2005 Mercury 90 HP 4 stroke cranks but won't stay running

[bcribb52]

I have a 2005 90 hp Mercury 4 stroke carbureted engine that won't stay running. I have cleaned all of the carbs , installed new plugs and have hooked up fuel supply from a separate fuel tank. The engine runs for a few minutes and shuts off. It does have a little bit of a rough idle. I can put the throttle in the warm up position and give it gas and it it will let you run the rpms up to full throttle.When you pull it back to neutral position it shuts off.Try to crank it back up and it won't start unless you raise the throttle up and still won't stay running. Any ideas? i'm exhausted trying to figure this thing out..

 

[Faztbullet]

Did you check sync the carbs after cleaning? Dashpot adjusted correctly? Made sure all intake sealing rings in place when reassembling?

 

[bcribb52]

All I did to the carbs was clean the 2 main jets and shot carb cleaner through each air holes. Simple cleaning as the carbs were pretty clean. Bottom carb jet was plugged. All gaskets and seals are seated properly. With the plugs out and grounded they dont seem to have a strong spark..

 

[bcribb52]

The 2 bottom cylinders are not firing.Plugs and wires are good.

 

[QUESTBLDR]

Did you find the cause for not idling? I am having the same issue. Will not idle and dies; can’t put in gear. A week earlier, ran fine.