i all, my uncle passed away and left my family a Yamaha MS24 with what i believed was a Yanmar YSE8 engine.
Unfortunately, we could not get it started after bleeding the fuel line, so i removed the fuel injector pump and found the fuel plunger had broken.
Initially I had a tool maker fabricate a new plunger (using the dimension from the broken one ) however that did not work.
Not being able to find any parts in my country - Australia , i have decided to order an OEM pump from Taiwan, but when i checked the identified plate on the engine it is not a YSE8 but a YS8.
Are these the same engine ? or more importantly is the fuel injector pump interchangeable on these two models ?
According the build spec sheet (found on the internet) they were built with an YSM8, which is also referred to as just YS8.
I have attached some pics, any help would be much appreciated.
Also if anyone has had experience with ordering a OEM fuel pump from Taiwan and if they are reliable that would be great also.
My next challenge will be re-seting the governer throttle, as I have only found instructions as it relates to the YSE8.
Thanks in advance.
( i have photos but first timers can't post images - hopefully in time i can attach them )
Hi Charli
welcome to the wonderful world of the Yanmar YS diesels.
RE: when i checked the identified plate on the engine it is not a YSE8 but a YS8.
Are these the same engine ? or more importantly is the fuel injector pump interchangeable on these two models ?
Yes they are the same engine and the fuel pump is interchangeable. How ever if you can contact the sell/ manufacture and supply a photo of you engine ID plate it would be a good move.
RE; Also if anyone has had experience with ordering a OEM fuel pump from Taiwan and if they are reliable that would be great also.
I have never bought Taiwanese parts, but I would not doubt the quality.
RE; My next challenge will be re-seting the governer throttle, as I have only found instructions as it relates to the YSE8.
Resetting the fuel injector flow rate is in the manual but it is a bit confusing.
I have rewritten it and will post here.
I have also made up an "Owners Manual" for the YS series engine and will PM you to send by mail.
So go ahead with the Taiwanese purchase, basically, you have no other choice at this stage.
gary
Hi Gary, thank you for your responses.
I will go ahead and order the OEM part from Taiwan, fyi the current cost including delivery $420AUD.
This includes the fuel pump, spring, plunger pin, bolts etc.
Thank you for the Governor throttle instructions, I believe the instructions I found on the internet are the ones you had already posted - so thumbs up !!!
I have attached some pics, hopefully the admin will let me post them.
Here are Charli's photos.
That broken fuel pump piston has me a little worried.
Why did that happen?
It could have damaged the inside bore and that is probably why your replacement didn't work.
Sealant has been used between the pump and the crankcase.
Originally. it was a very thin gasket.
I made mine out of printing paper.
gary
Giving this a little more thought.
I think you should try to check for any internal damage.
A simple check is to remove the oil filter (a triangular flange with a T handle sticking out) from the front housing.
Scoop out any oil inside into a clean dish.
Stuck a magnet in to check for steel or iron debris and run the oil between your fingers to feel for any other stuff.
I have done this with two YS engines and found nothing.
gary
Hi Gary,
I just received the full story behind the snapped plunger, a relative re-installed the fuel pump with the plunger in front of the plate and not inserted within the grove/rebate.
So what I can gather is when they turn the motor over, it was forced down into the fuel injector pump causing it to snap.
Which is how i found it when I subsequently removed the fuel IP.
This now makes me think it was pushed too far into the pump and most likely fouled/destroyed the bottom of the throttle pin.
Which is why when the new new plunger was installed properly no fuel was passing through the bottom injector - i thought maybe the tolerance of the the new plunger was incorrect. i.e. not pushing the fuel through.
I did remove the oil filter and didn't find anything other than oil in there.
I also added the sealant, but when the bolts are nipped up firm all of it squeezed out.
Ordering a new fuel pump from Taiwan.
New non genuine fuel pump arrived today, and i noticed the pin stamp is missing on the top of the throttle pin. ( picture attached)
I guess i will just seat the throttle pin, remember the location of the screw head and CCW 90 degrees for the correct setting ?
Will also change out the oil and clean the oil filter, i already have some Shell HX5 15/40 (new) on the boat, or should i go with something else ?
Taiwan - Sunity YS8 replacement fuel pump
Replaced the original fuel filter, with a new filter and bleeder screw and new fuel hoses, with a pump to assist with bleeding.
Hope not thread drifting but I fitted a Matsumo hand pump and Cooper filter to overcome bleed issues - works perfectly. See here - I forget which model Matsumo it was but you can choose........
www.seabreeze.com.au/forums/Sailing/General/Diesel-upgrade-in-80s-25ft-long-keel--4k-yacht-summary-photos-and-notes-hope-are-of-interest
www.onlineautoparts.com.au/product/zpn-15843-fuel-primer-pump-assembly-matsumo
Cooper filter from Burson
www.burson.com.au/
