Spark test (video!) and mystery wire questions Thunderbolt 1400

[Buzz Killington]

Spring is in the air which means I am back in the garage working on the neverending project, part of which is the probably-too-big '72 1400 hanging off the back. I finally finished redoing the timing belt and re-assembling everything properly. Now I'm trying to diagnose a no-start using this list:

http://forums.iboats.com/showthread.php?t=158071

Motor spins freely and will just keep on spinning as long as the battery has juice. Plugs are basically brand new. Battery is good.

I did the spark test to check the intensity of the spark and here's a vid:

http://www.youtube.com/watch?v=xXyo54th-ng

Having no idea what to expect an outboard spark to look like, I'd appreciate your thoughts on whether it looks OK. My next step will to be rebuild the fuel pumps. I was told the carbs were rebuilt a couple years ago and the boat probably has 45 minutes of running time since then. Won't catch with a gas/oil mix shot into the carbs either.

Second question:

This short wire (circled in red) is attached to the carb linkage and moves up and down when the electric choke is used. It looks like it might attach to the manual choke...but it also appears to be a bit short. What the heck is it and where does it go? It was not connected when I got my boat.

Thank you!

Dave

 

[Chris1956]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

Dave, The spark test seems to be fine. Merc used wires to attach the top carb shutter to the manual choke pull.

If the motor won't fire with fuel shot into the carbs, either the timing is way off, or the compression is real low. You should test the compression and post back.

Timing light should show top plug fires at 4-6* BTDC. Set top cylinder to TDC with a screwdriver and confirm timing mark on flywheel matches TDC on cowling support.

 

[merc850]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

That wire is held in by a bolt at the bottom of the manual choke pull, for sure check the flywheel indexing, if there are rings around the center hub bolts somebody has taken it apart and put it together out of positon. They did it to me; jerks.

 

[Buzz Killington]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

Thanks, I will check the compression. I got the old girl running last summer though after cleaning up the wiring so I don't think it's that. Vid here:

http://www.youtube.com/watch?v=7M2wJOxQnFQ

Probably would not hurt to remove the carbs and clean them by hand. Could be some old crap from the gas in there.

I am the jerk that took apart the flywheel when I first attempted to replace the timing belt, LOL. After I read a few more DIY posts I thought to myself, WAY TO GO STUPID. Oh well, I learn by stupid mistakes I suppose

 

[Chris1956]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

Buzz, It is real easy to make sure the flywheel is assembled correctly. Remember 360*/8 bolts means that you only need to get the timing marks lined up within 45* to have it right.

 

[Buzz Killington]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

Another data point. Cowling is off though.

Sadly I am don't have any timing lights or any timing tools as I always used to set my timing by ear once upon a time when I daily drove BMW 1600s and 2002s. Guess I'll go go beg/borrow/steal.

 

[Chris1956]

Re: Spark test (video!) and mystery wire questions Thunderbolt 1400

Invest in a timing light. Idle pickup timing is fairly important, if you want a smooth running engine. Max timing is extremely important if you don't want the motor to blow up. In a car, if you mess up the max timing, heck you never redline the motor for too long, it will likely survive. However, you will want to run that motor near redline for hours. The max timing better be spot on or kablowie!