Starboard engine died along with guages. still cranks but no start.

[MikeC3131]

2006 290 Sundancer with twin 5.0 mpi's. I changed out both seawater pump impellers and then took the boat for a cruise. ran it up to about 3500 rpm and cruised around for a bit. Everything worked great. Came back into the harbor and Boom, lost my starboard engine and gauges abruptly. No stalling, just dead. Strange thing is it will beep with the engine start switch and crank but not fire. No power to the gauges on that side though as mentioned above.

5 minutes later the port engine starts to hesitate and then dies and will not fire back up. Fuel gauge reads over a half tank. still have power at the gauge and all accessories for the port side too.

I'm going to try and trouble shoot when i get home but i'm leaning towards the cool fuel 3 in the port engine being gummed up. seems to be electrical on the starboard engine. Why would the gauges for that motor go dead as well? Any ideas would be appreciated.

This is a new boat to me so i'm in the shakedown stage and it'g going really wll so far. haha. Thanks in advance.

 

[Todd320]

Fuel pump relay or a bad relay harness would explain the engine cranking, but not starting, but does not explain the gauges not turning on. You can tell if it is the fuel pump relay if when you turn it on, do you hear the pump energize. That’s all I’m good for! Good luck.

 

[MikeC3131]

Thanks for the response Todd. One thing i forgot was the starboard engine also had some sweating on the left hand riser like it was getting wet. all 3 others were completely dry. Not sure if this is another issue or just residual moisture being burnt off from me cleaning the bilge out. (simple green and scrubbing)then rinsing with hose while on trailer.

 

[LG111]

I just had a similar issue. Mine was a bad crankshaft sensor.
I think you are on the right path on electrical. The ecm runs on a 5v ref system to all sensors. If a sensor goes bad it flags the ecm and may shut down your engine. A bad battery will do the same thing. It's not about the volts but more about remaining cold cranking amps. If the 5v rev gets less than 5v the ecm shuts off. Hence no spark.
You may need a mechanic with a laptop to look for flagged codes so you know exactly what to replace or fix. Fyi codes don't always show up... unfortunately if the loss of 5v ref is quick the ecm can't record it quick enough. That was my issue on the crankshaft sensor going bad. It took weeks of swapping sensors between engines until the problem followed to the other engine.

Good luck and you will find the gremlin!

 

[MikeC3131]

Where is the crankshaft sensor located? I seem to remember reading something about it being under the distributor cap? Is there a way to test this sensor? Would this make my gages go dead as well?

I'm going to swap the fuel relay and ignition relay today to see if anything changes. They are the same and mounted right by each other beside the ECM.

 

[Bt Doctur]

would need a engine serial number

 

[MikeC3131]

So i checked connections and both power and fuel pump relays mounted next to the ECM. both are good. I'm going to swap crank case sensors between motors tonight and try and find fuses located on block.

I don't have my engine serial numbers as they are wore off on the engine cover. Boat didn't have a manual when purchase either. I'm told there is plates on the back of the motors with my serial numbers but i have yet to even attempt getting at them. pretty tight spaces.

on a 2006 5.0 mpi, is there engine located fuses aside form the 50 amp breaker switch? where if so?

 

[LG111]

Where is the crankshaft sensor located? I seem to remember reading something about it being under the distributor cap? Is there a way to test this sensor? Would this make my gages go dead as well

I'm going to swap the fuel relay and ignition relay today to see if anything changes. They
are the same and mounted right by each other beside the ECM.

Its located on the top of the bellhousing. Held by one bolt and the sensor is approx 8 inches long as it magnetically senses the fly wheel spinning. When you put it back it press down after the o ring snaps in place and bolt back in. The sensor must be very close to the wheel or it won't let your engine start. They do go bad from time to time.

 

[Espos4]

One thing i forgot was the starboard engine also had some sweating on the left hand riser like it was getting wet. all 3 others were completely dry. Not sure if this is another issue or just residual moisture being burnt off from me cleaning the bilge out.

I just had a similar issue with the riser "sweating".
There was a hairline crack on the manifold which allowed seawater to drip down and collect on top of the 2 center exhaust ports, on the outside of the exhaust manifold. This could be seen by looking down from above through the narrow space between the valve cover and the riser/manifold assembly. This sea water would vaporize once the manifold got hot enough and as the steam rose, it condensed on the onboard side of the riser. This gave the appearance that you describe.

If this has been happening on the riser that has the ECM attached to it, you may have poor harness connections or even rust on the harness pins. Disconnect and clean those wire harness connectors on the ECM.

By the way, my fix was new manifolds and risers.

 

[Sublimetime]

If all gauges and such went dead check the main connector on the wire harness to the engine, most everything passes thru this harness except sometimes the starting circuit which they will wire outside the connector.(you mentioned major cleaning of bilge_ maybe it got wet or jarred loose in cleaning.)