1976 Evinrude 15 Questions

[chevysam41]

Excessive slop is definitely an issue with that twist grip - I need to look at that in more detail.

DOH! I know for a fact that the spark plugs were in (except the one I was testing, obviously). Guess that's what I get for doing it late on a Monday night. I've always removed all of the plugs when doing compression tests on car motors, but I've never understood why that matters...will it really throw off readings? Its supposed to rain here the next several days, so I'll do another compression test over the weekend after running some seafoam through the motor.

I snagged an old plastic barrel from work and started up the motor yesterday. I had a heck of a time getting it started on muffs last week, but on three separate attempts yesterday, it cold started within two pulls from a barrel. Ran like a top after I adjusted the carb. I let it idle for probably 8-10 minutes, put it in gear, etc and it seemed to run fine. I have a laser thermometer and the temperature got up to about 165* after 3 minutes or so, and just as I was about to shut it off, it dropped to the 120-130* range and stayed there. I'm guessing that was when the thermostat opened up as I was measuring at the top of the head. I thought those thermostats were supposed to open at 130*, but maybe not.

 

[flyingscott]

Dont worry about the compression I would change the plugs to champion as they seem to like them better. The thermostats open at like 142 deg sounds like it runs good.

 

[OptsyEagle]

The compression of the other cylinder was reducing how hard you can pull the motor over and will reduce the compression readings you get, so remove the other spark plug and check both cylinders that way.

OMC seems to recommend Champion plugs in almost all their motors but the model you have really wants those NGK B6HS. The Champions will foul after only a couple hours of trolling and may not make the season even if you don't. The NGKs will get you through a season or two. I would change them every year or two anyways and try not to troll too much with that motor. If you are going on a long trip take a spare set of plugs with you in the boat.

 

[chevysam41]

Sounds good. Yeah, I was originally going to go with the champions but switched to the B6HS at the last minute. Thanks for the help everyone. Looking forward to taking it out this spring!

 

[flyingscott]

I have owned that motor ran champions and never had problems trolling. My plugs lasted for years trick with them adjust the carb for trolling if you keep the NGK plugs keep an eye on them they seem to be a litter hotter plug. When I had mine the NGKs tended to run hotter so I had to run the idle jet richer which caused idle issues. Don't let people tell these motors can't run right they can and when set-up right they are great little runners i enjoyed mine very much. My friend is still running mine on his boat as the kicker he has a lot of hrs trolling on it.

 

[oldboat1]

My 9.9s run in that 120-130F range when I'm idling them in a barrel, sometimes will climb a little higher. 142 degree t.stats are new and tested -- water temps are probably a factor. As I recall, running in the lake gives temps in the 140-150 degree range (lake temp a little warmer, and the motor is working a little harder). The standard warning for testing in barrel is that the water heats up and can overheat the motor. I haven't run into that, but keep the hose running, water level up, and rpms low.

I use the motors as kickers on a larger boat -- have a temp gauge I could use for the trolling motor, but haven't installed it (haven't felt the need). In the slip, I periodically clear out the tell tale as it's a favorite spot for bugs. But other than that annoyance, I just run them. I use a four-bladed 5 pitch prop, and can slow troll running at slightly higher rpms than with the stock prop -- better operating level.

Think your grandpa's 15 should do well. They're nice motors.

 

[racerone]

In my experience you can allow a 9.9 to run in a 45 gallon barrel for about an hr before temperature is a problem.-----In summer.

 

[oldboat1]

sounds right. I just keep an eye on them, but like to let them run for a good while -- watched an old guy do that when I was a young guy, although he was a pro with a vented shop tank (full of what looked like coal oil). Ain't smart enough to figure out how underwater exhaust gas might affect the cooling water, other than to heat it up -- and think I get bored and shut it down anyway, before getting into trouble.

 

[chevysam41]

Hey Folks,

Retested the compression on this motor over the weekend - 90psi on both cylinders, so I feel a lot better about that.

I think I'm getting close to having this motor dialed in. I fired it up Saturday morning - it was about 28*. It started after 3 pulls, so I was pleasantly surprised. I've been running it in a barrel for 20-30 minutes at a time while keeping an eye on the temperature. I'm trying to test it in various conditions (cold/warm days and cold/warm engine) to figure out potential issues before I take it out this spring. The only thing I've noticed is that after 10+ minutes of idle, it sometimes randomly starts to bog and fall on its face before shutting off. It then takes about 4 or 5 pulls to restart. Seems to happen randomly, when I'm not touching anything...and sometimes it doesn't happen at all. I still haven't touched the old points or condensors since I'm still trying to find a strap wrench big enough, so maybe its related to that...

Oh, yeah...and one of the spark plug wires broke off of one of the brand new coils I just bought. Guess that's what I get for getting cheap Sierra stuff. At least the original 40 year old coil still works...:lol:

 

[OptsyEagle]

The first thing I would do is when it starts to bog, try squeezing the primer bulb and see if that revives it. If it does, you have a fuel pumping problem and if it doesn't then it is something else. If it is a fuel pumping problem, it can be many things, including the fuel pump so let us know.

Also, if you have your fuel tank sitting on the ground when you are running the motor, raise it up a couple of feet. Those old fuel pumps can only suck fuel so high after 40 years. In your boat the tank will probably be almost level with the fuel pump, maybe 18 inches below at the most. That could be your problem.

 

[oldboat1]

^^think that's right. When testing in a barrel, I set the tank up on a stool -- seems to make a difference. When running, the tank for my motor is slightly higher than the engine (transom mounted 9.9). Also, check valves between motor and tank can be an issue (connectors, bulb), along with tank venting.

 

[chevysam41]

I installed a new fuel pump about a month ago and got a new gas tank (the original OMC was toast) and fuel line. I'll try running it with the gas tank elevated to see if that changes anything.

 

[chevysam41]

I decided to decarb this motor today since its been sitting so long. I mixed a small batch of premixed gas (2pints) and seafoam (1 can/1pint) in a separate tank. I'd planned to run this through the motor, but only got about a third of it through. It smoked like crazy which I know is normal, but it would idle for a few seconds and bog out- it would never run on it. I finally decided to switch back to regular premixed gas but now I'm still having the same problem- it doesn't want to run and stalls out, even at wot. I'm having to play guess and test with the choke every time I pull te chord. Any thoughts?

FYI, this is all being done in a barrel in neutral, so WOT is lower than in gear obviously. I haven't tried changing the spark plugs because they were new when I started this thread.

 

[flyingscott]

I would change the plugs first then check the carb. My guess is you cleaned something out of the fuel system into the carb. The best decarb is mercury powertune or the BRP equivelant. I would change the plugs first then check the carb.

 

[OptsyEagle]

I assume you have the gas tank a little higher now. I would change the plugs and give it another try. It if possible that one of them might be completely fouled from all the carbon flying around in there. Carbon is a conductor of electricity. If that doesn't fix it, you could mix up some gas in a spray bottle and spray it into the carb throat. If it seems to run on that then perhaps the seafoam did dislodge something that is now plugging up your carb. That would require another carb cleaning, unfortuneately.

 

[flyingscott]

OMC has a test for the fuel pump. I think it should be able to pump vertically 36" vertically

 

[oldboat1]

said you have a new tank, but had you been running on the old one? You might need to revisit the carb work, depending on the sequence of things --- But, I would get an adjustable spark tester as well, and check spark. At one point, I think you had some magneto parts but had not installed them -- Think you might need to back track a little. If spark is good (solid 1/4 inch), can go back to fuel issues.

 

[chevysam41]

Thanks for the replies everyone. Yes, having the gas tank higher up definitely helped. I'll try running a new set of spark plugs to see if that helps. If that doesn't fix it, then I'll go from there. As for the tank, I never used an OEM one, if that's what you mean. I have a 6 gallon tank that is oil/gas only. The tank I used for the seafoam mix was actually a cleaned out water jug. Lol.

I do have the points and condensers but haven't installed them yet. I can't find a strap wrench big enough to keep the flywheel still while I loosen the bolt. How do you all do it?

 

[oldboat1]

First get a $10 adjustable spark tester at an auto parts store, and see if your magneto is producing good spark.

 

[OptsyEagle]

If you can't find a proper strap wrench you can make one using some nylon strapping material and a strong thick piece of wood. I have also used electrical extension cord instead of nylon strapping that worked quite well.