Just a question is the fuel bulb still hard when it starts to miss. Might be a fuel pump issue.

Just another thing don’t go playing around with the HT leads while the engine is running or you’ll find out the hard way why they are called HT leads.

When I was working full time on outboards, I had a spark plug with a big alligator clip welded in it so when I was trying to diagnose engines with misses I could drive along the the cowling off stop when it started missing, switch the motor off and pull the HT lead of the cylinder I thought was missing plug it onto my spark plug clipped on to the engine somewhere and start the engine to see if there was spark at the plug

That leads me to another question what happens if you switch the engine off wait a few minutes then start it back up, does it still miss.

Mc Tool wrote: Are  all the injector plugs on tight , had a car once with the clip broken off the injector plug , had to give it a wiggle every now and then .... even showed the Mrs how to do it  , ungrateful  cow seemed to think I should just fix it .

Mc Tool, if you read my reply, you see I specifically said that I had experienced this. So your experience is very different to mine. And I know mine is correct because it happened. I did miss saying turn off when removing lead, something I am remiss for. My advise stands.

Humidity and temperature are kind of related so it is certainly possible

It is also possible for the conductor in the lead to crack without the insulating layers to crack. Thermal expansion and contraction can happen in that case. Say what you like. I've see it physically happen.

Yes  individual components on a circuit board  like capacitors , resistors  , triac's  , diodes  bla bla bla can fail as they come up to working temp  or overheat . Symptoms as you describe , and given time to cool will often work again . We used to refer to these parts as "wounded "

Alan to work on a Porsche you’re talking more like $500 plus an hour.

When you look at my original trade as an auto electrician in the old days we had to fix everything as there were not a lot of replacement parts around, we rewound some armatures for wiper motors. Re taped field coils even changed bulb holders in brake and tail lights.

Lots of replacement parts around nowadays and they are cheap, computers have made engines more reliable and the basics easier to diagnose. There will always be problems that are a bit out of the box but a good marine tech will be able to isolate the problem through trial and error and normal find the fault.

I worked on outbounds and motorcycle for many years and there’s a completely different thought pattern between 2 stroke and 4 stroke. Different fuel systems, ignition systems fuel pump diapharms on 2 strokes are the cause of many problems and get it wrong and you will damage the engine.

Misses are relatively easy, is the problem electrical or fuel, when it’s missing what’s the fuel bulb doing. If it’s soft then the problem is normally on the supply side. If it stays hard then it’s on the input side.

Another good indicator of where the problem is checking which cylinders are running hot. If one cylinder is cold then to me that indicates an electrical problem. next check the plugs they will will soon show you which way to keep looking. If one plug isn’t burning clean but has good spark, check the compression. Remember 2 and 4 stroke have different compression ratios. If it’s an EFI and the compression good look at the injector.


Just keep following the process through. But for me even when I was racing cars and boats the plugs are the eyes to what’s happening with the motor.

Yeah , I keep forgetting the labour costs  with these things . When I stopped working in 09 we had just started charging 80 bucks /hr  to service whiteware .That stems from  me fixing everything , I mean I got all day , look on the net , Bobs yer auntie , worth a crack Nigel,  AND its a wonderful excuse to buy....... "MORE TOOLS? " she cries   (  how well do I know that face ) .

Thats a pretty big drop in power along with the lack of 2S grunt. Hope it works out OK.

Mmmm 2500hrs is about 160,000kmin car years  so I spose that is getting on a bit . Just for interest sake , I get the notion that your well capable of maintaining an outboard and thusly its probly better than most its age , but other than the hrs is it showing signs of age / wear .  Just trying to get my head round this hrs thing .