Mercruiser 3.0 No Spark issues

[dubs283]

Don't hear the pinging in your video, but videos can sometimes not do justice. Maybe try one with the engine cover off.

Pics of plugs look meh, little lean and maybe a bit hot. Second pic shows debris/staining on the porcelain, may be cause for concern if you are detonating could be piston material. True test would be a plug burn at various rpm, gives you a better idea of combustion chamber condition under load

87 octane is okay, 91 would be my choIce for fuel grade, especially with knock/ping.

Would be nice to know total timing advance as well

 

[aidanmurphy]

Don't hear the pinging in your video, but videos can sometimes not do justice. Maybe try one with the engine cover off.

Pics of plugs look meh, little lean and maybe a bit hot. Second pic shows debris/staining on the porcelain, may be cause for concern if you are detonating could be piston material. True test would be a plug burn at various rpm, gives you a better idea of combustion chamber condition under load
B
87 octane is okay, 91 would be my choIce for fuel grade, especially with knock/ping.

Would be nice to know total timing advance as well

The pinging starts right at 9-10 seconds but I agree it is hard to hear. Sounds like bbs in a tin can.

I tried checking the timing advance but I need to read up more on how to check the total timing at 23 degrees. From what I can see the timing tab doesn't go that far BTDC so I am unsure how I would know if it is at 23. Maybe I misunderstand that though.

I will get some 93 to mix with the half tank of 87 I have next time out and switch to 91 after.

 

[nola mike]

You need an adjustable timing light. Might try some straight 93 after you burn through that 87. Also, did you check your fuel for water/crud?

 

[aidanmurphy]

Will get a digital light to check advance. PO drained fuel and put fresh in it he said. When I replaced the filter I poured some into a glass and it looked ok, it all evaporated out and didn't see any water left. No major gunk but wasn't crystal clear. Carb screen was very clean.

 

[Scott06]

Got the dongle in and got out to set base timing. Set at 1BTDC as per my engine serial. Still have the pinging at WOT, anything up to about 80 percent throttle is golden and I cruised at 70 percent for a while with no issues. Not that I will ride at WOT often/ever but it still irks me that it might be pinging. I recorded a clip where you can hear the chatter around the middle and the end of the video when I push to WOT. Pulled the plugs again after a few spurts at WOT and they look pretty similar to last time to me but maybe some experts here have better input. I put fresh 87 octane in with some seafoam, when I looked through the carb is was pretty clean. New fuel filter.

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To me those look lean. here is a read up on plug reading compared to article your base ring looks light http://wallaceracing.com/plug-reading-lm.html

if it were mine id verify fuel supply, float level, and given the your comment about this is only at wot check power valve is clean and functional, power valve piston operates correctly.

 

[achris]

An 'advance timing light' allows you to dial up an advance, say 21 degrees, and the light will fire 21 degrees before the spark, thus showing the timing marks at 0 degrees.

Chris...

Bet you're curious how the light can fire such a precise amount BEFORE it sees the spark...
It's not that difficult. The light doesn't actually flash BEFORE the spark, it flashes after it. When you're setting the light up you select the number of cylinders and the type of engine (2 stroke/4 stroke). The circuitry then uses that information to calculate when to fire the light after it detected a spark. Let's say you selected a 4 cylinder 4 stroke and want to see the flash 21 degrees before the spark. The light then knows to fire 699 degrees after the spark (4 strokes fire once every 2 crankshaft rotations, 720 degrees)... It uses the frequency of the sparks to determine engine speed, and then calculates how long it would take for the crank to rotate 699 degrees, and fires the flash at that time. Easies....

 

[aidanmurphy]

An 'advance timing light' allows you to dial up an advance, say 21 degrees, and the light will fire 21 degrees before the spark, thus showing the timing marks at 0 degrees.

Chris...

Bet you're curious how the light can fire such a precise amount BEFORE it sees the spark...
It's not that difficult. The light doesn't actually flash BEFORE the spark, it flashes after it. When you're setting the light up your select the number of cylinders and the type of engine (2 stroke/4 stroke). The circuitry then uses that information to calculate when to for the light after it detected a spark. Let's say you selected a 4 cylinder 4 stroke and want to see the flash 21 degrees before the spark. The light then knows to fire 699 degrees after the spark (4 strokes for once every 2 crankshaft rotations, 720 degrees)... It uses the frequency of the sparks to determine engine speed, and then calculates how long it would take for the crack to rotate 699 degrees, and does the flash at that time. Easies....

Great explanation thank you!

 

[alldodge]

Motor is designed for 87, and using anything other then 87 is only masking a problem. Wonder if your reading the timing mark correctly

 

[nola mike]

Motor is designed for 87, and using anything other then 87 is only masking a problem. Wonder if your reading the timing mark correctly

View attachment 359148

Agree on both points... The high test would be for diagnostic purposes to see if the pinging goes away.

 

[alldodge]

Side note: Is this too much water out of the bilge after a few hours on the water? Seems to accumulate more with riding.

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Unless you had water splashing in, any water is to much water and you have a leak

 

[aidanmurphy]

Motor is designed for 87, and using anything other then 87 is only masking a problem. Wonder if your reading the timing mark correctly

View attachment 359148

Hmm, my timing tab looks slightly different than that one and I used this diagram from the manual. If I was supposed to use the diagram above my base timing would be one degree advanced... Motor is a 91. I can try to retard it by a degree and see how it runs unless someone knows for sure which diagram I should use.

 

[aidanmurphy]

I also managed to get this still image from a video I took. Here you can see my timing mark, this is where I set it in base timing and still have pinging.

 

[alldodge]

I'm unable to read yours in pic, maybe use some sand paper. My pic came from manual 13

Unless the firing order is incorrect

 

[aidanmurphy]

Firing order is correct, double checked when I installed new dist cap. I can try some sandpaper but it is a bit rusted as well.. Was just going off the notches in relation to the manual.

As for the leak, I inspected my bellows and noticed some light cracking. Do these need to be replaced? The shift cable also only has a zip tie on the small end, not a clamp. Potential leak area?

 

[alldodge]

Yes boots need to be replaced. Any cracking and its time

 

[Bondo]

The shift cable also only has a zip tie on the small end, not a clamp. Potential leak area?

Naw, the zip-tie is the better way to do it, than the ole style clamp,....

 

[Scott06]

Firing order is correct, double checked when I installed new dist cap. I can try some sandpaper but it is a bit rusted as well.. Was just going off the notches in relation to the manual.

As for the leak, I inspected my bellows and noticed some light cracking. Do these need to be replaced? The shift cable also only has a zip tie on the small end, not a clamp. Potential leak area?

Thats the exhaust bellows which is in need of replacement. Would assume the driveshaft bellows and shift bellows are in similar shape. Exhaust bellows are open to water and will not leak inside the boat. Drive shaft and shift bellows are likely cause of your leak but you replace them all while you are in there

 

[aidanmurphy]

Thanks guys, just ordered OEM transom seal repair kit from quicksilver. Digital timing light coming this weekend will update with the advance numbers and try a higher octane fuel for troubleshooting purposes

 

[aidanmurphy]

I should be getting out with the digital timing light in the next day or two to check the advance. In the meantime I pulled the fuel pickup to check for any blockages and check the anti-siphon valve. The valve is moving freely, however, there is no filter in the pickup tube. Is this a cause for concern? Should I add a filter into the pickup or just be diligent in checking the filter on the pump and the in-line filter before the carb?

 

[alldodge]

No filter on pickup tube is best. The motor filter will catch the stuff