My outboard is driving me nuts

[Andy Taylor]

I have a 1990 25HP Johnson that may be posessed. One day it runs fine. The next time out it will bog down and die when you are at full throttle for at least 15-20 seconds. If you back off the throttle a little, it will run fine again. Then yesterday it was dying out also at low speed. Does this make sense to anyone? Is it definitely a gas flow problem? Thanks for any advice.

[burleytog]

How is the primer bulb?  

[Jim Grouch]

I have a suspicion it may be the vent screw may not be opened up on the gas tank. Check that out first. Have you changed the spark plugs? How long has it been doing it (did it run fine earlier this season)? Is it fuel from last year that sat over the winter (water in the tank)? Check the inline fuel filter (may see water and fuel seperated in there). Is the choke lever getting switched on? When was the carb cleaned?

[Sfritr]

Been having similar issues with my 150 Johnson.  See Sickly Johnson posts.  The shop hooked to the Dyno, changed the filter, and are now telling me it was the power pack.  I pick it up today so I will let you know if was corrected.  Similar issue though.  Engine just died while under load.  So far, I'm at $522.00   >   Good Luck

[grizzly1654]

My 40hp merc did the same thing. I pulled the carbs off and cleaned them with some carb cleaner and now it runs like new.

[Andy Taylor]

I'm no mechanic, but I'll check these things out. The gas is new, plugs were changed the beginning of this season, the tank is being vented. I normally just use the choke to start it when cold.  The tank is an old 6 gallon steel one. There's no vent screw on cap, I was told to just crack the cap open slightly to vent it. So the problem must be something with the tank, dirt in fuel system, or fuel pump? How do I check the primer bulb? Thanks.

[Jim Grouch]

It has been my experience with the venting of the tank. Try to take the tank cap off and screw it back on. If the motor runs fine for a minute and then starts to cut out then you have found your problem. You will just need to pick up a vented cap. If that is not the case then my next approach would be to clean the carbs. -Jim

[Raul]

The tank is an old 6 gallon steel one. There's no vent screw on cap, I was told to just crack the cap open slightly to vent it. .

I would change that old RUSTY steel tank for a new one. ( rust particles getting into the carb and choking it )

I would change the hose, connector ( it may be allowing air to get in, the O ring is cracked, broken or inexistant ) and bulb ( it may be allowing the gas to return to the gas tank ) for new ones and add a gas filter in between the bulb and the connector.

Check the carburator for debris

Check the fuel pump ( the membranes become brittle with time )

[bass or bass ?]

At the very least, make sure all your fuel line connections are absolutely tight. My motor's been running like crap for a while now, and I found two loose connections in the fuel line. The clamp where the hose connects to the fuel pickup on the tank, and my glass fuel filter wasn't screwed together tightly. Now I need to do some carb jet adjustments and/or carb rebuild. My motor is a 1967 Evinrude Starflite 80hp.

[Andy Taylor]

Raul, I didn't say the tank was rusty. I sure don't see any rust. Thanks everyone for your input. I picked up a shop manual from the library today.

[ohioriverrat]

I don't know if this will help or not, but while reading my Johnson service manual last night (I have a 1988 110 HP VRO), it mentioned the fuel pump on some 150s as being too small. The only fix for it was to install the newer style high output fuel pump.

It also mentioned that, on some models (again, I don't have the particulars) that some of the carburetor venturis were too large. And again, the only fix is a new carb.

Both items were said to cause the high speed symtoms you all describe. Sorry, I don't remember the exact years that had the issues, nor which horsepower (other that the 150 mentioned). I can look again tonight, but as I don't do Internet on weekends, I cannot post it quickly.

All this information is covered in the Clymer service manual for outboards up to about 1989. One issue is in the "carburetor synchronization" section and the other is covered in the "Fuel System" section.

Cheers,

Mark

[Raul]

Raul, I didn't say the tank was rusty. I sure don't see any rust. Thanks everyone for your input. I picked up a shop manual from the library today.

Old steel tanks develop rust, a little or a lot but with time they develop rust, rust particles can be very tiny but still they are there and make their way to the carburator ( or injectors ) and clog it. Like you my friend a buddy of mine when facing similar problems said the exact thing to me when I told him the tank was rusty, it only took a gas filter to prove him he was wrong, small as dust, but still, rust particles appeared in the gas filter.

[Way2slow]

I agree, junk the steel tank.

Power Pack can cause your problem but I would be more prone to believe your problem is in the fuel delivery system.  That's a classic sympthom of a bad fuel pump.  Try squeezing the primer bulb the next time it does this.  If you can keep squeezing the bulb and it picks up and runs, good chance the pump is gone.   A stick needle in the carb  can cause it also but that's not a common as the pump.

[Andy Taylor]

Today I checked the gas filter screen and it's clean. I hope to be able to run it tomorrow and see if pumping the primer bulb allows it to keep running. What brand of plastic tank do you guys recommend? Thanks.

[natanestaban]

Don't forget to try some SeaFoam in the gas line and SF Deep Creep in the carb intakes to clean out the junk in the lines and valves.   Before you go rebuild the carb, this is easier and worked on my '88 Johnson 90HP ( at least so far ).  

[BrnzeBckStalker]

I just recently had this happen to me (within the past week). I had the carbs cleaned and tuned obviously in a half-@#$ed manner. I was only able to achieve half throttle and at full throttle it would bog and die. Then start up to idle it would die as well. I went through and noticed a couple of things. 1) even though i had new spark plugs, my oil-gas mixture was off just a hair fouling out my plugs. 2) Also figured that I had a high speed jet clog seeing that i could not achieve full throttle. So (assuming yours is a 2-stroke) i filled my 6gallon tank to exactly six gallons. The MAX FILL line on the tank is not actually six gallons. Therefore the mixture was getting messed up with my ratio 50:1 or 2.56oz of oil to one gallon of gas. Or close to 16oz to six gallons. I also added seafoam treatment to the gas. I tightened down all the fittings to the clamp ends as well as the primer bulb because I heard air passing through somewhere when I squeezed to prime. I took it on the water and after about five minutes trying to throttle up I felt the seafoam push whatever was clogging the carbs up shoot through the system and I can now get full throttle and the bogging stopped. Seafoam works wonders!! Recommended use! Also if there is a reason to have the steel tank, like to fit where ever the tank is supposed to accessible, there is a product kind of like a primer sealer deal that you put in the tank and shake it around to re-coat the interior to rid of rust. You can go that route or just buy a new plastic tank. Hope this gives you some more options in your process.

good luck!

[bass or bass ?]

Don't forget to try some SeaFoam in the gas line and SF Deep Creep in the carb intakes to clean out the junk in the lines and valves. Before you go rebuild the carb, this is easier and worked on my '88 Johnson 90HP ( at least so far ).

What is this SF Deep Creep and where do you get it?

[bass or bass ?]

I just recently had this happen to me (within the past week). I had the carbs cleaned and tuned obviously in a half-@#$ed manner. I was only able to achieve half throttle and at full throttle it would bog and die. Then start up to idle it would die as well. I went through and noticed a couple of things. 1) even though i had new spark plugs, my oil-gas mixture was off just a hair fouling out my plugs. 2) Also figured that I had a high speed jet clog seeing that i could not achieve full throttle. So (assuming yours is a 2-stroke) i filled my 6gallon tank to exactly six gallons. The MAX FILL line on the tank is not actually six gallons. Therefore the mixture was getting messed up with my ratio 50:1 or 2.56oz of oil to one gallon of gas. Or close to 16oz to six gallons. I also added seafoam treatment to the gas. I tightened down all the fittings to the clamp ends as well as the primer bulb because I heard air passing through somewhere when I squeezed to prime. I took it on the water and after about five minutes trying to throttle up I felt the seafoam push whatever was clogging the carbs up shoot through the system and I can now get full throttle and the bogging stopped. Seafoam works wonders!! Recommended use! Also if there is a reason to have the steel tank, like to fit where ever the tank is supposed to accessible, there is a product kind of like a primer sealer deal that you put in the tank and shake it around to re-coat the interior to rid of rust. You can go that route or just buy a new plastic tank. Hope this gives you some more options in your process.

good luck!

My motor symptoms have been very similar to yours. I've always used Sta-Bil marine in my gas mix. I've seen many posts on here about Sea-Foam, is it that much better? Is it an ethanol treatment like Sta-Bil or Star-Tron? My motor is a 1967 Evinrude 80hp. What's yours?

[bass or bass ?]

Today I checked the gas filter screen and it's clean. I hope to be able to run it tomorrow and see if pumping the primer bulb allows it to keep running. What brand of plastic tank do you guys recommend? Thanks.

I bought a new plastic Tempo, but I still use my old steel tank as it is clean and rust free inside and nearly all the responders to my old post said to just keep it unless there was an obvious problem. Tempo makes many sizes and shapes. Go to their website and I'm sure you will find a replacement if you choose to go that route.

[grizzly1654]

Don't forget to try some SeaFoam in the gas line and SF Deep Creep in the carb intakes to clean out the junk in the lines and valves. Before you go rebuild the carb, this is easier and worked on my '88 Johnson 90HP ( at least so far ).

What is this SF Deep Creep and where do you get it?

It is a seafoam product in a spay can. It works really well, you can find it at most napa auto parts stores

[BrnzeBckStalker]

I just recently had this happen to me (within the past week). I had the carbs cleaned and tuned obviously in a half-@#$ed manner. I was only able to achieve half throttle and at full throttle it would bog and die. Then start up to idle it would die as well. I went through and noticed a couple of things. 1) even though i had new spark plugs, my oil-gas mixture was off just a hair fouling out my plugs. 2) Also figured that I had a high speed jet clog seeing that i could not achieve full throttle. So (assuming yours is a 2-stroke) i filled my 6gallon tank to exactly six gallons. The MAX FILL line on the tank is not actually six gallons. Therefore the mixture was getting messed up with my ratio 50:1 or 2.56oz of oil to one gallon of gas. Or close to 16oz to six gallons. I also added seafoam treatment to the gas. I tightened down all the fittings to the clamp ends as well as the primer bulb because I heard air passing through somewhere when I squeezed to prime. I took it on the water and after about five minutes trying to throttle up I felt the seafoam push whatever was clogging the carbs up shoot through the system and I can now get full throttle and the bogging stopped. Seafoam works wonders!! Recommended use! Also if there is a reason to have the steel tank, like to fit where ever the tank is supposed to accessible, there is a product kind of like a primer sealer deal that you put in the tank and shake it around to re-coat the interior to rid of rust. You can go that route or just buy a new plastic tank. Hope this gives you some more options in your process.

good luck!

My motor symptoms have been very similar to yours. I've always used Sta-Bil marine in my gas mix. I've seen many posts on here about Sea-Foam, is it that much better? Is it an ethanol treatment like Sta-Bil or Star-Tron? My motor is a 1967 Evinrude 80hp. What's yours?

I have a 1971 johnson 50 hp electric shift. I was just planning on using one treatment (16oz) and then be done with it until i noticed a problem come back. I am not one to say it is better or worse or the same. I have only used seafoam thus far and i dont mix anything now but my johnson/evinrude brand oil to gas. Check these sites out.

http://www.mastercraft.com/teamtalk/showthread.php?t=4681

http://www.seafoamsales.com/motor-treatment/index.html

[Stagerlee]

Something might be lodged in the fuel pump? Same thing kinda happened to our  Evenrude.

[K_Mac]

How is the primer bulb?

This question could have saved me many headaches and a good bit of money several years ago. The bulb had deteriorated just enough so that after a few minutes of full throttle it would begin to clog and restrict flow.

Good luck.

[bass or bass ?]

Something might be lodged in the fuel pump? Same thing kinda happened to our Evenrude.

Had the fuel pump apart and rebuilt it 2 outings ago.

LOVE your avatar. Happy birthday Jerry.

[bass or bass ?]

How is the primer bulb?

This question could have saved me many headaches and a good bit of money several years ago. The bulb had deteriorated just enough so that after a few minutes of full throttle it would begin to clog and restrict flow.

Good luck.

It seems to be fine, but they are inexpensive. I guess I'll replace it.