1985 johnson 150

[south599]

Hey guys so im having an intermittent problem. some days ill go out and ill be running at about the 5000 rpm range for 5 mins or so. Actually cruising at this rpm not just bumping it. Then all the sudden ill lose power almost like a bank a cylinders shuts down. I am able to floor it and hold 3000 rpms and even stay on plane somewhat but i have to let off the pedal all the way till it kicks back in and i am up and running. the weird thing is some days this wont occur and some it will and it will do it multiple times. My Fuel system is all new/ rebuilt got a fuel water separator in line. So would a power pack be shutting down for some reason? can it even do this? These are the 5850 limited rpm power packs. Could the timing be out of wack and cause this? Just looking for for something to try or test because when im at 5000 rpms im doing 60ish and my boat is mostly in the air so it is not a pleasant experience.

The only thing i can think to do is place a spark tester on each plug and try to cause the problem. Could maybe the shifter solenoid be getting jared and causing a bank to shut down since i know it does that to allow the motor to shift into gear easier?

[Lockjaw]

The SLOW circuit could be kicking in. On my eagle 150, when my powerpack went out, I lost a whole bank of cylinders, and letting off the gas didn't help. Basically it would cold start fine, and usually get me to the first fishing spot. Then when I'd crank it back up, I'd get up on plane and then drop the bank. So it is heat related. Once it sat for a few hours, then I would hit on all 6 again.

Do you have a factory manual? It tells how to test the slow circuit and see if that is the issue. Normally there is a warning horn that sounds too.

[EMDSAPMGR]

Possible you are losing spark to one or two cyls. You need to determine which ones may not be firing. If the non-firing one(s) is/are on one head, you can do a test. Swap the two identical power packs and see if the "no-fire" situation moves to the other head. If so, it's a back pack. Do any spark testing after the engine is well warmed up. Weak ignition components tend to work ok when cold, crap out when warmed up to normal operating temps.... A cyl drop test, or an inductive timing light test are both good spark test methods. 5850 packs are all that are available from the factory anymore.

[south599]

Crossflows dont have the SLOW programming i know that for sure. Its not a bad pack because they all work great 95% of the time this only occurs when i am cruising the in the upper 5000 plus rpm range. i let my motor warm up well before taking off and i would not be able to get on plane without all cylinders. I would notice if one lost spark/compression. Hope i dont sound rude i really appreciate the input, just working through the thought process.

[Lockjaw]

Then I would be concerned about fuel flow if you don't think its electric.

My GT175 had SLOW, I got the water intakes plugged up one time at Guntersville, and that sucker shut down to under 3K and wouldn't come back until it cooled off.

My pack got progressively worse too. I'd tinker around with something and it would behave, then I would think its all good, and then back to acting up.

I would try to duplicate the issue with a partner. Leave the boat strapped on the trailer and load the motor and see if you can get it to act up, then pull plug boots, or use the timing light to make sure each cylinder is firing.

[south599]

hmmm i would probably need a timing prop to put the right strain on it right? What year was you GT175? maybe there were some years where they did it to test. Mines not an original GT.

[Riverratt]

Next time it does it push in on the key activating the primer and also have someone pump the primer bulb to see if that keeps it running. Sounds like bad fuel pump. No SLOW mode on 1985 crossflow

[Riverratt]

I just re read your original post. You also do not have the shift interrupter that cancels out one bank when shifting so you can rule that out. What kind of fuel pump are you using?

[Riverratt]

After thinking some more did you pull the plugs and look at them? Are you sure it is not seizing up? If you are running a long distance at 5000 rpms I think that may be the lean rpm area of these motors and if the carb is off just a little and the timing a little high they will lock up especially with lower grade fuel.

[south599]

I've got the retrofitted dual vacuum pumps. and right good point on the fuel thing i hope not cause i know that can lead to melted pistons. and didnt know i didnt have the shift interrupter good to know. But like i said this isnt a regular problem which wouldn't flue flow problems occur every time you say went above the 5000 rpms? Its probably been 5+ trips since its done this. and i have pushed the motor to sit on its rev limiter at least twice in the 5 trips without a problem.

[Riverratt]

1985 should have had the vro pump and not the dual pumps. My 1985 XP2.6 acted just like yours when the fuel side of the pump was going out. The easiest way to check is when it acts up have someone squeezing the primer bulb and if that makes it run better than it is a fuel pump problem. If you have a portable tank laying around try a separate fuel source to rule out a problem with the fuel pick up in your tank. Check the fuel vent and anti syphon valve in the tank if you have one. I am betting fuel problems. My experience with power packs was usually they either worked or don't or double firing on a cylinder which ends in a stuck piston. I would check all electrical grounds and connections just to be sure. it could be as simple as a ground somewhere. Also check all your fuel hose clamps to make sure you are not sucking air especially since you have the problem after installing a water separator.

[south599]

The fuel water separator came with the boat. i've never had it off. I just went through the fuel system but will try again since thats the simplest option. and yes it should have the VRO but it was retrofitted and its no different. they literally just put the VRO onto the 1984 and up crossflows. Ill be checking the fuel system again but like i said went through and tightened, replaced, sealed up, and rebuilt from the fuel tank all the way through to the carbs. Motor wont have ground problems because i just replaced all the gaskets in the motor and have ran it several times since then without any problem. but ill check again since that dang ethanol fuel eats up lines it seems. could have put a hole in a pump diaphram i guess.

[Lockjaw]

On my seadoo, when I put a higher compression head on it, it ran fine under WOT, it had issues at midrange, and seized a piston. Wished I had known I needed to rejet, because that sucker was running good.

You could feel a slight stumble.

Wonder what would happen if you did a fuel cut when running where you have the problems and pulled plugs to see.

[south599]

That might be possible i just hate the backwash that comes over the back when i cut before Im off plane. but thats def something to try after the primer/bulb check.

[Lockjaw]

Deflate a basketball, stick it down in the plate and then pump it up, that will help a lot. That is what I did to on my basshawk when I hung a 200 Venom off the back.