Johnson 4.0 weird problem please help :(

[Mizzie]

Hey everyone,
I recently picked up a nice and real clean Johnson 4.0hp outboard. It's a 1990 in really great shape under the hood.

My problem is.. I bought it, guy said he recently had it serviced.. I took it out yesterday attached to my 12' jon boat.. motor cranked!! fast for what it is.. ran great, perfect! Was only out for about 2 hours fishing.

I took it out today, ran great again, starts first pull.. but then I was fishing in a cove for about an hour, when it came time to leave I pulled it, started right up got about 200 ft out at half throttle then stalled out.... took a couple pulls to get it going again once it was going it went fine,, but it wasnt giving it all it seemed.. I was at about half throttle and it started to want to stall so I pulled out the little lever that squirts fuel into the engine (not the primer, the choke looking lever) I had to keep messing with that giving it random squirts of fuel when it wanted to die... when it's running it runs GREAT. but this problem can't be healthy for the engine...

I'm new to outboards I've had a bunch of inboard/outboards but never a little outboard... I'm pretty mechanically inclinded I just need some help on what to look for... I'd like to go out fishing tomorrow but I don't want to get stranded out there haha


thanks guys any helps apprecited... Like I said yesterday I had no problems,, today it\ still ran good but a couple times It wanted to die,, or did die.

Sorry for the long post, I just wanted to explain my problem in detail.


-Mike

 

[1946Zephyr]

Re: Johnson 4.0 weird problem please help

If it acts like it wants to die, just tweek out the low speed adjustment 1/8 of a turn. That's it. No cause for alarm here. It sounds like you're in good shape

Welcome to iBoats, Mizzie

 

[Mizzie]

Re: Johnson 4.0 weird problem please help

Thanks for your reply!

I'll definetly try that,, theres only one knob on front.. would this be the low speed or high speed adj? (sorry for my mis knowlage) I used to rebuild 33-49cc engines but this is a tad differant.. I'd clean the carb and all but i'm not sure I want to mess with any of that on a type of engine i'm new with..

It just alarms me because it was fine yesterday it didn't do this... so would I still need to adjust the screw if it just started doing that today? It made me think yesterday I hurt something..

Question about the knob on the left.. the one that looks like a choke lever..

when you pull it out it squirts fuel into the carb correct? next to that same lever theres an left arrow that shows a gas pump and a right arrow that shows an Xed out gas pump emblem.. I assumed it was like a petcock but i can just turn it and turn it it doesn't seem to stop at any certain point... how should I be running this knob, and should it be pulled out mid way or in?

when it started to stall I pulled that knob out and the motor reved back up and took off again,, it's definetly weird! when i pulled the lever to squirt gas in it ran great again so i have no clue if the adjustment knob being off would run great then randomly crap out?

 

[Mizzie]

Re: Johnson 4.0 weird problem please help

also to add, it started making random rpm changes underway.. not major but you could hear it rev up a tad then go back down to normal rpm.. it does seem like a fuel delivery problem, it was smelling alot like gas,, maybe too much, or too little,, when it wanted to die if i pulled the lever it was fine again and it seemed to run better with the lever all the way out

also about the mixture.. sticker on the side near the fuel line adaptor says 100:1 so If my mixing is correct that should be 4oz of oil to every 3 gallons of gas? hope I did that right! haha

 

[Mizzie]

Re: Johnson 4.0 weird problem please help

Can anyone help? The lake is calling my name!

 

[JB]

Re: Johnson 4.0 weird problem please help

The 100:1 mix was withdrawn in favor of 50:1 Mizzie. Use only 50:1.

Sounds to me like you may have a fuel supply problem. Make sure the vent on your fuel tank is open and there are no air leaks in the fuel lines.

Good luck.

 

[Mizzie]

Re: Johnson 4.0 weird problem please help

Thanks for your reply.
well I'm glad I only ran the 100:1 for a couple hours all together hopefully I didn't scar anything! I just filled the 6gallon external tank with fresh 100:1 mix (8oz to 6gallon), so what would I do to up it to 50:1,, add another 8 0z, so next time add 16 oz to 6 gallons, this seem correct? I'm assuming this diluted fuel mixture will give me a little less performance than the other day right? I'm willing to sacrafice a little speed to maximize engine life!


I just bought the primer ball/fuel line from the tank to the motor it's brand new so i'm hopeing thats not the problem! now that you mention it.. when I pump the ball it wont get hard hard like it should be.. It will get firm and stay that way it doesn't soften up but it doesn't get it's full harness either.

can anyone reffer me to a diagram of fuel lines on these kind of motors, rather than pinpoint an airleak I rather just replace them all! i appreciate your help...

if anyone has a free minute can anyone comment on question about the choke lever set up, when I pull that out, its supposed to squirt fuel into the carb tube or is there a problem here? ive never seen a choke setup that also squirts gas.

thanks and sorry for the mess of questions i'm not on a computer alot and just trying to soak up as much info now as possible haha

-mike

 

[bonzoscott]

Re: Johnson 4.0 weird problem please help

I'm not familiar with your motor and choke thing, but what you described sounds like dirt getting into the carb. That has occurred with mine (9.9) and you have to make sure everything in fuel supply is spotless.

 

[Rick.]

Re: Johnson 4.0 weird problem please help

http://epc.brp.com/SiteMods/BRP_Public/BRP_Public_Login.aspx?ReturnUrl=/Index.aspx

Here is a site that will have all your parts diagrams. Sounds like a dirty carb.. When it tries to stall out pump your fuel bulb and see if that makes a difference. Best of luck. Rick.

 

[Vic.S]

Re: Johnson 4.0 weird problem please help

You don't say exactly which model you have. Model number would identify.

On front panel you have a knob which pulls to operate the choke and turns to turn on the fuel (from the integral tank ??) The choke is a strangler flap type not a pump type. Pull the knob out to start then return it as the engine warms up

If you have another knob , similar looking , which turns through a bit less than 1 turn then that is the slow running mixture adjustment. If the carb has been set correctly then that should be in the middle of its adjustment range and should not normally need altering.

If your running is improved by pulling the choke knob out then it suggests that the carb may require cleaning but the setting of the slow running mixture should be looked at first (see "How do I Adjust my Carbs" in TD's "Top Secret File" .

I dont think an air leak in the fuel line is the trouble, you would be able to overcome that by keeping pumping the ball, not by operating the choke.

You'll find diagrams ( not very good of some versions) in the parts catalog at http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

Some of the things you say makes me think your engine is a couple of years older than 1990. A 1990 model should not be marked 100:1 for a start. Only '85, 86 and 87 I think would have been so marked. Have you checked the model number for the year?

You are correct ... add another 8ozs of oil to the tank to make 100:1 into 50:1

The ball is probably only going firm ,not hard, because there is some air trapped in it. Point the outlet end skywards and you'll get rid of the air, not that it matters. Once running the ball should loose its firmness. If it tends to get sucked a bit squashed then look at the tank vent or for any restriction in fuel pick up

 

[Mizzie]

Re: Johnson 4.0 weird problem please help

Thanks for the replies guys very helpfull I appreciate it!

About the model info, I'll check that tonight after work i'll post a pic or two as well... The guy I bought it from said it's either an 89-90 and shyed more towards 1990.. (I'm sure he probably lied and my motors a few years older, it's not the first time i've been mis lead on a sale!) it does however run good besides this minor (hopefully minor to repair) problem.

I guess i'm going to have to deal with it though! My old 5.7 mercruiser was broken every other time I went out! haha got to love boats

-Mike

 

[kbait]

Re: Johnson 4.0 weird problem please help

Turn the knob counter-clockwise to open petcock to fuel tank. Pulling the knob primes carb throat, Make sure the knob is fully 'in' when running, as I've seen 'em flood out if not seated. There are some o-rings in that assembly that need to be good. I'd check on that before pulling carb. Get your model number, and go here for schematic/part numbers: http://epc.brp.com/SiteMods/BRP_Public/BRP_Public_Login.aspx?ReturnUrl=/Index.aspx

Good luck!