2001 Mercruiser 5.0 Timing Question

shepster

Cadet
Joined
Oct 30, 2008
Messages
25
I have a 2001, 5.0 MCM, two barrel with Thunderbolt V. My question comes about timing. I copied this out of the tech manual and I don?t know what step (3) means (base timing mode). Can someone post a pick or give me some detailed instruction as to how to do it. I did do a search on timing and base timing mode, but all I found was to put it into the base timing not how to do it.

Thanks in advance,
Shep

Timing
Thunderbolt V Models
1. Connect timing light to number 1 spark plug wire.
2. Connect a shop tachometer to the engine.
IMPORTANT: Before starting the engine, connect a jumper wire from the ignition timing
lead to a good ground. This has to be done before the ignition key is turned ON
to lock the Ignition Module into Base Timing Mode.
3. Before starting the engine, connect jumper wire from timing lead to a good ground.
NOTE: The PUR/WHT timing lead is located towards the front of the engine near the fuel
line or near the distributor, as equipped for your model.

4. Start engine and run at 1300 rpm until it reaches normal operating temperature.
5. Disconnect throttle cable from the carburetor.
6. With engine at idle rpm, adjust the carburetor idle rpm screw to the specified engine idle
rpm.
7. With the engine still at idle rpm, check the ignition timing. If incorrect, rotate the
distributor until timing is correct. Torque clamping screw to 18 lb-ft (25 Nm).
8. Adjust the idle mixture screw. Inward is LEAN, outward is RICH.
9. Recheck ignition timing.
10. Stop engine. Remove timing light, jumper wire and shop tachometer.
IMPORTANT: Timing jumper wire has to be removed or the Ignition Module will stay
locked in the Base Timing Mode and it will not be able to advance the ignition timing
correctly when the engine rpm is increased.
11. Adjust and reinstall throttle cable. Open and close remote control throttle lever to make
sure that the carburetor?s throttle lever returns against the rpm adjusting screw every
time.
12. Restart the engine, increase rpm to 1300 then return to idle position slowly and shut the
engine off. Ensure that the carburetor throttle lever came back against the idle rpm
screw.
13. Shut engine off.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: 2001 Mercruiser 5.0 Timing Question

3. Before starting the engine, connect jumper wire from timing lead to a good ground.
NOTE: The PUR/WHT timing lead is located towards the front of the engine near the fuel
line or near the distributor, as equipped for your model.

1. Find the Purple/white wire near the carb.
2. Pull the plug out of the purple wire
3. Make a jumper wire that will plug into the purple/white wire with an alligator clip on the other end so you can hook it to a good ground.
4. Connect your jumper wire from that purple/ white wire to ground.

Move to step 4 in your instruction
 
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