Optimax iddle speed problems

[caribbean boater]

Over last two or three months my engine (Optimax 135 hp 2008) has not been working properly at low rpm's. When I go in or out the marina at low speed, the engine fails and sometimes shut down completely but I start again without problem. When I go out the marina and I start to navigate at high speed my engine works fine. To resolve the problem I have changed the spark plugs, the impeller, the fuel filter and I checked the spark plug wires which looked fine.

But the failing at low rpm's or iddle speed continues ! I always use the DFI Oil and all Mercury parts.

A technician at the marina told me that it could be dirty air-fuel injectors.

What I should do? It could be a fuel injectors problem? Could I try a fuel injector cleaner?

Thank you for your suggestions!

 

[Waterdog1]

Re: Optimax iddle speed problems

Sounds like you have a poppet valve issue. My 05 135 Opti does the same thing, replacing the impellor only solves the problem for a little while. I am on my way to the store to buy a new poppet valve today. For the longest time my alarm would go off after extended low RPM idling, put the boat in neutral alarm would go off and then I would bump my RPM's up a little and no problems.

Currently my motor stalls at high RPM?s no alarm. Spoke to quite a few people in the business and they all seem to think it?s my poppet valve.

 

[caribbean boater]

Re: Optimax iddle speed problems

Thank you. Let me know about your results with the new poppet valve!

How an engine failing at iddle speed is related with the poppet valve instead of fuel system related issues?

 

[sxmerc]

Re: Optimax iddle speed problems

Over last two or three months my engine (Optimax 135 hp 2008) has not been working properly at low rpm's. When I go in or out the marina at low speed, the engine fails and sometimes shut down completely but I start again without problem. When I go out the marina and I start to navigate at high speed my engine works fine. To resolve the problem I have changed the spark plugs, the impeller, the fuel filter and I checked the spark plug wires which looked fine.

But the failing at low rpm's or iddle speed continues ! I always use the DFI Oil and all Mercury parts.

A technician at the marina told me that it could be dirty air-fuel injectors.

What I should do? It could be a fuel injectors problem? Could I try a fuel injector cleaner?

I don't see anything in this post that talks about over heating issues??? Air or fuel injectors could be the problem, but I'm more tempted to believe it's a fuel delivery issue, whether it be fuel pressure, or a fuel restriction. Where it's an 08, I'd check and see if you're still under warranty. If so, why not swing it by a dealer and let them play with it for a bit?

 

[caribbean boater]

Re: Optimax iddle speed problems

Thank you. I'll try Quickleen or fuel system cleaner before any visit to the dealer.