Troubleshooting stalling Detroit Diesel 6V92

[hfschwing]

I have a 1996 43' Express with twin Detroit Diesel 6V92's.

The problem I have is as follows:
If I start the Starboard engine first and then start the Port engine second during the starting of the Port Engine the Starboard engine loses RPM's and stalls.

If I reverse the sequence starting the Port Engine first and then the Starboard the Port engine does not lose any RPM's and both engines run OK.

Troubleshooting so far has amounted to swapping the batteries around and running a direct ground cable. No changes to the problem.

Suggestions from a mechanic are 1- possibly the Port Engine starter has a problem or 2- the ECM is bad or has a problem?

I am confused about how one engine can affect the other in this way?? Any ideas on what is going on and troubleshooting steps?

[johnjen50]

Sounds more like fuel. Are they both pulling from the same tank or line?

[Boatsb]

Are they electronic engines?If so the power to start the second could be dropping the voltage for the electronics and the solenoids on the other.

[hfschwing]

Sounds more like fuel. Are they both pulling from the same tank or line?

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

[RonNP]

Sound like a bad fuel pump if it's all coming from the same tank.

[hfschwing]

Sound like a bad fuel pump if it's all coming from the same tank.

If it's the fuel pump was does the sequence of starting matter? If I start the port engine first no issues. If I start the starboard first then the port the starboard stalls out?

[JLR]

I had the same boat, year and engines. When/where did you buy it? Curious to see if it was mine. Or, perhaps post a picture of the dash. BTW, I never had that problem but do know something about the boat. Thanks.

[Pascal]

Sounds electrical not fuel. It sounds like the voltage drop when cranking causes the other engine to stall

Do they each have their own battery or do they share one?

If they have their own batteries make sure they re not paralleled. Some boats have a parallel switch not a solenoid

Measure voltage drop for each engine while cranking and compare


Years ago I had a boat with twin gassers. One of the engine shared start battery with the generator and the voltage drop cranking would stall the gen

[hfschwing]

I had the same boat, year and engines. When/where did you buy it? Curious to see if it was mine. Or, perhaps post a picture of the dash. BTW, I never had that problem but do know something about the boat. Thanks.

Bought from a fellow in Palmetto FL. He bought in 2005 used from Galati Yachts on Anna Maria Island.

I just replaced the dash with new electronics.

[JLR]

Not mine. Oh well. Have you tried starting with the battery charger on and the generator on vs. shore power? Thinking voltage drop as well. Also, I do not recall, which bank of batteries feeds the house vs. starting the engine only? Finally, mine were not DDEC's. If you do have DDEC's, it is most likely, a voltage issue. Have you tried using the parallel switch to see if that makes a difference when starting the port engine after having started the starboard?