Yanmar 3JH5E - difficult starting - advice please

[sandiegoskipper]

That affect on rubber lines is probably due to Ethanol, not Kerosene. Kerosene (aka white gas) is closer to diesel in the refinery cracking process than gasoline and those rubber lines handle gasoline just fine. Alcohol is a different story... Automobiles, for example, cannot have any rubber seals, lines, o-rings etc. in fuel delivery systems on vehicles designed to run on E85. It's bad for aluminum parts as well.

To determine if ethanol is in the fuel: In tall narrow glass jar with a lid, make a permanent line about two inches from the bottom. Fill with water to this line, then fill the jar to the top with fuel. Attach lid, agitate and let it stand. The ethanol and water will mix and separate out together. If the water level appears to have increased, the fuel contains ethanol and should not be used. Ethanol percentages of less than 5% can sometimes give a reading below the line. Therefore, any deviation in the water line indicates the presence of ethanol and should serve as a basis for rejecting the fuel.

Skip

[Wotname]

Originally Posted by feebs

Hi,

I have two Yanmar 3JH5E 39 hp motors on my cat. One of which is difficult to start, occasionally.

I prime each engine for 4 to 10 seconds before starting. .......
Thanks Brett

Brett, please help me to understand about what you mean by priming the engine before starting.

How do you prime your Yanmar engines?

[Robert Tilbury]

Originally Posted by Compass790

Chinese manufacturer of your fuel line???

It could have been Chinese fuel line ,,, it did have a SAE number ?

Maybe it could have been for a different type of fuel ,, my tub is a 1979 year .

At least it wasn`t Garden hose like i saw on one Yacht ,,, then again it did look better than my fuel line ,<<<<

[Robert Tilbury]

Originally Posted by sandiegoskipper

That affect on rubber lines is probably due to Ethanol, not Kerosene. Kerosene (aka white gas) is closer to diesel in the refinery cracking process than gasoline and those rubber lines handle gasoline just fine. Alcohol is a different story... Automobiles, for example, cannot have any rubber seals, lines, o-rings etc. in fuel delivery systems on vehicles designed to run on E85. It's bad for aluminum parts as well.

To determine if ethanol is in the fuel: In tall narrow glass jar with a lid, make a permanent line about two inches from the bottom. Fill with water to this line, then fill the jar to the top with fuel. Attach lid, agitate and let it stand. The ethanol and water will mix and separate out together. If the water level appears to have increased, the fuel contains ethanol and should not be used. Ethanol percentages of less than 5% can sometimes give a reading below the line. Therefore, any deviation in the water line indicates the presence of ethanol and should serve as a basis for rejecting the fuel.

Skip

This is a sample of what came out of my tank ,, I ended up removing the tank cleaning , new lines filters ,,, Never went back to Picknick Point Boat shed again ,,,

The boat shed closed down not long after ,,

[jimbunyard]

So your boat doesn't like neapolitan?

[Squanderbucks]

If indeed an air leak you st least have an idea where to look. If air leak before the Racor filter then you would see a different pattern. Starting would be ok but filter would fill with air after running and then engine quit. Larger the leak the faster the time to shut down. If not loosing fuel in filter the leak likely after fuel filter.
Once that is made sure of then next idea would be to check the injector timing.

[feebs]

Thanks for everyone’s suggestions.

So I have started with the simple fix first. Have tightened each hose clamp on that engines fuel lines - less than a 1/4 turn per clamp. After tightening I had four normal starts throughout that day as opposed to previous day where four out of four starts were failed starts. I hope this problem was fixed so easily.

Wotname - when I say “prime” what I do is turn ignition on ( allowing electric fuel pump to run) for a few seconds, before engaging starter motor.

Again, thanks for everyone’s input.

Cheers Brett

[Wotname]

Originally Posted by feebs

Thanks for everyone’s suggestions.

So I have started with the simple fix first. Have tightened each hose clamp on that engines fuel lines - less than a 1/4 turn per clamp. After tightening I had four normal starts throughout that day as opposed to previous day where four out of four starts were failed starts. I hope this problem was fixed so easily.

Wotname - when I say “prime” what I do is turn ignition on ( allowing electric fuel pump to run) for a few seconds, before engaging starter motor.

Again, thanks for everyone’s input.

Cheers Brett

That sounds positive, easy fixes are always the best!

It would be interesting to know how well both engines start without using your priming action.

[Savanna]

I experienced a similar issue with one of the Yanmar 3JH5E engines in my catamaran. It happened immediately after changing the fuel filters. It turned out that when changing the filters I had allowed some air into the fuel line. After about 12 problematic starts the issue went away. I hope yous does too.

[feebs]

So looks like my problem has been solved by changing fuel lines & hose clamps.

Thanks for all your inputs.

Cheers

[charliehows]

I treat fuel lines as a consumable - if I suspect them of leaking enough to bother undoing the clamps I just replace them

[florentin]

Originally Posted by Privilege

If your engine runs fine once started, then the likelihood is that you have a fuel supply issue. Any air getting into the system in the fuel supply set-up will make an engine difficult to start. Pending the advice of those more knowledgeable than I, I would take a jerrycan of clean diesel and run a hose directly to the engine filter. Give the priming lever some pumps and then try to start it. If it starts O.K the problem is not with the engine. This way, you will narrow down whether the issue is with the fuel supply system or the engine itself.

hi,

would you know some workshop in the Carribean area, that can rebore and hone cylinder blocks of the engines 3JH5E in the topic?

regards,

Flo

[florentin]

Originally Posted by Squanderbucks

If indeed an air leak you st least have an idea where to look. If air leak before the Racor filter then you would see a different pattern. Starting would be ok but filter would fill with air after running and then engine quit. Larger the leak the faster the time to shut down. If not loosing fuel in filter the leak likely after fuel filter.
Once that is made sure of then next idea would be to check the injector timing.

hi,

would you know some workshop in the Carribean area, that can rebore and hone cylinder blocks of the engines 3JH5E in the topic?

regards,

Flo

[feebs]

Just an update for those that have been following this thread...

So after draining water separator, changing fuel lines & hose clamps, I found a loose banjo fitting on my water separator.

Problem hasn’t occured again, fingers crossed!

Hope this info helps someone...

[Wotname]

^^ thanks for the update.