Yanmar Ysb8 not starting, injector pump doesn’t seem to be pumping

[Wotname]

Originally Posted by Halifax Sailor

OK, here's my level of understanding. As far as I know compression is good as this only started after I adjusted the valve clearance, Moved it too close as I read the manual wrong. Engine started real hard so asked some questions and reset it to manual. I am going to check the spray pattern next, just wondering if I am overlooking something?

Halifax Sailor, have you resolved your slow cold starting issues yet?

[Halifax Sailor]

Hey Wotname, yes I think so. Went to the boat today, first time in a week. 3 cans of Sea Foam working in the fuel, I hope. Crossed my fingers, started in 5 secs!! Thats good enough for the wife and I am going to leave it be until I hawl the boat for the winter. Prob pull the injector then. Thx for the advice, it was as you said, Cudos to you and everyone who chimed in.

[Halifax Sailor]

BTW, changed out all the fuel lines, re-checked the valve clearance. Did find that the intake valve was a little bigger gap, not by much, feeler gauge was quite loose. So both now as to spec. Used 3 cans of Sea Foam, have run the engine about 5 hours since, idling, in gear, low spped, high speed. Start time is way down, today after a week away 5 secs. And a re-start 40 minutes later was immediate. So leaking fuel line? valve a little out of spec? new filters? Sea Foam? any combination of the fore mentioned? Anyway, am happy for now, wife is happy, going sailing!!!!!!!

[Halifax Sailor]

Hey Wotname,

since we are on the subject.. when i was adjusting the valve clearance, I noticed the rocker for the intake valve can slide along the shaft. Not much but enough that I wondered if it was missing a lock, spacer or something. It moves enough that when I was gapping the valves I pushed it to the center of the valve but doesnt move enough to come off the valve. Cant find anything anywhere that says there is a spacer, screw, lock washer or anything like that in any manual. Wondering if thats why I have a little more noise when the engine is running, doesnt seem to affect the performance. The exhaust valve rocker doesnt slide at all.

[Wotname]

Originally Posted by Halifax Sailor

Hey Wotname,

since we are on the subject.. when i was adjusting the valve clearance, I noticed the rocker for the intake valve can slide along the shaft. Not much but enough that I wondered if it was missing a lock, spacer or something. It moves enough that when I was gapping the valves I pushed it to the center of the valve but doesnt move enough to come off the valve. Cant find anything anywhere that says there is a spacer, screw, lock washer or anything like that in any manual. Wondering if thats why I have a little more noise when the engine is running, doesnt seem to affect the performance. The exhaust valve rocker doesnt slide at all.

Hmm... There isn't any locking mechanism and I'm not aware of any problems.

Maybe you have a tiny bit of wear in the inlet rocker arm bushing.

I have attached a couple of pages from the YSM manual. While the head and valve gear is the same as your YSB, the YSM manual gives a more detailed description.

Maybe Compass790 knows more???

[Compass790]

On the inside of the rocker cover there are two tabs that stop the rocker arms from coming off. I wondered about the wandering arms as well when first trying to do the tappets.
Find it strange that his exhaust v/v rocker arm wont slide along the shaft as well. I'd check it for ease of movement but if it goes up & down freely without slop in it there should be no problem.

[Wotname]

Originally Posted by Compass790

On the inside of the rocker cover there are two tabs that stop the rocker arms from coming off. .........

Ah yes.....I had forgotten about the tabs inside the rocker cover - thanks for the reminder!

You do know more

[Uncle Bob]

Originally Posted by Wotname

Ah yes.....I had forgotten about the tabs inside the rocker cover - thanks for the reminder!

You do know more

Either that or he has forgotten less.

[Compass790]

Originally Posted by Uncle Bob

Either that or he has forgotten less.

I think the Kings mind is on electrical circuits & the YSE8 & 2QM20 pathway neurotransmitters are in standby mode

[Halifax Sailor]

So update on my ysb8 slow starting. Last week I had put in another can of Sea Foam. Thats 3 now. Ran it for about 2 hours, some idling, some under power, various speeds. Got my second covid shot so was under the weather for a couple of days. went back today, first time in a week. Engine started just like it used to so...................new filters, new fuel lines, adjusted valve clearances, sea foam??????? I dont know but it started so easy, just like new so am crossing my fingers that that continues and will keep you updated. Have watched multiple videos about taking the injector apart so that will be a winter haul out job unless I have further problems. Thanks to all for the advice and assistance. I may have settled the wife so she will have some confidence.

[Compass790]

Originally Posted by Halifax Sailor

So update on my ysb8 slow starting. Last week I had put in another can of Sea Foam. Thats 3 now. Ran it for about 2 hours, some idling, some under power, various speeds. Got my second covid shot so was under the weather for a couple of days. went back today, first time in a week. Engine started just like it used to so...................new filters, new fuel lines, adjusted valve clearances, sea foam??????? I dont know but it started so easy, just like new so am crossing my fingers that that continues and will keep you updated. Have watched multiple videos about taking the injector apart so that will be a winter haul out job unless I have further problems. Thanks to all for the advice and assistance. I may have settled the wife so she will have some confidence.

Yea no rush if you have the wife pass, just go boating & look at injector in winter especially as you have a short season. They are simple really if you have the w/shop manual. I found injector quite difficult to seal in the head & ended up using a bit of Loctite 518 on injector face when re-installing but I didnt buy a new copper washer & just annealed the old one.
If it's running as good as new injector wont be too bad but given the age a check & clean wouldnt hurt. My guess for your issues is fuel lines but have no experience with sea foam.