2004 Johnson Compression Test Procedure

[Fj40toycruiser]

I have a 2004 Johnson 115 2 stroke I will be testing by spark gap & compression today. I want to confirm what I believe is the proper procedure for both. Feel free to light me up as I am a major greenhorn to the outboard world. I have read JD's compression procedure and maybe I am just too stupid but I came out a little vague.

Compression
Warm boat up for a few, pull spark plugs, ground plug wires, pull safety lanyard, Insert compression gauge and turn over with key, repeat for each cylinder. If that doesn't work I will use a jumper/switch at starter all else the same.

Spark gap
Pull all wires, ground wires except wire to be tested, use a gap tester capable of gaping 7/16" grounded to the motor look for spark to be blue and jump 7/16" gap.

I am chasing why I cant get above 3000RPM under load without pressing the primer solenoid ie key. Pumping bulb does nothing when squezed. In neutral revs fine, carbs have been cleaned and were pretty clean to start, all gaskets replaced during cleaning. When I press key rpms go up over 4000.

 

[jakedaawg]

Yes, do those tests. You may also need to preform a fuel vacuum test to determine if you have a fuel restriction. This assumes you actually got the high speed circuits of carbs clean and that the throttle plates open fully.

Model number would be nice also

 

[Fj40toycruiser]

Model no j115plsrc sorry I meant to post that initailly. Compression reads pretty close to 120 across the board. will check gap later after family fun time. Whole carb pretty was clean didn't see anything really. I was able to juice through each hole it was apart. But I have heard of these past passages and their vulnerability. Thanks for the input. Where are these high speed passages the high speed jet is in the base of the bowl and that was spotless. Again im new to this. The throttle plate opens wide up when the throttle control is pushed forward.

 

[ricohman]

I use a piece of fine brass wire to pass through every single circuit. The high speed circuits are on the climbing side of the throttle plates.

 

[Fj40toycruiser]

7/16" spark gab checked good, nice an blue too! So I guess I am on to the fuel vacuum test. Place the gauge between the vapor separator & the OMS pump with a t-fitting & 8" of clear hose, under load? Is that correct? I don't have a suitable test tank so does that mean i'm going to the lake for this test?

In regards to the carb cleaning I knew it seamed too easy. I only cleaned the plastic carb bodies. I didn't touch the aluminum throttle bodies. I guess that's how you learn. I hope i don't have to go back into them. I don't want to have to buy new gaskets again

 

[jakedaawg]

Tee in a guage and somebclwar hose between filter and vro pump.attach vacuum guage. You want less than 4"Hg.

 

[oldboat1]

How's that work, Jake? Is a vacuum test useful on regular old fuel pumps too?

 

[Fj40toycruiser]

Do I need to be in gear in the water to do the vacuum test?

 

[jakedaawg]

Do I need to be in gear in the water to do the vacuum test?

nope. We are just checking for a fuel restriction some where up stream of the pump. The clear hose will also aloow us to see any air leaks in the form of little bubbles. The manual states what rpm and such, if I remember I will double check today.

oldboat1 - yes, many manuals mention this test.

 

[Fj40toycruiser]

Thank You Jake. I will let you know the result In the next couple of days.

 

[jakedaawg]

After re-reading this thread I might suggest...

Beg, borrow or steal a known good portable tank and fuel line. Take it for a ride, better now?

Have you checked the VST for leaks around the gasket? Squeeze bulb till firm, keep squeezing gently, do you see any fuel leaking from the top of the VST or any where else?

Have you messed with any of the linkages? Have you verified that the throttle plates are completely horizontal when throttle lever is fully advanced?

Do you have a service manual? A real one not after market.

 

[Fj40toycruiser]

Beg, borrow or steal a known good portable tank and fuel line. Take it for a ride, better now? I will try to find one as I was thinking of trying that to eliminate fuel tank/connections as the problem.


Have you checked the VST for leaks around the gasket? Squeeze bulb till firm, keep squeezing gently, do you see any fuel leaking from the top of the VST or any where else? I will look tonight.

Have you messed with any of the linkages? No, Definitely not intentionally.

Have you verified that the throttle plates are completely horizontal when throttle lever is fully advanced? When I am WOT when lever is fully forward the throttle plates look parallel to throttle bodies.

Do you have a service manual? A real one not after market.[/QUOTE]

Yes I purchased the real Johnson service manual as defined on the evinrude site by part number. I would say its a good one but like many things it leaves some to be desired hence the original need for this post. Under compression test it told me to unplug the CPS (crank shaft position sensor) but never told me where said connection was. Also it did not say anything about making sure flying spark plug were grounded to prevent ignition damage. I learned that stuff from you guys on this forum.

Thanks a bunch for at least supporting through this so far. I will keep you posted.

 

[Fed]

If squeezing the primer bulb does nothing but pushing the key in increases the rpm it would surely point towards a carb problem.

 

[Fj40toycruiser]

Fed I will try the things jakedaawg suggested but do you think perhaps the throttle bodies need to be cleaned as well ie the aluminum housing between the plastic carbs and the intake manifold? Should I do as ricohman suggested with the brass wire in the throttle bodies.

 

[jakedaawg]

Yes, i would tend to agree that the throttle bodies and carbs could be cleaned but I dont reccomend poking wires through jets. Many do it but we were always taught not to. Carb cleaner and comoressed air. I thought you had already cleaned them though.

When you cleaned carb did you do the high speed jets?

 

[Fj40toycruiser]

jakedaawg I took the plastic carb bodies off, disassembled, cleaned passages with carb cleaner and compressed air, soaked carb body in simple green 50/50 with water in a ultra sonic cleaner for 20 minutes, repeated spraying carb cleaner and compressed air, replaced gaskets, and reassembled. I did remove the high speed jet in the bowl and clean as well. Everything was really clean looking to the naked eye though. I then reassembled. What I did not touch was the aluminum throttle bodies between the plastic carb bodies and the the intake manifold. Do you think I will need to repeat procedure onto the throttle bodies? Do I need to buy new gaskets if I go in there again, I did replace the throttle body gaskets between the throttle body and intake manifold. I just did all this a couple weeks ago. As always I have to learn the hard way. What should I do at this point? Proceed to the original plan as you mentioned above or go into the throttle bodies?

 

[Fj40toycruiser]

Also, forgive my stupidity but why can it rev all the way out when out of the water on earmuffs if the high speed circuit is dirty?

 

[jakedaawg]

Also, forgive my stupidity but why can it rev all the way out when out of the water on earmuffs if the high speed circuit is dirty?

inadequate fuel delivery.

Yes clean throttle bodies as that is where the carbs get the fuel from I believe on that model. i would try a portable tank and fuel line first though just to rule out the easy stuff

 

[Fj40toycruiser]

I figured as much. I always learn the hard way! Do you think I can get away with tearing it apart cleaning the throttle boddies and reassembling it with the gaskets I just replaced? It wasn't more than 2 weeks ago. Or should I suck it up and buy new ones?

 

[Fj40toycruiser]

So went out last night and boat performed the same. Then I hooked up a portable fuel tank and once again it performed the same. Would not get up above 3K RPMS but would if I pressed the key in. I tried again pumping the bul with both the on board tank as well as the portable tank and neither resulted in any increase RPM or motor speed change. So I am onto the throttle body cleaning. As this is now a new process I going to start a new thread.