Engine Trouble - Page 3

Pikey Dave · 15 May 2020, 13:26

Quote:

Originally Posted by A1an

The trigger coil detects tabs on cam pulley, I have set these tabs as per spec. The exciter coil under flywheel is not adjustable as the coil sits on dowels.

The trigger coil is basically an electronic switch, these do deteriorate and can give intermittent problem whereas the exciter coil just makes electricity, generally these work or don't, it is possible that it's not making the correct voltage, still waiting for an adaptor for multimeter.

Tbh it will be the exciter that I change first, gut feeling.

I had problems with a V twin Honda, not an outboard & it was the pickups at the flywheel. I’d set them up as per manufactures spec, still no joy. I spoke to a mechanic at the local mower place & he said to ignore the spec & use a playing card as a shin for setting the gap. This was a much smaller gap than the spec. Worked a treat.

A1an · 16 May 2020, 18:59

Well, it's not a valve spring.

mikehhogg · 17 May 2020, 18:18

I had a similar problem a few years ago. We replaced everything but to no avail.Owner bought a new engine and left me the faulty one for parts. I decided to try and find the fault, turned out to be a small crack in the gasket between the two engine halves. I verified this by filling the crankcase up with petrol and leak was quite visable.This may not be your problem but is worth considering

breezeblock · 17 May 2020, 18:59

Quote:

Originally Posted by mikehhogg

I had a similar problem a few years ago. We replaced everything but to no avail.Owner bought a new engine and left me the faulty one for parts. I decided to try and find the fault, turned out to be a small crack in the gasket between the two engine halves. I verified this by filling the crankcase up with petrol and leak was quite visable.This may not be your problem but is worth considering

won't affect a 4 stroke engine as the crank case isn't scavenged

breezeblock · 17 May 2020, 19:00

close up the plug gap a bit and move the coil closer to the flywheel are the magnets still strong and on the flywheel

A1an · 17 May 2020, 20:55

Magnets are good and where they should be. Can't move the coil, it sits on dowels. Can try gapping plugs though.

breezeblock · 17 May 2020, 21:14

Quote:

Originally Posted by A1an

Magnets are good and where they should be. Can't move the coil, it sits on dowels. Can try gapping plugs though.

can you run the engine with a spark plug tester and see if the spark is fizzling out after a while as this would definitely tell you whether its an ignition problem or a fuel issue is the breather on the tank restricted and you have changed the petrol?ive got a Honda power pack in the workshop that if you run it on stale petrol it fizzles out and will start straight of after it cuts out

A1an · 17 May 2020, 21:26

Spark tester used while I had the coil from the 20hp on as it has longer leads to be able to fit. Intermittent spark then just flicks to running fine.

I've tried 2 different tanks and lines, I've even tried bypassing the connector/pump/filter by connecting fuel line straight to the carb and using primer as a pump. No difference.
Today I launched the boat, engine started but was misfiring, after a couple mins pooling about it started running perfect. I opened the throttle and ran it at WOTfor 40mins without so much as a cough. I then brought it down to idle but still in gear, I trolled about for 7 or 8mins before it it flicked back to rough running.
It nearly found itself being chucked off the back of the transom.

breezeblock · 17 May 2020, 21:29

sheared flywheel key or very worn perhaps and the flywheel is moving about

breezeblock · 17 May 2020, 21:30

I think ive got a service manual for that engine (well I did have if last tango returned it) I will search

A1an · 17 May 2020, 21:32

Key is good.

I've got the workshop manual off PDF File
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breezeblock · 17 May 2020, 21:40

its definitely the correct plugs for it maybe try a different manufacturer

A1an · 17 May 2020, 21:45

100% correct plugs. I've set them to factory specs but maybe I should try and close them up a little. It's a weak spark on these engines at the best of times.

breezeblock · 17 May 2020, 21:47

try an unresisted plug

neil.mccrirrick · 17 May 2020, 22:30

Does it have an air filter? It would do that if it’s blocked

A1an · 17 May 2020, 22:40

No filter Neil, just a gauze you could chuck a house brick through.

breezeblock · 17 May 2020, 22:41

Quote:

Originally Posted by neil.mccrirrick

Does it have an air filter? It would do that if it’s blocked

an air filter wouldn't make the ignition play up

A1an · 05 July 2020, 16:28

To put this one to bed.....it was the CDI unit. I bought an exact same engine and first thing I did was swap the CDI on to the bought engine, guess what happened?!

Can I interest anyone in a perfectly running 15hp

Pikey Dave · 05 July 2020, 17:21

Quote:

Originally Posted by A1an

To put this one to bed.....it was the CDI unit. I bought an exact same engine and first thing I did was swap the CDI on to the bought engine, guess what happened?!

Can I interest anyone in a perfectly running 15hp

Glad you nailed it Alan[emoji106]

neil.mccrirrick · 05 July 2020, 17:40

Always nice to see the end of the tale cheers Alan [emoji1][emoji106]