Merc 1500 won't rev

[SKDave]

Sitting at launch and can't get the motor to rev passed 2k with the throttle advance. Throttle response is slow as well. Not sure what to do. Ran fine on the muffs this morning.

 

[SKDave]

Re: Merc 1500 won't rev

Just pulled the plugs and they had a fair amount of brown oil coating them. Same stuff that came out of the prop last night when I sea foamed it. Cleaned em off, will try again

 

[SKDave]

Re: Merc 1500 won't rev

With engine running, 1000rpm. Push in choke and it will die

 

[SKDave]

Re: Merc 1500 won't rev

Motor is a blue stripe, will post serial number here shortly. Ran great in the morning, I did a sea foam treatment through tanks and also sprayed into carbs. When I got to the lake it had a hell of a time starting, and would only idle around 1500rpm and stumble.
Wondering if anyone can help me track down the problem. Simple voltage checks first? I currently only have a clymer manual to work with. Seems like I might have a varnished carb

 

[SKDave]

Re: Merc 1500 won't rev

Got her fired up, another dose of seafoam seemed to help. Need help adjusting idle, any links or help much appreciated. Serial number 7067278. Carbs WMK 19

 

[wired247]

Re: Merc 1500 won't rev

Unlikely your timing changed itself. You might have sticky floats or plugged jets. I'd go for a thorough carb cleaning and adjustment.

 

[SKDave]

Re: Merc 1500 won't rev

Can I adjust idle with out changing timing? Idles fine at 1000, but stumbles and dies at 800. I'd rather not pull the carbs off if I can avoid it.

 

[merc850]

Re: Merc 1500 won't rev

Idle is adjusted in water in gear moving forward not in neutral. set the idle screws at 1 1/4 turns to start then at about 1200 rpm turn them one at a time until motor speeds up and runs smoothly, hit the throttle to full and see if engine bogs - if it does then turn screws richer (out) until it responds smoothly. If engine is idling too low or hi adjust the "idle stop" screw in or out. That brown crap maybe fouling one or more of the plugs.