Yanmar YSE12 Diesel Injector Pump Dismantled

Made before I got the engine running!

[@chanakathilakaratna590]

My Yanmar TS50 has the same fuel injection pump. It behaves as same as yours. It pumps fuel when the adjustment screw is fully tightened.
That is not a fault. It is designed to behave like that. Obviously the fuel is adjusted by the tightness if the adjustment screw. Its tightness depends upon the spring force applied by the spring located at the governor lever. As far as I understood the fuel adjustment is within a range of 1 to 5 degrees (or even less) of the rotation of the adjustment screw. That's why we can't see any change in the amount of fuel pumped by the pump when testing the pump manually by rotating the adjustment screw by hand.
Hope this helps for the guys who are rebuilding old Yanmar engines.

[@abdhamid2326]

Terimah kasih yanmar atas pembelajaranya lanjutka terus mengispirasi banyak orang

[@joonahartman5256]

G'day, I've got a non-starting YSB8G which I'm currently trying to bring back to life. Problem seems to be in the fuel pump or the injection valve. Nice to see the pump dismantled like that on your video before I get to dismantling mine!! It seems to be the same model as on my engine. In principle the system is dead simple but still difficult to troubleshoot.

[@Aussie50]

G'day mate!
I found that mine was mainly an air problem when I started it up, but that was because I had the head off for repair before I could even start it.
The system is VERY simple, but the close tolerances in the system mean even a tiny amount of wear or dirt can foul it up, if you can get the injector out non-destructively, I would suggest turning the engine over with the Governor lever on full and see if its even giving a proper spray. I could not even get my injector out without destroying it (rusted in) so I just played around with it until I got it primed and it worked thankfully.
Being such a small and simple injector I imagine it would not be too costly to get it reconditioned at a shop, assuming its not rusted in like mine.
is the engine cranking and belching white smoke/vapor out the exhaust? or is it just giving no fuel at all?

[@joonahartman5256]

After my engine failed the first time I managed to get it running by bleeding the fuel line and it ran fine. After that I haven't been able to start it up anymore.
I got the injector out clean and was able to confirm that there's no spray coming out at all. Now I'm wondering if it's the pump or the injector that is misbehaving. I was hoping that cleaning the injector might solve the problem but I wasn't able to open it manually with wrenches. Will need to use heavier tools to open that one if nothing else helps.
I noticed I'm missing the spring in the anti-dribble valve on the outline of the pump. I may have lost it while checking the line. Luckily there's an online store still shipping parts for this engine for not very ripoff prices. If nothing else helps, I'll order a new pump and/or new injector.

[@Aussie50]

Joona Hartman Sounds like the culprit, without that check valve the fuel will not build pressure in the line high enough to break out of the injector tip.

[@bosatje7656]

thanks really appreciate your quick reply.getting the yse pump, seller was kind enough to take measurements so I know it will fit. yes the nts70r is much older but seems to still have a lot in common with your engine. the only time I have seen mine running was when I picked it up off the guy selling it, he had it sitting under a tarp in his yard for the last couple of years. I imediatly stripped it down when I got home and drained old black deisel out. amazing little engine, apart from severe rust in the water jacket (all removed now using electrolysis ), every seal and gasket leaking and a couple of broken or missing external parts tthere seems to be very Little wrong with it. only now its nearly all back together i,ve run into the first real problem.

[@techdavey3486]

That pump is known as a Deckel Pump and getting a steady tickover is very difficult. I expect you know that YSE decodes to Yanmar, horizontal cylinder, Early. The B in YSB decodes to "Between". If you can find a YSM (M decodes as Modern) it will have a Bosch style pump and spillway cutoff is done quite differently. Allegedly the needle in the Deckel pump needs a lot of attention such as lapping it in or buying new ones. If possible buy spares from an industrial diesel specialist such as Bryco but avoid chandlers like the plague.

[@Aussie50]

@HDXFH everything has a bit of wear and tear, but it works for now

[@zx8401ztv]

Looks smashing :-)
That pump looks like a pain in the arse, the adjustment looks too easy to upset.
Shame you cant find another type thats not so touchy.

[@martinsbr123]

Hi. 10 years later, i wonder if i can get an opinion
i've disassembled mine now... but:
With the pump out , in my hand ( only with the fuel line to the tank connected) i´ve notice that it keeps leaking from the Plunger scew
Is it "normal" or it should be dry?
Tks

[@HDXFH]

I wonder if that needle and seat are worn, seems like a tough fault to diagnose.

[@yanmar3944]

Hey there... The spring and the ball is turned 180 degres . It should work as a one way contra ventil, and it is pointing the wrong way...

[@alexjinks6172]

I spotted that and have been searching for further evidence to confirm it because my NTS85 is giving me a hard time ...Thanks for that !

[@ahdennis]

Hey Aussie! Uploading em pretty late eh? You live in Melbourne right? I'm from country Victoria! Please keep the vids coming I really enjoy listen to and watching your progress and I'm a random 14 year old dude! But I like your motors, my bros a motor mechanic on large diesel machines :)

[@NOLIMIT69NOLIMIT2000]

Hey boss with such little movement in the gov. do you think it may work if set just right once it's warmed up and all? Also what kind of paint did you use cause that looks pretty good?

[@Nucul3arTOAST]

ive got one of these on a log splitter ! its a ts105c, though, they look identical

[@angelitolacson8521]

i have yanmar tf70l model made in indonesia the fuel pump is not working.how to repair it?

[@mcbain3949]

I have a Yanmar T160XL same pump, these pumps are a real pain in the ass, from what I see the adjustment screw is pointless as it only pumps when shut, On my engine you need to take the complete pump off the engine to adjust it its a nightmare .

[@bosatje7656]

Thanks for the video mate! I'm trying to get an older engine (yanmar nts70) going. It has an almost identical injector pump that is causing all the troubles. Getting no spray from the injector and very little pressure in the line. Plunger barrel has pitting from corrosion in it, regulator/unloader valve is showing more wear than yours and its leaking fuel from the adjusting screw at the top. Strange thing is engine was running a couple of months ago before I pulled it apart for a refurb. I had left the injector pump alone till now and since I've cleaned and polished everything it seems to pump even less fuel at less pressure!
Anyways was hoping you had found a solution, like yourself I can't justify several hundred $ in parts for this engine that I don't really Need.
Have the opportunity to get a second hand pump fairly cheap from a yse12, looks the same but would a pump from a different model be ok? Or would it be possible to adapt a new chinese pump somehow?

[@Aussie50]

G'day,
I ended up getting mine working, cleaning the pump and priming the system was enough, I just had to make sure the line was properly primed before it would build pressure.
It sounds like your copped a bit of dirty/wet fuel :(, not cheap to rebuild and I am not sure if a China clone pump would work. as for the interchangeability, as long as the pump can displace the same or very close volume of fuel in theory it would work. my only concern would be if the pump was from a substantially smaller engine, but yours looks almost the same size as my YSE, the video I found shows it with an open flywheel tho, not a marine gearcase, I wonder if thats the only difference?.
Either way, if you can get the pump cheap enough it might be worth a try, just be prepared to change the governor setting it a bit if it overfuels (have hand on decompressor just in case it tries to over rev before you have it calibrated)
Worst case is it does not work properly and you just sell the pump again on ebay or somthing, done that plenty of times when cross matching parts did not work out.

[@pamacesarkol2931]

Nice 👍👍👍👍👍👍

[@Bristol24guy]

G'Day from California. I have a YSB8 engine with the same injector pump and have a question that you might be able to answer. My pump has recently decided to leak at the base of the governor/regulator housing. It is my understanding that the gasket (or packing as the service manual and parts catalog say) is a copper crush washer. Is that correct? Also, can you make anything out of this bizarre wording from the Service Manual regarding the installation of the governor/regulator body?: "Tighten the regulator, with the regulator body turned counter-clockwise to the degree within which it does not come off. Check that the regulator spindle moves lightly." I know that last sentence means to insure that the spindle turns easily but what of the first sentence? Is the regulator (governor) body left-handed? Any insight would be appreciated as I am heading off to the boat (a 3.5 hour drive) to further address the issue. FYI: I rebuilt the YSB8 11 years ago and it has been the most dependable engine ever. We have motored out sailboat at sea for as many as 20 hours at a stretch without a hitch. Thanks...

[@Aussie50]

G'day mate.
I do recall using a copper washer in mine, been a while tho.
I did not take my govenor body off mine so I cannot tell you how to adjust it, it sounds like it has a gland packing type arrangement in it and tightening it allows the shaft to move, but no crank case oil to seep out?
I would just make sure it moves freely and does not bind in any position (don't want a runaway if it decides to jam in the full on position! )

[@Bristol24guy]

Aussie50
Thank you for replying so quickly. The governor body I am referring to is the fitting on the top of the pump that houses what you referred to as the "unloader valve" together with the threaded spindle to which is attached the throttle/governor controls, all of which you had disassembled and laid out in the video. From what I would gather, there is a "packing" which, in the parts drawings looks like it might be a copper crush washer and then there is an O ring on the spacer between the valve and the threaded spindle. I would assume that those two components keep the fuel from leaking. Any input you might have in that regard would be appreciated. Thanks!

[@seanhersey2357]

+Cliff Unruh hello cliff I have a 1977 ysb8 in my Paceship py26 which has just started having a similar issue. There appears to be fuel leaking from the top of the pump, base of the governor tightening of the brass nut in this location caused the fuel leak to improve but caused the motor to not turn over. Loosening this nut allowed the motor to run normally but with a continued fuel leak. How did you fix this issue on your motor??

[@MrPaulcoster94]

hey is there any trick to the settings when you put the pump back on with a new fuel regulator .please

[@Aussie50]

Paul Coster not too sure what the factory settings are, I just set the needle valve to closed with the governor arm sprung back and adjusted it accordingly so that at idle setting the needle was open just enough to keep the engine running. its been a while since I did this so thats all I can remember :(.

[@MrPaulcoster94]

thanks aussie50 for getting back to me . ive got factor settings so im gonna try to stick close as poss to that . some said be careful of the engine running full bore and i wont be able to stop it ,is there a way of stopping the engine ? also im putting the fuel injecting pump back on do i need gasket seal ? thanks for your help ive watched all your yse8 vids very very helpful cheers

[@Aussie50]

Paul Coster If the engine does take off and start to rev too fast, just hit the decompression lever, it will belch smoke and fuel vapor as it coasts down, but without compression it cannot keep firing.
If the gasket is in reasonable order, i would just reuse it, but that's up to you. if its going into a boat and is not going to be looked at often, I would just use new gaskets to avoid leaks.

[@MrPaulcoster94]

Aussie50 thanks mate thats what i thought ,some one scared me . there was no gasket on the pump just somne shims and padding i may smear a bit of silicone sealer between the injector pump and the padding to stop air getting in .when i unbolted it it just came apart very easily .thanks my friend

[@HomeDistiller]

stuff buying parts.. you have a lathe fab some new ones

[@shinyfuzzy]

what the hell is that inhale snorkel noise? snurk

[@jonnoMoto]

@shinyfuzzy His nose

[@nstahlable]

yeah im number 0 somehow