Spark Problem

[Faztbullet]

Re: Spark Problem

This is a very simple ignition system, check your DVA voltage on the high speed side of stator(blk/wht) and see if voltage falls off, if so stator is bad. If it is steady the rectifier inside switchbox is bad. All readings are from imput to ground....

 

[matth121]

Re: Spark Problem

thanks for your reply. so you're saying my stator is bad then right? Although theres some question as to whether or not my DVA is working properly, it is definitely showing a drop as revs increase, instead of going up. 5V at idle(way lower than the 125V it should be) and down to 3V at 2000rpm. So I'm getting a new stator i guess- what's the likelyhood of the trigger needing replacement?
Matt

 

[Faztbullet]

Re: Spark Problem

If it was dropping a cylinder I would say test it (trigger). The stator charges the capacitor in switch box(internal rectifier is for change over from low to high).The trigger tells the SCR in switchbox when to fire (cyl #1 or #2) and capacitor drops stored charge to coil. If you are checking voltage at stator connection on switchbox I say yes stator is bad. If voltage is low at coils and stator voltage is Ok i say it switchbox. The voltages supplied for testing by CDI are usually static cranking voltages with stator disconnected from switchbox. Retest stator disconnected from switcbox as switchbox could be bleeding your high speed voltage to ground internally...

 

[matth121]

Re: Spark Problem

i'm on it. Thanks. I decided to bite the bullet and order a new stator but it'll be a week or 2 before it arrives. Is there any chance contamination like grease could cause problems with the stator. Looks pretty slimy under there. I'll have the flywheel off today so I'll get a better look.

 

[j_martin]

Re: Spark Problem

Thanks for your thoughts Mark, I Guess I may need to get a proper DVA or have it tested. But what do you think about those #'s dropping instead of increasing with rpm's? Also, an online mercury manual i've been looking at under ignition troubleshooting, they list weak spark as a sympton of a defective stator. What do you think of that? Please don't hesitate to get in on this conversation. I need all the help i can get

edit- what about using an oscilloscope for the measurements? I could have that done way cheaper than a DVA test by my local shop.

If you have an O-scope and know how to use it, it's fun and interesting way to investigate this ignition.

If you have to pay someone to do either one, why don't you just get a proper DVA and consider it a relatively small investment. Mis-diagnosing electrical parts on these things can put you in the poor house quickly.

 

[matth121]

Re: Spark Problem

i was definitely considering getting one. Here's the thing though. It's a relatively straight forward ignition, and it's 30 yrs old. For less than $400(not including the flywheel) it can be completely replaced. That should straighten the whole weak spark issue out anyway. I know thats not cheap, but i figure with new parts I really shouldnt have to worry about them again for years. I don't own an Oscope but i'm pretty sure I could get someone to bring one(that also knows how to use it) and test it for around $20-30.
I don't know this history of this motor as it's new to me so I'm planning to do a full teardown of the powerhead this winter, I've already had to replace the exhaust tube which had rotted off the adapter plate and was blocking exhaust port in bottom of housing. I would love to get it working properly before the end of the season. So next week or 2 when parts I ordered arrive, I'll be installing a new CDI stator and 2 new coils. It already has new plugs and wires although after the way its been fouling them, I'll probably throw a new set in once ive got good spark. All that leaves is the switchbox and trigger and i'm pretty sure my triggers good since it'll run all day without problems. so if this doesnt fix it i'll have to drop the $150 for the new switchbox, although, i'm pretty sure it's the stator at this point.

Im sure ive got some people shaking their heads right now as it makes alot more sense to replace what's broken, but i'm looking at this as an investment. Once Its running right, i'll be able to maintain it properly and I expect many years of enjoyment from it. Thanks again for everyones thoughts and please keep em coming

 

[matth121]

Re: Spark Problem

Ok guys, flywheel's off, got some pics.[

pretty grimy. Stators quite rusty too.

going to clean er up and see what happens. I'll post some more pics later
matt

ps- looks like a CDI Stator so i guess it isnt 30 yrs old

 

[matth121]

Re: Spark Problem

cleaned the stator, very gently, here's before and afters
BEFORE

AFTER


Big difference eh?
Put it back together, fired up 1st pull, and sounds like a new motor. Haven't rerun any DVA tests yet but it sounds way better and shakes less at idle. It smoked like a B*st*rd for a good 45 mins and then cleared up again. Think i just got rid of a pile of carbon. I did redo the spark gap test. Still jumping the gap, I still cant see it, but i'm thinking it's stronger. Going to the lake 1st thing in the morning. Will let you all know how it goes,
fingers crossed,
Matt

 

[matth121]

Re: Spark Problem

just a few thoughts i had- the extreme grime under my flywheel must mean i need an upper main seal, if thats what its called. I've read that a bad seal will allow the flywheel to contact the stator or trigger- ive got slight rub marks on both and also a faulty seal will allow oil to pass through, which would explain the grime. Also, the high speed wiring pickup(again, not sure if thats right), the big one on the stator, was very, very corroded. I cleaned it as best i could, but it still doesn't look great. Guess i'll know tomorow for sure.
matt

ps- notice the difference from the 2nd before pic to the 1st after pic....lol, grime free

and my last thought- i wouldnt have had to run any tests at all if I'd been told to pull my flywheel and inspect my stator, pulling it was relatively easy and the ammount of corrosion tells me its not going to be working great, no matter what. Instead I built a DVA im not sure works and ran a bunch of tests. My fault I guess, shoulda dropped $100 on and real DVA....

 

[abelardo]

Re: Spark Problem

Hello I am new at this but here gos I have a 1989 VIP fish & ski boat with a 1989 125 hp Force engine I just replaced the head and replaced the spark plugs . Went out last week and had a great day fishing boat get up to 42 mph and gets 55 rpm . I went out today and was not able to get past 35 mph or 32 rpm after fifteen min of pushing wot my heat buzzer went of I shut off the engine and fish for about 45 min i then started the engine with out a problem I cruise it back to dock at about 20 - 25 mph found a green wire going to the long chrome bar with a hold bunch of wires connected to it on the left side of engine .This green wire was disconnected could this be my only problem for lost of power and buzzer going off . Thanks please help as I am a new kid to all of this .

 

[matth121]

Re: Spark Problem

start a new thread bud, you'll get more people looking at it- disconnected wire isnt good, do you know where it connects?
good luck

 

[abelardo]

Re: Spark Problem

Hello I am new at this but here gos I have a 1989 VIP fish & ski boat with a 1989 125 hp Force engine I just replaced the head and replaced the spark plugs . Went out last week and had a great day fishing boat get up to 42 mph and gets 55 rpm . I went out today and was not able to get past 35 mph or 32 rpm after fifteen min of pushing wot my heat buzzer went of I shut off the engine and fish for about 45 min i then started the engine with out a problem I cruise it back to dock at about 20 - 25 mph found a green wire going to the long chrome bar with a hold bunch of wires connected to it on the left side of engine .This green wire was disconnected could this be my only problem for lost of power and buzzer going off . Thanks please help as I am a new kid to all of this .

 

[abelardo]

Re: Spark Problem

Yes I do it was hanging right out side the booth that holds the connecter .

 

[matth121]

Re: Spark Problem

i would reconnect it and see what happens

 

[abelardo]

Re: Spark Problem

Hello I am new at this but here gos I have a 1989 VIP fish & ski boat with a 1989 125 hp Force engine I just replaced the head and replaced the spark plugs . Went out last week and had a great day fishing boat get up to 42 mph and gets 55 rpm . I went out today and was not able to get past 35 mph or 32 rpm after fifteen min of pushing wot my heat buzzer went of I shut off the engine and fish for about 45 min i then started the engine with out a problem I cruise it back to dock at about 20 - 25 mph found a green wire going to the long chrome bar with a hold bunch of wires connected to it on the left side of engine .This green wire was disconnected could this be my only problem for lost of power and buzzer going off . Thanks please help as I am a new kid to all of this .

 

[matth121]

Re: Spark Problem

ok, definite improvement- I now hit 3100rpms on the water and i get up to 8.5 Mph. Bows up in the air but it doesnt ever get on plane.

What does the trigger do? I mean i know what it does but, about the movement of the trigger...when is it supposed to move. I know theres a link rod connected to my choke thats supposed to pull it forward a bit, but is there any other reason it would move.

Reason i ask is I decided to manually advance it with a piece of line I had tied to it while i was out on the water- instantly got it up to 3400 rpms, maybe 9 Mph. Seems to run much better with it moved forward. It'll only move so far though as the wires coming from it are tethered to the block. How much range of movement should it have?
Thanks guys.
Matt

 

[matth121]

Re: Spark Problem

just an update, after speaking with Laddies, it was determined that I may have a different powerhead than the one that came with the lower end. Checked the sn stamped in the block and sure enough, lower unit is 7178637 and powerhead says 8728379. I guess that could be a B instead of an 8 at the start. So now i have to figure out what I even have before tryiing to fix the spark problem. bummer. If anyone can help with that #, i'd appreciate it- been thru all the model lookup charts and I dont see it fitting anywhere.
Thanks

 

[matth121]

Re: Spark Problem

Just wanted to update everyone who helped me with this- still dont know what year my powerhead is, the number i found was a part# not sn, but with my new stator on, i now have a nice blue spark jumping the 7/16 gap. Havent gotten a chance to run it yet, but i'm hopeful, i'll let you know how it goes. If it gets on plane, i'll be happy, but if it works the way it should, well, i'll be doing a happy dance, and im not much of a dancer

 

[matth121]

Re: Spark Problem

Ok guys, sparks good, bit of a different problem now.
got to the water, started er up, noticeably better acceleration, but still not great. Got an extra 2 mph out of it, so 10 mph. So i decided to run it for a bit, cruised around the lake, after about an hour, i dropped anchor and sat for about 20 minutes. When i started it back up and started accelerating, all of the sudden, way better, got up on plane, 18.5 mph, fastest that boats ever gone since I owned it. Motor sounded great. I turned to start heading back up the lake, and lost power- right back to 10mph and not on plane. Couldnt get it back. Another 20 mins playing and i decided to try letting it cool again. After 20 mins of floating, i started it up, gunned it and was back on plane, 18.5 mph again. Same problem though, after 5 mins of WOT, i turn and lose power. Any thougts as to what this may be?

 

[Faztbullet]

Re: Spark Problem

This is a chrome bore block so take a compression guage with you and test compression when you get to lake(cold) and when it loses power.