1976 johnson 85 misses at high rpm

[billgrob]

i have a 1976 johnson 85 that needs some help. the first time i had the boat out this season the engine quit while i was about half throttle. it shut off like i turned the key off. then i could not restart the boat because the battery had completly drained. i bought a new battery and the engine would crank but was getting no spark on any cylinders.

so next i changed out the power pack with a used one. the engine would then run fine until almost full throttle, then it started missing. its like it would try to open up then fall back about 1000 rpm and stay there even with the throttle pushed all the way forward. it would then try to open up then fall back on the rpm. so i went back to the dock to try spraying some carb cleaner in the carbs. when i tried to restart there was once again no spark to any of the cylinders.

so i then changed the stator and rebuilt the carbs. i got the engine running again and took it out yesterday but it still does the same thing. it wont open up when full throttle. please help.

 

[tashasdaddy]

Re: 1976 johnson 85 misses at high rpm

check compression, spark, and fuel flow. coils could be breaking down when heated and failing. fuel pump may be weak. vent clogged on fuel tank. high speed jets in carb could be partially clogged, low compression when warm. time to start trouble shooting. electrical testing: several pages here, find your engine http://www.boatpartstore.com/page30.asp

 

[ezeke]

Re: 1976 johnson 85 misses at high rpm

Couple of other things you might want to check: One is to look down the carburetor throats with the control lever fully forward, and make sure that the throttle plates are wide open or horizontal; the other is that one or more of the high speed jets may be fouled. The are at the very bottom of the float bowls behind the drain plugs, where they easily pick up gum and debris.

BTW, The fact that you can start the motor at all, and that it will run all right at low speed, indicates a problem with linkage and synchronization.

 

[billgrob]

Re: 1976 johnson 85 misses at high rpm

i had the boat out yesterday after replacing one of the coils. i still had the problem with one of the cylinders droping out near full throttle. i should have a new power pack to put on the boat sometime this week. im planing on ordering all new coils too... it was pointed out to me that all of them have cracks in the plastic casing.

 

[tschamp20]

Re: 1976 johnson 85 misses at high rpm

i too am having the same issue.new coils new stator. just ordered timerbase and powerpack if that dont fix it time for the dynamite.j/k
but seriously if you dont have the manual use the link above to test your sensor coil{timerbase}.super easy test!be sure to test for ohms on all four wires to ground,all should read zero or infinity.good luck!
DOUG

 

[tschamp20]

Re: 1976 johnson 85 misses at high rpm

btw,that link above is the best prices ive found for ignition parts excluding ebay.also try ishopmarine.com

 

[billgrob]

Re: 1976 johnson 85 misses at high rpm

the new power pack was the fix... had it out today and it ran excellent. i do however need to make some linkage adjustments still but im sure ill be able to search for that. thanks guys for the help

 

[kwilford]

Re: 1976 Johnson 85 misses at high rpm

Re: 1976 Johnson 85 misses at high rpm

I have a similar problem. I have a 1976 Johnson 85 HP, on a 16 foot Vanguard hull. I've had it since almost new and had very few problems in 32 years. For the last twenty years, it only gets used about three weeks a year, when I come in for my summer vacation. It is fairly well maintained, but it sits in a boat house almost 11 months between uses, which it is dry and I make sure that the gas is stabilized after every summer and engine storage spray is used at storage time.

Last year, it developed a full throttle "stumble" on acceleration, but only intermittently. It feels like one cylinder is cutting out, but it could also be fuel starvation I suppose. It happens mostly when pulling a skier, when coming out of the hole, but also when just accelerating from a stop at full throttle. It does NOT happen at 3/4 throttle or less.

When it happens, if I "feather" the throttle back to 3/4, it will sometimes recover and pull to almost max speed (sometimes I can give it full throttle once up to speed, but sometimes not). Other times it will pull fine, and run great. It's tough to pull a fat old guy like me out of the water with a 68 inch competition water ski and double bindings at 3/4 throttle, so I either need to fix it, lose some weight (not likely at fifty) or buy a new motor (tough to justify for three weeks a year).

The boat is at my cottage many hours away from where I live, and about a one hour drive to the closest "centre" (if you call Warroad MN a "centre"). As a result, my availability of tools and diagnostic equipment is somewhat limited.

Things I have done so far:
1) replaced all four plugs
2) replaced one coil pack, and then moved it around to all four cylinder positions looking for a defective coil
3) tried pumping the primer bulb during the hesitation: no effect
4) opened up the power pack and ensured it was dry, all wires secure, and no signs of cracking or melting
5) ran carb cleaner/"tuneup" in a tank of gas (I was hoping for "magic in a can")
6) replaced the fuel line, and cleaned the fuel filter

Things I have observed:
1) lots of water from the pump (although that is on my list of things to replace, as it has NEVER been done in 30 years!)
2) moving the coil packs didn't provide an immediate solution, but it does seem to stumble "less". But I couldn't tell if one particular coil was defective.

Things I am planning to do next:
1) replace the plugs again (cheap, and it wouldn't be the first time I found a new defective plug)
2) check the compression (I'll bring my tools from home when I get back in August) and the timing
3) use the timing light to diagnose which cylinder is cutting out, if is indeed one cylinder
4) buy a couple more coils and maybe a power pack

I haven't been able to find a fuel pump kit for this engine yet, but if I can I'll also rebuild or replace that. It seems that fuel pump kits are only available for the 1978 and newer 85 HP Johnsons, unless someone can steer me straight.

Taking this boat into a shop to repair is problematic as I only get in once or twice a year, and to have it sit in the shop would be quite frustrating while I am on vacation at the cottage. What I am saying is I am happy to spend a few $ to buy and replace parts if they might solve the problem. But the shop might have to happen if I can't get it running well enough to ski behind this summer.

Thanks in advance for your advice.

Keith

 

[ezeke]

Re: 1976 johnson 85 misses at high rpm

I would suspect debris in the float bowls has clogged or partly clogged the high speed orifices (a/k/a jets).

The fuel pump can be rebuilt, see: http://forums.iboats.com/showthread.php?t=240864. His pump has only two hose nipples compared to three on yours, but the inside is basically the same. The later pumps were mounted over a hole for pulse and yours got the pulse via a hose.

I found that Sierra kit 18-7800 had just about everthing I needed except a sealer. I found surface rust in some of the units that I looked at and that has to be dealt with.

 

[kwilford]

Re: 1976 johnson 85 misses at high rpm

Last week we arrived at the cottage, and the old 85 HP Johnson motor ran terrific. For a day and a half....

I had installed new plugs (Champion QL77-JC4) right off and hoped that was the ticket. On day two, the "miss" or lost power at full throttle came back, and actually became worse over the next couple of days. That night, the engine died on my nephew and he had to catch as tow as he couldn't get it going.

As it turned out, that seems to have been a different problem, as either the fuel hose between the motor fitting and the fuel pump was plugged, or the fuel tank hose itself clogged (squeeze bulb check valve perhaps?). Whatever, as there was no fuel inside the pump filter when I removed it. I disconnected and flushed out the connecting hose (no sign of a blockage) and replaced the fuel tank hose with my spare. At least THAT problem was fixed.

While I was "at it", I replaced the fuel pump with a new one, as I had come armed with a number of spare parts: a fuel pump, an upgraded water pump kit, an ignition coil and two carb repair kits. The local Johnson supply store only had the complete pump, no repair kits ($ouch$ as in $436 CAD total, including a spare control cable)

Long story short, it still has a mild to severe "bog" at full throttle, and that is after all the above parts were installed. It runs best at about 4/5 throttle, and actually loses speed when opened wide open.

The carbs were very clean inside, with no sign of sludge or varnish. The jets were clear, which I removed using the "proper" tool (a 3/16" shafted short screwdriver with a short straight blade to exactly fit the jet). I cleaned the carbs with spray carb cleaner and blew them out with compressed air, and set the floats to "level" as per my Seloc manual (an original Johnson 1976 85 Factory Service Manual was bought on eBay last week but is still in the mail ).

I started to suspect that it was a fuel problem because the "miss" or "bog" becomes less severe if the choke was manually partially closed at near-full throttle (the linkage doesn't allow the choke to actuate at full throttle). But after rebuilding the carbs and replacing the fuel pump and hose, the choke still helps, but it really acts more like an ignition miss, as the tach bounces a bit at around 5000 rpm, +/- 250 rpm (normal full throttle with the 19 inch pitch blade is exactly 5500 rpm, at 35 mph).

I also synced the linkage and set the timing (5 degrees at idle, 26 degrees at 5000 rpm).

I checked the compression, and it was 95 psi on #3, 105 psi on the rest (I know that the "difference" is what is important, but is 95 psi a bit low?)

Lastly, since I now have two new ignition coils, I tried switching them from cylinder to cylinder to see if one or more of the old coils were defective. There is lots of spark at all positions when cranking, but this seems to be a high-speed or high-load-only ignition problem.

The #3 plug seems to be a bit more fouled than the rest, so I am suspecting either the low compression is the problem, or I have a defective power pack, or sensing coil. The test recommended by the Seloc manual refers to a "Neon tester", which I don't even know what one is, let alone do I have one. A new power pack is $220 locally (ouch again) and I haven't priced the sensing coil. I am leaning towards trailering it the two hours to a service dealer.

On a positive note, it starts and idles better than it has for years. The old water pump was actually almost perfect (after 32 years!), except the top seal had cracked. The new pump is the upgraded version, with the molded resin housing and the stainless steel impeller cup. On that note, although the Seloc manual just says to "align the coolant pipes up with the water pump housing grommets" which is flat impossible in the space available when raising the lower end into place, there were plastic tubes up over the pipes that, when slid down over the pipe ends, fit into the grommets and aligned the pipes into the grommets perfectly in one try. One success

Any other suggestions as to why this still has a full power bog? I have four more days here, and the calm water and 85 degree temps are driving me crazy what with a broken boat

 

[jbjennings]

Re: 1976 johnson 85 misses at high rpm

Have you made sure your tank is getting plenty of air through the vent?
If your carbs have that fixed jet in the bottom of the carb, I hear they have to be beyond spotless to function correctly, and that could be your problem.
Have you replaced your old fuel lines? If not, you may be getting some crud in your carb from them.
I really think it is one of your carbs. Your compression I believe to be fine. Idle is where that low cylinder would show up the worst, not wide open.
Here's something to try (at your own risk!!!)
Take the cowl off and have your partner drive the boat while you sit in the back by the motor. Try blocking off the air flow a little with your hand while he's got the throttle full forward if the carb throats are not covered with an air box and see if it picks up on wide open. Try all the carbs that way--you may be able to find the guilty carb. without taking all of them apart and recleaning.
I'm not at all knowledgeable on big motors, but I really believe what you're describing may not be electrical in nature but fuel related. It's not getting enough fuel from at least one of the carbs on WOT which is why the choke seems to help. I believe running it with low fuel to a cylinder bank is a recipe for a ruined piston, too.
I hope you find the culprit,
JBJ

 

[kwilford]

Re: 1976 Johnson 85 misses at high rpm

Re: 1976 Johnson 85 misses at high rpm

Thanks for your reply.

I have tried both tanks, and two different tank hoses on each tank, so I don't think it is a fuel supply problem. But I can try a neighbor's tank and hose just for grins and giggles.

I will try the individual carb throat trick, although the back of the airbox can't be removed while the engine is running as the control cables attach to it. But the face can be removed and I can try to "choke" the individual throats just to see. It might at least point me to the offending cylinder, even if it is an ignition problem. A week ignition can function better with a more easily ignited mixture, so perhaps the richer mixture created by choking it, does just that?

I also wondered if my float settings are correct. The manual simply says to make then "level", rather than a specific height setting as is the norm on most carbs. I had to bend the float tabs down a bit to get them level with the new needles and seats (increasing the level in the bowl, as "down" is "up" when the carbs are right side up). The carbs were VERY clean, and the jets totally clear (even the low speed orifices, which are pretty small) so I don't think I have a plugged jet. The current condition is virtually the same after I re-built the carbs (except it idles a bit better) as before; again it doesn't "feel" like a carb problem.

It "seems" to be ignition, as the tach does jump around quite a bit when it bogs, and occasionally when it DOES kick in, it "feels" like a fourth cylinder coming on, rather than a "surging" that a fuel issue might create. I am going back to check on the sensor and charge coils and also the power pack, as I found some other suggestions regarding checking them that doesn't require the neon test light.

Again, thanks for your advice and please let me know if you have any other ideas.

 

[wildbillhemphill]

Re: 1976 johnson 85 misses at high rpm

I had a 82 model 140hp that did the same thing had it for years and tried replaceing all the ign. parts and rebuilt the fuel system to no avail so finally I ran a comp. check and it came up about the same as yours so I pulled that head and found a dinged up piston and head so I went ahead and tore the engine down and found the top ring on that cyl. broken I replaced that piston and reassembled and that motor is still running good today (I bought a new boat and gave that one to my dad)

 

[jbjennings]

Re: 1976 johnson 85 misses at high rpm

I agree, if it occasionally "kicks in" it certainly sounds electrical. Sorry you haven't found it yet. Maybe pulling the intake covers near the low cylinder would be helpful to take a peek before taking the head off which is a bigger pain. I still think the compression is o.k. but I haven't even worked on a single big motor other than a 65hp so I most surely could be mistaken.
Hope you find it!
JBJ​

 

[kwilford]

Re: 1976 johnson 85 misses at high rpm

I tried the neighbor's tank and hose, but alas, it made no difference. I had run out ideas, and almost out of vacation time. So onto the trailer the boat went (first time since it went to town back in 1989 for a blown power pack) and I hauled it into Roseau MN (home of Polaris snowmobiles, an hour's drive from our cottage at Moose Lake Manitoba Canada) for the mechanic at D&E Sports to look at. The hardest part was making the trailer serviceable, as the taillights were broken, the tires had gone flat, and I had trouble finding where my late father had "stored" (aka hidden) the wheel bolts. THAT all took a day and a half, hence my reluctance to trailer it to a shop.

Alas again, after chatting with him for a half hour (at least THAT was free!), he said the work I had already done (the new fuel pump, the carb kits, and the coil packs and plugs) were EXACTLY what he would have tried first. The next step, in his experienced mind, was to replace the power pack, as he had seen this exact behavior caused by an intermittent fault in a power pack several times (in the past thirty years!). He said the best diagnoses would be to put it on a scope when fully loaded, but their outboard motor dynomometer was broken, and the motor couldn't be fully loaded in their test tank. So short of putting it back in the lake with the mechanic and scope hanging off the back, the best and cheapest solution would be to simply change out the power pack.

The final "alas" was that the nearest power pack was four to six days away, and since this was Thursday and we had to pack up for home Saturday, we towed it back to the cottage, where it will sit in the boathouse until I come back to close in the fall. With a new power pack in hand, and possibly a few other replacement parts (maybe a new charge coil?) to make sure that this doesn't repeat itself NEXT summer vacation

 

[kwilford]

Re: 1976 johnson 85 misses at high rpm

The saga continues...

Another year, another vacation, the same continuing problem. I bought a new power pack, and for good measure, two new coils (now have four brand new coils) and four new plugs. Same old problem. So back on the trailer, D&E still doesn't have their dyno working, but Supreme Boats back in Blumenort (the other side of Steinbach) do, and they also have a test pond. They're a two hour drive, but with no boat, no fun, so off we went yesterday (Wednesday). Almost immediately they diagnosed #2 cylinder with intermittent power, but good spark all around, and the compression was actually a bit better than I had measured, with two at 118 psi, one at 110, and one at 101 psi (I forgot to ask which was which). They say the problem is a blown crankcase seal, which is causing no air/fuel into #2. The solution is a mechanical rebuild, at about $1000 CAD if we don't replace the pistons.

The problem is they can't seem to source many of the required parts, especially standard sized rings. Apparently the parts sources don't go back before 1980 in most cases. If I want to pay another $700, they can get 0.030" over pistons from BRP, not including pins or bearings, so it's a pretty expensive rebuild. He's looking for crank seals, and if he can get them we'll do a "patch" job. I will ask them to de-glaze the cylinders, but with old rings that might be problematic.

The other solution, of course, is to replace the engine, either new or used. My neighbour gave up on their 1978 70 HP Johnson this year and bought a new Honda 70 HP four stroke. Very quiet, pretty powerful as it pulled me up on a my 68 inch double harness O'Brien slalom ski right quick, but a hundred pounds heavier and $10k. Ouch. So far, no used motors in my quick search and the vacation time is waning...

Stay tuned for the next instalment of "This Old Johnson..."

 

[kwilford]

and Continues and Continues..

and Continues and Continues..

As it turns out, #2 cylinder was pretty badly scored, so the mechanic now says that the problem is the scoring, NOT the crank seal. ANYWAY, the choices presented are:

1) rebuild the motor; they have sourced all the required parts for the over-haul with over-sized pistons, and since I have already replaced virtually all of the ignition system, the motor would be "like new". Total cost about $3100

2) buy a used motor; after looking through all the local Kijiji ads and calling several dealers, nothing available this week

3) buy a used boat and motor; much more available, but not much under $7,000 that is decent, and nothing sized to fit our small boathouse (9 ft by 19 ft)

4) buy a new motor; Supreme offered a new 90 HP Yamaha 2-stoke installed with controls for $9k. All of the other motors in stock are 4-stroke, which would be very nice, except they are HEAVY! The Honda 90 (an over-revving 75) is 400 lbs, and the 115 is 540 lbs. Virtually a Civic engine for the 90, and an Accord engine for the 115. Nice cars, but I don't want one hanging off the transom of my boat.

So the final decision is door #1, which means it won't be ready before the end of this vacation. When I get back to close in October it will be done and go straight into the boathouse for the winter.

The moral of the story is that an apparent ignition problem can be mis-diagnosed, and too much money and time spent to cure what is actually a mechanical issue.