Yanmar Issue

[Farmer Piles]

Talking to a mate who has started using his father's Plymouth Pilot with a little single cylinder Yanmar. It starts and runs like a beaut, until you stop it and want to restart it. If it is still hot/warm it doesn't want to start. It will reluctantly with a booster on the battery, the battery is new and powerful enough. It will run for hours at working temperature, just it won't restart when hot.
Any suggestions appreciated.

 

[rotrax]

I had exactly the same with a big Yanmar, a 4JH4-HTE 110 BHP Turbo Diesel.

Being a diagnostic specialist and also having the reputation for not spending money on diagnosis by substitution - actually, getting money out of me is like trying to poke butter up a porcupines arse with a red hot knitting needle - I spent two years carefully diagnosing the issue. I could have got there quicker, but it was EXACTLY what I first suspected, a dodgy injector pump. £1600.00 later, pump overhaul, new injector tips, all is well, starts if you look at it, hot or cold.

From cold, the diesel fuel viscosity was enough for the pump to work and as long as it was going, keep going.

Once hot the worn pump could not provide enough pressure to 'pop' the injector open, due to the lower fuel viscosity of warm/hot fuel.

Next time it stops, try giving it a one second squirt of 'easystart'.

If it lights up instantly, a bad pump is the likely cause.

 

[Farmer Piles]

I had exactly the same with a big Yanmar, a 4JH4-HTE 110 BHP Turbo Diesel.

Being a diagnostic specialist and also having the reputation for not spending money on diagnosis by substitution - actually, getting money out of me is like trying to poke butter up a porcupines arse with a red hot knitting needle - I spent two years carefully diagnosing the issue. I could have got there quicker, but it was EXACTLY what I first suspected, a dodgy injector pump. £1600.00 later, pump overhaul, new injector tips, all is well, starts if you look at it, hot or cold.

From cold, the diesel fuel viscosity was enough for the pump to work and as long as it was going, keep going.

Once hot the worn pump could not provide enough pressure to 'pop' the injector open, due to the lower fuel viscosity of warm/hot fuel.

Next time it stops, try giving it a one second squirt of 'easystart'.

If it lights up instantly, a bad pump is the likely cause.

Hi Rotrax,
Thanks for that, I will pass the message on to Rob and he can take it forward. I have no idea how old or how many hours the engine has done. I had come to the conclusion that it had to be to do with the heat and viscosity, just hadn't made it to the conclusion that you have made. As you say, pump and injector should sort it.

 

[B27]

Talking to a mate who has started using his father's Plymouth Pilot with a little single cylinder Yanmar. It starts and runs like a beaut, until you stop it and want to restart it. If it is still hot/warm it doesn't want to start. It will reluctantly with a booster on the battery, the battery is new and powerful enough. It will run for hours at working temperature, just it won't restart when hot.
Any suggestions appreciated.

If the battery is 'good' then adding a booster or jump pack should not make any difference?
Does the engine crank as fast as it should?
If not that's either battery, starter motor or some wiring in between.

If it's taking a lot of cranking to start, it may be a fuel side problem.
How much throttle is being applied?

Do check the throttle and 'stop' cables are operating correctly!
Also worth checking the engine fuel filter is bled and the lift pump is working properly.

 

[Farmer Piles]

With regard to the porcupine: presumably you wore welding gloves due to the heat and the spines?? Butter; salted or unsalted?

 

[Farmer Piles]

If the battery is 'good' then adding a booster or jump pack should not make any difference?
Does the engine crank as fast as it should?
If not that's either battery, starter motor or some wiring in between.

If it's taking a lot of cranking to start, it may be a fuel side problem.
How much throttle is being applied?

Do check the throttle and 'stop' cables are operating correctly!
Also worth checking the engine fuel filter is bled and the lift pump is working properly.

I think that it is just that with the booster on the battery it spins it just a little faster and overcomes the thinness of the warm fuel.
The issue is just for restarting after a long run when the engine is hot - hence Rotrax's reply. It starts and runs well from cold and keeps running well, just the restarting when hot that is the issue.
Thanks for the reply though. I am sure that my pal will check everything out.

 

[Farmer Piles]

Hi Rotrax,
My mate tried the Easystart when the engine was hot and wouldn't restart as it should. Bingo! She fired up and ran like a goodun. The engine is ancient so his plan is to keep the Easystart handy for this season and then bang a new engine in overwinter as it's not worth spending money on the old Yanmar.
He is delighted with the easy, quick, temporary fix.

Many thanks.

 

[vas]

not my money, but rebulding a HP pump and an injector is surely much cheaper than replacing the whole engine...
I recently learnt that they are still produced (if we're talking 1GM) and are 5k brand new

 

[garymalmgren]

What model yanmar single are we looking at?
YS series or GM?

gary

 

[Farmer Piles]

Hi Guys,

I don't know the details, just that he reckons that it is of an age and condition where he would rather invest in something like a new Beta 20 and be done with it. His call really.