1969 25hp Johnson - Lack of power

[EastCoaster]

a buddy of mine just picked up a 13' valco with a 1969 25hp johnson of craigslist. he was told that the engine hadn't worked in two years but came free with the boat. the engine had an aftermarket kit with an electric starter that he was told was never used and not working.

i took the engine and rewired the electric starter and got it working. then i did a compression check and although somewhat low, they were both within 5lbs of one another. i then took off the carb and put a new kit on it, then changed the plugs and fuel filter and hit with some starting fluid cranked it over and it started right up.

it blew out a ton of black gook in the barrel and was idling high and not spitting out any water. i serviced the lower unit and put in a new impellar and clean out the top end of tubing and started it back up. after some additional throttle linkage adjustment and lean adjustments i got it idling and spitting out water.

after that we let it run to get all the gook out and took it down to launch ramp for a test drive. the engine runs pretty good, but it really doesn't seem to have much power. with one person on the light little 13' valco is almost planes out, but with 2 people it barely does 7 mph and its a 25hp.

i put my kicker 9.9 off my arima on that boat and go faster than with the 25hp. i don't know how to adjust the timing on this motor but it seems to be running fine and i have the throttle adjustments to flat out maxed.

i then took out the plugs and clean them, even cranked it a few times to get any other gook out of it and put it back together.

although i do not think this has much to do with this problem, the prop on this motor has some damage and seems very small for the engine, what pitch would be recommended for this engine to get better speed?

any help with ideas to get more power would be appreciated. please chime in.

thank you in advance for any assistance you can offer.

 

[Rick.]

Re: 1969 25hp Johnson - Lack of power

Eastcoaster: Everything you have done to this point is good and your certainly on the right track. Compression? What was it? I noticed you haven't said you pulled the flywheel. Do so and check/replace the points and condensers. Check the condition of the coils. If they are cracked, replace them if they look good, do a spark test. You may be running on one cylinder. Replace the fuel lines as well. Once you get it running right, do a decarb treatment. Keep us informed and don't be afraid to ask questions. Last, but very important, get an OMC factory service manual for your specific motor. It will pay for itself many times over and give you the information and confidence you need. Best of luck. Rick.

 

[Howard Sterndrive]

Re: 1969 25hp Johnson - Lack of power

do a spark test. You may be running on one cylinder.

that's exactly what I was thinking.

Those 18/20/25 E/J's run pretty smooth on one..can really fool ya.

After spark check - sync n link procedure

 

[EastCoaster]

Re: 1969 25hp Johnson - Lack of power

hey guys,

thanks for the quick responses. i can't for the life of me remember what the compression is/was when i checked it, i was more concerned they were both close to equal. i will check that again tomorrow and repost those results.

i didn't remove the flywheel and have not checked the points. any pointers on doing that would be greatly appreciated, i intend on working on it tomorrow.

to test the spark i just pull the plug and keep it close to the block and check for a spark, correct?

any other suggestions of things to check while I messing around with it tomorrow?

synch and link? more info please.

 

[Mas]

Re: 1969 25hp Johnson - Lack of power

It's best to see how far a spark will jump. You want about a 7/16 inch bright blue spark. Buy a spark tester at most auto parts stores for about $10. The device has an adjustable screw that allows you to change the "gap" distance for the spark to arc across. One end of the tester gets plugged into the spark plug wire, the other end is grounded to your block.

This test will be very telling if you have an ignition issue.

MAS

 

[Rick.]

Re: 1969 25hp Johnson - Lack of power

http://forums.iboats.com/showthread.php?t=294072
For removing flywheel and checking points

http://forums.iboats.com/showthread.php?t=167352
Setting needle adjustments

http://forums.iboats.com/showthread.php?t=158086
Awakening a sleeping outboard. Some things you've done and some you haven't.

http://forums.iboats.com/showthread.php?t=158076
How to decarb. and why.

That should be lots to keep you going. The compression is important in that if it isn't good enough the motor will not run right. If your within 5 lbs. that is very good but hopefully the numbers will be above 80 and even better if higher. I couldn't find the post on the linc and sync but when your ready for that ask and I'm sure someone will find it for you.

For the compression check remove both plugs and ground the wires to the motor. Put the gauge on the top hole and pull the rope, counting the pulls, until the pressure stops climbing. Write down the number. Move gauge to the other hole and pull the rope the same number of pulls and write down the number. After the decarb. I would expect your compression to improve and it will certainly clean up the combustion carbon. Rick.

 

[tashasdaddy]

Re: 1969 25hp Johnson - Lack of power

you will not find a link N sinc thread, as it is different for each motor. i personally prefer this method for decarb on smaller motors.

Decarb, take a can of seafoam put 3/4 of it in the gas tank, with only 1 gallon of premixed gas. put the rest in a spray bottle. start the engine, and let it come up to temperature. then remove plugs, and them some real good shot of seafoam into the cylinders, replace plugs, let sit 15 minutes. restart, and spray the rest of the seafoam into the carbs, so the the motor almost stalls, wait and repeat until the seafoam is gone.then take for a wide open spin. then put in new plugs, ad premixed gas to the tank, and take it for a wide open throttle spin. it is going to smoke like a house on fire, during this process.

afterwards compression.recheck

 

[EastCoaster]

Re: 1969 25hp Johnson - Lack of power

Hey Everyone,

Thanks for all the advice.

Today I tested the spark in each cylinder when I got started and both were firing. The engine had 124 PSI in the #1 top cylinder and 132 in the 2nd bottom.

I swapped out the condensors and the points (gapped them to .030) and installed new champion JC4's (gapped at .020) and we instantly got back the missing power, but the engine was running really rich after that and idling way too high. it ran for a good bit before i mistakely turned the carb needle too rich and the engine died out after reving up pretty heavily. i'm not 100% certain i adjusted the point correctly either, as the Seloc book had hardly any information on the procedure, but to my best estimates it was close to the factory marks and i chalked it up before i reinstalled the fly wheel. i ended up cranking the battery dead trying to get it started back up after that with no success.

i figure i just flooded it, tomorrow i'll try getting the carb adjusted and then do the decarb, double check the fuel delivery and filter and check everything else mention.

unfortunately when i did the carb kit one year back i noticed the acrylic insert that goes into the carb housing was worn away and pretty torn up, and that that needle wad tweaked from people trying to crank it down without the acrylic sleeve insert fuctioning properly. i straightened it out to the best of my ability on the anvil and cleaned up the sleeve best i could, but those carb kits don't come with that acrylic piece and I didn't have another needle.

the engine idled pretty decent before, so hopefully i can get it back to where we were until i can get those parts. hopefully now that we are getting the extra RPM's i can get it back to idling correctly and back on the lake again. thanks for the advice. i will follow up tomorrow and let everyone know how it works out.

also, i noticed today that it popped it to gear from neutral when it was idling really heavy and then went back in nuetral before i could even react. my buddy said it just started doing that last trip out, so I guess i'll be digging into that chapter next.

best regards,
Craig Rofhok

 

[Rick.]

Re: 1969 25hp Johnson - Lack of power

Popping into gear at a high rev. can smash your gears. Be careful. The work you've done sounds good. The plug gap should be .030 not 020,( points are .020) That alone can cause the plugs to foul more quickly. Keep up the good work and I'm sure you will be rewarded. Not sure what you mean regarding the carb. Never had a 25 HP pulled apart but someone who has will know what to say. Rick.

 

[Mas]

Re: 1969 25hp Johnson - Lack of power

...as the Seloc book had hardly any information on the procedure...

This is why most recommend only OEM manuals. Seloc, Chilton, and others try to cram too many models in one book, thereby explaining and illustrating each model insufficiently. OEM manuals will only cover a couple very similar models of the same year at most.

MAS

 

[coolguy147]

Re: 1969 25hp Johnson - Lack of power

dont use starting fluid.

ur using 50-1 oil mix tcw-3 right?

how is it pumping water most likely needs a new impeller.

good compression

check spark for us and tell us if both cylinders r sparking.

 

[EastCoaster]

Re: 1969 25hp Johnson - Lack of power

rick, thanks for catching the gapping error, but it was only a typo here and not in the repair, luckily!

today i found out why it wouldn't start after the repairs yesterday. overnight i thought that i may not have tightened the points down enough and they losened up, so i started popping off the flywheel only to find that the key which holds it in had broken. installed new key, rechecked points and engine starts but once again idling way to high.

adjusted the needle and got it down but it's not happy. won't idle at an acceptable low enough RPM's and goes from wants to stall to reving way to high. i did a quick test with the choke cleaner in the carb to see if i had ignition or fuel isssues and when i sprayed it in the carb, i revs up more. therefore, i am assuming it's a fuel deal.

then we decided to do the de-carb. it ran slighlty smoother after that and blew out some more black gooky stuff, so i removed and cleaned the plugs and kept tinkering with the carb but couldn't get it to run smooth.

then i took off the carb, gave it a quick cleaning since it had a kit change not too long ago and reinstalled it. same issues. the engine also is very rough at it's lowest idle, almost like it occassionally backfires, but i don't think it's actually backfiring. at this point, i am not sure where to go with this. i can drop it off at my outboard tech to get it fine tuned, but i would really like to fix it now that i got started, i would feel defeated if i had to pay at this point.

we ran out of light and my buddies parents didn't want to hear that over-idling engine again, so we are done for the night. these are some ideas i have that may or may not be on the right track. in the book, although it says to gap at .020 it says you should only be able to fit a .016 in between them when they are gapped correctly. it was able to fit the .020 so i think we'll try to correct that.

then from there, I guess i can start checking the fuel delivery and try to get that acrylic piece for the carb and double check that needle. any other suggestions would be great.

The engine definately has the power back, now i just can't get it idling steady and smooth. also if this is any help for some reason when i turn the throttle from the handle, it dies out, but if I rev it from the carb directly it revs right up. clue?

i am going to read the book over again, and i have ordered the OEM book off e-bay it just hasn't arrived and we had time over the weekend so we been working on it, trying to get it ready for the bass spawn.

 

[jbjennings]

Re: 1969 25hp Johnson - Lack of power

I'm suspicious you may have a problem with the timing synchronization due to a possible tiller gear mis-mesh. It could be a throttle gear tooth has slipped past, or you need to do a linc-n-sync, or possibly even the throttle cam follower (roller) pin is bent. You need to see if the throttle plate (not the choke plate) in the back of the carb is just starting to open when the throttle cam follower (roller) passes the little timing mark on the throttle cam.
Anyway, those gears are bad about slipping. I'm just thinking something like this is the problem since you have good spark or it wouldn't run wide open, and your carb sounds clean since turning the low speed adjustment is doing something at least. Synchronization is about the only thing that I can think of.
I'm also thinking timing sync. problems because when you sprayed fuel in the carb is sped up, rather than richening the mixture and slowing it down.

BTW, I reread your last post and noticed you said when you turned the tiller grip it died out, but not if you did it at the carb. This further points to a tiller gear mis-mesh or incorrect timing/throttle syncrhonization to me.
Just some ideas,
JBJ

 

[Rick.]

Re: 1969 25hp Johnson - Lack of power

Sounds like you've had a busy but productive weekend! Do what ever JB says to do as he has forgotten more about these outboards than I will ever learn. The only thing I would add would be to look for possible air leaks in your fuel line. With the motor changing speeds on it's own that can be caused by it getting more/less air into the fuel line with the throttle staying at the same position. I'm not sure what the acrylic thing is you mention. Could that cause an unstable air/fuel supply? Keep going, it sounds like your winning and that is important. Some times it's one step forward and two back but your gaining ground. Rick.

 

[River - Runner]

Re: 1969 25hp Johnson - Lack of power

although i do not think this has much to do with this problem, the prop on this motor has some damage and seems very small for the engine, what pitch would be recommended for this engine to get better speed?

I'd recommend the standard 9 x 10 prop.
The standard factory prop supplied with the motor is the 9 x10.

To show this motor...
My 1969 25 hp Johnson. I bought it new.

Running the standard aluminum 9 x 10 prop. And it scoots!

You have one of the greats.
It's the first year for 25 hp. in 22 cu. in.
Weighs 78 lbs. and it's the lightest 25 hp. factory built motor ever made.

Hope you get it running proper soon. You'll enjoy it!

 

[jbjennings]

Re: 1969 25hp Johnson - Lack of power

Nice transom shot!
Think we could work out a trade? I've got a really nice mercury 7.5hp I'd trade you for it.....
JBJ

 

[River - Runner]

Re: 1969 25hp Johnson - Lack of power

Thanks, but NO WAY!

This motor will outlast me and EastCoaster's buddy is very lucky to get his motor the way he did, free with the boat!

 

[EastCoaster]

Re: 1969 25hp Johnson - Lack of power

as the saga continues.

i now have the points gapped correctly (i believe) and now the engine sounds great, and idles well. unfortunately when i inspected the lower unit casing, i found a crack.

when i drained the lower unit oil nothing but water came out. i took a dremel tool the crack and cleaned it out best i could, scuffed it up and put two part marine puddy (bond well) stuff for an emergency repair. i filled it with lower unit oil and ran it in the tank and it held.

however, when we took it for a splash down cruise, when the engine was in gear no power (RMPS). when it is in nuertral there is plenty of power. so i wasn't sure what went wrong from the garage to the launch ramp.

i went check the plug wires and apparently the bottom cylinder is not grounded because the bottom wire was shocking me something awful, and the engine sputtered when i became the ground. does this mean i have a bad coil?

then when i put it in gear after reving it up in nuetral is seemed that the engine at half throttle had full power 2 cylinders, and then after about 1/2 throttle it bogged back down and actually goes slower than at 1/2 throttle. you can hear the change in the sound and the overall vibrations in the motor.

i'm assuming one of the coils is bad, or there is short or lack of ground in the wire for the bottom cylinder. i could also feel a slight shock on the top wire but nowhere near the same jolt coming from the bottom one. any suggestions?

i have faith the engine will perform well, i got a little taste of it today, a couple times it started running on two cylinders on and off and that engine has never had that kind of zip to it, unfortunately it only lasted a couple of seconds at a time.

the engine idles nice now, and no puttering or fake backfires, i am hopeful that i am getting close. it is too bad the lower unit casing is cracked, and that i still have to fix the poor gear shifting problem. but it's hanging in there for now.

i also thought air in the fuel line and noticed a hair line fracture at the tank and a lack of firmness on the pump ball. however, marine emergency repair puddy to that rescue again and it miraculously held and i got full pressure in the ball after that, but it didn't solve the problem.

so......back to the book. i hope the OEM manual gets here soon.

 

[Rick.]

Re: 1969 25hp Johnson - Lack of power

If your getting a shock that means your coils are working but your plug wires are bad. The plug wires don't have a ground. They deliver spark to the plugs and the spark wouldn't be there if they were grounded. They ground at the plug and after the spark is completed. Repace them with new one including new boots (caps). With new plug wires you will notice a huge improvement if the spark has been grounding out before the plug. Nothing but water is a bummer. If the crack doesn't seal with your putty you should take it to a welding shop and see if they think they can weld a repair for you. Best of luck. Rick.

 

[EastCoaster]

Re: 1969 25hp Johnson - Lack of power

thanks rick. i will change out the wires and see what happens. so far the puddy is holding up just fine, i sanded it down smooth and didn't notice and saturation or oil stains.