Timing on 1990 Merc Black Max Carb 2 strk 175 - hope Fast Bullet weighs in

[OldGuy77]

Engine was running before repair - exhibited symptoms of bad stator. Have replaced stator and trigger - engine started on first key turn but but at high rpm - shut down immediately - checked carbs butterflies closed - trying to set timing according to Maintence manual which says go to TDC 0 with dial - did that then counter rotated fly wheel 1/4 turn past . 462 and returned it to . 462 - removed black and white wire from switch box according to manual which supposedly disconnected the idle stabilizer module - however got no spark ie no light from timing light so reattached wire - tried to check timing with advance light set on zero with pointer set at .462 according to manual. Could not see markings - put tape on fly wheel and finally saw where the #1 piston was firing - it's like approximately 20 degrees ATDC approx from 0 mark and if using . 462 for TDC about 40 degrees ATDC - pulled fly wheel checked to make sure it was on key and stator and trigger were properly installed everything seemed to check out. Measured trigger arm and it is at 11/16th per manual. Tried to retard the timing via the timing pickup screw saw some improvement but not nearly enough. Any suggestions or ideas are appreciating - this is very frustrating.

 

[Dukedog]

"removed black and white wire from switch box according to manual which supposedly disconnected the idle stabilizer module"

what about tha red/white??? don't think thats ya problem but ya never know.. sounds like ya have something not quite right but hard ta say ona computer.. for me anyway........................

 

[OldGuy77]

Thanks - it's a head scratcher for sure

 

[OldGuy77]

1990 Mercury Black Max 175 Timing and wiring issues

 

[Dukedog]

so what are we lookin' for?.. can't see anything that might be a problem?.. ya might wanna get rid of tha idle stabilizer completely.. jus fab a white/black (bias circuit) jumper between tha switch boxes.. reset timin'

 

[stresspoint]

why did you suspect the timing was an issue in the first place , was something worn like a linkage bushing , some extensive mods done or some nuff nuf mechanic had a ply with screws ?.

FWIW , your symptoms seem to be what happens with an intermittent fault from the switch box. IE high RPM shut down and easy restart.

 

[OldGuy77]

Thanks all - definitely a learning process - pics were irrelevant they both concerned the tilt and trim solenoids and wires to starter solenoid. Actual problem remains quick start but at excessive rpm 2500 plus. Thinking either switch box(es), throttle position sensor (if there is one) or idle stabilizer??? Any suggestions?

 

[vroom ZOOM]

Thanks all - definitely a learning process - pics were irrelevant they both concerned the tilt and trim solenoids and wires to starter solenoid. Actual problem remains quick start but at excessive rpm 2500 plus. Thinking either switch box(es), throttle position sensor (if there is one) or idle stabilizer??? Any suggestions?

All I can say (may be obvious) is that high idle rpm is caused by two things:
1. carb settings (too lean or throttle not fully closed)
2. too much timing advance.

You could be dealing with both.