Generator won't start

[newhaul]

Ok I have a yanmar air cooled single cylinder 4kw diesel generator. It has good compression good oil and fuel but won't start . It's an old engine so no electronics . Replaced a bad injection pump and now she won't run . I did verify that the injector is working good so she has fuel . Could she be getting to much fuel?

[sjrider]

Is the injection pump timing off?

[newhaul]

Originally Posted by sjrider

Is the injection pump timing off?

No it's correct and direct off the crankshaft single cylinder

[motion30]

Considering you just replace the injection pump, I would think the 2 things to look at would be air in the system or timing of the injection pump

[MicHughV]

As above...
My 2c is an air lock/bubble somewhere, likely happened when you changed the pump.
A thorough bleeding of the fuel system, feed and return lines, will probably cure the problem.

[newhaul]

Originally Posted by MicHughV

As above...
My 2c is an air lock/bubble somewhere, likely happened when you changed the pump.
A thorough bleeding of the fuel system, feed and return lines, will probably cure the problem.

All well bled .
Did find an o,d video on YouTube talking about exhaust valve tappet walking with much running so that's the next thing to check . I am well versed in marine diesel but this 1 lung chineese engine is a bit different. L100WG-GEY. Is also a 186f so here's hoping . But if not a new engine is only $600 from Amazon.

[Chotu]

could something be wrong with the injection pump itself? Even though it’s new? Could it possibly be some incorrect timing with the pump itself because it kind of a hodgepodge of parts with the Chinese engines?

I have some experience with the Chinese engines. If you are ordering aftermarket parts for them, it’s kind of a guessing game a lot of times. If your new injection pump is supposed to be keyed off of a different point on the shaft, it might be shooting at the wrong time.

I would definitely double check that. And make sure people with the exact same model engine you have gave it a good review for working. And just double check that it’s the exact same pump. Just as a sanity check. Before you get into other stuff.

[newhaul]

Originally Posted by Chotu

could something be wrong with the injection pump itself? Even though it’s new? Could it possibly be some incorrect timing with the pump itself because it kind of a hodgepodge of parts with the Chinese engines?

I have some experience with the Chinese engines. If you are ordering aftermarket parts for them, it’s kind of a guessing game a lot of times. If your new injection pump is supposed to be keyed off of a different point on the shaft, it might be shooting at the wrong time.

I would definitely double check that. And make sure people with the exact same model engine you have gave it a good review for working. And just double check that it’s the exact same pump. Just as a sanity check. Before you get into other stuff.

Runs off cam 3 lobes right intake left exhaust and center Injection pump.


https://www.amazon.com/gp/product/B0...language=en_US

All identical to the origional that was seized (just needed cleaning and reassembly) but new is always best .
All measurements and numbers matched but was a semi basket case when I got it so may be missing a shim . Over fueling?

[MicHughV]

This is a shot in the dark, but I had a similar problem once....finally tracked the problem down to some mud dobber wasps that had built a nest, or were trying to build a nest in the vent line to the diesel fuel tank on the outside of the hull, blocking off air to the tank. Cleared that and problem was solved.

Finally, I removed an old diesel fuel tank once, and for funsies removed the inspection plates so I could peer inside. Much to my surprise the bottom and bottom sides were covered in a thick gooey black slime. The pickup point for the fuel intake line was barely a 1/2" above this mess. What I'm saying is, could be a blockage in the tank ??

[skipperpete]

I have the same Yanmar generator....... with a pull start and the only way to get it going is to turn it to just after compression, open the decompression and haul on the ripcord like your life depended on it..... it mostly starts first pull but it’s an angry noisy little beast more suited to an industrial rather than a marine environment but once started it will run relentlessly from tank fill to tank fill for days on end.
The injection timing is adjusted by adding or removing shims under the pump mounting flange..... if the original shimset is lost and the pump refitted, the injection timing will be advanced dramatically.

[newhaul]

Originally Posted by skipperpete

I have the same Yanmar generator....... with a pull start and the only way to get it going is to turn it to just after compression, open the decompression and haul on the ripcord like your life depended on it..... it mostly starts first pull but it’s an angry noisy little beast more suited to an industrial rather than a marine environment but once started it will run relentlessly from tank fill to tank fill for days on end.
The injection timing is adjusted by adding or removing shims under the pump mounting flange..... if the original shimset is lost and the pump refitted, the injection timing will be advanced dramatically.

I bet that's the issue then as the pump was as I said in a basket and removed from unit so timing is likely way off.
I have been using a drill start setup similar to what is used to start an rc airplane engine . Wish it wax electric start . Was free to me when I bought an old diesel drip heater. Will try some shim materials tomorrow . Thanks for the review of the unit as a whole .

[Wotname]

Agree with Skipperpete.

Timing should be fairly easy to check although I haven't worked on your particular engine, only on vintage Yanmar marine single cylinder engines. Usually timing has to be reasonably close to specified point BTDC but never too late.

Your can often hear the injector 'squeak' as you rotate the engine towards TDC of the compression stroke. I am assuming there is a decompression feature on the engine.

FWIW, over fuelling won't be the issue, the engine will (or should) start with WOT i.e. max fuel. I would venture excess fuel (unless huge) might raise the compression ratio slightly and assist starting, assuming you can pull it through compression fast enough.

[MicHughV]

I hope you post back here once you get it running. I love to file these threads in my box of "things to consider" if something doesn't work.

I give credit to this CF as there are some remarkable knowledgeable folks on here that really know what they are talking about.

[newhaul]

Originally Posted by MicHughV

I hope you post back here once you get it running. I love to file these threads in my box of "things to consider" if something doesn't work.

I give credit to this CF as there are some remarkable knowledgeable folks on here that really know what they are talking about.

I definitely will post my findings for others to use to stay sane

[skipperpete]

Here’s a Yanmar tip for doing the timing, just release the injector pump hold down bolts a bit and slide strips of shim into the gap rather than laboriously cutting a series of shims, lifting out the pump, refitting it and checking the timing several times. When you get the timing right, just cut one thick shim to suit the collective thickness of the strips. Hopefully the plunger didn’t bottom out if the shims were lost.