Yanmar YSM 8 starting

[S2Jimlad]

Hi,
Hoping someone can help here. I have a Yanmar YSM 8 engine in the boat I have just bought. I launched her yesterday and the engine refuses to start. I have been through all the usual trouble shooting routines and it seems there is fuel going as far as the injector pump and no further.
Has anyone had a similar experience and can possibly shed some light? I's rather exhaust all avenues before I replace the pump............

 

[Spyro]

Hi,
Hoping someone can help here. I have a Yanmar YSM 8 engine in the boat I have just bought. I launched her yesterday and the engine refuses to start. I have been through all the usual trouble shooting routines and it seems there is fuel going as far as the injector pump and no further.
Has anyone had a similar experience and can possibly shed some light? I's rather exhaust all avenues before I replace the pump............

I think there is a bleed nipple on that pump also try bleeding at the injector with the throttle wide open.

 

[sailorman]

dont remove the injector without having a replacement washer / gasket.
if its the injector pump you mention i think they will be like rocking horse poo

 

[S2Jimlad]

Thanks I'll look for the bleed nipple tomorrow. I did try the injector but there is no fuel that side of the pump. I'm thinking either an air locked or defective pump?

 

[S2Jimlad]

dont remove the injector without having a replacement washer / gasket.
if its the injector pump you mention i think they will be like rocking horse poo

Good advice, thank you. The sales blurb with the boat state the injector pump was replaced 3 years ago however no invoices etc on board..........

 

[Topcat47]

Don't get too hung up on the injector. Yanmar almost certainly do not make their own. The on in my 1GM10 was "serviced" by a local specialist firm and came back bearing little similarities to the one I put in. I very much doubt they stripped it, cleaned it, re-painted it and returned it to me in such pristine condition. I think they just replaced it in the sleeve.

 

[earlybird]

AFAIK, there are no bleed nipples in the fuel system, bleeding is done by slackening the pipe joints. Don't forget to set the speed control to fast whilst this is done.
The service manual, findable on-line, suggests that the pump and injector are Yanmar design and manufacture, so alternative suppliers might be scarce.
The Yanmar manual also gives very detailed instructions for stripping and reassembly of the pump and injector.
IIRC, I removed and replaced my YSE8 injector more than once, without replacing any seals etc, although I never dismantled it.
The whole design is fairly agricultural for DIY, although some specialist equipment would be needed for setting up the fuel pump pressures etc.

 

[CJU]

Don't get too hung up on the injector. Yanmar almost certainly do not make their own. The on in my 1GM10 was "serviced" by a local specialist firm and came back bearing little similarities to the one I put in. I very much doubt they stripped it, cleaned it, re-painted it and returned it to me in such pristine condition. I think they just replaced it in the sleeve.

+1
We also had our injector and pump O/H by a local truck company when our YSM12 wouldn't start after we bought it. The seats in the head had to be replaced too, as compression was leaking past them due to corrosion. We also found the piston rings were stuck in their grooves but on the plus side it is an easy engine to work on, as all the work was carried out in situ. I didn't replace the injector gasket as I couldn't get it out but it didn't cause any problems.
We found to get it to start reliably we had to use full throttle until l fired then throttle back. Sometimes in cold weather I would heat the inlet manifold to help it fire.
One thing I did notice was that when the engine was turned over slowly with the starting handle there was a very audible click when the injector opened, which wasn't there if there was air in the system. Once we got it running it was very reliable. The fuel overspill from the injector also goes back to the filter not the tank on some engines, which makes bleeding the system a lengthy process.
Hope this helps.

 

[rotrax]

I overhauled my 12HP version which was fitted to a narrowboat. At the time I was working at the largest Lucas Service depot in the UK, so I had Takis our Greek Cypriot diesel guy do the injector.

As others had suggested, full throttle, crack the union at the injector, decompress the exhaust valve and crank-manually or with the dynostart-untill fuel is pumping from the injector union every revolution of the engine. The tip re listening for the " click "is relevant and usefull.

I modified mine and fitted a separate 40 gallon fuel tank. IIRC the standard tank had a fuel tap on the outlet-worth checking it is actually on and passing fuel!

When you get it going you will have a strong and reliable engine. The only weak point on our was the raw water cooling pump constantly getting grit under the valves from the dirty canal water.

 

[CJU]

Hi
did you get to the bottom of your starting problems.

 

[S2Jimlad]

Hi,
No it still won't start. I had the pump and injector serviced, fuel is now spraying from the injector. I have bled all the lines up to the injector but it still won't fire up. I have a brand new battery too so that isn't an issue. Really stumped now......

 

[sailorman]

Fuel - Air - Compression
which one is missing

Add some drops of engine oil into the intake manifold, there is a lift-up cap especially for cold start application

 

[RichardS]

Fuel - Air - Compression
which one is missing

Add some drops of engine oil into the intake manifold, there is a lift-up cap especially for cold start application

Or just spray some WD40 or "Easy Start" into the intake whilst a helper cranks her over. If she fires up but fails to keep going then you still have a fuelling problem. If she fails to fire even once you have a compression problem which can be quickly verified by a marine engineer with a compression tester.

Make sure the cooling water intake is closed until she fires.

Richard

 

[sailorman]

Or just spray some WD40 or "Easy Start" into the intake whilst a helper cranks her over. If she fires up but fails to keep going then you still have a fuelling problem. If she fails to fire even once you have a compression problem which can be quickly verified by a marine engineer with a compression tester.

Make sure the cooling water intake is closed until she fires.

Richard

only bodgers use es
engine oil will seal the bore if the compression is down. this horizontal engine suffers from any water vapour in the cylinder always drops to the bottom of the bore & corrodes the same area

 

[paulg567]

I have a YSM 8 and had exactly the same issue.

As said previously, work your way through the fuel system bleeding as you go. You should be able to turn the engine over and hear the injector click if everything bled ok. Mine had a seized fuel pump, easily stripped and cleared.

If you have fuel, it will be compression. Can you turn the engine over without the decompression handle activated? If so, and you hear a hissing noise, air is escaping. Some oil in the bores and left to soak may free up seized piston rings. IS white mist coming out of the exhaust? If so, fuel is getting through and you might try a hot air gun in the intake as you crank the engine (easy start is too aggressive)

I eventually got mine going but it was a VERY slow starter. I finally took the head off and found the valves leaking. Reground them and fitted a new head gasket and it not runs like clockwork. They really are simple and strong engines.

Engine manual can be found here:
http://www.devill.net/Documentation/Yanmar/YSM-8-12.pdf

Feel free to drop me a message if I can help. Good luck!

 

[RichardS]

only bodgers use es

Lol .... in this case a bodger who's forgotten more about engines that you'll ever know. :encouragement:

Richard

 

[alexey]

I have a YSM 8 and had exactly the same issue.
...
Feel free to drop me a message if I can help. Good luck!

Hi,

I'm also unsuccessfully trying to bleed air from my YSM8 fuel system. I need to do this after I cleaned CAV primary filter and changed secondary fuel element.

I made sure there's no air after primary CAV filter. No air, looks good. Then I followed the engine manual to bleed (in this order): 1. secondary filter bleeding plug, 2. joint bolt on injection pump inlet, 3. joint bolt on injection valve return pipe. It looks ok to me, no bubbles, just fuel.

I couldn't bleed air from the fuel injection valve inlet. Where's decompression lever? How do I find it? There's some lever that I use to stop the engine, but I'm not sure if it's stop engine lever or decompression lever. What is the difference? The manual is a vague about them. I did try cranking the engine with this lever in "stop" position a few times, for 10-20 seconds each time. Absolutely nothing comes out of the loose injection valve inlet bolt. No fuel, no nothing.

Before all of this the engine worked perfectly. One day it did fail to start, fortunately after 10 minutes later it started just fine. (It was during a critical moment, so it made quite impression on me.) I now believe the reason was temporarily stuck engine stop (or decompression?) lever. But back then I decided fuel system was to blame. That's why I started the servicing fuel system. There was a bit of dirt in the CAV filter, and no dirt in secondary filter.

Alexey

 

[earlybird]

. Where's decompression lever? How do I find it? There's some lever that I use to stop the engine, but I'm not sure if it's stop engine lever or decompression lever. What is the difference? The manual is a vague about them..
Alexey

The decompression lever is on the valve cover on the cylinder head. Probably operated by a wire cable which might be jammed. It shouldn't be used for stopping the engine. That's done on the YS engines by closing the speed control lever. For bleeding the fuel system, the decompressor can be operated. The engine will then turn over much more easily. Make sure that the speed control is set to maximum for bleeding.

 

[alexey]

The decompression lever is on the valve cover on the cylinder head. Probably operated by a wire cable which might be jammed. It shouldn't be used for stopping the engine. That's done on the YS engines by closing the speed control lever. For bleeding the fuel system, the decompressor can be operated. The engine will then turn over much more easily. Make sure that the speed control is set to maximum for bleeding.

Oh, I found a lever in that area, thank you! There is no wire cable connected to it. The level is just sitting there alone, with a spring that keeps it in place. I think I need to find another pair of hand, to crank the engine with Start button at the stern, while I hold the decompression level on the engine and check the fuel and bubbles.

1. Is there a way to do it alone?
2. Do I need to tighten injection pump inlet while the engine is cranking and producing pressure?

 

[alexey]

Correction for the 2nd question: injection *valve* inlet (not pump)