15hp Chrysler won't start

[handirifle]

Today, I was given a 1978, 15hp 20" shaft outboard, yes given. Supposedly it runs, but I haven't been able to get anything but a "bang" out of it, twice actually. I have a 12ft sears alum boat to mount it on, but plan that, if the long shank does not work out, I will try to swap it for a short one.

Now, to list what I have done so far. There is great paperwork that came with the motor, including a service manual. There are receipts, to show the coils and condensers have been replaced ( a few years ago) as well as the plugs. The previous owner also changed out the points cam, not sure why, but it is installed correctly (letters up, and aligned with key).

Evidently, over time it has had running or starting issues, based on what has been replaced. The fellow that gave it to me said it runs (not for me) and revs freely, but stumbles under load.

I have pulled, and gaped the plugs according to manual (.030") and have pulled the flywheel, checked the keyway, and set both sets of points at .020", carefully. I tried to test the coils and condensers, but am not sure how, really. All I have is an ohm meter. I also tried to test compression, but my screw in tester's threads do not match the motor's. Are they metric?

I used new fuel, and after cleaning the connectors, I hooked them up to the tank, and the motor. Pumped the bulb, and started to pull. First thing I discovered, is the pull starter seems screwed up. It barely lets me pull 1/2 rotation before it comes to a hard stop. So to get around this, I rigged up a pull rope and would it around the top of the flywheel, where it's designed for one.

Pulling this way i get a good run on it. So after pulling and pulling, choke in and out, and in again, I finally get a loud "bang", not even sure where it came from. One thing I should mention here, is that when checking the plugs, I MIGHT have mixed up the plug wires, but I have looked the service manual over front to back and there is NO MENTION of firing order. I need to know which coil fires which cylinder. Currently, if memory serves me, the front coil, serves number 2 cylinder, at least the one marked number 2 on my motor. That is the lower cylinder on this one. Not sure if that is correct either, since the manual says NOTHING about it.

Anyway, an advice on what to do next?

Any help appreciated.

 

[JB]

Re: 15hp Chrysler won't start

Loud bang only happens if a plug fires when the exhaust ports are open. Two things commonly cause this: Plug wires reversed or flywheel key is sheared.

Think about this: Firing order can only be 1-2 or 2-1. There is a 50-50 chance that you hooked them up wrong. Very complicated to find out. Swap them and try again.

Good luck.

 

[handirifle]

Re: 15hp Chrysler won't start

Well I did figure that part out and I did try swapping them, but doesn't even bang then. And checked the keyway, like I mentioned. It is fine. The odd thing about your theory though, is why would I hear the bang so loud (very loud, like a fire cracker) when the exhaust port near the prop is under 15" of water? No bubbles either.

I am going to try and pick up a compression tester today that will work on this engine. My suspicion is possibly a broken/bent intake reed, but am really guessing there.

 

[JB]

Re: 15hp Chrysler won't start

You asked, I said. Now it's up to you.

 

[handirifle]

Re: 15hp Chrysler won't start

Uhh ok not sure what you mean. I had already tried reversing the wires and had already checked the key (see first post). Any one else with suggestions on where to start.

Has anyone tried squirting gas in the carb kinda like you would ether?

 

[huskerdaninva]

Re: 15hp Chrysler won't start

DO NOT spray raw gas/starting fluid into the carb!!!!! You can use pre-mixed fuel/oil in the ratio required for your engine and spray the pre-mix into the carb in an effort to get her started, but you shouldn't have to. Is the motor being choked while trying to start? Good luck...

 

[JB]

Re: 15hp Chrysler won't start

Have you tried here? http://forums.iboats.com/showthread.php?t=158071

 

[handirifle]

Re: 15hp Chrysler won't start

DO NOT spray raw gas/starting fluid into the carb!!!!! You can use pre-mixed fuel/oil in the ratio required for your engine and spray the pre-mix into the carb in an effort to get her started, but you shouldn't have to. Is the motor being choked while trying to start? Good luck...

I wasnt going to use raw gas, but thanks. Was going to draw from the tank it's hooked to (50 tto 1 mix). Definately not starting fluid. I agreee ii shouldnt have to but it was simply to see if fuel supply wwas the problem. Carbs are a pain to pull and only want to if I need to. Yes i have tried it with choke on and off and halfway.
i picked up a compression tester with metric fitting so i will hopefully rule compression/reed valves out.

 

[handirifle]

Re: 15hp Chrysler won't start

I also checked a boat repair shop and guys there didnt know on the coil setup. Weird.
he did ask if the wires" looked" like they went a certain way and I said" yes but when hooked up that way, that's when it backfires". Very frustrating that part. I do not like guessing on those things. I realize(d) its only one of two ways but it does not try to start either way and i do not relish the thought of ruining a reed valve from guessing.

 

[handirifle]

Re: 15hp Chrysler won't start

OK did comp test. Top cyl after three pulls gets to 85 psi. It's about 60-65 first pull. Bottom gets to 125 in second pull. Top jumps to 125 on first pull after oil was squirted into cyl, so looks like a compression ring issue on top.

That and there is some sort of problem I haven't figured out with the recoil starter as well. Even after squirting gas in the carb, it doesn't start, so it's either the compression imbalance or electrical, which puts me back to square one.

Question;
Assuming I can ever get it to start, how badly would it run with those two cylinders the way they are? I know it will not have full power, but will it have power at all?

Also how hard are those engines to pull and re-ring (assuming parts are still available)?

I just may end up giving this thing away to someone that has the cash to put into it, especially since it's a long shank and my boat uses a short shank.