1978 175 Black Max, Electrical truobles, need some direction

Hello, Looking for some direction to start looking for a problem that doesn't always show itself.

The 175 is on a Starcraft Holiday 22, gutted, reworked inside with treated wood and glass. Approx. weight 3000-3500

Boughtg motor, run it, backfired when starting. The trigger was sticking and the ear broke off. I replaced the trigger. Anyway, I set the timing per. manual 14deg. prim. and 20deg max wot(cranking speed) I then set the 14deg. primary when at idle(around 700-750 in gear). I did use the dial ind. to set the .462 BTDC, then set pointer to TDC.

Had a miss, #4 and #6 no spark. Moved some leads from other cyl. to verify the coils were working. I replaced the swithch box for #2#4#6, I then had fire. I also went through the book and made sure the throttle linkage was set according to book.

Took the boat out, ran very well, maybe the best I've ever seen it run. I know the prop is too large, can only get 4500WOT with a 13.75 x 21P.

Anyway, took boat out next morning, hard starting, some backfiring(exhaust), once it started it seemed to run fine. Mad a couple runs to/from a favorite fishing hole, later in the day it wouldn't start at all.

There was also a time it was running well, but not full rpm, then all of a sudden it increased rpm like you turned a switch on.

I plan on checking the ign. switch/circ. as well as the merc./tilt switch to make sure it's not grounding out.

If the motor was run too long out of time would it damage the stator? If the stator and/or switch box wasn't working correctly would it then throw off the #1 Spark or firing order? I can use a timing light but the #1 spark would have to be on time?????

Amy help is Greatly Appreciated

Andy

Re: 1978 175 Black Max, Electrical truobles, need some direction

hello sir,

no you wont hurt the stator by being out of time however you can burn a piston up.

also did you use factory mercury replacement parts? I have seen several for instances where aftermarket such as cdi ignition parts don't work properly with oem parts.

Some aftermarket ignition parts use special meters and values that differ from that of OEM electronics and the books show you OEM values so you can run into problems there.

ignition problems are difficult to diagnose via internet but check your replacement parts that will get you everytime!!

keep us posted!!!

Re: 1978 175 Black Max, Electrical truobles, need some direction

i would suggest to do a compression check to see where you are there..be sure your plugs are in good order and the right ones... when i bought my boat... it had the wrong plugs in it and was running poorly... hope this helps... some how

Re: 1978 175 Black Max, Electrical truobles, need some direction

From what you posted you set the timing correctly. The surging could still be a electrical problem (other switchbox bias' circuit) or a fuel problem from when engine has set during repairs. I would check the bias circuit i other box to make sure it was not cause of 1st boxes failure ,clean carbs and replace fuel pump diaphram. Remember if it has a fuel problem and that one or more cylinders are not getting fuel they not getting oil...

Re: 1978 175 Black Max, Electrical truobles, need some direction

junkfishin said:

I set the timing per. manual 14deg. prim. and 20deg max wot(cranking speed) I then set the 14deg. primary when at idle(around 700-750 in gear). I did use the dial ind. to set the .462 BTDC, then set pointer to TDC.

Click to expand...

Something seems amiss here. Are you saying primary (idle) is set at 14 advance or retarded crankin'? Either way that sounds extreme......

"I did use the dial ind. to set the .462 BTDC, then set pointer to TDC"

Are setting tha pointer to tha 462 mark or at tdc (0)? Tha pointer should stay on tha 462 mark after its found. Thats where both settings (idle and max) are based from.

I may be just reading this wrong......................

Re: 1978 175 Black Max, Electrical truobles, need some direction

Well, I did some inspecting after I had posted the questions. I do believe I found a major problem LOL.

I noticed a small portion of insulation missing from the wires coming from the stator. I cut off the plastic sleeve, oh my. 4-5 wires have almost no insulation on them. I don't know how it even ran? I'll replace the stator and the original OEM switch box, it may have been fine.

Does anyone else out there think that CDI parts don't work with OEM parts??

I also found the merc. switch had bare wires, that too will be replaced.

I may replace the dia. in the pump, although when it run, it run like a scalded dog.

Responding the the previous reply......
I used the .462 on the flywheel to make sure the pointer was in proper place. If you don't use the dial. indicator, you can be a little off. There's that small delay before the piston goes back down, so you don't know exactly where you're at.

The manual had a primary setting(idle) at 14deg above TDC and 20deg max WOT, below TDC, does this sound correct?

I think the stator wires arcing together could cause some issues.

I did find a local guy with a used stator, two switch boxes and a merc. switch for $100, that don't sound too bad. Can I test the stator on the bench?

It's amazing how much you can learn, both by hard lessons and being forced to work on your own junk , Keeps life interesting I guess.

I'll keep ya'll posted.

Andy

Re: 1978 175 Black Max, Electrical truobles, need some direction

Your idle timing is way to high, should be something like 2 degrees after top dead center, I usually set my timing right at top dead center and did you remember to disconnect the white/black bias wire when setting wot timing?

Re: 1978 175 Black Max, Electrical truobles, need some direction

Their is no magic to these electronics, cdi parts will work with oem parts it is usually the later models that have RFI (interference) that can mess with the computer. Even then their really is no problem.