So, what have I blown?????

papajoe · 11 April 2016, 20:14

Ok, finally got the rebuild finished on my yam mariner 689 30hp 2 stroke 2 cylinder 1992 autolube and super stoked at how it looked, I decided to run in it today so, stuck in a tank, added 50.1 in the fuel as a precaution with the autolube checked and ready to go. I didn't have the remotes so read up on how to loop the plug (black/yellow pin 1 to black pin 4 and yellow/red pin 7 to red pin 8) to bypass the kill switch.

Anyway, the engine started first pull

but.... after running for about 15min it suddenly died barrrrrrrrrrrrrrrr , so I though the worse that it had a heat seize which it didn't. So checked everything, compression good, fuel good, all wiring, fuse etc missing a spark though. So went to the boat, removed the remotes, plugged the engine in with the electric start and it turns over but still no spark.......so, what have I fried?

ShinyShoe · 11 April 2016, 20:56

Master Fuse?

papajoe · 11 April 2016, 21:03

Quote:

Originally Posted by ShinyShoe

Master Fuse?

nope, fuse all good

Poly · 11 April 2016, 21:17

Just one spark that's not firing?

papajoe · 11 April 2016, 21:33

Quote:

Originally Posted by Poly

Just one spark that's not firing?

no both, even removed the caps (new screw on champion type) to see if the wires sparked but nothing. Could it be the CDI?

Poly · 11 April 2016, 21:59

Quote:

Originally Posted by papajoe

no both, even removed the caps (new screw on champion type) to see if the wires sparked but nothing. Could it be the CDI?

Well it could be, but it would be rotten luck to rebuild an engine and have something major die 20 minutes later. Someone else (http://www.rib.net/forum/f50/maiden-...cue-71616.html) had a very similar issue recently. My money would be on a wiring issue (perhaps something came loose, wore through, got hot, shorted out).

spartacus · 11 April 2016, 22:31

Outboard kill cord?

jyasaki · 12 April 2016, 03:04

50:1 plus auto-lube? Change plugs and see what happens.

jky

slate1234 · 12 April 2016, 05:22

Check the coils they could be breaking down once warm could check with a muti meter

beerbelly · 12 April 2016, 05:58

Quote:

Originally Posted by jyasaki

50:1 plus auto-lube? Change plugs and see what happens.

jky

and run it on just petrol cos your weakening the afr putting oil in

Poly · 12 April 2016, 07:26

Quote:

Originally Posted by beerbelly

and run it on just petrol cos your weakening the afr putting oil in

He's just rebuilt it. Normal run in procedure is 50:1 plus the autolube for the first tank.

papajoe · 12 April 2016, 08:43

Plugs are new and clean, adding oil as it's a rebore with new pistons rings etc and standard practice for rebuild. So thinking stator coil, ignition coil or cdi?

uncle al · 12 April 2016, 16:50

no spark at the s/plugs check all earth connections are clean and tight, then check other connections, if ok check the stator and trigger voltage with a multimeter,then the switch box working your way from stator to s/plugs.

Superjetjim · 12 April 2016, 17:02

Most likely an earth or coil issue.

beerbelly · 12 April 2016, 19:23

Quote:

Originally Posted by Poly

He's just rebuilt it. Normal run in procedure is 50:1 plus the autolube for the first tank.

with autolube jet sizes adding oil to the fuel tank will reduce the amount of petrol in the mix the air volume is fixed with the throttle opening the jets can only flow so much fluid so by adding oil you will lubricate more but be running a weaker air fuel mixture which we all know isn't good burns pistons ect, surely a better idea would be to increase the amount of oil the oil pump sends into the inlet . or am I overthinking this I grew up on 2 stroke mopeds and kh 250,s and had a few seizures in my kack handed tuning attempts

thestig1973 · 12 April 2016, 19:28

Quote:

Originally Posted by Poly

Well it could be, but it would be rotten luck to rebuild an engine and have something major die 20 minutes later. Someone else (http://www.rib.net/forum/f50/maiden-...cue-71616.html) had a very similar issue recently. My money would be on a wiring issue (perhaps something came loose, wore through, got hot, shorted out).

I'm still struggling to diagnose this issue, although I haven't had much time as I was away last weekend
I have purchased a multi meter, I'm now trying to figure out all the various settings before I can test ignition components, I can't say I'm particularly confident in my electrical diagnostic abilities though :-)

diver 1 · 12 April 2016, 19:38

Just checking the obvious, but you haven't mentioned it. Have you run out of fuel or developed a fuel issue?

diver 1 · 12 April 2016, 19:40

Ignore that. Didnt RTFQ. Apologies.

papajoe · 12 April 2016, 20:15

Gone through it all and think it all fingers are pointing to the coil which now thinking aback would explain the random knocks here and there before I stripped the engine as the pack started to fail

Superjetjim · 12 April 2016, 21:40

Quote:

Originally Posted by beerbelly

with autolube jet sizes adding oil to the fuel tank will reduce the amount of petrol in the mix the air volume is fixed with the throttle opening the jets can only flow so much fluid so by adding oil you will lubricate more but be running a weaker air fuel mixture which we all know isn't good burns pistons ect, surely a better idea would be to increase the amount of oil the oil pump sends into the inlet . or am I overthinking this I grew up on 2 stroke mopeds and kh 250,s and had a few seizures in my kack handed tuning attempts

Yeah that would explain the lack of spark?

Modern synthetic oils burn as part of the combustion process, old mineral oils didn't..