Years of work, engine won't run. Running out of options and about ready to sell.

[kippstakes]

50hp Evinrude '72 Lark, 50273c.

I've been working on the damned engine for years and it just refuses to run right (or maybe I refuse to fix it right, anyway..). The previous signs were low power output, poor fuel economy, and intermittent hard starting.
Recently I discovered a crack in the fuel line that was effecting the vacuum. While repairing it, I decided to service the carbs and reed valves, and install new gaskets.
After the work was all done the engine wouldn't start. I managed to get it to crank on by opening the throttle and cranking repeatedly. After that, she seemed to run well, but today when I tried starting it up I couldn't get a pop out of her.

The engine has:
New spark plugs/caps
New head gasket (125 psi on both cyl.)
New power pack- spark is fine
Solid, tested wiring
New fuel pump
No evident leaks from p' head flange
Good fuel & bulb that pumps to rock hard (good vacuum)
Sparkling clean carbs and all new gaskets
Floats adjusted to manual specs- no lower than 1 5/8, no higher than 1 1/8'', from flange to float bottom (I basically set them both in the middle of these figures).. maybe I managed to set them wrong somehow.
Reed valves seem fine. When I removed them a few of the reed petals had bent up a bit so, by lightly tugging them down repeatedly, I managed to get them back flush with the block.
The carbs don't have mixture needles, so that's out of the equation.

.. I just don't get it!

One thing I did notice yesterday was fuel leaking down the inside of the exhaust cover, out at the lower unit vents. I chalked it up to flooding, but could it be an indication of something else?

Also, I removed the spark plugs today and gave it a few cranks with my hand over the plug holes. What I got was white-ish vapor, which I assume is correct; it didn't get my hand wet, but appeared to be vapor. However, the 'puffs' coming from cyl. 1 were noticeably stronger/more forceful than from cyl. 2. This doesn't seem good.

ANY ideas???

Thanks for bearing with me, I know this was a long one.

 

[healey8390]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

Sounds like a stumper! Did you put a new diaphragm with the fuel pump?

I'd link and sync and check timing. You may have sheared a flywheel key. Take the number 1 plug out and turn the flywheel till the piston is at tdc and see where your timing marks are!

 

[phillnjack2]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

reeds
youl never bend them back to correct settings, they are a lot more delicate than you might think.
just 1/2 though can cause mayhem with reeds, a spec of dirt on one can give problems even.
had a friend who got an engine and done everything with it, then I said reeds, so he took them out and they were rusted.
new reeds ran like a dream, until he sank the boat .

I would definitely look at getting new reeds before condemning it.


phill

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

I'll throw new reed valves in and see what happens. Will also check the timing.
Thing runs like a top once it starts, the trick just seems to be getting it going.
Thanks, guys.

 

[Daviet]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

What type plugs are you using?
Remove the front cover for the carbs and squirt some fuel mixture directly into the carbs and see if it will start.
Where do you have the slow speed needles set at?
Have you checked the flywheel key, a very slight amount of offset will cause it to start hard.

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

I'll check on the plugs when I get home today and get back (not sure what they are, they were installed by a marine shop).
My carbs are a later model than the engine- somebody switched them out. they have plugs and pre-calibrated brass tubes (can't think of the name for it) behind them.
The engine runs like a top once it starts, and starts easily immediately after it's been ran a bit. Just has trouble starting cold.

 

[HighTrim]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

You have a fixed high speed jet, but adjustable low speed needle. Have a pic of it?

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

Sounds correct, thought I'm not sure where the high speed needle adjustment is done. It has a high speed nozzle, but I don't see the needle. I tried loading a pic but it failed, many times.
Still waiting on the reed valves. I plan to take the carbs off for a second appraisal, since they will have to come off for the reed replacement anyway.

The plugs are QL77JC4. Think they're the right type.

 

[Daviet]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

Is this your carb?
The high speed orifice is fixed, you cannot adjust it. (#35)
The low speed, idle, is adjusted by the low speed needle valve. (#30)
:: iShopMarine.com ::
That looks like the correct plug, have it gapped to .030?

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

Not quite mine I think. My carb has an orifice plug over a calibrated brass hole instead of a needle valve, #30. The high speed valve is also fixed.
Gap is .030, but the plugs actually look a bit fouled (which makes some sense since I've only been able to run the engine at slow speeds so far). New plugs are in the mail.
Tested the spark with an open air gap tester and it's producing a snapping 3/8'' arc, so that's a relief.
New reed valves are on the way, so once they're installed we'll see if she's more cooperative. If not I guess it'll be time to check the timing and flywheel key integrity. I'll get back to you.

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

Not quite mine I think. My carb has an orifice plug over a calibrated brass hole instead of a needle valve, #30. The high speed valve is also fixed.
Gap is .030, but the plugs actually look a bit fouled (which makes some sense since I've only been able to run the engine at slow speeds so far). New plugs are in the mail.
Tested the spark with an open air gap tester and it's producing a snapping 3/8'' arc, so that's a relief.
New reed valves are on the way, so once they're installed we'll see if she's more cooperative. If not I guess it'll be time to check the timing and flywheel key integrity. I'll get back to you.

View attachment 231440View attachment 231440

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

this is my carb. looks like someone maybe yanked it off a 60hp.

http://www.*****************/parts/evinrude-johnson-parts-diagrams/JOHNSON/44594.gif

 

[kippstakes]

Re: Years of work, engine won't run. Running out of options and about ready to sell.

There it is. Replaced the idle jets, re-set the floats, new plugs- thing started right up and seems to be running well. Going to take her out this weekend for a good load test.
How does the idle sound?

https://www.youtube.com/watch?v=atLB...ature=youtu.be

Thanks for ALL the help, everyone!