Engine turns over but will not...

[Royalboater]

Engine turns over but will not start - 1999 330EC 

Engines - Horizon 7.4 L 380 HP MPI's / Serial#'s 0L303781 port and 782 starboard

10/03/21 - starboard engine died while maneuvering at a gas dock, restart would last for a minute and die, repeat, then would not start at all. Took apart fuel pump and put back together, seems to be operating fine. Looks like no spark when remove coil wire from distributor cap.  We swapped almost all components from port engine to the starboard, not work

I put two new Distributor Caps and rotors on each engine.  Swapped ECM, Relays, Ignition Module, Coil, switches in cabin for on/off for motors, air intake monitor, check all connections between the two engines.

Does anybody have any ideas what to try next?

Do these engines have the port to plug in a computer to see if its throwing any codes?

[wingless]

The first step is to measure the fuel pressure at the fuel rail. A fuel pressure gauge is an essential tool for anyone who turns their own wrenches on fuel injected engines. What does the fuel pressure measure?

The Quicksilver DDT has been discontinued, but is an excellent tool for these engines. It plugs into the diagnostic port near the ECM on the starboard side of the engine.

https://live.staticflickr.com/4357/36075822920_55df4c9044_c.jpg

The symptoms sound almost like heat soak vapor lock.

The Mercruiser solution is a ~$1K per engine series low pressure fuel pump.

My solution was a thermostatically controlled heat exhaust system. My solution has been 100% effective when operating in the tropics.

[Royalboater]

Wingless thank you very much. I just spoke to a very knowledgeable mechanic and he was almost positive its the reluctor ring under the distributor. We need to get spark before we look at fuel. Hoping to keep this post going so others can benefit!

What is a camshaft Reluctor ring?
The reluctor ring is mounted on the crankshaft so that as the crankshaft rotates the magnetic sensor is triggered by notches in the reluctor ring. The magnetic sensor provides position information to the electronic control module, which governs ignition timing.

[wingless]

YW

If it operates fine when cold, then has issues when hot, that points to heat soak vapor lock.

Yes, fuel/air, compression and spark are the prerequisites for the Pakled go condition.

[ngaydazng7]

My mechanic said it sounds like vapor lock as well especially it it starts when it is cold. try the next morning

[Royalboater]

ngaydazng7 - thank you, but right now we dont have spark. Mechanic on the phone seems to think its the reluctor ring. trying to get him to look at it and will advise.

[toner]

I had similiar problem on a 2000 sunsport, the emergency cut off switch was bad

[d9ever]

I had the electrically operated shutoff solenoid fail shutting down the engine under power. Back at the dock tried starting an hour later no problem. There is a knurled knob on the shutoff switch that you can rotate to open but you lose any anti siphon protection. I've had mine manually opened all summer with no problems. Found a new solenoid (rare as hens teeth $238) and will install this winter

[Royalboater]

thank you..... had one of them fail as well in the past. right now need to get spark and waiting for mechanic.

[wingless]

Here is the label that I made / affixed near all three fuel valves.

https://live.staticflickr.com/65535/48901381777_a53823f14b_c.jpg