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Engine starts and runs great - for awhile

E

Ed Kelley

New member
I just purchased a Carolina Skiff J-16 with a 2000 25 hp Johnson - Tiller, electric start, manual choke, 2cyl 2 stroke. Using 40-1 oil mix. The engine starts quickly using half choke, and is plenty strong for the J-16. It quickly comes up on plane with two on board and runs plenty fast. Took it out for first time yesterday and it ran great for a while before starting to cut out and run rough. It did not stop running and I made it back to the ramp OK, but it was still cutting out when throttle was advanced. I bought new plugs and new fuel filter - a large inline one that looks like an oil filter. But I doubt that these change outs will fix it.

Does this behavior sound familiar - and what would be the next things to check. Since it didn't stop completely perhaps the problem is related to just one cylinder. Also does this model have any ignition switch other than the lanyard kill switch? I couldn't find one. Also #2, Is there a way to check the water pump with a garden hose fixture. Barrels are mighty hard to find, but I could put it back in the lake.
I just joined this forum and this post is very wordy. I just have a lot of questions. Thanks for any ideas.
 
Perhaps heat comes into the picture.----Have you checked the impeller.---------If it is the original it is due for replacement.
 
Thank you for the prompt reply. Very good suggestions. I was shopping for a good service manual when I noticed your post. I believe one of he plugs was darker than the other - they both looked rather dark -I 'll take a closer look.. Will I need a carb kit to clean it - or just clean out all the ports? Are the gaskets reuseable. I haven't looked at the fuel lines - standard hoses or molded lines? Heck, I'll just go take a better look at the thing. Thanks, Ed
 
I'll try that. I took another look at the plugs. the lower cylinder plug was sooty black and the upr was a tan - healthy color. Now, this seems to say that the lower was not firing properly - but now I really need a manual. I'm not sure if this model has a Mag or just an electronic ignition. I would say that it looks like an electronic module - but maybe it re-times and amplifies the mag pulse. The engine looks pretty simple so it should be no problem to remove and clean the carb - and replace electronic module, fuel pump or just about anything that's needed. I hate to break down and take it to a shop with an engine analyzer - but right now it looks like a spark problem - that I'll confirm if it will misfire while running in the backyard. Again, thanks for the tips. Easter egg hunt will take priority tomorrow........Ed
 
Do a cylinder drop test on it with an insulated pliers when running and it acts up.
 
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I hadn't thought to borrow a compression tester from an auto parts store - good thought. I need to check to be sure the cylinder is OK.

It may need a new water pump impeller as I I didn't see any water coming from the port up by the head. However as you suggested, it may be a stuck thermostat instead of the water pump. When I ran it today it seemed to get pretty hot. I'll try the six second rule - when I get a chance to work on it - to see if something is amiss with cooling system..

Do you use Quicksilver oil at 50-1?

The first boat I owned back in the '60s was powered by a mighty 35 hp Johnson. We learned to ski behind it after figuring how to make your body as low drag as possible when getting up. The only mechanical problems were the ingestion of a reed intake valve and a throttle cable that failed with the engine wide open approaching the dock. Pretty exciting for a bit.
 
??????------A year 2000 model 25 hp is not a 22 cubic inch motor.-----The 22 cubic inch block was last used in 1976 or so.-----Does the primer bulb go hard when you operate it ?------Have you run with a timing light ?
 
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The priming bulb does not stay hard when it is operating - I think this is normal. correct? The next diagnostic test I plan to do is to switch ignition modules between upper and lower cylinders. If the misfire moves from the lower to the upper cylinder then I know it is ignition related. If it stays on the lower it must be something else - compression, fuel etc. I will also do the six second test for overheating. Question: When I remove the lower unit to get to the water pump are there any special precautions during the reassembly? I suppose the drive shaft and pump shaft are splined and or keyed. Is there a particular clocking required? I ordered a service manual but it won't be here for a week or so.
 
SOME TEST RESULTS:
1. COMPRESSION - 102 PSI EACH CYLINDER - i DON'T HAVE THE MANUAL YET, BUT SINCE UPPER AND LOWER CYLINDERS WERE EQUAL I FEEL GOOD. NOT BAD OF A 15 YEAR OLD TWO-STROKE

2. SPARK INTENSITY: GOOD STRONG SPARK WITH 1/2 INCH GAP - BOTH CYLINDERS.

3. SWITCHING UPPER AND LOWER SPARK PLUG MODULES _ THE ERRATIC FIRING IN BASELINE CONFIGURATION ON THE LWR CYL CONTINUED TO BE ON LWR CYL -TELLING ME THAT THESE SPARK INTENSITY MODULES [WHEN i GET A MANUAL I'LL CALL THEM BY THEIR RIGHTFUL NAME] AND THEIR ACCOMPANYING SPARK PLUG WIRES ARE OK. THE PROBLEM MAY BE FURTHER UPSTREAM IN THE PICKUP COILS - WHICH I ASSUME WOULD REQUIRE PULLING THE FLYWHEEL TO ACCESS. MEANWHILE i WILL LOOK FOR LOOSE CONNECTIONS OR WORN WIRING INSULATION AS IT ACTS LIKE IT MIGHT BE RELATED TO VIBRATION OR HEAT. i NEED TO FIGURE OUT A WAY TO MONITOR THE LOW VOLTAGE SIGNALS FROM THE PICK-UP UNITs. NOW, IF i JUST HAD AN OSCILLOSCOPE AND A MANUAL..

Please pardon my shouting with the CAPs. I had typed a couple of sentences before looking up - and I'm lazy. Also, It occurs to me that the two "modules" that feed the spark plugs are probably coils and the CDI is another larger module on the port side. as it has low voltage wires coming from it to the "coils". And the part number "BRP 2SL/6100 with additional numbers:585224 26CIJ_DG" would indicate the capacitor discharge unit. I'm not sure how to checkout this module or the pickup coils [once I find them] - perhaps there will be something in the service manual. I think I'll price the CD module........Ed
 
SOME ADDITIONAL TEST RESULTS: I replaced the CD unit [Part # 0585224 PP AY, CD 2SL (6100)] and this seems to have cured the misfiring. I ran it for quite a while and dropped cylinders while idling. It ran smoothly on either the upper or lower cylinders and would rev up without protest. I'm glad I didn't have to pull flywheel and get into that. Next up - Replace the water Pump.

I would like to thank you fellows who gave me very good advice on this project. I still don't know what the engine displacement is - probably 737cc used for 25 thru 55 hp] nor do I know what the compression ratio or compression value is supposed to be. It is a 2000 25 hp - Model J25TELSSD if anyone has a spec look-up table. Someone said it should be around 125 psi although it measured 102 both cylinders, in a test. I don't think I will do anything more regarding this if it continues to run OK.
Hey, Fishing season is here in Georgia.
 
The ignition issues seem to be resolved but the water pump just wasn't pumping. I dropped the lower unit, installed a wate rpump kit with new impeller, impeller housing and base plate. I also replaced the thermostat. Cranked it up and still no water coming from the telltale. After it runs awhle steam issues forth. SO I removed the lower unit again,.checked everything I could think of - Impeller blades correct for clockwise rotation - the base plate intake slot is opposite side of impeller from output - gasket properly fitted - the O-ring that nests with the shift rod bushing was left out so I added one. I also removed the water tube and made sure it was clear. I drained and replaced the oil in the lower unit. Actually I did't find anything that should interfere with proper water pump action. BTW the old impeller was pretty chewed up but all vanes were still intact and in my opinion it shoud have worked at some level. Also, found salt deposits on the head cover plate when I replaced the thermostat. I would think any other salt deposits would eventually dissolve with flushing.

Before I put the lower unit back on is there anything else that I should do. I don't have the foggest idea how to get to the top end of the water tube. But it doesn't seem to be obstructed since water runs out the telltale when I run the engine with a muff [instead of in a barrel]. Is there any way water could become lost near the thermostat. There are no external leaks a the cooling plate to head joint. I replaced that gasket.

I also read the thread started by fishon1 - 'johnson 25 not pumping water' and I'm looking forward to repeating his successful outcome.
 
I'm going to re-install the lower unit and try again. I will raise the garbage can a couple of inches to cover the intake screens more and check to see if water is getting to the head. They say "Insanity is repeating the same thing and expecting different results" - so now you know me. Maybe we can just call it "Perseverance".
 
After checkin everything and re-installing the lower unit the water pump worked - for awhile. I removed the lower unit again and checked the impeller. No problem - it looked just like it did when I installed it. I again installed the gearcase - it doesn't get any easier with practice. there is something that hangs up just as you are making sure the water tube is going in the right hole. Then hangs again when about 3/8 from all the way up - this is possibly the drive shaft not qujite seating in the upper spline socket. BUT I digress - It is pumping water out of the telltale even at idle. Now a question: Hot water with a little steam spray out of the exhaust port (?) on the aft side of the extension This is intermittent. Is this related to the thermostat opening and closing?
And finally -- this is very perplexing--The engine is running rough. However when I pull the plug wires one at a time while running the engine smooths out. When the wire is replaced it starts running rough again. This seems to indicate a problem other than electrical. Have you fellows encountered this before?

I don't know how old the gas is - so I,m going to replace it,
 
I don't mean to be rude but I can't figure out how to ask a question but I have and over heating problem with 1990 omc cobra 3.0 check for clogs new impeller t-stat good any thought at all again sorry to interrupt this post with something else please feel free to message me ty
 
Kourt, I'm a new member also and probably not a good one for advice. There is a "Post new thread" button on the first page of the forum that best fits your problem [there are several categories]. Tap that and state your problem clearly. Within a day or so someone will probably respond and you are off and running. The old hands here are quite knowledgeable and can help on just about any subject.
 
Even if you get great water flow from the tell tale, it does not mean the engine block is getting cooled, it just means your pump is pumping water. In my experience in my Florida run saltwater engine purchases, I found that 6 out of my 8 engines needed to have the head's taken off, and the water passages mechanically cleaned with a flat screw driver and other scraping tools. The salt, sand, or aluminum sulfation turns hard and could not be cleaned out any other way. Even with the scraping tools, it is hard to take off, no way any product is going to remove that stuff. I have a 1993 25hp, and I had to clean the heads on it, although the water pump and the telltale were fine. I test all the engines with a laser thermometer like this http://www.amazon.com/Etekcity-Lase...4&sr=1-1&keywords=Infrared+IR+Temperature+Gun, you have to put the red dot right on (the gun within like 5", read the instructions) the different spots of the water flow to see if the engine really is getting water all the way through. If it is not, as in my 25hp, then you have to take the heads off and clean them manually. The water flow diagrams are in the back of the OMC services manual for the engine.

81qA1ElbNxL__SL1500_.jpg
 
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When I replaced the thermostat I had to pull the head cover plate which had some deposits - that I cleaned off. Should I now remove the head to look at other water passages? Can the head be removed without pulling the powerhead? I'm doing this shade tree style so I don't have a way to lift the powerhead.
 
I did it on a 115hp Johnson "shade style", and it has two heads. The head on a 25hp comes off just like the head cover plate, except the head is like 1.25" thick and the plate is like 5/16" thick. The head actually comes off easier as you have thicker bolts and less of them compared to the cover plate. The bolts on the head is thicker, so less chance of breaking a bolt than with the cover. Once you do the job, you'll know you have spotless passages. BUT, remember to first test the engine with the laser thermometer before you start disassembling the cover and head. The best Shade work" is no work!

Do you have the manual? One the last pages they have the schematic of the water plow through the engine. It is good to have, so you can check the different points in the flow.
 
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I ordered the Laser thermometer which should arrive Saturday. I was surprised at the reasonable price [$13.88 + ship]. I'll probably pull the head anyway, but it will be educational to check out the water passages first. Speaking of an education, I now understand the importance of flushing the motor after a trip to Florida. I didn't realize that salt would be caked inside.

Do you understand why the engine runs smooth on one cylinder [either one] but rough on two? Can there be some kind of cross feed between them that shuts off when only one is firing? Very interesting phenomena to me.
 
Ed Kelley said:
Do you understand why the engine runs smooth on one cylinder [either one] but rough on two? Can there be some kind of cross feed between them that shuts off when only one is firing? Very interesting phenomena to me.
Click to expand...

Don't worry about the why's, you said it is fixed, you said: " It ran smoothly on either the upper or lower cylinders and would rev up without protest". On to the next problem.

On my 1992 Johnson 115 hp it was providential that it had various issues that did not allow it to run at high rpm's, it made me test it further to find that it was not cooling right. Had I run the engine full speed, I would have fried it. Don't run that engine fast till you have verified that it is getting water to the heads, and is cooling properly.
 
While I can't really argue with your advice, "Don't worry about the why's, you said it is fixed, you said: " It ran smoothly on either the upper or lower cylinders and would rev up without protest". On to the next problem. " . BUT in the course of cleaning the head's water passages I think I'm going to find the answer to why it runs smoothly on either cylinder but not both. Looking at the water flow diagrams made me realize that a blown head gasket between cylinders would be very disruptive to flow in the just primed - ready to fire - cylinder, as burning exhaust gas is squirted through the gap. It could pre-ignition and certainly disrupt the critical fuel charge flow pattern in a two-stroke. With no explosion in adjacent, non-firing cylinder the disruptive effect would be much less. I'll report the condition of the head gasket in a couple of days. My "shade tree' operation depends on cooperative weather and the weather girl says 100% rain tomorrow. But heck, I fish in the rain so I might as well do something productive.
 
Keep a close eye on the re-installation of the three deflectors #8 and 9 on this parts diagram for your engine http://www.marineengine.com/parts/j...urer=Johnson&section=Cylinder+&+Crankcase . On my 1993, if the deflector on top does not go all the way back, it leaves a small gap in the back for the water to flow through, it does not totally block the water. The bottom two do block all the flow. On my 115 hp all the deflectors totally block the water flow. You'll need the water flow diagram to fully understand how it cools.

The deflectors on my 1993 25 hp are identical to yours, and I had BIG problems getting them to fit, when you get to it I'll send you a link to my forum posts about my problem and how I finally got them to fit.
 
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I may have a chance to pull the heads tomorrow. What is the function of the deflectors? Will their location be obvious when the head is removed. I can't tell from the parts blowup where they are installed. On the sketch they look like short sections of rod or tubing. I scanned the water jacket cover on the aft side of the heads with that neat laser thermometer but results were inconclusive. It is interesting just going around measuring temperatures on the hot motor. The highest I recorded were in the spark plug recess ~ 140 F Once in a while it would flash over 200F but I couldn't get a repeat on those high readings. Most areas were lower than expected. I think I would need a better understanding of the location of water passages to use the thermometer properly.

Should I also pull the exhaust cover plates? Are there any water passages exposed by their removal? Are there any other removals that might be necessary? I have a gasket set ordered which includes gaskets for just about anything that needs to be removed. Since I'm asking questions, Are the head gaskets installed with gasket cement or dry?
 
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The deflecters are rubber hoses.----------Water does NOT go through these hoses.--------Hoses are used for manufacturing simplicity.----------------------These deflecters guide water around the block for proper cooling.
 
Read the instructions on the laser thermometer, the red dot spot is only accurate if you are withing inches of the target, as you get further back there is no way of knowing what spot it's testing.

Nothing should read over 140 when you are running it on a hose at the permitted rpm's (under 2000). Mine went to 140 quite quick then kept increasing in temperature.

Regarding the deflectors, I had a hell of a time getting the old ones completely out, they came out in pieces, and when I though I had everything out there was still a rubbery feel to what I though was aluminum, more pieces!

I also had a rough time putting in the new deflectors and here's my ordeal described in another forum: http://forums.iboats.com/forum/engi...-outboards/8623785-water-deflectors-don-t-fit

Here's my diagram of the water flows and deflector locations on my 1993 25hp J25RETS (I did not mess with the side covers, the 3rd & 4th picture, I just include them so you can understand the complete water flows):
Cyl water flows.jpgCyl Head rear view water flow.jpgExhaust parts.jpgExhaust housing - Copy.jpg
 
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FINAL REPORT - I HOPE ----I removed the head to find only minor deposits. The head was low in the middle where the cylinders are very close and apparently there had been some fuel charge leaking past the gasket. I found a machine shop that would plane the head bue when I was talking to the machinist I mentioned sanding it flat. They had an impressive belt sander and after a couple of passes the aluminum head was precisely flat. I re-installed the head and cover plate and assorted electronic stuff that I had removed. Tried to start the critter and it would only fire occasionally. Sounded like it was way out of time. Had my son over and described my plight. We traced the wiring from the CDI to the coils and I said I was pretty sure I had got the wiring correct. My son knows me and he promptly switched the wires going to the coils. The darn thing started and purred like a kitten. I measured the head temp with my new toy pyrometer. the top of the head near the thermostat got to 147F (S/B < 140F) after idling for about 15 minutes. but it cooled down to 115 when i increased throttle mid range. I'm happy. I never did get around to cleaning the carb - and don't intend to. First a test run on the lake and then try a bit of fishing...Can't wait.

Thanks to you fellows, Racerone, Kimcrwbn1, Klink, and others who held my hand through this. Your advice was always useful and appreciated. Mainly just knowing that you were there for support meant a lot. BTW if I get stranded mid lake I'll be calling again - but it will be with a new thread Maybe "Fisherman survives 3 days eating raw fish- found on motor-less boat mid lake"
 
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