8.1 Horizon Start Issues

Timeflys

Well-Known Member
Dec 7, 2013
731
Thousand Islands, Ontario, Canada
Boat Info
"Frequent Flyer"
2002 Sundancer 360
Engines
Merc Horizon 8.1s
Engines have 400 hrs on 2002 Model 360 sundancer ...no start problems till today... cruised and anchored for a couple hours...port started right up (both engines usually start within 4 secs of cranking) but starboard fired up and quit after about 3 secs, never reached stabilized idle. Subsequent start attempts led to abnormal cranking periods with intermittent firing..
Batteries are good. Oil and coolant levels are up. New plugs 100 hrs ago.
I'm thinking a fuel problem...electric fuel pump not supplying the engine pump. Now that I suggest this, I should have trouble shot in the boat.....normally when I hit the start rocker switch, you can hear the elec pump pressurize....but in my frustration, didn't t think of this..
Any body else had this????
 
I have an 05 360 with 200 hours and just had to replace the cast aluminum exhaust manifolds. One on the port engine let go while in a no wake zone, alarms went off ( i suspect cause of misfiring) and then I shut it down. When I went to try a restart, after checking all the basics, had the abnormal cranking and suspected water in the cyl. Later i removed all the spark plugs and sure enough water out of one side. Luckily I shut it down and only tried to crank a few times, because once I replaced all the manifolds (replacements are all cast iron now) and cleared all the water out... and changed the oil... all was fine.

Hopefully this is not your same problem, but I would check to make sure so you don't have a similar problem. The abnormal cranking doesn't sound like a fuel problem to me, so better safe then sorry.
 
Possibly bad IAC. Did you try starting with slight throttle or can you keep it running with some throttle.

Yes id also check to see if the pumps pressurise. Also check fuel pressure at the rail.
 
Looking in the right places. How 'bout the age of the plug wires? But bad plugs and / or wires usually cause rough starting or running, that is sometimes heard as rattling in the transmissions while idling in gear. With regards to what Scott says above, check your dipstick for proper oil consistency.
 
Thanks for responses ... throttle position/movement would not keep her going...
fwiw...was at boat show and asked Mercury factory rep if it was worthwhile changing plug wires on 2002 engines with 370 hours on them (freshwater, used 4 months/yr). He smiled and shook his head, don't bother!!

As an aside....it's been an expensive season so far....fixing coolant leaks,seals, new impellers, oil change, 2 new batteries, battery charger. Hate to say it but it is 15 yrs young,things are adding up.
 
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Went back to the boat today...tried to hear a difference in the electric fuel pumps. The bad engine pump definitely sounds different than the good engine. It's in the hands of the mechanic now anyway.
 
It was a failure of the electric pump in the cool fuel module...unfortunately the labour was more than the parts...strbrd engine under the exhaust manifolds and next to fuel tank and generator..felt sorry for the mechanic.
 

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