2002 90hp ruff idle and hard start.

[BoatinBob]

2002 90 merc 3 cyl, primer bulb never gets firm, gas will run out exhaust while priming on to the ground. It will crank and run good, but sputtery idle, stops running a lot at idle, and really never completely the same but starting at a fast idle will crank it. need suggestions on all I need to replace ,check, adjust. I'll start with he primmer bulb making sure its good. Prices on rebuild kits etc. would be great. Compression is good on all three cylinders per Sylacauga Marine who I bought from few months ago. Needs some loving fuel maintenance help.

 

[BoatinBob]

I guess this source is not active, oh well.

 

[racerone]

Check fuel pump diaphragm for a hole in it.

 

[BoatinBob]

Thanks, I rebuilt carbs, replaced all fuel lines, bulb, filter, holds prime now all good now on fuel. (Bad varnish build up.) However checking spark by removing plugs wires while running, number one cylinder does not seem to effect it as much as 2 and 3 cyls. Is this an indication of a weak CDM possibly? It will start and idle, seems rich on idle, bottom 2 carbs idle screw about same on 1 1/3 turns number one like a more lean setting. I dont have a DVA for my meter. Can pulling plug wires give an indicator for bad CDM ? It runs great while giving it gas and on plane, back down to idle in gear a lot of smoke and struggles to hold its idle and then stabilizes with a rich smoking idle .

 

[BoatinBob]

any advise ????

 

[fastjeff]

Try switching two coils and see if the problem follows it.

Jeff

 

[BoatinBob]

Thanks, what a easy way to check.