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Old 12 August 2010, 15:56   #1
Country: Ireland
Boat name: Ocean Escapes
Make: Excalibur
Length: 9m +
Engine: 150Yamaha&300Verado
Join Date: Jan 2007
Posts: 221
two plugs not firing?!?

mounted my engine on my boat today for her first voyage and when we started the engine we noticed that 2 out of the 4 cylinders was not firing, the first and last are but not 2 & 3, there is no spark as we checked and the coils appear to be ok as we switched wire and got spark but the engine was running out of sinc, The engiue is a 2004 90hp 4stroke engine Mercury, has anyone experienced this before, if so what was the problem? Thanks guys

Andrew O'Riordan
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Old 16 August 2010, 05:34   #2
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,538
"shared coil" is quite common on 4- strokes- it basically halves the number of coils (therefore weight), and they're wired such that the piston on the power stroke shares it's coil with the piston on exhaust, where the spark will make s*d all difference to the engine.

I assume you've done the "swap everything one at a time" trick? My going in guess would be a dodgy connection or a gubbed coil. Which wire did you switch?
9D280 is offline   Reply With Quote

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