Yanmar SB8 diesel starting problem

[peterstump]

The SB8 is a single cylindar engine, in a H27(1977), that has performed well until recently. The engine does not use a glow plug, instead has a compression-release lever for cold starting.

The fuel line between the pump and injector developed a leak. We smelled fuel but the engine did not stop and would restart normally. We were on a trip, wrapped and clamped the line to minimize leakage, and restarted to get the boat back to our home port, without difficulty.

We replaced the line afer making the replacement. Also installed a new fuel filter. The engine started and ran for an hour plus then stoped. It would not restart. Checked the fuel line and it seems to deliver fuel as expected. After several intervals to let the engine dry out, it still will not start. What are we overlooking?

 

[Don S/V ILLusion]

only 2 things

can prevent a diesel from starting/running - no air or no fuel. Given you were working on the fuel system, that's the likely place to look. Did you bleed both the low and high pressure sides of the fuel system? Report back if you aren't getting fuel to the injector as there are a number of people here who are excellent at diagnosing engine issues

 

[Randy Burns]

Same problem

Same motor. Have a mechanic bleed the system to be sure your doing it right. In my case I was, there was some other problem. I gave up & bought a new yanmar.
I do have a shop manual if you want it.

Randy

 

[Don S/V ILLusion]

one caution

DON'T use ether! If you have to use anything to provide an assist for ignition, use WD40. The ether will work but your head gasket won't like it

 

[Rob19574]

bleeding lines

You should have bleed vents in the fuel system to allow the air out. Do you have a manual? If not, check along the fuel system for vent screws. On my YSM Yanmar (single cylinder as well) - I have a manual lever for bleeding the lines...its on the fuel pump. I open all the vent screws and manually pump until fuel spews out. Ive done this several times and its fairly easy.

If you do not have a manual - do some googling online and you can locate a free manual online.

- Rob

 

[kloudie1]

Diesel Starting Problem

Everyone so far has hit on some good ideas.. One more to consider.. If the new line that was installed had any debris in it at all, it could have fouled or plugged the injector. There are no filters at all in the line between the HP pump and injector and the opening in the injector is extremely small. After bleeding the system, if it still doesn’t run, take the injector to a diesel shop and get them to check it out

 

[TimCup]

Don- GREAT Suggestion!

Gas engines use ether to prime. Diesel engines use WD-40. Here at your local Ford dealer, we're working on diesels every day, and we ONLY use WD-40 in diesels. It's safe for the engine, as opposed to ether.

And besides, don't we all have WD-40 lying around from when we thought it worked on rusted fittings?? Thanks, Maine Sail!


cup