Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

[imported_airxsteel]

HELP


Ok, big problem today on the water.

You know it is going to be a bad day on the water when you forget the boat key...

So after I get the boat key....from my wife .....who brings it to me at the lake.....

I get in and start it up. Well as soon as it turns over, it starts up and acts like I have the throttle all the down. So it revs up all the way as if I got the hammer down on it. I quickly shut it off, then try it again. Same result.

Ok, now last time I went to the lake, which was last week. I had no problems.

Here are the things that did change:

1. I put on a new SS prop.
2. The throttle tension knob on the control box unscrewed and fell off. It worked however that day last week and I didn't think nothing about it since it was working ok.

I don't think the prop had anything to do with it , since all that had to deal with was the lower unit.

I think the throttle is stuck somehow and it isn't letting me throttle down the engine. I tried to see if it was stuck under the hood somehow, so I lifted it and made sure that it could move (shift cables to throttle) and they were moving back and forth ok, not stuck.

I then tried to move the throttle back and forth at the control box, and I could see the cable moving the throttle at the motor.

So if it is stuck some kind of way, I don't have a clue why or how.

Any advice on this would be much appreciated. Talk about a bad day fishing.

79 Johnson 140 HP

 

[F_R]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

You will want to read the recent thread titled Runaway Revs J48ESLEDC. It's on page 2 now.

DO NOT START your motor till you see if you have a similar problem. His motor was in the process of swallowing a screw. If it had gone on into the innards, it would have been good-by powerhead.

 

[tashasdaddy]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

click here for the thread

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=28;gtid=1213161

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

HOLY CRAP !! That sounds scary. I am hoping it isn't that serious. :%

I will do what those post had mentioned and see if I can see if anything is making it stick wide open or not.

Thanks, I will repost when I find something out.

 

[Joe Reeves]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Remove the carburetor face plate so you can look at the throttle butterflies. At a idle setting, they should be closed (all).

Notice that the throttle butterflies are operated by the nylon roller attached to one carburetor (linking to the other carb), and sliding against a cam. Something in this view should reveal the problem. Let us know what you find.

 

[rodbolt]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

ya dont even have to remove the face plate.
while having an assistant move the throttle to WOT observe the roll pins on the side of the throttle shaft. then throttle back to the idle position. do this with the engine off. you should observe about 80* of arc.
then look at the linkage from the timer base to the throttle arm that drives the accelerator cam.
make sure the ball clip is not broken and the timer base rotates about 20* between idle and WOT.
its amazing how many no load RPM's you can get if the timer hangs wide open.
the timer arm is the little thingy under the flywheel on the stbd side.
Ill get real technical with a whatcamacallit soon.

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Thanks everyone for your input. I did what Joe Reeves mentioned and took off the carb plate.

Sure enough it was trying to eat a screw. It was one of the four screws that holds the carb plate to the carbs.

I did some surgery and extracted it with a long pair of needle nose. The throttle was open with the bolt there.
Once I removed it, it would close properly. I looked for any other parts in there, none that I could see. I cranked it up and it ran fine. Although it isn't real tight against the carbs, I am thinking that is how I am losing a little bit of fuel. If it isn't all the way flush against the carb plate, then fuel can escape there I suppose.

Now here is the big question:

How in the world does something like that get unscrewed?

I tried putting the screw back in , but guess what, there were no more threads left in the hole where the screw was at. (Guess that is why it came out huh?)

So what do I do now, have someone rethread the hole? Helicoil?
What can I do with this or should I have a mechanic redrill the hole or have a new plate put on?

 

[Joe Reeves]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Apparently someone removed the screws to the throttle plates, then when re-installing them cross threaded the one you speak of. I don't know what anyone would do that but that's my thought.

Don't attempt to re-thread it with a larger thread/screw as that would probably just weaken the throttle shaft.

I'd suggest that an attempted fix would be to use a aluminum rivet of the proper size and length such as the ones included with a hand held pop rivet tool. For such a one time use, if you do not have that tool, check with your friends first.

The second, and proper fix is to purchase a new throttle shaft for whichever carburetor is involved along with a half dozen screws or so, install the screws using loc-tite, then with a fine chisel tap the threaded end of the screws so that a "x" is indented to really lock them in place. Brace the head of the screw when tapping with the chisel to avoid bending the shaft.

Let us know how you make out.

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

I think I am confussed on the terminology and the parts.

The throttle shaft , is that on the carb itself? I wish I could put a picture on here to show you.

If you go to the BRP catalog and look under my engine model number, under INTAKE MANIFOLD.

JOHNSON > 1979 > 140 HP > 140TXL79R 1979 > INTAKE MANIFOLD

The "BASE , Air Silencer" is the part that has the hole where the screw is stripped out of. It is part number 0322985 or number 28 in the diagram. The screw is number 14 in there.

The air silencer cover fits on to this piece. All of the other bolts are ok.

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

I think I am confussed on the terminology and the parts.

The throttle shaft , is that on the carb itself? I wish I could put a picture on here to show you.

If you go to the BRP catalog and look under my engine model number, under INTAKE MANIFOLD.

JOHNSON > 1979 > 140 HP > 140TXL79R 1979 > INTAKE MANIFOLD

The "BASE , Air Silencer" is the part that has the hole where the screw is stripped out of. It is part number 0322985 or number 28 in the diagram. The screw is number 14 in there.

The air silencer cover fits on to this piece. All of the other bolts are ok.

[attachment]

 

[tashasdaddy]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

posting pictures, when you get to the bow in the upper left, backspace the line then hit ctrl v

http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=37;gtid=1179789

 

[Joe Reeves]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

I didn't go to that site but rather checked my books. Sorry to say that I wasn't aware that the throttle shaft itself in the 1979 model couldn't still be purchased.

I looked back to the 1977 model and it (the shaft) could be purchased seperately but unfortunately it is different in design. The throttle shaft is the shaft that the throttle butterflies attach to with those small screws you speak of.

All I can suggest at the moment is to check with the various dealerships and other outboard repair shops to see if they might have a good used carburetor as a whole component or for parts.

If you want to take the time to collect all the numbers you can find on that carburetor, relating where there are on the carburetor, along with the measurements of the throat diameter (front, back, and inside), and email that info to me (address below), I'll check with what I have left in my remaining stock (new and used). a picture of the carb would be helpful also.

 

[ezeke]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Airxsteel, If you look at the ears on the carb face that the air silencer base plate bolts to, you cans see that the ear is not very thick and that it has litlle extra surface to tap.

I don't think that a heli-coil is a good idea there because of that but tapping up one size for the bolt is practical. If you have a good machine shop nearby, that should be a very simple job. If you do it youself, work your tap back and forth slowly so that you don't crack the ear.

Good luck.

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

http://www1.snapfish.com/slideshow/...ID=2708078876/a=56327208_56327208/t_=56327208

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

http://www1.snapfish.com/slideshow/...ID=2708078876/a=56327208_56327208/t_=56327208

That just sucked. Can't really see it in that pic

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Ok, finally got some pics of this. If you guys can even remember my postings.

here is a pic showing the screw and the location of it or the lack of it. There is no bolt there, just where the threads use to be.

 

[iwombat]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Looks like there's enough meat in the flange to set in a heli-coil. You've got a few other options though.

1) Permatex thread repair - an epoxy treatment for stripped threads. Sometimes it does a great job othertimes notsomuch.

2) Aluminum brazing rods and set a steel bolt in place while it's all still liquid. The steel won't bond with the brazing material. That'd be my choice, but ya gotta have the right brazing rods as well a fully disassembled carb (no plastic melty bits).

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

thanks iwombat. That may be a job for a shop right there. I get nervous just looking at this motor, better be safe and let someone know what the heck they are doing mess with it. Sounds like solid advice though.

 

[mikesea]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

is there room to sneak a nut back there,i recall the threads to be 1/4 20.you could grind a nut to fit baack there possibly,if 1/4 20 is to big you might be able to use a smaller nut and bolt with a large washer inside,that would be a quick fix,i know there are lots of those carbs around in old outboard shops,might could get one used and be a ease doin it right,when you put those bolts back in,use lock tight,that is a common problem with crossflow engines that dont use locktite after removing and reinstalling,they had loctite from factory

 

[imported_airxsteel]

Re: Engine is full throttle when starting....HELP!!! 79 Johnson 140 HP

Someone else mentioned that as an option too. I work with a guy that is a gear head and he mentioned doing the exact same thing. So loctite should be used on the new bolt then? Is that the putty type stuff you knead with your hand and apply it around the bolt ?