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Author Topic:   1985 Johnson 70hp sluggish
billmontauk posted 11-28-2003 07:29 PM ET (US)   Profile for billmontauk  
First time doing outboard maintenance....Engine was sluggish plugs were fouled I put to much oil in mixture Changed plugs and lower end fluid... Wanted to spray carbs for carbon build up..How do I get to them do I unscrew the black plate in front of engine. Thanks Bill
whalersman posted 11-28-2003 07:52 PM ET (US)     Profile for whalersman  Send Email to whalersman     

There are two ways that I know of that you can accomplish this...

1. Remove the Air Cleaner in front of the Carbs. (what you call the black plate). You will then have access to the carbs.

2. Install a quick connect Valve that replaces your manual primer valve. This unit cost was $5.00 and is very easy to install. This new unit has a screw on type valve (just like a tire valve stem) that allows you to connect things to it like foggers, decarbonizers, etc.... The Bombardier part number is 175158 for the 150hp engine. I believe it is the same for the 70hp but check with your dealer to make sure. The name on the package is "ADPTR KIT/VALVE".

Good Luck,

BugsyG posted 11-29-2003 07:00 AM ET (US)     Profile for BugsyG  Send Email to BugsyG     
Hi Bill,

I have a 1984 70hp. Johnny. Originally when I bought the boat, the engine would go up to 1800 RPM's and cut out. So for an additional $1,800, I had the engine rebuilt.

It ran good the first year, now this year I did have trouble starting it, it was the plugs my plugs are L77JC4's.

Then I replaced my fuel filter (the round disc). Perhaps your problem lies in the fuel filter.

However, there is 1 more problem with the engine that I have. I have an electric choke on the ignition. I soon realized that when I would turn the ignition over, and push it in, there would be no more "click". The "click" would signify that the choke is being activated. No click.

So what I ended up doing, I would take the cowel off and flick the little red switch on the side to let fuel in. It would release some sort of pressure. I have no idea where because my fuel line is replaced and no dry rot. So after releasing the pressure, I would put it back in the original position and it would fire. Once shes up and running, its fine.

But for you, I think its the fuel filter. Check it periodically, but it shouldn't act sluggish.


whalersman posted 11-29-2003 01:26 PM ET (US)     Profile for whalersman  Send Email to whalersman     

That little Red Lever you are turning is the Manual Primer Valve.. If you are getting pressur in there, you may have a clogged primer hose. This is the Red Valve I am referring to in the above post that could be replaced with the newer version that has the orifice for hooking up Foggers and Decarbonizers, etc....

The primer hose is a small black hose that is routed to the very top of the engine and plugs in somewhere above and behind the upper carburetor..

Remove the hose from its' fitting there and then use your Push to Choke switch and see if fuel comes out.. If you don't get any clicking sound like you mention, then there could be something wrong with your switch, the wiring, or your rectifier. If it is clicking and but fuel is not coming out of the hose, then something is blocking the hose and you will have to take the hose off and clean it out..

I know the rectifier I mentioned above may sound funny to many people. Well, it happened to me... I could not get my engine started using the Push to Choke, I had to go back and manually flip the switch until it started and then flip the switch after it started. This was going on for several weeks and then my Tach started acting up.. I replaced the rectifier and everything started working fine again... Go figure....


BugsyG posted 11-29-2003 02:26 PM ET (US)     Profile for BugsyG  Send Email to BugsyG     
Hi Whalersman (Joe),

About a month-and-a-half ago, I had my switch tested with a meter to see if power was brought to it. There was power to the switch but no go.

I really didn't want to experiment around with it. I am going to take the boat to a guy up here in the spring to get it looked at.

This all started to happen when I changed my spark plugs and fuel filter. I got them changed and my choke wouldn't work. Its a bit of a hassle with that switch.

Thank you for the information by the way. No one has provided me with that much information before about it. Thank you!

JAZZ -- I will keep experimenting around with it.

frank_king posted 11-29-2003 09:01 PM ET (US)     Profile for frank_king  Send Email to frank_king     
the "pressure" that you are hearing is fuel going into the front of the engine. as you pump the bulb up you have infact created a small amount of fuel "pressure" in the hose.

as you flip the valve fuel is going into the front of the engine for ease of starting.


Sal DiMercurio posted 11-29-2003 09:34 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
That little red switch isn't a preasure reliefe valve, it puts fuel right into the cylinders & your engine should fire right now after you do that.
To decarbon your engine just take the carb covers off , start the engine & let it run at idle or just a "bit" more, not to fast of the cabon remove wont have a chance to settle in the cylinder.
While at idle, spray a good slug of Engine Tuner [ from Bombardier ] or Sea Foam [ most good auto parts houses ] into each carb, the engine will bog down but don't let it choke itself out until you have put at least 1/2 of the can into the carbs, then flood the engine out with Engine Tuner or Sea Foam & remove the spark plugs & spray the rest of the solution into the cylinders, then turn the engine over "BY HAND" not with the starter a couple turns &* let it sit over night or a couple hours.
Then turn the engine over by hand again trying to get most of the solution out of the cylinders, put the plugs back in & start the engine & let it idle for about 15/20 minutes.
You will thinkyou ruined the engine & your neighbors will most likely call the fire depart because there will be more smoke then you have ever imagined but that just the crud & solution burning off.
Take the boat for a ride on the water, [ not on the hose ] & just take a nice easy run for about 15 minutes, remove the plugs because they will be filthy & replace with new plugs gapped at .030 ...30/1000.
All omc Bomb engines take 30/1000 gap.
Do this every 50/75 hours, [ no longer ] & your engine will be very happy & so will you.... & so will your wallet.
"NEVER" run your engine faster then 2,000 rpms while on the muffs or in neutral at "ANY" time.
Thes engines are designed to run under a load, such as in gear, not high rpms in neutral.
If you use Sea Foam, it dosen't come in a preasurized can & must be sprayed into the carbs & engine with a hand spray bottle or buy "Deep Creep " which is the same as Sea Foam but in a preasurized can but 4 oz less in the can & the same price as the 16 oz can of Sea Foam.
The way these solutions work is, the solution turns the hardened carbon into liquid & then burns it off with the cleaner, you wont see chunks of carbon coming out of the exhaust, but "LOTS & LOTS & LOTS " of smoke.
Thats absolutly the best treatment [ maintenance ] you can do for your engine to keep it running like new & keeping it from an early death.
simonmeridew posted 11-30-2003 07:23 AM ET (US)     Profile for simonmeridew  Send Email to simonmeridew     
That's absolutely the best directions I've seen for using the Sea Foam stuff. I did a search last week for Sea Foam and found bits and pieces of instructions but for once I think I get the whole picture.
BugsyG posted 11-30-2003 08:12 AM ET (US)     Profile for BugsyG  Send Email to BugsyG     
Hi Sal & Frank,

Okay, here is the procedure of how I start my engine:
1.) Since the choke isn't working, I pump the primer bulb a few times (The primer bulb doesn't get firm, so I don't know what is wrong since it is a brand new hose and it is on right too.)

2.) Crank it over just to make sure that fuel is getting in there (won't start.)

3.) Uncover the engine cowel, flick the red switch. Releases pressure, then I put the switch back to where it originally is.

4.) Crank the engine over, sputters and shuts down.

5) I repeat steps 3 & 4 until it starts and runs.

I am probably going to have the boat and engine taken in for service in the spring to have it professionally looked at and fixed. But thank you for your time and posting.


billmontauk posted 12-01-2003 09:19 AM ET (US)     Profile for billmontauk    
Well I changed plugs still runs at 1700 rpm...After a while at this speed I can get it to open up.... Once she is opened up I was able to run as long as I want and ajust rpm's but as soon as I went to neutral and tried to open up again she would bogg down and only run 1700 again.... Do you think this is do to too much oil in mixture and if so should I remove and put in fresh gas mixture
Bigshot posted 12-01-2003 02:54 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Nothing to do with mixture. Have you run a compression test on it? Sounds like a cyl is not working either due to low compression, gunked car, coil or other malfunctioning or a bad fuel pump(where I would start). To eliminate a fuel issue have someone(sitting down) pump the fule bulb when you can;t get over 1700. If she comes to life your fuel pump diaphram is shot.
rsgwynn1 posted 12-01-2003 08:25 PM ET (US)     Profile for rsgwynn1  Send Email to rsgwynn1     
I agree with Bigshot. Sounds like the fuel pump will only pull enough fuel at high rpm's. Replacing it (or the diaphragm) is simple.
Sal DiMercurio posted 12-01-2003 08:48 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
It could be any number of things.
A sick power pack will do the same thing.
Better have a tech check it out, because it will cost you more to relace a power pack, fuel pump, coils & all the rest of the things that can go wrong & you still may not hit the right one.
billmontauk posted 12-02-2003 07:53 AM ET (US)     Profile for billmontauk    
Thanks for all your suggestions on why she is running sluggish, She is all winterized and wrapped up now, but I think I will try to solve the problem myself this spring. I just brought this rig so I have no service records for this 1985 Johnson 70hp engine, so to be on the safe side I am going to change the powerpack and the fuel pump and fuel filter and plugs I am also going to empty the gas tank and put in fresh gas & oil mixture....that should cover it all...Wish me luck
Bigshot posted 12-02-2003 11:57 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Skip the power pack for now, I highly doubt it until you exhaust the other issues.

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