Fuel problem HELP

[newage1461]

Tuesday evening the Yanmar 2qm15 runs perfectly. So today I change the fuel filters, run the electric fuel pump to fill the filters. The engine runs for a few seconds, then poop...

The only place to bleed the air is on the top of the secondary filter, so I crack the lines at the injectors and wear out a finger or two.

I finally got the engine to start, but it only runs on 1 cylinder. When I crack the nut on the first cylinder ( at the injector ) fuel sprays out but the engine keeps running with no change.

When I just barely crack the nut on the #2 cylinder, the engine kills right away.

So to me this means that the engine is running on the #2 cylinder only.

Would I be safe in guessing that the injector suddenly went south, or could it be worse ??

Once again, it ran perfectly before I touched it !!

 

[Don S/V ILLusion]

My guess is that during the filter change, you got some contamination entrapped causing one or both injectors to get clogged.

 

[newage1461]

I pulled the injector this AM and had it tested, and it was fine. I switched the 2 injectors and was able to get the engine running, but the same thing, the rear cylinder is still the only one firing.

 

[kloudie1]

Probably not a thing here, but easy to check.. Make sure that your valve clearance is as recommended.. I think for that engine, .0059" .. If this gets too tight, you can't develop compression pressure.. Make sure the decompression lever on that cylinder is not engaged, even if the external lever is in the correct spot.
Look into the intake with the filter removed and be sure there is nothing blocking that cylinder's air.

 

[fredr]

Do I understand correctly that you loosened the nut at the nozzle (injector) and pumped the lift pump handle to bleed the air out? ..."wear out a finger or two"...
The only way fuel comes to the nozzle from the injection pump, through the steel line, is when the engine is turning. To bleed the air out of the injection pump, you must loosen the line feeding the injection pump, and pump the lift pump to get the air out of the injection pump.
Then to get the air out of the steel line feeding the nozzle, loosen the line at the nozzle and spin the engine until fuel spits out.
When air is trapped in the line or injection pump, the fuel compresses the air but does not push the air forward.
Are you getting foam & fuel at the nozzle when the engine is running and you crack the # 1 cyl line? The nozzle may have trash holding the pintle open and compression from the engine is blowing the fuel back.
Did you happen to loosen or remove the line / fitting at the injection pump?
There is a check valve / spring under the fitting that the line attaches to that lets the fuel into the steel line and does not let the fuel back flow.
Is the decompression lever activated for cyl # 1?

 

[newage1461]

Finally got it.. I bled out about 10 oz of fuel by opening fuel line nut at the injector, but it didn't help. I was finally able to loosen the nut on the injection pump without twisting the steel line in two, while engine was running. One little squirt of fuel came out and the engine roared to life. Stopped & started it a few times and it's just like I never laid a hand on it. I figure with the 2 gallons per year that I use, the filters should last about 10 more years !!

Thanks for your ideas everyone..