Johnson 115

[Matysiak]

First things first, what a great forum. I have spent three hours just looking at past messages.<br /><br />Now, back to the help i need. I am not new to boating but new to my 1980 115 Johnson. <br /><br />When i bought the boat i took it to a dealer to fix the faulty trim/tilt, he fixed that but said the engine was getting warm and to fix it, they took the heads off and resurfaced them. Anyway, i was happy i was eventually going to get to try my "new" boat out.<br /><br />Took it to the dam last weekend (JHB South Africa), but it was a pig to start and wouldn't idle or if i got it in gear before it stalled wouldn't get past 2000 RPM.<br /><br />Anyway, got it home and noticed that the quick fit fuel connection onto the motor was leaking fuel when i primed the carbs. Have since replaced the quick connector and new hose clamps on all fuel lines and she runs fine on ear muffs. Could the connector have been the problem? IOf not, what else should i be looking for?<br /><br />Finally, she idles fine and sounds well while running higher revs in gear but has a "splutter/miss" every now and again, followed by some extra smoke through the exhaust, what is causing this? Should i be worried or does she just need a good run?<br /><br />Regards <br /><br />Stephen

 

[bubbakat]

Re: Johnson 115

I would rebuild carbs and fuel pump and change plugs. I would start with a good decarb and fuel pump rebuild first

 

[OBJ]

Re: Johnson 115

Hello Stephen and welcome to the iboats forums.<br /><br />You made a good start repairing the fuel line quick connect.<br /><br />First a little caution. Don't rev the engine up on muffs above 2000rpm. It is possible for the engine to "run away". <br /><br />Engines usually will "seem" to run OK on muffs because there is no back pressure against the cylinders. This lets the engine run very easy.<br /><br />Put the boat in the water and try it. You will know right away if you've done any good.<br /><br />I would also consider asking the previous owner when the last he had a full tune up including compression test, ignition test, rebuilding the carbs and a sync and link. <br /><br />The hard starting and stalling could be one or a combination of the above or the fuel lines which you've already fixed. At the very least, rebuild the carbs and go back and look at the condition of the fuel lines. Replace any that are hard and have lost their flex.<br /><br />Also get a service manual. OEM preferred. It will tell you tons about your engine and how to give it the proper care it needs. May even help you get off the water someday.

 

[Matysiak]

Re: Johnson 115

Thanks for the quick feedback. The carbs were serviced just before i bought the boat. I will do a compression test tonight. Should the engine be warm when testing for compression?<br /><br />I hear the reading should be over 100 and should be within 10 % of each other, correct? I'll post the results tonight.<br /><br />Thanks for the tip about over revving.<br /><br />Stephen

 

[OBJ]

Re: Johnson 115

90 or over for compression is great, 100 or better is ideal.<br /><br />All cylinders should be within 10 to 15% of each other. So you could be below 90psi and still be OK if the cylinders are with in limits.<br /><br />I like to do compressions with the engine warm.

 

[Matysiak]

Re: Johnson 115

Did the compression test tonight, with both a hot and cold engine. The reading's remained virtually identical. <br /><br />Readings were #1 118 psi, # 2 118 psi, # 3 116 psi, # 4 116 psi.<br /><br />I also tried running the motor in a large dustbin (To simulate the back pressure) and i eventually got it started but i did battle. I guess what you guys were saying about the back pressure was true, but why is it affecting the motor if it has good compression?<br /><br />I also noticed a lot, (and when i say a lot i mean a lot)of oil coming out between the lower housing and gearbox casing. It is definately unburnt two stoke oil. I rememer the boat store telling me not to worry about it, should i be worried?<br /><br />Anyway, any other ideas before i re-do the fuel pump?<br /><br />Stephen

 

[OBJ]

Re: Johnson 115

Stephen....with the engine out of the water, the cylinders are exhausting to atmosphere. In the water, the cylinder exhaust has to push against the water to move it out of the road so it can get out to atmosphere. That's about as easy as I can explain it.<br /><br />The stuff coming from the lower unit will go away once you run the engine real good.<br /><br />Compression sounds great.<br /><br />Before tearing into the fuel pump, why not wait for the manual and do sync and link to see if that cures the problem?

 

[Matysiak]

Re: Johnson 115

Decided to take my boat back to the dealer who re-faced the heads and fixed the trim/tilt.<br /><br />They said that they think the reeds are fautly. Do the symptoms i mentioned earlier agree with their diagnoses?