220 mariner EFI won't idle well.

[Nielmcque]

I have a new to me 220 mariner EFI that doesn't idle well when on the water rpm gauge shows its around 750. Where should I start. Makes shifting in and out of gear near the dock difficult.

[Dave Strong]

750 in gear?

Dave

[Nielmcque]

Ill have to double check i was more concerned with not coming alongside the dock to hard then i was looking at the gauge. What should it be in gear?

[tunnelmike]

A cylinder with low compression will cause idle problems on a carb motor

[Nielmcque]

Last I checked compression was pretty even. Also its an EFI motor

[Bruce2]

Idle stabilizer still hooked up??

[luv2gofast]

Lots of possibilities. Injector, spark plug, reed. You need to start pulling plug wires and see if it's a particular cyl that's not keeping up with the others at idle. Then you can move parts around to track it down. Sometimes and infrared thermo ($25 at Harbor Freight) will help find the cols cyl.

[luv2gofast]

Bye the way...picture in my tag line should look familiar. That's my son driving it and I'm in my Lavey on the far side.

I put Boyesen reeds in that motor and still have the stock steel reeds in my parts bin. If you need them I will send them to you. I also have the ECU test box and a spare ECU but I don't think it will tell you anything about idle.

[Nielmcque]

Thanks I put new plugs in it before the last time out. Ill take a look at them. Pic sure does look good. I have one of those thermometers ill try and use it next time.

[luv2gofast]

Sometimes you can get a reading off of the base of the plug. I have also just felt the base of the plugs to find a cold one. If you are going to pull wires while it's running be sure you do it from inside the boat, not standing in the water...ask me how I know...OOOWWWIIIEEE!!!

[Nielmcque]

Haha ya i bet those coils throw some voltage. Thanks for all the trouble shooting ideas im headed out to laughlin this weekend so ill mess with it.

[luv2gofast]

Damn...Wish I was going. Still not done with the little stuff on my boat. Steering was pissing fluid from the ram from sitting so long so put new seals in the whole system last night.

[Nielmcque]

Yeah that sucks I've spent the last few months working on the boat.

[Dave Strong]

Ill have to double check i was more concerned with not coming alongside the dock to hard then i was looking at the gauge. What should it be in gear?

600 to 700rpm.

Dave

[Magcat 62]

i have a 220 efi. check tpi voltage should be .135=.150at idle 7.48 wot. @750 should shift fine. what do u mean doesnt idle well?

[Nielmcque]

What do you mean by tpi. It dies when i shift into gear.

[Go Time]

Throttle position indicator....

[Nielmcque]

Got it

[Nielmcque]

Idle stabilizer still hooked up??
I don't know if its still hooked up what does it look like and how does it work?

[luv2gofast]

I don't know if its still hooked up what does it look like and how does it work?

It's a black box mounted with 3 screws and has 3 wires, blk, r/w and w/blk. It advances the timing to stabilize idle. They get removed a lot of the time and seem to work fine without them. I had it on when I owned the boat. I figure Mercury spent a bunch of money to put it on so if it worked there was no reason to remove it. I probably would not buy a new one if it failed.

[Nielmcque]

Thanks ill check it out

[Bruce2]

Idle stabilizer can go bad and not do it's job properly, that's why most have been removed and they can and do cause idle problems.

[Nielmcque]

Will it cause the motor to die shifting into gear.

[Bruce2]

Will it cause the motor to die shifting into gear.

Could since it regulates timing...

[Dave Strong]

Idle stabilizer does not do a thing until idle drops below 550rpm. Then it advances timing to get the speed up. A proper link and sync with the TPS set with the Merc tool that motor should run fine and never require a idle stabilizer.

Dave

[Nielmcque]

Alright I'll try disconnecting it this weekend while I'm out testing.

[Nielmcque]

Idle stabilizer does not do a thing until idle drops below 550rpm. Then it advances timing to get the speed up. A proper link and sync with the TPS set with the Merc tool that motor should run fine and never require a idle stabilizer.

Dave

I dont have a merc tool. The last 2 place i called either didnt have the time to tune up the motor or wouldnt even touch it due to its age.

[Nielmcque]

Can someone recomend a good merc outboard mechanic in so cal

[tlwjkw]

send me an email addy.. i'll send ya a pdf oem manual.. will at least help identify' parts.