mecruiser 3.0L won't go into timing mode

[uaw9fan]

I recently pulled the cylinder head from a customers boat to find the gasket blown on number 3 cylinder toward the intake. Also there was a exhaust valve tuliped on number 2 cylinder. The customer had the head redone and I reinstalled it.
Problem is that when I test ran it and tried to set timing I couldn't get the engine to go into timing mode. I made sure my jumper was good. I verified power was getting to the bypass wire, but no timing mode. I removed my jumper and shift interrupt works fine. I ordered a new module, thinking it has to be defective. But when I installed the new one it does the same thing.
Has anyone else experienced this before and what are some probable causes. The service manual does not cover EST ignition that well and the only way to test the module is with a tester I don't have.
Thanks in advance for reading and responding

 

[Don S]

Re: mecruiser 3.0L won't go into timing mode

Did you have the engine running while you put it in base timing mode? You don't mention what manual you have or what year 3.0L you have, but here is from Merc oem manual for 90 thru 97 models.

1. Start engine and allow to reach operating temperature.
2. With engine running, install a jumper wire across
the two WHITE leads on the distributor using
(91-818812A1), or fabricate one using a 6 in. (150
mm) section of 16 gauge wire with two male bullet
terminal ends connected.

3. Bypass the shift interrupt switch by disconnecting
wires at shift interrupt switch. Temporarily join the
engine harness wires together.
IMPORTANT: Do not fail to reconnect these two
wires to the shift interrupt switch when timing
procedures are complete.
4. With timing light connected, check timing. Timing
should be 1? BTDC.
5. If required, loosen distributor hold down clamp
and rotate distributor to obtain specified timing.
6. Secure distributor hold down clamp, and recheck
timing as above.
7. Reconnect the two wires to the shift interrupt
switch. Remove jumper wire at distributor white
leads.
IMPORTANT: Be sure to remove jumper wire before
returning engine to service, otherwise timing
will not advance.
8. With timing light still connected, and engine at
IDLE, verify that timing did advance to 12? BTDC,
(plus or minus 2?). At 2400-2800 RPM maximum
(total) advance is obtained and should be 27?
BTDC (plus or minus 2?).

 

[uaw9fan]

Re: mecruiser 3.0L won't go into timing mode

Thanks for your response Don.
The engine is serial 0M675544. I am using service manual #26.
I started the engine installed my jumper wire and connected the two shift interrupt wires together. The engine never slows down and never moves timing. Being that the cylinder head gasket blew and if you look at page 4B-15 of the service manual, where it states that the timing spec on older engines should be changed if the engine suffered a blown head gasket coming out from the intake side, I'm assuming this engine is way too far advanced on timing.
As previously staed I replaced the module with no result. I guess I'm just making sure that I know how this system works. As far as I can tell the only thing in control of timing advance is the module. I know it is highly unlikely that my new module is faulty but it is possible. Heck I even hooked up my temporary harness for volvo penta to make sure that there was nothing wrong in the boat harness.
Thanks again for your input

 

[Don S]

Re: mecruiser 3.0L won't go into timing mode

wire and connected the two shift interrupt wires together.

You don't connect the 2 wires from the switch, that does nothing, you hook the ones together you disconnected the switch from. The wiring harness side.
Re-read item #3 in my previous reply.