Mercruiser 3.0 ignition WAY advanced???

[Phil527]

2002 Mercruiser 3.0 with Alpha one sterndrive, new to us 1.5 years ago and slowly working through all the repairs from P/O that was not too mechanical. I am new to boats, but fairly experienced with cars, tractors, etc. Knowing the condition I did the basics - new plugs, wires, cap and rotor, oil and gear oil changes. I checked the compression with the plugs out and they range from 130 -145 psi. With a shot of oil in the pistons they all hit 175-180. Probably some ring wear, but for an 02 and from what I have read it is not too far off normal. First time in the water last summer it stalled in the marina, when I restarted the starter bolts snapped and it dropped to the bottom of the boat! One bolt was broken for a while and I never noticed. Pulled the engine in the fall, extracted both bolts and replaced. I added the back bracket as well this time.

Finally got the boat out this summer and no power above 2000 rpm. Engine pings like crazy at 2500 rpm. Tells me timing. I put a light on and I can't find anything that looks like a mark on the crank pulley. Rotate crank manually and find the v-notch and hit it with a sharpie. I put it at the 0 mark and verify the rotor is pointing to the #1 spark plug wire. I jumper the distributor wires and shift interrupter per the manual I have and check the timing. Still can't find the timing mark, I adjust the timing advance on my light and find it at 32 degrees with the module jumped out. When I put things back to normal and dial back the timing light until the v-notch is at 12 BTDC I am 32 degrees advanced as well.

Is this a typical failure mode of the ignition module? I would have thought they would fail by not advancing. Any other possibilities I should be looking at that would cause a 32 degree advance?

Phil

 

[alldodge]

What is the motor serial number?

Most the motors today are timed using an advance timing light.

Timing will be when placed in base timing mode

1-BTDC for serial number 0L096999 and below
1-ATDC for serial number 0L097000 - 0L0340999
2-ATDC for serial number 0L341000 and above.

Plugs MR43LTS

Advance

• If initial timing is 1° BTDC: 12° BTDC, plus or minus 2°. At 2400-2800 rpm maximum
(total) advance is obtained and should be 23° BTDC (plus or minus 2°).

• If initial timing is 1° ATDC: 14° BTDC, plus or minus 2°. At 2400-2800 rpm maximum
(total) advance is obtained and should be 25° BTDC (plus or minus 2°).

• If initial timing is 2° ATDC: 15° BTDC, plus or minus 2°. At 2400-2800 rpm maximum
(total) advance is obtained and should be 26° BTDC (plus or minus 2°).

 

[Phil527]

All the numbers on the flame arrester are no longer visible. The transom has a S/N of OM213334, the drive looks like DL972663. Anywhere on the block in particular is the s/n? I found above the starter a 14097080 number in the casting.

I am using a digital timing light, when I adjust the timing light to get the v-notch at 0 it put it at 32 BTDC. That is with the module jumped and the shift interrupter switch jumped per the manuals instructions. With no jumpers it is supposed to be 12-14 BTDC and I have to adjust my light by 32 degrees to get the engine there as well. It seems that there is a 32 degree advance regardless of the ignition module being jumped out or not. I ordered a new one because it seems likely and it is not acting as it should - but I was wondering if there is anything else I should be looking at in the meantime while I wait for it to arrive.

It seems to be a strange failure mode.

 

[alldodge]

32 is to much

With a plate above the starter then the motor may be a reman

 

[Phil527]

That number was cast in the block, I am assuming it is the original motor. I agree on the 32 being too much, would explain the pinging and no power above 1500 rpm.

we'll see what the new module does for me.

 

[Phil527]

OK still stumped here. I purchased a replacement distributor module and installed it this evening. I put the module in base timing mode:

-Jumped out the two white wires coming from the distributor module, I verified with a multi meter on the distributor connector that my jumper was working
-I bypassed the shift interrupt switch and verified that 12V was going to the black lead on the distributor module connector.

I found my engine S/N M035849 so I set my base timing to 1 degree BTDC at idle. I increased the engine RPM and verified that the timing advance did not move in the base timing mode.

Disconnected and reconnected the wires and rechecked the timing. From my understanding the timing should move to 10-14 BTDC at idle. It was still at 1. When I increase RPM the timing will move, it will go to around 12 at 2000 rpm and 14 just under 3000 rpm. Which puts me off by the same 10 starting degrees it is not moving to.

I am going to put the old module back in and verify how it operated once more. Could a bad or weak pickup coil pulse cause erratic operation of these modules? Or do I have a new bad module?

I'll ohm out the pickup coil tomorrow when I get some daylight, but I am starting to run out of ideas.

 

[alldodge]

Its possible but new normally is good. If it was bought from Ebay or amazon then who knows. Would also say that I don't know if if a module would fail to advance and still run, but that is what it appears yours is yours is doing.

You have to much advance and now to litlle

 

[Phil527]

OK I figured it out. YOU HAVE TO KEEP THE ENGINE RUNNING WHEN YOU REMOVE THE JUMPER WIRES! Nowhere in my Clymer manual or the Mercruiser service bulletin does it say this clearly. I was shutting down the engine after setting the base timing while re-connecting the wires back to normal state ( I have shorted my fair share of wires doing things live- learned safety habit of getting burned I guess) The Procedure should be:

1.Start and warm up engine (note leave engine on during the entire timing adjustment procedure)
2.Jump out white wires at distributor module
3. Bypass shift interrupter switch that sends 12V to the module
4. Adjust base timing to Spec of engine S/N
5. Return shift interrupter switch wiring to initial state, thus removing 12V to the module
6. remove jumper on white wire leads at the distributor module
7. verify that idle timing increases to 10-14 degrees BTDC.
8. turn engine off and restart to verify that idle timing goes to 10-14 degrees BTDC*

*note at startup timing will start in base timing mode for a few seconds then move to the advanced 10-14 degrees state. If you are too quick with the timing light you will see it back in base timing mode and might start cussing loudly and wake up the neighbors !!

I still need to check what the advance is at higher RPM once my teenager helper wakes up, but I am much more confident that it is operating properly now and don't expect any issues. Modifying the mechanical advance curve on my 86 Ford 460 was not so much of a "black box" process- all you need to do is change springs and measure to get different advance curves.

Thanks for the help- I will put it in the water tonight and test it out. Just in time for the hottest day of the week up here!

 

[havoc_squad]

OK I figured it out. YOU HAVE TO KEEP THE ENGINE RUNNING WHEN YOU REMOVE THE JUMPER WIRES! Nowhere in my Clymer manual or the Mercruiser service bulletin does it say this clearly. I was shutting down the engine after setting the base timing while re-connecting the wires back to normal state ( I have shorted my fair share of wires doing things live- learned safety habit of getting burned I guess) The Procedure should be:

The steps listed in the OEM/factory mercruiser manual for base timing mode does make this matter clear that the engine is kept running by closely following the steps outlined, many times this is the risk in getting aftermarket manuals.

I highly recommend you sell,recycle or trash that Clymer manual and get the factory manual.

You can view the manual on boatinfo.no for free if needed.

 

[Phil527]

Update and followup issue:

Boat runs much better now. Was out a number of times tubing and skiing. Moving on to next issue -rebuilt carb because accelerator pump was dribbling gas in when throttle was moved slowly, it would work better if you moved the throttle faster.

Anyhow, as I am adjusting the idle and the throttle cable after the rebuild and I am having a hard time with getting the RPM to return to same idle RPM every time. I set it to about 900 out of the water, it seems to drop to about 650-700 in the water in gear. I get it set and move the accelerator a few times, all looks good then all of a sudden the RPM drops to 450. After readjusting several times I get the idea to put the timing light on the engine and sure enough the timing is dropping to the base timing from being advanced.

So starting up the boat the timing starts at the base timing (1 BTDC) then after a few seconds moves to 10 BTDC. What triggers that change? is there and internal timing circuit or is that change triggered by an outside signal? Tack signal?

What would cause it drop to the base mode randomly? It advances fine as I increase the RPM.

If it is taking an external trigger then maybe I have a bad wire or connector somehere. If that move from base to 10 BTDC is handled all internal then maybe my module is bad again?

Phil

 

[alldodge]

Timing is controlled by the module in the distributor. If its not acting correctly and the connections are good, then its the module of input signals from pickup coil

 

[Tropix]

Update and followup issue:

Boat runs much better now. Was out a number of times tubing and skiing. Moving on to next issue -rebuilt carb because accelerator pump was dribbling gas in when throttle was moved slowly, it would work better if you moved the throttle faster.

Anyhow, as I am adjusting the idle and the throttle cable after the rebuild and I am having a hard time with getting the RPM to return to same idle RPM every time. I set it to about 900 out of the water, it seems to drop to about 650-700 in the water in gear. I get it set and move the accelerator a few times, all looks good then all of a sudden the RPM drops to 450. After readjusting several times I get the idea to put the timing light on the engine and sure enough the timing is dropping to the base timing from being advanced.

So starting up the boat the timing starts at the base timing (1 BTDC) then after a few seconds moves to 10 BTDC. What triggers that change? is there and internal timing circuit or is that change triggered by an outside signal? Tack signal?

What would cause it drop to the base mode randomly? It advances fine as I increase the RPM.

If it is taking an external trigger then maybe I have a bad wire or connector somehere. If that move from base to 10 BTDC is handled all internal then maybe my module is bad again?

Phil

I am having timing issues too. I found out that you need a filter choke in the power wire from the coil. If you just use a wire without the choke, the timing randomly goes to base mode due to noise from the coil firing. I put a 1mH choke rated for 400ma current, which measures 2 ohms with an ohmmeter, which I bought from Digi-Key, and now it doesn't jump to base timing. But it still only goes to 2 deg BTDC at idle, not 10 BTDC. Maybe the aftermarket modules are just automotive modules being misrepresented as marine modules?