1994 90 hs issue!

[MarkS.]

1994 90 HP Force issue!

Today, 11:19 AM

My 90 hs motor starts fine. Runs good at full throttle but but it seems like once it gets warm it bogs down and dies when throttle is added after putting it in gear. Seems to only do it after a long ride or mutiple starts, that's why I feel like it may be a temperature thing because first start after taking it off the trailer or first start in the morning it's fine. I have replaced fuel lines, checked vaccum lines, plugs, filters. I was thinking possibly jets clogged but again it doesnt always do it. Any ideas of what else could be causing this issue

 

[foodfisher]

Check wiring for rubbed bare spots up around the flywheel. Metal expands when heated, maybe just enough to short out.

 

[Jiggz]

Have you checked the plugs? What do they look like? When was the last time you replaced or cleaned them? When the engine is idling, can you touch the plug boots without getting shock? If not, either apply a thin film of dielectric grease to the plugs tip that connects to the boot or replace the boot. The grease thing is easier and cheaper. If none of these will fix the problem, report your idle rpm when you first start the motor (cold), in neutral and also in gear (idle). And the idle rpm's when it is warm.

 

[jerryjerry05]

Test the overheat system.
The sending unit has an orange lead.
Key on, ground the wire to the block.
It should make the buzzer sound off.
Then using an analog meter.
Test the sending unit by hooking it to the OHMs meter and dropping it in hot water.

 

[Frank Acampora]

Try pulling each spark plug one at a time when the problem appears OR--Have someone with Mercury electronic diagnostic tools check the trigger, stator, and CD box when the engine is hot. Or, if you can find a proven good CD unit borrow it and swap it into your engine. Yeah, you might as well check the voltage regulator while you are at it.

My money would be a defective CD box with an intermittent short when the box heats up.