77 Johnson 115 won't hole shot without choke

[NickMcCabe]

Re: 77 Johnson 115 won't hole shot without choke

I'd be at the dealer pointing the finger at them. If they tuned it up definitely shouldn't be having those problems...

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Thanks for checking in Nick. I have not yet decided if I want to let them have another go on it. It is apparently a Frankenmotor that I bought from a rebuild shop and was apparently assembled using parts of different motors/years, but man, it ran awesome for years. Always had a leaky nature which initially I was told is what Johnsons do, but I thought maybe time for a carb rebuild and it was due for new control cables. Took a chance. What is really strange is it starts up and revs like mad, but then in the water, behaves totally different. It will still start up easy and rev up, but then sneezy, and sputters and no real power unless I give it the choke button.. Very frustrating.


Oh yeah, I forgot to say I did my compression test on a cold engine. I guess its been sitting a couple weeks now and I completely forgot to start it up and warm it up first. I just pulled the plugs and checked compression. Would they test up a little better then if its was warmed up or am I good with 125psi cold??? Thanks, Greg

 

[emdsapmgr]

Re: 77 Johnson 115 won't hole shot without choke

The 125 compression is very good. Likely the original compression was slightly higher, over 130+. Still-your compression numbers are solid and indicate the powerhead is worth investing some additional effort/money into it.

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

The 125 compression is very good. Likely the original compression was slightly higher, over 130+. Still-your compression numbers are solid and indicate the powerhead is worth investing some additional effort/money into it.

Thanks for the encouragment. I feel like it is still a good motor too, just have to chase down the reason it's not giving me full power.

I do have a better idea now after all the input from here that at least my fuel pump can be ruled out as possible cause. Just need to sort out why its not getting proper fuel. Maybe the floats aren't at the right heights, or jets have blockages. The dealer did tell me they didn't change the jets, just cleaned them. I seriously doubt that the jets were even removed from the carbs and likley just cleaned with compressed air... maybe. I also think it could simply be that the carbs are old and the throttle shafts are worn out. I have put some heavy grease around the throttle shafts to check this theory. It is likley something simple and just not readily apparent. If I find a vacuum hose has pulled off, I will be happy, but my luck is not that good. I need to pull the carbs back off and go through them again and really make sure there is no debris in them that could be causing this, but it would seem that if they were clogged that maybe just one or two throats would be having trouble, not all four and it is so weird that the motor totally wakes up when I press the choke button. So, pinched fuel line? Maybe, that is it if the fuel lines got replaced with non factory lines and there are a couple of decent bends right there at the filter and pump. Maybe a fuel line is pinched. But that doesn't seem right if the primer bulb pumps easy enough. Bad primer bulb be the culprit? It was replaced too??? Have to figure out why its acting like its not getting the fuel delivery..

Thanks for all the help, I appreciate it. I will get this figured out.
Any more thoughts or reccomendations, please let me know.

Greg

 

[fireman57]

Re: 77 Johnson 115 won't hole shot without choke

Hitting the choke/primer is definitely fuel related. Put anything electrical out of your mind. Had to be in the carbs.

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Yes, this is what I am thinking. Maybe the floats are not at the correct heights. I do remember when I pulled the carbs off a while back, the bowls seemed to have good mount of gas in them, but I did not really measure it. I did not ask if the floats or needle and seats were replaced during carb rebuild. In my mind, I'm thinking when you pay the dealer to rebuild your cabs, they rebuild them, not just put in a couple of gaskets and spray some carb cleaner and use a air hose on them. That was likely all they needed, but somehow something got out of adjustment.
If I can ever get some time to pull them back off and take a caliper reading and get the jet sizes, maybe it is just a matter of float adjustment. Probably find that the throttle shafts are worn a little too and I'd bet I'm getting a little vacuum leak there as well. Thanks for your thoughts

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Well, the grease around the throttle shafts seems to be helping to keep it from sneezing and sputtering. The idle is smoother too, but it did nothing for the hole shot or top end.
It's Labor Day Weekend and we have been out running it around the bays. Not going to take it apart until later and take measurements or jet readings. Plus, this summer has been wet, seems like it has rained every day off I've had, just haven't gotten a dry day for weeks.
I did pull the fuel pump cover off and looked at the screen. Screen was clean. I am going to replace the fuel filter just to see. Would not be the first time I have installed a new part only to find it defective. Put new shocks on the truck last month and one was bad. That was a crazy ride, but easy to figure out. LOL

So far, here is my theory. Older than dirt motor and mis matched carbs from a newer motor that was put together by an old guy who really new what worked. When I had the dealer rebuild the carbs, they cleaned them so well, it removed beneficial "varnish" or sealing greases around the throttle shafts and butterfly's. I'm guessing the if the throttle shafts need re-bushing, then the butterfly's and throttle bores need to be re-honed and next oversized butterfly's installed???? Need to find a good shop that can actually rebuild the carbs or at least pull the shafts and install bronze bushings and hone to fit. Sound logical or unlikely this is what's causing the motor to not hole shot or reach top RPM without being choked?? Thanks for any input.. Regards, Greg

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Clymer Manual Chapter 5, Link and Sync. I just can't wrap my brain around what to do or what order. The manual goes on about too many different motors. See if I can find a good step by step someplace to help the manual make better sense for my V4-115

 

[fireman57]

Re: 77 Johnson 115 won't hole shot without choke

You can find link n sync on here. Just do a search. I put a fuel filter on my 48 special and lost top end because it couldn't get enough fuel. Try removing it once and see what happens.

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Do you mean the fuel filter on the engine? I didn't think to disconnect it. I just had it replaced when they did the tune up/down. I had a fuel separator that I took off, but it made no difference.

I will try a new fuel filter. Maybe the one they put on got clogged or is otherwise faulty. Worth a try.

Talked to a local guy the other day. He suggested I just see if the throttle plates are opening all the way at full throttle. I was telling him about the new control cables they put on it and he said it is possible that there is nothing wrong with any of it, just needs a good link and sync or at least make sure the carbs are opening up all the way.
Thanks for the input

 

[phillnjack2]

Re: 77 Johnson 115 won't hole shot without choke

now before anyone gets carried away about changing spark plugs on the v4's.
these engines came from factory with surface gap plugs (no electrode sticking out) these plugs were mainly for high speed reliability
and OMC only ever advised to use the "normal type plug if doing a lot of slow speed/idling.

When this engine was made is was considered as mainly for high performance usage only.
None of the early engines were ever designed to run or be run for long periods at slow speeds, every OMC had a sticker advising
the owner / operator that 4500-5500 was optimum to for the engines use.

the only plugs to steer clear of are NGK as they do NOT do a proper plug for these engine that correctly cross matches the original
Champion plugs.
That answer is what I got from NGK advice line when asking the question on the phone !!!!!!!!!!!
they do plugs that are "SIMILAR" but not a exact cross reference !!!!!!
surface gap is definitely the best way to go with the older v4 engines.

Yes the carbs have been updated, but that should not be a problem, the problem is that the engine is sucking in air, and that's probably bad gasket from carb to inlet manifold or 1 of the tiny pipes has come adrift from the choke solenoid !!!.

looks perfectly natural to be a 1977 engine, its not before 1974 and not after 1980.
the lid is from a 70's engine not 60's.

125 psi compression is very good for these engine too, they were not the high comp engines like the 140hp of same time.
BUT if you find a normal plug hits the piston !! then this could of had high comp heads put on at some time to give the engine more power.
just because it says its 115 on the lid means nothing, it could be a souped up 90 souped-up 115 or even a hot rod 125 now ?
without knowing whats been done to it youl never know unless it gets stripped right down.

I would be looking for that air leak big time, start at the manifold and work forward, it has to be a bad gasket or pipe off.


phill

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Hi Phil,
Thank you sir for that info. I appreciate the time it took to write it all out. Great info!!

Well, finally got time, it was a clear dry and sunny afternoon, had the boat in front of me, no sweety wanting to go out to dinner, so off came the carbs again.
Took a few pics, wrote down some jet numbers. Maybe I will get lucky and stumble over what's causing my little motor to behave badly. This motor on my 15 foot boat would stand it on the transom and be at full speed once the bow settled, usually it took all of two or three boat lengths.

Still could not find what is causing the crap performance, gaskets looked good, no nicks or debris smashed into them. Looks like the carbs have 1 and 3/16 bores on them which is what the micrometer was showing as well. The idle jets are 36's, and the mains are 260's. A regular Craftsman multi driver is perfect size driver to get the jets out.

So, took a few pics, blasted ever orifice with cleaner. Tried to get a visual on spray patterns through the various openings and jets. I couldn't tell that there was any difference between the same openings of either carb. Made sure the upper passages were clean. I think this is what was talked about and mine were spotless, see the pics and let me know if I did right or not.... Basically, put it all back together again. I did change out one of the choke solenoid fuel lines since it is easier to get to the bottom carb once the top one is off.
Kind of late tonite to fire it up, so tomorrow will have to wait and see. I'm getting it wet first light.

There is a vacuum (pulse line) line coming off the base of block and goes to the fuel pump. I can't tell if it was not replaced or not and I know I have not replaced it. For that matter, it's a tight squeeze to get my finger underneath the block to feel where it stopped. Within a fingers length, so that should be doable some how. I am thinking if it is still running like poop in the morning, this is my vacuum leak and I have to figure out a way to get underneath between the block and case to pull that hose off and push on a new one..
Thank you all for the help and info, it is much appreciated.
Greg

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

A few more pics. Only seems to let me upload 5 at a time. These are just the lower carb and I was trying to show how the float sits against the needle valve.

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Alright!!

Must have done something right. Maybe the bolt that holds on the starter was causing a air leak as I found it had vibrated loose. Possible something (trash or something, I don't know) was in the carbs and got blown out for sure this time.
I did notice that I had a little adjustment to make to the linkage, so it would line up the little roller between the two marks again. Must have gotten it out when I took the cables off again to pull the carbs??
I really have no idea what I did right this time. Seems like the third time is the charm.

Today she is a running little machine.. Yeah baby! I mean, hole shot even with my back up prop which is a bit more pitch, like a 17 instead of the 15 I had before. Top end, back to keeping up with traffic over that bridge, so around 50MPH+/- Everyone speeds across that bridge at 60mph on average and it is a 45mph bridge.

Thank you everyone. I mean it, really appreciate all the encouragement and suggestions. Right or wrong, they kept me at it and that is what it took. Like my old auto shop teacher always told me "you haven't learned all there is to know about that carb yet"..

Many thanks guys... Cheers!!

Greg B.

 

[fireman57]

Re: 77 Johnson 115 won't hole shot without choke

Glad to hear it. I love it when someone says they have cleaned the carbs three times. Now you know what it really means to clean one. Enjoy what's left of the season.

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Ha ha, yeah, thanks. I don't know if it was cleaning them again or... I never saw any evidence of blockage while blasting cleaning spray through it all again. Probably something may have made it past the filter.

I believe it was a combination of issues such as the lower carb choke solenoid supply tube had not been replaced. You can see I had to use Tygon tubing as I had leftover from rebuilding my line trimmer.

There was a bolt that holds the starter onto the case that was loose, very loose and may have been a vacuum leak there if the hole goes all the way through the block. Not sure. I will pull it off and put a drop of locktight on it.

The throttle linkage was off a little once I got it back together. Had not noticed it before, may or may not not have been out of specs before. I did have the new control cables installed, so who knows at this point. I do not write it all down and did not take very many photos of before and after which would have been more helpful.
I went back and looked at those earlier photos, but could not really tell.

The carbs were clean as I was shooting the latest photos of them while I took them off and pulled em apart again. You can see the bearing grease I had previously put on the throttle shafts thinking they might be worn out causing a vacuum leak
It seems that between the last two times and this time, I replaced the solenoid choke supply tube and re-adjusted the linkage, and tightened one bolt on the block. Linkage and that choke fuel tubing seem the most likely reasons for the poor performance.
Although that old tube was on good, it was pretty stiff and should have been replaced sooner. I blew through it underwater and could not see any bubbles... Kind of goes back to the linkage being slightly off.
Would that have caused the timing to be off? I had previoulsy watched the throttles plates and they went from completely closed to perfectly open at full throttle. Seems like the timing must not have been advancing due to the linkage being off the mark. Amazing if that is it, how much of an improvement a little tiny adjustment made.

Well, hopefully if someone else ever has the same issue and they read through this. Maybe it will help them get it sorted out.

My 1977 Johnson 115hp with 1983ish carbs is still running strong. We took it out last weekend and found it is also doing much better again on fuel economy. Really can't run it flat out for too long, just too fast unless it is super glassy or just a little small chop (15 ft boat). Have to throttle it back to about 3/4, but then when you push it down again the boat just moves out and pushes you back in the seat. What a great feeling!

Don't give up, keep at it.

Thanks again for all the help.

 

[fireman57]

Re: 77 Johnson 115 won't hole shot without choke

It is crazy how everything needs to be set right. When these things are on they are a thing of beauty and power, when they are off they are the ugly pita mother in law. Enjoy.

 

[JRegier]

Re: 77 Johnson 115 won't hole shot without choke

Wow, glad to hear you got it.
Just thought I'd chime in, it's been a while since I checked my carb throat sizes on my 1970 115 but I'm pretty sure my calliper read 1.53"

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

It is crazy how everything needs to be set right. When these things are on they are a thing of beauty and power, when they are off they are the ugly pita mother in law. Enjoy.

Thanks fireman!
I am stoked at how well it's running again. I may tweek it a bit more. Not that it needs it, just see if it makes any difference. I'd like to get a tach on it too.

It has that awesome Growl Sound again when taking off. Full speed is loud, but throttle back to 3/4 and it is quiet and still hauling. Back to being a Fish n Ski Boat.

Thanks, Greg

 

[Greg Boswell]

Re: 77 Johnson 115 won't hole shot without choke

Wow, glad to hear you got it.
Just thought I'd chime in, it's been a while since I checked my carb throat sizes on my 1970 115 but I'm pretty sure my calliper read 1.53"

Thanks
I can not say for sure, but you probably have an original 115HP motor. Mine was rebuilt by an old timer who knew what worked and put it together with what he had at the time. Likely, since it looked just like the 85HP in the shop that was sitting next to it at the time, that is all it is. Just an 85hp with a 115 sticker on the cowl. Still, it goes pretty good for a 115hp and really really good for an 85hp LOL.

Thanks for checking in

Greg