Yanmar Engine not Starting after Prime

[Scot_]

So I bought a new (to me) Mirage 27 ft and sailed it back across Lake Ontario.

The boat had been sitting all year prior to me getting it on July 1st.

It sailed fine for the first of 3 days, but on the 3rd day there was no wind at all and we were on motor. We had motor sailed for about 50% of the time prior.

After about 8 hours at 60-75% throttle, there was the occasional sputter, but never stalled out. It would cut out when going down to idle, but I think the throttle stop was set to low.

An hour after dark (I know, I shouldn't have kept going) the motor sputtered and gave out.

I suspected the raycor was filled, drained it, re-primed the system, and of course batteries started to give and could not get it restarted (despite adding a new spare battery).

We were towed in, and I came back the next day to re-prime the system, and charge the batteries. I did so, but left filters as were. It eventually started for about 30 seconds and then gave out. Keep in mind, I was alone and did not have the started rigged up so I was above deck while cranking, and using the hand crank to prime.

The next day I brought a buddy who when he cranked it, I could see diesel coming out of the return line to the canister filter (which I loosened when purging). I over tightened it and stripped the housing after this.

Once replaced, I purged right up to the injector (opened the return line side and had bubbless diesel coming out).

The motor would not fire at all. I suspect maybe an injector pump, injector, or perhaps water still in the fuel.

The boat is in a rural area and quite the trek to get to, so I am asking for any other obvious input that I may be overlooking before I make my next trip out there. I'm going to drain the bottom of the tank to hopefully take any water out, replace the raycor, and check output pressure on the injector pump - but beyond that, I'm at a loss - unless the injector if faulty.


Thanks for any input!

[FlyingScot]

Am I reading this correctly, you still haven't changed out the fuel filter(s)?
What model yanmar?
What model fuel filters?
My 3YM30 has a small fuel filter on the engine and a separate Racor water separating fuel filter before it.

It's like step one to eliminate the easy causes (IE fuel filters).

[alamoana]

Hi Scot, I believe your issues are fuel related. Either you do not have fuel or you are sucking air into the fuel. I would try with a short length of hose on a clean jug of fuel with clean filters, a good prime and check the connections. Good luck

[Scot_]

I have changed the canister filter, as well as the housing (due to stripping the return fastener). I have not changed the raycor as the cansiter wrench I had was too big (its in a stupid spot). I do have the replacement, and will change after..

However, the fact that I'm getting a steady stream to the injector makes me feel it is not the raycor.

The motor is a Yanmar 150 SB8

[Compass790]

yep it sounds fuel related. You can pull the injector out & spin the motor up to see if it's spraying. ( Keep clear of spray ) But I'd be checking all your joints especially if you've stripped one. It's good to have a primer bulb to pressurise your fuel likes & wrap all the joints in toilet paper to check for leaks. Sounds like air in their somewhere but strange if you are getting a steady stream from injector pipe. Shudnt be a steady stream should be squirts

[charliehows]

hate to be a harbinger of doom but...it took me 2 years to fix all the fuel system problems after I bought my present boat - and I was keen to renew everything I suspected, and things not suspected, from the start. On the good side, unpredictable breakdowns really helped me focus and improve on my engineless boat management skills.

[Wotname]

Originally Posted by Scot_

So I bought a new (to me) Mirage 27 ft and sailed it back across Lake Ontario.

The boat had been sitting all year prior to me getting it on July 1st.

It sailed fine for the first of 3 days, but on the 3rd day there was no wind at all and we were on motor. We had motor sailed for about 50% of the time prior.

After about 8 hours at 60-75% throttle, there was the occasional sputter, but never stalled out. It would cut out when going down to idle, but I think the throttle stop was set to low.

An hour after dark (I know, I shouldn't have kept going) the motor sputtered and gave out.

I suspected the raycor was filled, drained it, re-primed the system, and of course batteries started to give and could not get it restarted (despite adding a new spare battery).

We were towed in, and I came back the next day to re-prime the system, and charge the batteries. I did so, but left filters as were. It eventually started for about 30 seconds and then gave out. Keep in mind, I was alone and did not have the started rigged up so I was above deck while cranking, and using the hand crank to prime.

The next day I brought a buddy who when he cranked it, I could see diesel coming out of the return line to the canister filter (which I loosened when purging). I over tightened it and stripped the housing after this.

Once replaced, I purged right up to the injector (opened the return line side and had bubbless diesel coming out).

The motor would not fire at all. I suspect maybe an injector pump, injector, or perhaps water still in the fuel.

The boat is in a rural area and quite the trek to get to, so I am asking for any other obvious input that I may be overlooking before I make my next trip out there. I'm going to drain the bottom of the tank to hopefully take any water out, replace the raycor, and check output pressure on the injector pump - but beyond that, I'm at a loss - unless the injector if faulty.


Thanks for any input!

Welcome aboard CF, Scott. Great first post, it highlights all the problems of becoming a new (to you) SB8 owner.

It sounds like you have a few issues to solve along with getting the engine going again.

For instance, the batteries sound shot - presumably they sat for a year without maintenance and I would be confirming the output of the alternator as well (should be around 14V depending on the condition of your batteries).

Back to the engine, do you have a copy of the SB8 operation manual - if not get one - they are available on the web or I can send you one). This engine is an old design and as such, they have some peculiarities which are not so well known any more. A careful read can save you some heartaches!

As others have suggested, it certainly sounds like a fuel issue - it ran for some time OK and now doesn't - classic fuel issue.

After confirming you have a clean supply of fuel (new filters, no air leaks etc), bleed (re-prime) the engine as per the book (mentioned above). The method you described is not suitable for this engine / injector pump.

However you can tell if an SB8 engine is correctly bleed by listening to it!!!

Decompress the engine, set the throttle to full power (i.e. WOT), turn the engine over with the hand crank and unless you are hearing impaired, you will a squeak from the injector each time it operates. If it doesn't squeak, it is not injecting.This is all in the operators manual.

Second thing to note is that the injector pump does require some user adjustment occasionally - again the technique is in the operators manual.

Might I suggest learning how to start the engine using the starter motor and the compression lever - this allows one to start the engine with a near flat battery.

There are a couple of threads about the SB8 / SB12 you might find interesting.

http://www.cruisersforum.com/forums/...or-221204.html

http://www.cruisersforum.com/forums/...up-222071.html

[copaco]

I fixed my SB 8 following Wotname’s advice.See Copaco.








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[Scot_]

This forum is so unbelievably helpful!

Regarding the fuel flow - what I meant by 'steady' was that there were no bubbles, not so much a steady flow.

And good call on the cranking the starter while decompressed while the battery is low. Makes perfect sense!

I'll give this a try over the weekend and hopefully I'll be back on the water!

[Compass790]

Originally Posted by Scot_

This forum is so unbelievably helpful!

Regarding the fuel flow - what I meant by 'steady' was that there were no bubbles, not so much a steady flow.

And good call on the cranking the starter while decompressed while the battery is low. Makes perfect sense!

I'll give this a try over the weekend and hopefully I'll be back on the water!

I always start the motor decompressed as the other benefit is you get the oil pressure up before the engine fires which must be kinder to the bearings.
Please report back what you find. Wotnames posts should sort your problem out. He is the CF guru for that model injection pump

[GordMay]

Greetings and welcome aboard the CF, Scot.

A ‘Remote Starter Switch' can be an invaluable troubleshooting tool.
➥ https://www.amazon.ca/Actron-CP7853-.../dp/B0009XQUKW

[copaco]

À Bombardier small engine mechanic tells me that putting 100 ml of automatic transmission fluid in the fuel will greatly help a starting a small Diesel engin?

[a64pilot]

Originally Posted by copaco

À Bombardier small engine mechanic tells me that putting 100 ml of automatic transmission fluid in the fuel will greatly help a starting a small Diesel engin?

Not really.
This is a VERY old school injector varnish remover, it does actually work, it works because ATF is a very high detergent light weight hydraulic fluid and it’s the detergent of course that cleans.
There are likely better products out there, and maybe you don’t want to do this on modern road Diesels with their exhaust catalysts etc. but for an old type Diesel it’s effective and causes no harm.

Back in the 70’s with the Mercedes Diesels of the day, when they got so that even when warm they knocked and rattled like they were cold, it was time to add a quart of ATF to the fuel and it would slowly stop the rattling knock at idle. The rattle / knock comes from the injectors not having a fine spray but rather a stream of fuel, that affects timing and raw fuel is even left over from one ignition event to the other and having fuel present as the piston begins compression causes a pre-ignition and therefore a rattle / knock.