Help I'm stuck! 7.4 Mercruisers wont start

[brad614]

I have two 7.4 mercruisers in a 99 Carver with the v drives. The boat has been running awesome all day. Anchored for about an hour and now they won't start. They fire up and run for a second or two, and then died. Identical symptoms on both engines. Any suggestions?

 

[Bt Doctur]

fuel tank is empty?

 

[brad614]

Over three-quarters in both tanks. Generator is running fine.

 

[Bt Doctur]

are the engine fuel lines"T`d" or does each have its own feed line

 

[Lucrative]

Shot in the dark here, but I had something similar happen to me on my 7.4mpi. One of the fuel vacuum hoses had gotten disconnected. Not sure how that would have happened in your case, but maybe a possibility.

 

[brad614]

Finally got both of them to start by feathering the throttles and we're back in safe now. Still no clue what caused it.

 

[Fun Times]

Carbureted or fuel injected?

If fuel injected, do you happen to know if the engines are linked together via possibly the ECM data connector? Possibly a yellow wire/cable running between the two engines.

? Twin engines can be connected together with the ?EFI Data Link Harness? (84-805696A-2). This will allow you to scan both engines when connected to either engine. This cable will also make sure that if one engine goes into Power Reduction mode, the other will also.

But keeping in mind that by 1999 the power reduction was not installed in the ECM. But I'm just thinking possibly if one engine is down it might be bringing the other down with it for whatever reason.

? All 1997 models use the MEFI 2 (GM 96) ECM case, but are loaded with MEFI 1 (GM 93) software. MEFI 2 cases can be identified as having long mounting bolts, instead of the short bolts used on MEFI 1 cases. Power reduction mode has been disabled on all 1996 and newer models. If it is a MEFI 2 case, it does not have power reduction, regardless of the software loaded inside.