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Mercury 90Hp 6-Cylinder 2 Stroke Running problems

B

Barry Prior

New member
Hi All.

I am very new to 2-Strokes having been fixing car for nearly 30 years tarting at Porsche cars, I know a bit about 4 strokes, Ignition systes and carbs.

I have just bought a speed boat with a 90Hp 1989MY 6 Cylinder 2-Stroke.

1) It is hard to start but I put that down to the choke only opperating on the top 2 carbs ? (Is this right)
2) There seems to be a lot of fuel dripping out of the carbs when engine is not running especilly when the ouboard is tilted ?
3)Ide is high sounds like its aout 1000rpm. Do you adjust the idle by retarding the timing ? ? ?
4) is there a basic settin for the miture screw ? i.e 2 turns out ? ? ?
5) There also seems to be fuel comming out of what look like another jet which seems to be connected to the revesoir which is in-line with the emoloution tube/jet but ngle away from the engine ? ? ?
5) Looking for a workshop manual as wel

Thanks in advance

07748 655731
[email protected]
 
..."Do you adjust the idle by retarding the timing ?"

Speed, yes. Your carbs need cleaning and adjusting.

Jeff
 
Hi Jeff.

Why do you say my carbs need cleaning and adjusting ? I cleaned out the middle one because he resevoir jet was leaking causing it to over fill. Where would I find the correct manual for my engine please Ive looked on this form but it's not very clear which one I need. Please advise.
 
All three carbs need to be clean and adjusted properly. If the motor has sat around for a time with gas in the carbs, the tiny passages need to be cleaned out. That can only be done properly by disassembly and soaking. (You'd be surprised how many people think spraying the carbs with a cleaner is "cleaning" them!)

Also, the fuel pump diaphragm and gas lines need to be changed (if they are hard and crumbling inside).

Jeff
 
I did fully strip and clean the middle Carb. Including removing all the brass air correctors, emolosion tube and which I think was the main jet: Long brass tube. All correctors and jets were clean so I could see through the middle. The fuel lines are fine and will check the fuel pump and will clean out the other 2 carbs(Propley)
Is there a baic setting for the mixture screw ie 2 turns out etc. I guess these need balancing as well afterwards with a carb ballancer as a bit of hose will be usless as the engie is very loud.
Thanks for our help
 
One and a half turns out is a good STARTING point, but you need top dial it in properly: warmed up, in gear, with the boat tied to a dock or on the trailer. And when you find best idle for all three carbs, add 1/4 turn OUT on each to reduce bogging.

Jeff
 
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