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Old 13-09-2021, 13:22   #1
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Yanmar YSE 8 Won't start Cold

Hello and thank you for taking the time to read this, it is my first post and first inboard diesel engine!

I have a YSE 8 engine which has been causing me alot of trouble since I purchased it 5 months ago.

my first problem was that It would start fine cold every time, but never hot - I replaced the oil, changed/cleaned filter, changed fuel pump, charge on battery seems good enough, checked the exhaust manifold (could see some build up in there but did not seem much) and checked the impeller which seemed fine, but I did not have a spare to replace it (plenty of water seems to be coming out of the exhaust ). I then went to see a mechanic after the problem was still occuring and we found that no fuel was coming back out of the fuel return line, causing the fuel pump to get extremely hot - he recommended that i set a line that went back into the fuel return line, before going into the engine - I did this and now the fuel pump does not overheat. (at this time i also changed all the water hose lines in the engine and tightened the belts to the correct tightness.

HOWEVER the engine started up first time cold and then wouldn't turn on hot again - i found an explanation on how to adjust the governor arm and did this.

NOW IT STARTED HOT EVERY TIME!...but didn't start cold. Unless i played around with the governor setting while trying to turn over the engine, when i set it to a "lower" setting it turns on and then i quickly adjust to the correct position. She seems to be running as good as, if not better than ever when running.

HOWEVER as of yesterday I couldn't get the engine to start at all (bled lines and checked battery level) and had to use quick start... this morning it was the same.

I am trying to keep moving but am currently at a marina in Campbell River, BC with a minimum 2 week wait time to see a mechanic and would much rather do the work myself if possible.

I am thinking that I will top up/buy new batteries to see of that is the problem.

other than that perhaps I should buy a new exhaust manifold? or take appart the fuel injector?

sorry for the long ramble but im trying to get all the information in!

many many many thanks for any advice you could send my way

Regards
Pete
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Old 13-09-2021, 13:26   #2
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Re: Yanmar YSE 8 Won't start Cold

Welcome to the forum, PincoyaBlue. Now I'll go back and read your question.
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Old 13-09-2021, 13:43   #3
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Re: Yanmar YSE 8 Won't start Cold

Well, for starters (ouch!, my bad) a weak battery will not turn the engine over; that's separate from failing to start whn it does turn over. If it is cranking OK, eliminate the battery from your possible sources of the problem.

By "quick start" do you mean starting fluid/ether? It's starting when you use it? If yes, then we're on the fuel side of air, fuel, and compression, the only three things a diesel engine needs. So the problem is either the nature of the fuel itself or the delivery of it.

I'm suspicious of an air leak into the fuel system. Also of a partial blockage. That lack of return fuel is a clue to there not being enough fuel under at least some regimes.

Now I've got to turn you over to a specialist, who perhaps knows that engine.
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Old 13-09-2021, 13:54   #4
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Re: Yanmar YSE 8 Won't start Cold

The last YSE8 rolled off the production line in 1976 so yours is at least 45 years old.


One way that diesel engines show that they are worn and in need of service/overhaul/replacement is that they become more difficult to start. The root cause can be: worn valves or rings, worn injectors, worn injection pump, or a combination of these.



It is not uncommon for ether to be used to start these much older machines when they are near the end of their service life. Use as little as necessary, and remove or disable any heating devices such as glow plugs or intake manifold heaters.


I would not fuss much with governor settings as you can damage the engine by overfiring.


My recommendation would be to use ether (carefully) to start it until it can be looked at by a mechanic.
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Old 13-09-2021, 15:41   #5
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Re: Yanmar YSE 8 Won't start Cold

Welcome to the forum PincoyaBlue.
Whilst it's true that your yse8 is an old engine they are rebuildable indefinitely. We have a ysm8 which is nearly the same but one difference is the injector pump.
Although noisy shakey beasts they are very reliable & long lasting with a bit of maintenance & if you ditch that yammer destroying cast-iron horror of a yanmar mixing elbow. Well the mixing elbow would be ok if replaced at recommended intervals but a bronze one would probably last a lifetime & an ss one 15+ years

I'd suggest your problem definitely lies with the injector pump if it gets extremely hot, I dunno what the mechanic was doing suggesting you change the rtn line layout. Can you post pics of what he did. Have you checked flow frm mechanical lift pump?
In our case when no flow came frm injector rtn line the delivery valve in injector pump was stuffed. But that may not be your problem.

Your compression should be fine if it starts easily when cold.
Wotname has a yse8 & he knows more about that style of injection pump but I know you have to follow the setup for pump lever linkages as described in the service manual exactly. I can send you both a yse&ysm service manual for free if you PM me yr email. If you look for Halifax sailor threads i think Wotname has posted how to adjust injection pump/governot linkage on one of those.
The regulator needle wears in the injection pump too.
You could pull the injector & check the spray pattern. If the exhaust mixing elbow has never been checked you should take that off & clean it .
HDI marine makes ss copies that are much better than yammers but I like my easily made with stick welder design better still as it cant drop water on top of exhaust valve.
You should not need engine start on these 23:1 comp ratio diesels. I never do down to 4oC & just at idle setting but before rebuild I had to squirt oil in the air intake to get it to start. ( Don't try this at home, too easy to bend a pushrod or worse)



Wottie may be along shortly to help you out & correct any yse specific mistakes i've made. All it's problems can be fixed AFAIK so hang in there, we'll try & help ya out
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Old 13-09-2021, 18:37   #6
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Re: Yanmar YSE 8 Won't start Cold

Welcome aboard PincoyaBlue. Sorry to hear you have troubles with your YSE but hang in there, most likely it is fixable once you isolate the actual problem.

It could well be the governor adjustment as this is critical for this injector pump and it does require adjustment occasionally when the engine becomes hard to start. It is easy adjustment to make once you know how but it is also very easy to stuff it up if you don't follow the instructions to the letter.

I'm time short ATM but will post more later today / tonight.

If you log on before then, perhaps you could answer the following question. What fuel pump was getting hot? Was it the injector pump or the lift pump? I can't see why either should get hot and neither should have a return line.

Also it is easy to isolate any electrical starting issue if you do the following. Set everything up for starting then decompress the engine with the decompression lever, spin the engine over using the starter motor for a few seconds until it spinning over smartly then release the decompression lever while keeping the starter motor engaged. If the engine starts promptly using this method but doesn't start when using the starter motor alone, then you have an electrical issue in the starting circuit (flat battery, poor wiring, corrosion, weak starter motor etc).

If it remains hard to start when using the decompression lever as a starting aid, then you will need to look elsewhere (fuel / compression etc).

If you get a chance, try the above to isolate the fault to either electrical or otherwise.

More later...
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Old 13-09-2021, 18:38   #7
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Re: Yanmar YSE 8 Won't start Cold

Quote:
Originally Posted by tkeithlu View Post
Well, for starters (ouch!, my bad) a weak battery will not turn the engine over; that's separate from failing to start whn it does turn over. If it is cranking OK, eliminate the battery from your possible sources of the problem.

By "quick start" do you mean starting fluid/ether? It's starting when you use it? If yes, then we're on the fuel side of air, fuel, and compression, the only three things a diesel engine needs. So the problem is either the nature of the fuel itself or the delivery of it.

I'm suspicious of an air leak into the fuel system. Also of a partial blockage. That lack of return fuel is a clue to there not being enough fuel under at least some regimes.

Now I've got to turn you over to a specialist, who perhaps knows that engine.
Thank you for your warm welcome and your reply!

Good to know with the batteries. Ether is what I have been using and it seems to start the engine every time (just one quick squirt)

I agree the lack of return fuel does seem to be a clue...
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Old 13-09-2021, 18:49   #8
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Re: Yanmar YSE 8 Won't start Cold

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Originally Posted by Compass790 View Post
Welcome to the forum PincoyaBlue.
Whilst it's true that your yse8 is an old engine they are rebuildable indefinitely. We have a ysm8 which is nearly the same but one difference is the injector pump.
Although noisy shakey beasts they are very reliable & long lasting with a bit of maintenance & if you ditch that yammer destroying cast-iron horror of a yanmar mixing elbow. Well the mixing elbow would be ok if replaced at recommended intervals but a bronze one would probably last a lifetime & an ss one 15+ years

I'd suggest your problem definitely lies with the injector pump if it gets extremely hot, I dunno what the mechanic was doing suggesting you change the rtn line layout. Can you post pics of what he did. Have you checked flow frm mechanical lift pump?
In our case when no flow came frm injector rtn line the delivery valve in injector pump was stuffed. But that may not be your problem.

Your compression should be fine if it starts easily when cold.
Wotname has a yse8 & he knows more about that style of injection pump but I know you have to follow the setup for pump lever linkages as described in the service manual exactly. I can send you both a yse&ysm service manual for free if you PM me yr email. If you look for Halifax sailor threads i think Wotname has posted how to adjust injection pump/governot linkage on one of those.
The regulator needle wears in the injection pump too.
You could pull the injector & check the spray pattern. If the exhaust mixing elbow has never been checked you should take that off & clean it .
HDI marine makes ss copies that are much better than yammers but I like my easily made with stick welder design better still as it cant drop water on top of exhaust valve.
You should not need engine start on these 23:1 comp ratio diesels. I never do down to 4oC & just at idle setting but before rebuild I had to squirt oil in the air intake to get it to start. ( Don't try this at home, too easy to bend a pushrod or worse)

Wottie may be along shortly to help you out & correct any yse specific mistakes i've made. All it's problems can be fixed AFAIK so hang in there, we'll try & help ya out
Thank your for your reply, I think my original post was a little unclear.

I have an electric fuel pump that pumps into the fuel pump on the engine, that them goes to the injector. The electric fuel pump was overheating (red hot after a small amount of time) so i installed a line that goes directly to the return line back into the tank. I can't take a picture at this time but will try to upload one ASAP

The engine is no longer starting when cold bit starts very well when hot.

I have not checked the spray pattern yet but will try to find out how to do that - I have however cracked the nuts at the injector and found that fuel is getting there but not coming back out of the return line.

Perhaps a new mixing elbow would be a good investment!

I do have a copy of the service manual but appreciate the offer.
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Old 13-09-2021, 18:58   #9
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Re: Yanmar YSE 8 Won't start Cold

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Originally Posted by Wotname View Post
Welcome aboard PincoyaBlue. Sorry to hear you have troubles with your YSE but hang in there, most likely it is fixable once you isolate the actual problem.

It could well be the governor adjustment as this is critical for this injector pump and it does require adjustment occasionally when the engine becomes hard to start. It is easy adjustment to make once you know how but it is also very easy to stuff it up if you don't follow the instructions to the letter.

I'm time short ATM but will post more later today / tonight.

If you log on before then, perhaps you could answer the following question. What fuel pump was getting hot? Was it the injector pump or the lift pump? I can't see why either should get hot and neither should have a return line.

Also it is easy to isolate any electrical starting issue if you do the following. Set everything up for starting then decompress the engine with the decompression lever, spin the engine over using the starter motor for a few seconds until it spinning over smartly then release the decompression lever while keeping the starter motor engaged. If the engine starts promptly using this method but doesn't start when using the starter motor alone, then you have an electrical issue in the starting circuit (flat battery, poor wiring, corrosion, weak starter motor etc).

If it remains hard to start when using the decompression lever as a starting aid, then you will need to look elsewhere (fuel / compression etc).

If you get a chance, try the above to isolate the fault to either electrical or otherwise.

More later...
Hello Wotname

Thanks for the swift reply

I have an electric fuel pump that pumps into the fuel pump on the engine, that them goes to the injector. The electric fuel pump was overheating (red hot after a small amount of time) so i installed a line that goes directly to the return line back into the tank.

They sound like great suggestions, I will endeavour to troubleshoot with them tomorrow and report back.

I also have a noise that is perhaps getting louder/worse, it sounds like a valve tapping loudly but does not seem to be coming from a valve and it hard to isolate. At some RPM/high rpm it is alot quieter, I don't know if this could be related?

Again, much appreciated
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Old 13-09-2021, 20:48   #10
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Re: Yanmar YSE 8 Won't start Cold

Ok Pincoyablue, now I'm with ya.
I thought your problem was with the injector pump that is the one the steel pipe that goes to the injector comes out of. The pump that you are talking about is generally referred to as the lift pump. But I have been known to read posts poorly!
What is wrong with the original mechanical on engine lift pump ( low pressure fuel pump?) I would guess you need a new electric fuel lift pump but I trust the original mechanical ones more. If you have a loose tappet it could definitely be related as it can effect how much air is drawn in or allowed out hence affecting compression.. Easy to check that.
You can try gravity feeding your injection pump with some filtered fuel & see if it starts.

To check injector spray pattern remove injector & reconnect to injector line & spin engine over decompressed. Dont go near the spray as its around 2400 psi & can easily penetrate yr skin. Have a look at this vid another CF user posted to show you what a good spray pattern looks like :



Yea definitely trash that cast iron mixing elbow if its 4 years old or older. They are responsible for killing more YS series yanmars than anything else I guarantee.
Hope that helps
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Old 13-09-2021, 23:31   #11
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Re: Yanmar YSE 8 Won't start Cold

You're in good hands here, so I'll mostly stay out unless I can provide something of use....so here goes.

Starting speed is important, so check both your batteries and all the high amperage connections and cables.

If the engine is turning like erunh -erunh -erunh -erunh, she's likely not spinning fast enough. About 100 rpm starting speed should ensure that that's not the problem.

The intermittency has me a little baffled;certainly sounds like a fuel supply issue. Eliminating slow starting speed from the equation is an efficient trouble-shooting tool, as well as making your mechanical life simpler in the long run.
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Old 14-09-2021, 04:58   #12
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Re: Yanmar YSE 8 Won't start Cold

Sorry I forgot yse & ysb dont have mechanical lift pumps. Does the engine blow much smoke or burn much oil? You definitely could have air problems as others suggeest if you have been messing with the fuel hose/piping. Check all connections. Think you should check tappet clearance & injection timing anyway as it could be a long time since they were checked
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Old 14-09-2021, 09:27   #13
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Re: Yanmar YSE 8 Won't start Cold

The older and probably all bigger engineer have the gouverneur on full ahead when the engine is NOT running. The system tried to keep idle speed of.
So when starting, with the first strikes, it is pumping, onjectonh maximum fuel through the nozzles. A cold start mechanisme on those engineer is Just ligging the full ahead stop so itthose 4ngines so more can be injected.
As soon as. The engine runs it Will fall back because the hand regulator is on idle.
Now some where I thought you wrote changing the gouverneur. Perhaps you changed something the wrong way.
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Old 14-09-2021, 15:22   #14
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Re: Yanmar YSE 8 Won't start Cold

Quote:
Originally Posted by jakkum View Post
The older and probably all bigger engineer have the gouverneur on full ahead when the engine is NOT running. The system tried to keep idle speed of.
So when starting, with the first strikes, it is pumping, onjectonh maximum fuel through the nozzles. A cold start mechanisme on those engineer is Just ligging the full ahead stop so itthose 4ngines so more can be injected.
As soon as. The engine runs it Will fall back because the hand regulator is on idle.
Now some where I thought you wrote changing the gouverneur. Perhaps you changed something the wrong way.

No your description of how the governor works does not apply to the OP's YSE 8.
Thought I'd better point this out as we dont wanna confuse him more than I probably already have talking about mechanical lift pumps which they didnt come with
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Old 14-09-2021, 20:41   #15
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Re: Yanmar YSE 8 Won't start Cold

So a quick update and thank you to everyone's help so far!

The engine was smoking (white) and did seem to be getting alot worse before it stopped starting. I was seeing a fair amount of smoke, fuel and occasionally oil from the exhaust

I tried the compression leaver to check if it was the starter motor and still nothing.

Secondly I checked the spray pattern, as suggested and found the pattern to be weak looking and very linear. Not a spray pattern like the video above or in the service manual.

I have a habit of breaking things when trying to fix them so have decided to take it to a local( recommend) that will be able to take it apart and look at it for me. I am also going to bring along the engine fuel pump as I believe one of these must be the issue.

Hopefully this is the right thing to do..?!?

Looks like I'm going to be tied to the dock a little longer.... luckily Cambell River is full of interesting people!
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