155D Starting Problems

[N8-126]

I searched the forum and couldn't find this problem described before, so I hope that I am not posting a redundant question.

I rebuilt my YM155D last year and everything seems good (except for a rear main leak, which I will deal with next winter). Each time I go out to use it , it is harder to start than the last time. Once its warm it starts easier, but not as easy as it used to. I noticed a little diesel leaking around the banjo fitting at the injector pump so I am replacing both copper washers tonight. I also checked the fuel injector and return lines. They both seem okay, although the rear (number 1 cylinder) injector is not as strong as the front injector.

Question-what is the probability that the small leak on the low pressure side of the injector pump would cause it to start hard. By hard starting, I mean it turns over for a good 30 seconds before starting and then acts as though its only getting just enough fuel to survive. Then after 5 or 10 seconds of rough running, it ramps up and runs like a champ.

 

[HoyeTractor]

Question-what is the probability that the small leak on the low pressure side of the injector pump would cause it to start hard.

Diesels dont like air in the fuel system. A leak on the low pressure may possibly allow air to get into the system under just the right conditions. Air in the fuel lines can cause it to do what you are describing. Normally there would be a little bit of pressure on the lines though since the Yanmar's tank is higher than the pump. Air should not be able to get in.

the rear (number 1 cylinder) injector is not as strong as the front injector.

I might be leaning more towards the pump or injector.

Aaron
Hoye Tractor Parts
(940)592-0181
Contact Us

 

[N8-126]

Thanks, I will try replacing the copper washers and give it another go. If that doesn't work, my next thought was rechecking the timing for the pump. Does Hoye sell the shims if I need to buy some more?

 

[HoyeTractor]

Yes, we should have them but, unless you suspect that the correct number of shims were not re-installed, you should never need to mess with the fuel pump timing.

Aaron
Hoye Tractor Parts
(940)592-0181
Contact Us

 

[N8-126]

The reason I am suspect the timing is that I put the original number of shims in (without checking the timing). But I replaced just about everything in the engine (except the crank). I didn't get time to work on it last night so hopefully, I will get it up and running tonight and provide an update.

 

[204saskman]

Does the 155D have a glow plug or anything like that??? I find mine very hard starting also. Its only got 690hrs on it and i dont think its injectors or a pump but im not to sure. It starts fine when its warm but once it gets cold out its a royal PITA to get it going. I just bought the tractor last year and havent had any major issues with it but id like it to start easier.

Thanks

Kiel

 

[N8-126]

Saskman, have you tried to bleed all the fuel lines. Mine only has 15 hours on it since the rebuild, but it was over 4200 hours prior that. It sounds like you have the same basic tractor, including factory loader.

Over the years I have had to bleed the fuel lines for a multitude of reasons. Last year, the o-rings in the fuel filter went bad causing it to take on air. Before you spend any money, bleed everything starting at the tank. Attached is video that Tractorbynet member DieselFuelOnly created. He has a different Yanmar, but the setup is nearly identical to the 155D. And no-there are no gloplugs on the 155

YouTube - HOWTO: Bleeding air out of a small Yanmar diesel

 

[204saskman]

Cool. Ill give it a try and go from there. I bought it off the original owner and he said it never rolled over on the hour meter. I like the tractor alot and runs all of the attachments i currently own. It struggles sometimes, but thats what low range is for. Ill try bleeding everything and go from there.

 

[N8-126]

I replaced the copper washers and it did help-but the problem didn't go away it just got a little easier to start. But as they say "no good deed goes unpunished", while trying to bleed the fuel filter I noticed a little fuel around the threads of the nut that holds on the bowl. I tried to give a little tighten and it popped right off. After 20-minutes of messing with it I came to the conclusion that either the threads on the body are too small or the nut is too big.

Does anyone know where I could buy just the nut for the filter. I purchased the assembly from Hoye Tractor over the winter. Its not Hoye's fault, I should have paid better attention when I put it on. It just sucks that as I try to chase down one problem, others keep jumping out in front of me.

 

[N8-126]

Okay, I am in need of help. I replaced the fuel filter assembly, copper washers and checked the timing. I also checked each injector spray pattern and cleaned the injector pump mechanisms. Everything checked out, but it still has difficulty starting. So, I tried to trouble shoot the injectors by loosening the line to each injector while the tractor was running to see if one caused it to die out more than the other-no luck.

When it starts, it runs on one cylinder for a few seconds before the other cylinder kicks into full force. I acts as though the pressure and fuel is draining out of the injectors, but more so from one than the other. Does anyone know how the fuel pump restricts backflow of fuel. I think the injectors are bad, however it could also be a check valve in the fuel pumps if there is such a thing.