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Old 03-11-2020, 05:37   #1
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Ysm8 hard start cold, requires throttle to start

I have a ysm8 in a cape dory 27. As far as I know everything about the installation is pretty much as cape dory did it except now it has a racor filter in place also.

I've been sitting in nasty chop in block harbor waiting for weather. My engine eventually became hard starting, then died when it was running. I thought it was the filters being clogged so I changed the racor and the yanmar filter out. They both had some crud in them but weren't caked. I don't know how much is required to stop an engine from experience though. After changing the filters I realized the tank was also nearly dry. I fixed the mechanical fuel gauge that was stuck on full, and then put 5 gallons in it. It was a little hard to start as I bled it but it did start. It ran for a couple minutes like a champ then stopped. I bled again and it seemed to do the trick. I was satisfied.

However since then it has required a either a little, or full, throttle to get the thing to start. I've even had to bled again. I've checked the connections to make sure it's tight, a truck forum made me think the pressure is bleeding off while sitting....?

Any thoughts would be appreciated.

- AT
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Old 03-11-2020, 10:54   #2
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Re: Ysm8 hard start cold, requires throttle to start

The pressure does bleed off while sitting. It's not designed to hold pressure long term.

You probably have air getting into the system at some connection. The filters may not be tightly sealed. You also could have a hose that collapses from the lift pump suction.

It could be that the pickup tube is picking up debris and reducing flow. When the engine shuts down, what pressure there is in the fuel lines flows back and clears the debris. You also could have debris somewhere in the fuel lines.

But my money is on an air leak.
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Old 03-11-2020, 14:45   #3
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Re: Ysm8 hard start cold, requires throttle to start

What Lepke said,
They are a Pita to bleed but should run ok once bled properly. Don't know where in the world you are but if it's a bit cold it's not uncommon to need throttle to start especially if the compression is getting down a bit. It actually tells you to use some throttle in the operating instructions. We have the same engine & the lift pump priming lever drove me more crazy so I fitted an outboard type squeeze bulb to make bleeding easier. If it has the original fuel hoses they'd be getting real hard now & prone to leaks & you clearly have an issue if it always started with no throttle before.
Always use a filter funnel when filling tank & check your deck fill cap o-ring as it's common for water to get in there.
If you want a workshop manual that tells you virtually everything PM me ( no charge )
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Old 03-11-2020, 16:12   #4
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Re: Ysm8 hard start cold, requires throttle to start

I can check the tightness of the fuel filter connections. I had suspected the final filter of being loose, but there was no change when I tightened that. I would also just expect to see diesel on the way out if there was a leak...
There is a little confusion (to me) about which o-ring should be used with that filter. I've found 2 part numbers that seem to be for the filter. I replaced it with one that looked the same as what was in there... but we know what that can mean. Does anyone know how thick the proper oring for the final fuel filter is?

It's been about 40-50 (and even colder, I've had sleet on my boat in the last week). I'm thinking 30wt and no glow plugs might be making it a little harder to start, also. Sometimes partial throttle helps. Usually it kicks over if I go full throttle and slowly ween it back. It sounds like a happy one lunger after it settles in.

It also seemed a little laggy when I used it to change docks. It has been starting pretty well today (I've been starting it every several hours for 15 minutes or so).

I don't see any evidence of water in the racor. I have been using a fuel filter on the way in. I do remember the seal on the diesel fill being a little hard - I'll start taping that over until I can fix it properly. I'm working my way down the coast to Florida so time is very precious right now.

- AT
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Old 03-11-2020, 16:32   #5
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Re: Ysm8 hard start cold, requires throttle to start

Quote:
Originally Posted by Atcowboy View Post
I can check the tightness of the fuel filter connections. I had suspected the final filter of being loose, but there was no change when I tightened that. I would also just expect to see diesel on the way out if there was a leak...
There is a little confusion (to me) about which o-ring should be used with that filter. I've found 2 part numbers that seem to be for the filter. I replaced it with one that looked the same as what was in there... but we know what that can mean. Does anyone know how thick the proper oring for the final fuel filter is?

It's been about 40-50 (and even colder, I've had sleet on my boat in the last week). I'm thinking 30wt and no glow plugs might be making it a little harder to start, also. Sometimes partial throttle helps. Usually it kicks over if I go full throttle and slowly ween it back. It sounds like a happy one lunger after it settles in.

It also seemed a little laggy when I used it to change docks. It has been starting pretty well today (I've been starting it every several hours for 15 minutes or so).

I don't see any evidence of water in the racor. I have been using a fuel filter on the way in. I do remember the seal on the diesel fill being a little hard - I'll start taping that over until I can fix it properly. I'm working my way down the coast to Florida so time is very precious right now.

- AT

Oh yeah if you are in sleet weather you are definitely into needing throttle advance to start. Also the other trick to help you is spin it up decompressed & when its spinning hard out drop the decompression lever ( push cable in ) This has the added benefit of pre-oiling the main bearings which cost a kings ransom.
You can also use 10w-40 oil or 15w-40 diesel oil as well to help it turn over easier in the cold. Not as if they are an expensive oil change.
Couldnt attach manual file as it says too big. See PM for email.
Sorry cant help you with final filter as i ditched my ripoff Yanmar filters & got a cheaper & better setup
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Old 03-11-2020, 16:46   #6
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Re: Ysm8 hard start cold, requires throttle to start

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Originally Posted by Compass790 View Post
Oh yeah if you are in sleet weather you are definitely into needing throttle advance to start. Also the other trick to help you is spin it up decompressed & when its spinning hard out drop the decompression lever ( push cable in ) This has the added benefit of pre-oiling the main bearings which cost a kings ransom.
You can also use 10w-40 oil or 15w-40 diesel oil as well to help it turn over easier in the cold. Not as if they are an expensive oil change.
Couldnt attach manual file as it says too big. See PM for email.
Sorry cant help you with final filter as i ditched my ripoff Yanmar filters & got a cheaper & better setup
There is an area above the tank that looks ripe for a bank of filtration. I remember reading what seemed like a great idea of basically having an oil filter, then a coarse and fine racor all fed with an electric pump. Or at least one in line. The thought being that with some diverter valves you could use the electric pump to run fuel through the "oil" filter and straight back into the tank, polishing it yourself if required...

It's supposed to get near 60 starting tomorrow. I'll see if the warm changes things.

Thanks,
- AT.
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Old 03-11-2020, 16:56   #7
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Re: Ysm8 hard start cold, requires throttle to start

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Originally Posted by Compass790 View Post
........ Also the other trick to help you is spin it up decompressed & when its spinning hard out drop the decompression lever ( push cable in ) .............
This is very good advice and really helps for a cold start!

Main reason is because the rpm is higher at the start point, this higher rpm is maintained for a few cycles due to the energy stored in the flywheel. Secondary reasons are the injector pump (and lift pump) has cycled while spinning decompressed so should be giving proper injection at the start point.

Also helps any start if the battery is weak.
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Old 03-11-2020, 17:05   #8
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Re: Ysm8 hard start cold, requires throttle to start

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This is very good advice and really helps for a cold start!

Main reason is because the rpm is higher at the start point, this higher rpm is maintained for a few cycles due to the energy stored in the flywheel. Secondary reasons are the injector pump (and lift pump) has cycled while spinning decompressed so should be giving proper injection at the start point.

Also helps any start if the battery is weak.
I do think the battery is good. Just for fun I put on my lithium jump pack and noticed no difference in start speed...

- AT
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Old 03-11-2020, 18:42   #9
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Re: Ysm8 hard start cold, requires throttle to start

Had trouble with yahoo email so snt manual on gmail
here is a link to thread that might be of interest.
https://www.cruisersforum.com/forums...0f-241626.html
I'm pretty sure its the same fuel filter.
I dont think the o-ring is that critical, just go to any auto store & get one that fits on & is not wider than the threads. Too thin would be an issue of course.

I just looked at my old engine filter housing but its o-ring is not in a measurable state
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Old 04-11-2020, 13:35   #10
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Re: Ysm8 hard start cold, requires throttle to start

The Racor filter has an air leak.
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Old 04-11-2020, 13:59   #11
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Re: Ysm8 hard start cold, requires throttle to start

As other have said it sounds like an airlock. What is surprising is how little pressure the fuel pump puts out, it's only about 3~4 psi, so any small leak will compromise the fuel system. As an aside, in the Yanmar handbook, it recommends using at least half throttle to start, don't know why, as my 2GM20 starts at idle just fine. In fact I use it as an indication of when I need to give the tappets a tweek and get the injectors cleaned, if it needs more than about 1/4 throttle to start, that's the time to do some top end maintenance.
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Old 14-01-2021, 19:00   #12
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Re: Ysm8 hard start cold, requires throttle to start

We just purchased a 78 O'day 27 with ysm8 engine.
From experience what would be the approximate fuel consumption per hour on this engine.
I would also want to get some extra parts for the engine. Where would be a good place to order parts and a good manual for repair and maintenance ?
Anything specific about this engine I should know?

Thank you.
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Old 14-01-2021, 19:22   #13
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Re: Ysm8 hard start cold, requires throttle to start

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Originally Posted by fireant View Post
We just purchased a 78 O'day 27 with ysm8 engine.
From experience what would be the approximate fuel consumption per hour on this engine.
I would also want to get some extra parts for the engine. Where would be a good place to order parts and a good manual for repair and maintenance ?
Anything specific about this engine I should know?

Thank you.
Compass790 will be along sooner or later and will give you a more accurate response but in the meanwhile...

Fuel consumption is dependant on throttle setting but I expect you will use 0.5 to 1 litre per hour.

I can email a manual if you PM me with an email address.

These engines are very robust even if noisy and shaky. Some have some oil pump issues as they get older so having a oil pressure gauge is a good idea to spot any potential oil pump problems.

Some report head gasket issues - they are straightforward to change though.

As with all small marine engines, keep an eye on the water injection point on the exhaust. These corrode or clog and can allow raw water to enter the cylinder which will end in tears.

Although not many do, it is very good idea to leave the piston near TDC of the compression stroke after shutting it down. This ensure both valves are fully closed and thus helps to seal the cylinder from moisture when it is sitting.

INSPECT THE ENGINE ANODE regularly (i.e. often). If the anode is replaced as required and the block/head descaled very occasionally, the cast iron block will last forever (well almost forever).
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Old 15-01-2021, 02:55   #14
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Re: Ysm8 hard start cold, requires throttle to start

Slow to respond as been out watching opening day of the Prada Cup.
Brits have turned it around. TNZ will be on notice.
Back to YSM8, Wottie has given you good advice. I can point you to some rebuild parts.
Best to explain any problems you have.'
Usual issues on these engines are oil pump wear & exhaust elbows.
Our engine had a lot of problems & have rebuilt it including liner, piston & rings, crank bearings,valves injector pump, injector, fuel filters. Have learnt a fair bit.
If Wottie hasnt given you a manual I can help out & happy to answer any questions.
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Old 15-01-2021, 10:27   #15
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Re: Ysm8 hard start cold, requires throttle to start

Where is a good place to buy the maintenance parts in USA.

Engine seems to run great but i would like to have spare oil filter, Anode, water pump impeller and fuel filter at the very least.
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