1986 90hp inline 6 rpm problems only when in gear,

[MrMikeTN]

Re: 1986 90hp inline 6 rpm problems only when in gear,

I wondered about the heating up issue, but its happend on nights when it 50F outside, and after the motor has been shut off for 2 to 3 hours. and its happend within 30 minutes of it being shut off.

 

[Maxz695]

Re: 1986 90hp inline 6 rpm problems only when in gear,

Ok so lets look at this. You say it happens only after The key has been shut off but never cuts off while running? Did you try my suggestion of trying to start it with the pigtal disconnected when it refuses to start? I know you said you cleaned up the connection but if you did not try this you still have not eliminated the key switch the throttle neutral switch any Lanyard kill switch. Bad wiring in the dash. etc. A screwdriver across the soleniod will do the job but a Remote push button switch wired across the two big terminals is suggested. Testing parts without it being in the NO FIRE Mode is the only way to find the culprit on the engine componants as of course they work when there working. But narrowing all other reasons by just using the batt cables and the engine wiring is the best way to do it

 

[MrMikeTN]

Re: 1986 90hp inline 6 rpm problems only when in gear,

it did it the other night.
unpluged the harness and it still woruld not start.
tested continuity with key off and on it checked ok.

 

[Faztbullet]

Re: 1986 90hp inline 6 rpm problems only when in gear,

Sound like you got a stator failing or switchbox problem. I doubt its the trigger as you have 3 coils in it ands its rare to have all 3 fail. It could be a bad rectifier so disconnect it and test motor to see what it does.

 

[MrMikeTN]

Re: 1986 90hp inline 6 rpm problems only when in gear,

Weird update..

It didnt wanna start lastnight.
just put it in the water had not been started.
Wouldnt start.
pulled out the sparkplug tester.
ONLY #4 had spark.

tried starting it about 15 times over 20 min.
finally..
Kaboom, it fires up and runs.
Still not over 2200-2300 rpms.
Ran and started all night and during pretty wicked rainstorm.

Im gonna order a stator. and try that when I put on new trigger too.
If I can get either the start issue or RPM issue fixed, then I hope fixing the other one will be easier.

 

[narvlebenoit]

Re: 1986 90hp inline 6 rpm problems only when in gear,

I have a 90 h.p. that did the same thing change switchboxes stator coils and rectifier still did the same thing brought it to a friend that works on outboards changed the trigger runs like a new motor now only truns about 4800 RPMs on a 17 foot starcraft with a 19 pitch prop but i was told that was good RPMs for the 90 h.p. inline. GOOD LUCK

 

[CharlieB]

Re: 1986 90hp inline 6 rpm problems only when in gear,

I'd bet money that DVA testing will prove low output from the stator high speed windings. This will limit power under load to mid 2K range.

The intermittent 'No Spark' is cause for further DVA testing of the triggers to rule them out, leaving the switchbox(s) most likely culprit.

 

[Maxz695]

Re: 1986 90hp inline 6 rpm problems only when in gear,

I bet you could use a 17 P and get 5500 RPM . I have a 17.5 with a 70 HP 14 P and getting 5000 to 5200

 

[Georgesalmon]

Re: 1986 90hp inline 6 rpm problems only when in gear,

If your tach is the one installed on your boat and not an external one then the stator has to be good because thats where the tach gets its signal. Bad stator; no tach reading. And the rectifier/regulator only changes the stator AC to DC for charging the battery, it should not affect running the engine at all.

 

[CharlieB]

Re: 1986 90hp inline 6 rpm problems only when in gear,

If your tach is the one installed on your boat and not an external one then the stator has to be good because thats where the tach gets its signal. Bad stator; no tach reading. And the rectifier/regulator only changes the stator AC to DC for charging the battery, it should not affect running the engine at all.

Unfortunately the stator is really three seperate sets of coils, low speed, high speed and charging.

A weak or dead high speed winding will limit RPM as the high speed windings/coils will not generate sufficient voltage for the ignition to fire under the increasing cyl pressure of load at RPM, the charging coils will still charge the battery fine.

DVA testing of each pair of stator leads enables testing each stator circuit to positively determine if or what problem exists.