1984 Johnson 70 idles but won't go

Have a 1984 Johnson 70 hp. The boat has not been in the water for almost 7 years now and I decided to get it running again to do some fishing. I replaced the power pack in the electrical, polished/cleaned all (and yes I mean every single one) electrical points (ground and hot), took carbs off and cleaned them up nice and good like. Gave it fresh gas, and replaced two stroke oil (btw they are in separate containers, I believe it's called VRO or something like that)

Alas, after all the hard work she fired right up, a bit grumpy at first, but hey we all would be after 7 years right. Anyways, the darn thing was running like a clock. The thing will fire right up first thing and when you give it some throttle the response is awesome (this is all out of the water, hooked up to my hose).

Now this is where my problem lies. We put the boat in the lake before taking it out to sea. As we launch it we gave it enough time to warm up and all, and then we go to take off, hit the throttle and nothing happens...It will engage and you can putt around with it in gear but as soon as you apply any throttle what so ever it doesn't wanna go. The best way I can describe it is that when you give it some throttle it feels like it can't handle the load and kind of just bogs. But here is the funny thing, it doesn't just bog down and die, it just kinda keeps on bogging. Like it wants to go but something is restricting it. Almost like a dirt bike would if you try and ride it with the choke all the way open.

So then I took it back home, hooked it up to the hose. Fired it up, and gave it full throttle and with out any hesitation it takes off like any old two stroke would.

I was refereed to this website, because someone said you guys were "wizards" when it came to this sort of thing. So what would be causing the engine to do this only when in the water and pushing the boat?

Thank you for your time, and I will keep this updated with any advice that is given.

In the water there is a load on the motor and in the driveway there is no load.-------------The motor is not producing any power and something is wrong !!!-----------First thing, it is a big----- NO,NO------ to wind up a motor like that in the driveway, they were not engineered for that.Also that test proves absolutely NOTHING.-----------Mix your gas and oil at 50:1 untill you verify that the VRO is indeed working.-----------------------DO A COMPRESSION TEST ---------------DO A SPARK CHECK---- to make sure you have spark that will jump a gap of 7/16" or better at each plug.--------Did you remove the high speed jet in the bottom of the float bowl for inspection / cleaning,as that must be done to properly clean it ??.--------Does the primer bulb go hard when you use it to fill the carburetors ??

Applying full throttle, or any rpm over 1800 while on a flushette in gear or in neutral can very easily result in a runaway engine, the rpms continue to increase regardless of what you do. By the time you figure out how to stop the engine, connecting rods are flying out thru the side of the crankcase.

Start with the basics..... what are the compression readings of each cylinder?

With s/plugs removed.... spark should jump a 7/16" gap with a strong blue lightning like flame, a real SNAP! Does it?

Spark plugs should be Champion QL77JC4 plugs, gapped at either .030 or .040 . Are they?

Did you clean the high speed jets manually with a piece of single strand steel wire? If not do so.

Let us know what you find.

If and when the engine is sorted out --------------INSTALL A NEW WATERPUMP IMPELLER !!!

The spark on all 3 plug is excellent and working.
Primer bulb does get hard when the engine is running.
Compression is something that I might be able to check here in the next few days, have to find my compression gauge thing. But there is compression in all cylinders, I can tell you that much.

I talked to a buddy who owns a boat shop, and he also mentioned a high speed jet. I took every orifice in the carb out and hit it with carb cleaner and made sure they were clean. I am not sure which one is the high speed jet, but I will post a link/picture of the carbs that are on the engine and if someone could tell me what number the High speed jet is, that would help.

http://www.boatsnet/parts/search/BRP/JOHNSON/1984/J70ELCRD
984/CARBURETOR/parts.html

Let me know if the link doesn't work.

Thanks again.

The high speed jet has a 1/4x20 thread and is located in thr bottom center portion of the float chamber.... way in back of that drain screw/bolt.

joereeves said:

The high speed jet has a 1/4x20 thread and is located in thr bottom center portion of the float chamber.... way in back of that drain screw/bolt.

Click to expand...

If you mean #29 on the diagram I posted then yes all of those are nice and clean and free of debris.

Put the boat in the water and give it full throttle --------Than shine a strong flashlight into the carburetor bores.----------Compare the fuel coming up the main jet nozzles.---------------Put a timing light on the three plug wires and see if you have spark on all three.-------YOU NEED TO VERIFY PROPER COMPRESSION !!

Okay here is an update for the compression of the engine.

Cylinder 1(top): 147 (psi)
Cylinder 2 (middle): 145 (psi)
Cylinder 3 (bottom): 143 (psi)

Compression on all three cylinders is great and within range of each other.

Any other suggestions?

see post #8

Your diagram isn't showing up for some reason.

If you have proper spark and compression, and the carburetors are absolutely clean, possibly the timer base under the flywheel (spark advance) is sticking.

joereeves said:

Your diagram isn't showing up for some reason.

If you have proper spark and compression, and the carburetors are absolutely clean, possibly the timer base under the flywheel (spark advance) is sticking.

Click to expand...

Hmm...Well if you really wanna see what I am dealing with I will give you the website where I found the diagram.
Go to boats.net > go under Johnson outboard motors > year is 1984 > motor ID/Model # is J70ELCRD > the diagram is under CARBURETOR

If it were this timer base, how would I go about fixing that problem?

As far as post #8, next time i put it in the water (maybe this weekend) I will check the carbs and compare, maybe even post a video..... And the spark plugs are working, I have checked them in so many ways, all have a nice strong spark I know that for a fact.

I will take apart the carbs again this weekend and some other parts on the engine and give them a quick run around and make sure everything is all squared up, and get back to you guys. I am going to drop by my buddies boat shop tomorrow as well and see if he has any advice.

Once again thank you for the advice, and I will keep you posted.

If timer base is sticking, remove and clean it. Then apply a slight bit of grease to the timer base brass bearing and the related top portion of the powerhead, BUT use only oil on the nylon reaining ring. If any of the "L" clamps should be too tight, either bend them slightly or put a very thin washer under the tight one(s).

Checking the spark..... Are you simply using the spark plugs or are you checking to see the spark jump the 7/16" gap as we recommend above? The gap is important.

UPDATE:

Was tinkering around with the motor today and noticed that the top carburetor is shooting gas out of it, I shouldn't say shooting it is more of a light mist with an occasional small drop of gas every now and then. When I put my hand near the opening where the air filter normally is I can feel the light mist hitting my had, but it is not so heavy that my had starts to get wet and dripping with gas. After the engine has been running for several minutes you can notice gas start to pool at the bottom of the carb where there is a lip. Also when I give it some throttle the mist goes away, but this is probably due to the higher suction from the cylinder.

Now I checked the other two carbs and neither where misting gas like this. So I took the top carb off and gave it a glance and nice cleaning, and adjusted the float, but it is still misting this gas out of it.

I don't now if this is a bad thing, or if it is a sign to what is causing it to not run while in gear properly, or if it is normal. Just wanted to let you guys know.

Thanks again for the advice.

please let us know when you get a solution, i have the same problems on a 1985 50 hp

steve c said:

please let us know when you get a solution, i have the same problems on a 1985 50 hp

Click to expand...

Will do sir.

When you mean same problem are you talking about the motor not preforming when in the water and under the load of the boat, but will idle; I'm assuming?

yes, engine just boogs with throtle pushed foward, hit the electric choke and zoom boat takes off, rebuilt carbs with kits, idles great now, runs worse when i hit th throtle

On the 50 HP, there is still a problem in one of the carburetors.--Either not enough fuel in there or blockage somewhere.----------You must remove the highspeed jet from the bottom of the bowl to clean it !!---------------------Carefull if you keep running with carburetor problems as no fuel going in means no oil too.-------You have verified that it is running on both cylinders as they can often " run quite nice " on 1 only.

Thanks for the imformation. I have a freind with a 1978 70 hp with the exact same problem. I will relay the imformation to him , Thanks again

Update:

So I talked to a friend who is in the business of fixing boats.

I ran the engine with each spark plug out of one cylinder at a time, and the middle cylinder seemed to run the same when it was out, but the other two (when removed) just killed the engine.
But, I checked the spark when it was running on all cylinders and they all had spark still.

So, I am going to be checking the reed valves tomorrow and see if I can see any cracks or splits in them, but after that I run out of ideas....anyone?

i had to use a spark tester to get the proper blue spark at 7/16" and then i moved the pin out to 1/2" ..

UPDATE:

Okay so I checked out the reed valves today, and they all looked really good. One of the reed(s) had a small chip in the aluminum housing about the width of a small flat head screwdriver, but it was not deep at all (was barley letting light through when I looked through the other end, when I scratched it with my finger nail I couldn't really feel an edge that is how small it is. All the reeds looked brand new, only wear was around the edges where they rub against the aluminum housing, but wasn't much at all. I also replaced the gasket as it was hard as a rock.

I will be putting it all back together tomorrow. Gave the carbs a once over again. And hopefully be putting it in the water to give it a test run and see if anything changed. I might give the fuel pump a look tomorrow, if it is at all possible.

If it is still having problems I am at a loss of things to do! I have literally torn this thing apart on the top. Only thing left is the bottom, could something be jamming/clogging the lower unit causing it to not be able to run in gear?

If anyone is still reading this, I am still up to try just about anything you suggest.

Thanks

You say in one of your posts "hit the electric choke and zoom boat takes off".

Fuel is getting to the carburetor, fuel is not normally getting thru the carburetor, you're overlooking something within the carburetor(s).

Have not seen the result of " looking into the carburetor bores at full throttle with a STRONG flashlight "------------Believe it or not that is a very effective trouble shooting method.-------Takes little time and no money.-----------I see many posts where lots of money was spent on repair kits and new parts and next comment is " my motor still runs the same ! "

UPDATE:

Been a little busy lately with the golf clubs, but I got to putting the engine all back together today and fired her up! Still runs the same as far as what was good about it; still idles great, starts RIGHT up, runs strong.

Unfortunately when I dropped the engine in the water today still had the same problem, BUT! and this is a very big but, I noticed something. The primer bulb on the gas tank fuel line it soft and feels like there is no gas running trough there. Plus the little nipple that connects the gas tank to the fuel line is really not tight and doesn't seem like a good seal. So I investigated this! I put the motor in gear, went back and pressed hard on the nipple to give it a good seal and started to pump the bulb till it got nice and hard. Once it was nice and hard I went back and gave it full throttle and she took off! No sputter or bogging what so ever!

I will do a second test later today and see if I come up with the same results.

So should the bulb always be rock hard, or at least hard when the engine is running? Should I be looking at a new fuel line? Let me hear your thoughts...


P.S. I put a strong flash light through the carbs when it was open throttle and didn't see anything out of the ordinary, just gas spraying through the carbs...

Most people think that the bulb must stay " hard "---------------But that is a false assumption.-----------It does not stay hard , nor does it have to.

UPDATE:

Okay so I went to the marine shop and picked up a little fuel line connector that hooks on to the fuel tank, and replaced it with the one that wasn't working (~5 bucks). BTW, the oring was shot, all cracked and half was missing. Fired it up in the 1k gallon tank I have at home and it took off in gear!

I will be taking it out to the lake here in the next week or two just to see how she really performs, then off to the sound to catch me some salmon!

Now all that is left is to get that old kicker we have going.

Thanks again to everyone who has helped me out!

Hey guys, been doing some fishing lately in the boat. The idle seems to be a little low. Would increasing the idle speed be a screw on each carb, or something easy as just making the whole throttle linkage move forward by a screw or something? Which would be best way to go about this?

Just one screw on the idle stop !

about half way through this form i chimed in about having the same problem on a 1985 50hp johnson, problem being, runs good on hose but boogs in water execpt when i hit the chock it would took off, so i rebuilt the carbs(probably was a clogged jet to start with) and it ran even better on the hose but worse in water, well long story short - i had 1 float upside down! had some help from an old retired outboard tech, in fact he called it over the phone as a clogged high speed jet or backwards float