air inside, it has to come from somewhere else.


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