1994 Mercury 90hp two-stroke - stalls bad

[jtsaltwaterboating]

1994 Mercury 90hp two-stroke

All last year my motor could not pass 3500 rpm. Every time I try to WOT pass 3500 rpm it would just stall.
Before I took my boat out this spring I changed the following:

- Spark plugs and wires
- Change gear lube
- New fuel water separator
- Fuel filter

When I changed my old spark plug wires I noticed one of the wire were burnt. I thought maybe that would be the cause of my problem last year. But found out it wasn?t and now I have a bigger problem. I can?t even cruise at 3500 rpm like I would be able to last year. Now, I can get up to around 4500 rpm run for a minute or two then slowly die down. Then all I can do is cruise at around 1500 rpm.
Any help would be appreciated.

 

[jafaanton]

Re: 1994 Mercury 90hp two-stroke - stalls bad

im having avery similar problem with my 90 two stroke. 1989. very similar. when mine dies it wont start again the rest of the day. it dies at the exact same rpm though.i dont know what it is though,as i dont have an tach.me and my friend are going to change the stator ,and maybe the rctifier for good measure.

 

[CharlieB]

Re: 1994 Mercury 90hp two-stroke - stalls bad

Poster # 2, start your own thread as your problems are different, do NOT change any electrical parts without testing and PROVING any NON _returnable electrical part bad.

BOTH of you, troubleshooting any and all problems in a logical, systematic method will save you LOTs of time and piles of money.

Begin with the simple things, like testing compression and spark on each cyl. These will rule out many problems, or locate a problem in just a few minutes. You really only need a spark plug wrench, a screw-in type compression tester, an adjustable gap spark tester set to 7/16 inch, and maybe a helper to crank the motor while you watch the spark tester.

Remember to ground ALL the rest of the spark plug wires other than the one attached to the spark tester to prevent any errant sparks, they can cause damage to the ignition system, possibly ignite fuel fumes, or bite you, HARD.

Repost your findings in your appropriate individual threads and we'll go onto the next step.