"Patrick M. Ring" wrote in message
...
This is a problem that I can't seem to conquer. Hopefully someone has a
suggestion for me.

I have a Mercruiser Alpha One 3.0LX with the Electronic Spark Timing on
the
distributor. In recent years, I find that the engine floods out or
hesitates easily when I shower down on the throttle. So, I'm assuming
that
the timing is a bit off because when running idle or high RPMs steady, it
runs smoothly. Anyway, I'd like to bypass the EST to at least check it
(no
one has in a long while).

I have a (Chiltons) manual and I have referenced the Mercruiser shop
manual.
However, both say that after you've jumpered the 2 white wires on the 3
pin
plug of the distributor base (step 2), you should then disconnect the
harness wires from the shift cut out switch and then connect these
together
(basically applying 12V purple lead to the 3rd pin of the 3 pin plug of
the distributor white w/ green stripe lead. This is where the problem
occurs. Upon connecting these two together, the motor cuts out completely
(rather than retarding the spark to 1dg BTC).

This is the technique I'm following (from the Merc shop manual):
========
1. Start engine and allow it to reach proper 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 GA wire using two male bullet terminal ends connected.

3. Bypass the shift interrupter switch by disconnecting wires at the shift
interrupt switch.
Temporarily join the engine harness wires together ( the wires you
unplugged
from the switch).

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 degree
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 running at IDLE, verify
that
timing did advance to 12 deg
BTDC (plus or minus 2 degrees).
At 2400-2800 RPM maximum advance is obtained and should be 27 degrees BTDC
(plus or minus 2 deg).
=========

Can anyone tell me whether I'm doing something wrong? Or is it that my EST
is advancing the spark to where it needs to be for idle or smooth run, but
upon disabling it, the spark is so retarded that the engine won't run?

When running at idle (w/ spark advance) it registers 13dg BTC. But it
only
seems to advance to about 18 - 20 dg BTC when pushed to 2500 RPMs.

Thanks in advance,
Patrick M. Ring
ospam
webhost: www.classicmako.com


I have not worked on the EST but I will offer my opinion anyway.
You might try giving it a little more RPM to see if the full advance comes
into spec.
I do think your problem might be carb. related. A weak accelerator pump
would cause those symptoms. Also check your idle mixture and idle speed.
Jim