Troubleshooting stalling Detroit Diesel 6V92

[oscarvan]

The original post mentions a possible ECM issue. That means he s not dealing with a mechanical engine but electronic which will be affected by voltage drops

How would starting the second engine cause a fuel supply problem on the first one? This doesn’t make any sense.

OK. My bad on the ECM part. Missed it.

If fuel supply due to partial blockages is marginal and there is a directer path to one engine it may take it all or most of it causing the one that was running to stall.

But it's a moot point as the voltage drop with a DDEC is the obvious answer.

[johnjen50]

Sorry I missed the ecm part as well. Does sound electrical if there’s an ecm.

[SKYCHENEY]

OK. My bad on the ECM part. Missed it.

If fuel supply due to partial blockages is marginal and there is a directer path to one engine it may take it all or most of it causing the one that was running to stall.

But it's a moot point as the voltage drop with a DDEC is the obvious answer.

Each engine has its own fuel system from the tank through the valves and their own filters and on to the engine. Starting one engine would not affect the fuel going to the other one even if they were drawing from the same tank. Any fuel restriction would most likely show up under heavy load, not idle.

[davidwigler]

Yes one tank but all new fuel lines, filters and fuel/tank polishing.

This problem just started after new fuel lines? How does it run at WOT?

[Boatsb]

Look at post #3.

[kelpy]

I agree with Scott that it is electrical. BUT, a properly installed DDEC is electrically isolated side to side unless the battery banks are paralleled. There should also be a dedicated 12 VDC to 12 VDC or a 24 VDC to 12 VDC power supply feeding their respective DDEC ECU.
If one engines DDEC power is taken from the other engines start battery and the other engines DDEC power is taken from the house battery, or some combination of that, that would contribute to the conditions that the OP is experiencing. There should be isolated DDEC power.

That holds true for all versions of DDEC except the system used on the 24V-71. You don't want one of those!

[Glory]

Yes one tank but all new fuel lines, filters and fuel/tank polishing.

A new fuel filter in in a box.

[hfschwing]

Not sure if the question was answered, but I believe we're not taking about an electronic engine here.

Thanks for your thoughts but they are DDEC's I should have made that clear. I just thought that the two engines would be separated electronically but from the other posts, they may not be. So that is the path I need to follow.

[hfschwing]

This problem just started after new fuel lines? How does it run at WOT?

No, the problem was present before any new fuel lines installed.

[hfschwing]

If the engines are electronic voltage drop will affect them

I would also look at the charging system. Could bad isolator cause a voltage drop on the other battery? I wonder

May want to temporarily disconnect any charging wires

Thanks, you may be on to something.

The battery charger looks to be in poor shape at least from the exterior. It sits below an ice maker that is located in the helm deck above that had a leak in the water supply line sprinkling a spray of water on it for who knows how long(I only bought the boat recently and am in the process of rectifying some long-neglected issues). It is all rusted and I had to add straps just to keep it held in place. So I assume the interior electronics could be compromised as well.