94 Johnson 150 Fast strike falls flat over 3200 rpm

[Jim Crews]

Took to shop. They replaced a coil pack. Same problem. Took back. They want $2500.00 to replace all the intake items?
VRO has been rebuilt. When it's dying, choking does not help. New power pack. Haven't tried the neutral safety switch thing yet.
Have tried from a remote fuel tank.
any suggestions?

 

[racerone]

They do not want to work on it so that $ 2500 was a somewhat polite way to say " go somewhere else "---Checked carburetor float bowls for warpage ?------Post compression test numbers.----Check for spark on all cylinders.---Spark MUST jump a gap of 3/8" or more.-----Checked for overheating ??----Checked SHIFT INTERUPT switch ?-----Neutral safety switch only comes into play when attempting to crank it over for starting.----That neutral safety switch means nothing when motor is running.----How long have you owned it ?----Did this problem develop suddenly ??

 

[Jim Crews]

Checking things, one at a time!

 

[Jim Crews]

Ya know, now that I think about it, the problem started when I replaced the bowls with new ones. I didnt realize there were high speed jets behind the drain plugs. Saved the drain plugs, but threw the baby out with the bath water. Ran horribly. Ordered new high speed jets, still having top end problems. I wonder if the distributor sent the wrong ones? I believe they are supposed to be 57d? Does anyone know?
Did they offer different high speed jets for this model?
thanks in advance!

 

[Jim Crews]

Btw, it is a “Fast Strike” model 150.
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[Faztbullet]

Explain falling flat????

 

[Jim Crews]

If you ease the throttle forward, get on plan and climb to 3200 rpms, so far so good, any more forward throttle, engine spits, snorts, sneezes and will die if not pulled back.
have tried on test fuel tank. No diff. Squeezing bulb, no change. Choke makes it worse.

 

[Chris1956]

Sounds like it is starving for fuel. Are the carb floats set to the right height? You really need to check to make sure the main jets are the correct diameter.

A quick check shows Johnny 150HP motors from 1994 use either a 57D, 70 or 71 main jet, depending on model number. The crowleymarine web site can help you, if you have your model number.

 

[Jim Crews]

Ok. Now we're getting somewhere. Checked the Hi Speeds. 70D as they should be. (Thank you Crowley Marine)
Checked the engine cut-out switch. Operating as it should be. Haven't checked the spark-gap jum-distance-test yet, but I did buy the tool. ($10.00 Auto Zone) However, while lake testing today, discovered the following;
While trying get over 3200 RPM, spitting-sputtering and trying to dtop gasketie, I squeezed the primer bulb (a lot) absolutely no change. Tried moving the timing advance, real time, nothing. But then I tried holding in the electric primer on the key switch, all of the sudden, we have 4000 RPM's. Going back a little, I replaced the bowl, gasket and o-ring of the primer (red lever) valve, due to it leaking perfusly if I pumped the primer bulb. From that day forward, the lever would no longer point down. Like it was installed upside down or something. Never really thought much about it, until now.
I feel like I need to reorder the valve, (red Lever) top that accept the lever and gasket.
I haven't ruled out the stator yet. But sure seems to be fuel related.
btw, if your idling over 1200 ish rpm's and use the electric primer, it will stall the engine, so it's like only in the high speed area. I rebuilt the VRO oil side and fuel side so I think that rules that out. I don't really get the concept or know how to troubleshoot the "Vapor System" or the "Vapor pump" System.
Any other suggestions?
Thanks,
Jim

 

[Jim Crews]

And one other small detail.
when I removed the heads a while back, (different story. Thought i seized the engine, turns out it was the drive)
anyway, when I put heads back on, i reused the o rings and the thermostat seats. Now, water leaking out the headside of the head assembly’s both side, mostly around the thermostat areas. At high rpms, the water gushes out pretty good. Could the water be killing the two top cylinders from firing at higher rpms?
Ive new orings and theromstat seals so I will remedy asap.
thanks

 

[Jim Crews]

Progress! As suggested, I started up, in the water, and let warm up. Grabbed timing light and verified (pulse) on each wire.
HOWEVER, # 2 was acting kinda weird. Pull or move the sensor any and the timing light/tach would quit. Out of curiosity, swapped #1 & #2 plug wires. Problem stayed on #2. Grabbed spark gap tester and proceeded to test. As suspected, -0- spark on #2. All others nice and strong. Pulled coil. Has liquid substance coming out the #2 output side. Resistance test shows 200 ohms, a bit lower than in spec but believe is leaking spark to #4 coil below.
ordered new one. Will report back.
Happy Mothers Day!

 

[Jim Crews]

Replaced coil today. All cylinders firing now!
reset all the idle mixture screws. Starts and idles nice and smooth. Problem still exist at 32-3500 Rpms. Trys to die. Starving to death. Hold electric primer in runs good.
getting closer. Any suggestions?

 

[racerone]

Fuel from the electric primer goes into the engine.----That fuel bypasses the carburetors.----That points to the carburetors as being the problem.

 

[Jim Crews]

Hmm. What about the vapor pump and the little bowl with the float in it? Isnt that whats for? Big Fuel on demand?

 

[Jim Crews]

Re[laced the needle and seat in the vapor pump, same problem, Disassembled VRO pump rebuild, just in case, looks fine.
Still starving for fuel over 3k rpms.
Any more suggestions?

 

[Jim Crews]

Small update yesterday. Took boat out for a quick test and noticed something. First, out of the hole and up on plane good up to 3krpms and then the same. Anymore throttle, dies. Pull throttle back a little, back to a steady 3k.
however, lots of boat traffic on the lake, when my boat hit really rough water, rpms would shoot up! Hmm. Smooth water, back to same problem. Hit the primer will recover from the bog, every time. Squeezing the primer bulb does nothing. Also, fuel consumption seems to be very high!!!
I feel like we’re getting close!

 

[racerone]

The primer put fuel into the engine.------This fuel bypasses the metering circuits in the carburetors.------This points to carburetor issues.as already stated before.------Float bowls warped ?

 

[Jim Crews]

Dont appear to be, however this all started, from memory, when I replaced all 6 bowls due to leaking. However, at the time, I didnt realize there were high speed jets in the old bowls! (And threw them away!) ask you can quess, it didnt run over 3k rpm then. So, i figured, duh, theres the problem and ordered 6 new high speed jets. (70d for J150GLERV) hasnt ran over 3300 since!
as far as I can, theres only one model bowl.
I have since pulled #1 carb, verified float level, needle and seat, confirmed hs jet size.
all good.
also, a while back, I replaced the cover and gasket of the red lever shrader valve, due to leaking. The lever used to point down and stop in the normal “run” position, however, after the change, the pointer stop was in a different position. But would the manual primer knob have anything to do with the high speed circuit?

 

[Faztbullet]

Rough water making it run means carb problems such as float levels. When you repaired carbs did you install the washer under seat?? If so that's incorrect ...

 

[Jim Crews]

So no washer under the seat if its included in the kit? Has been a while but I will check.