Mercruiser 3.0L timing

[rbevis]

Guys,

I'm a little confused on exactly how to set the base timing. (EST)

I've hooked the two little white wires together coming off the distributor.
It also says to bypass the shift int. switch and join the engine harness wires (purple and white/grn I think) together...this kills my engine just as if the switch was engaged.

What am I doing wrong.

 

[bigdan1]

Re: Mercruiser 3.0L timing

waht year is the boat? efi or carb ?

 

[Don S]

Re: Mercruiser 3.0L timing

The manuals are a little off on that procedure, You have to bypass the shift interrupt switch wires before starting the engine. But the white wire jumper MUST be done while running.

 

[rbevis]

Re: Mercruiser 3.0L timing

The manuals are a little off on that procedure, You have to bypass the shift interrupt switch wires before starting the engine. But the white wire jumper MUST be done while running.

Ok. Plugging both shift interrupt wires together (engine harness side) effectively prevents the engine from starting. It is the same as engaging the interrupt switch causing continuity, which interrupts (kills) the engine. The interrupt switch is a normally open switch.

I must be missing something here.

Is it possible that my timing is so off that it won't run when it goes into base timing mode?



*note: 1997 Mercruiser 3.0L, carbed, EST ignition.

 

[rbevis]

Re: Mercruiser 3.0L timing

http://forums.iboats.com/showthread.php?t=393844

In the same boat but still don't have an answer. It keeps dying.


Don,
Per your earlier sticky on how the shift interrupt works...
"When this Y plate moves and activates the shift interrupt switch, the ignition coil is grounded and the engine starts to die due to lack of spark,"

Explain to me how the engine will start if the switch is bypassed (effectively doing the same as enabling continuity through the switch) and the ignition coil is grounded...

 

[rbevis]

Re: Mercruiser 3.0L timing

Figured this out. Apparently there is a sequence to it that is NOT mentioned other than what Don said above.

1. Start the engine as normal
2. Hook up jumper between white leads at distributor
3. Shut engine off
4. Join the two wires that lead to the shift interrupt switch
5. Start engine and it will be in base timing mode

How hard would it have been to state it this way in the manual??? Really...

 

[CPro]

Re: Mercruiser 3.0L timing

For what it's worth I swear that I've set my timing before (or at least I think I have...!) by doing both steps with the engine running. Undoing them definitely permits the timing to advance as it should.

 

[fishrdan]

Re: Mercruiser 3.0L timing

1. Start the engine as normal
2. Hook up jumper between white leads at distributor

4. Join the two wires that lead to the shift interrupt switch

That's how I timed my 3.0 EST ignition