1985-1995ish Mariner 200 low speed misfire

[tcpMariner]

I have a 1985-1995ish v6 200 Mariner (carb) that has a misfire when it reaches approx 1500-1800rpm. The motor idles fine In and out of gear until it reaches that rpm. If accelerated quickly it misses that bad spot and runs fine. If acceleration is slower from that rpm the throttle can be to the floor while going nowhere. Spark plugs are new and gas is fresh. This motor is very powerful and responsive other than the miss at that rpm range. My guess is electrical problem. Any ideas?

 

[Faztbullet]

Is the idle stablizer/advance box still attached??

 

[tcpMariner]

No, it’s not attached.

 

[Dukedog]

ya need ta be a little closer with year.. big difference in blocks, 'lectrics and carbs in that span....

 

[tcpMariner]

ya need ta be a little closer with year.. big difference in blocks, 'lectrics and carbs in that span....

I believe it’s a 1987-1990 block. The guy I got it from said it’s a 1995 but I doubt it. It’s a 200 power head on a 150 lower unit etc if that makes since so the serial numbers are not correct and I have not found the serial numbers on the block. They’re probably behind the power pack I believe however

 

[tcpMariner]

[No message]

 

[tcpMariner]

[No message]

 

[tcpMariner]

[No message]

 

[Dukedog]

looks ta be pre '88 2.4 200.. has two piece heads and 16 amp 'lectrics.. that pretty much rules out fuel/carb being tha problem.. 'lectric will be testy ta track down.. without being able ta touch/hear it, hard ta say where ta start...

 

[tcpMariner]

looks ta be pre '88 2.4 200.. has two piece heads and 16 amp 'lectrics.. that pretty much rules out fuel/carb being tha problem.. 'lectric will be testy ta track down.. without being able ta touch/hear it, hard ta say where ta start...

Why would that rule out fuel/carb problem? And could the high speed/low speed transition be sticking on the stator??

 

[tcpMariner]

[No message]

 

[Dukedog]

carb transitions instantly off idle.. no in-between idle circuit and run circuit... stator goes ta high side at 2500 ta 3000 roughly...

 

[Faztbullet]

The transition from low to high is done in switchboxes not stator.... Put a 1/8 gap between throttle cam and roller and see it that helps.

 

[tcpMariner]

The transition from low to high is done in switchboxes not stator.... Put a 1/8 gap between throttle cam and roller and see it that helps.

alright I’ll check it out! Could the switch box potentially be bad on it???

 

[racerone]

Run with a timing light on one plug lead at a time.---Observe spark behavior when motor has the miss.

 

[tcpMariner]

alright I’ll check it out! Could the switch box potentially be bad on it???

Also how would I do that without removing the flywheel?

 

[tcpMariner]

The transition from low to high is done in switchboxes not stator.... Put a 1/8 gap between throttle cam and roller and see it that helps.

Also is there a way to do that without removing the fly wheel? If I’m following what your talking about.

 

[tcpMariner]

The transition from low to high is done in switchboxes not stator.... Put a 1/8 gap between throttle cam and roller and see it that helps.

Never mind I see what you’re talking about. I haven’t done it yet but can you help me understand the concept behind the 1/8th gap between the cam and roller? Thanks!!

 

[Dukedog]

The transition from low to high is done in switchboxes not stator....

that can be kinda mis-leading ta some Faz… ya might wanna clarify it a tad.

 

[Dukedog]

I believe it’s a 1987-1990 block. The guy I got it from said it’s a 1995 but I doubt it. It’s a 200 power head on a 150 lower unit etc if that makes since so the serial numbers are not correct and I have not found the serial numbers on the block. They’re probably behind the power pack I believe however

look here for a number.. welsh plug top of block.