1990 Johnson 70hp w/Video - Chasing My Tail

[Fisherg3]

1990 70hp Johnson 70TLESB
A 2 months ago my motor was running great. Then it began to idle with a terrible but rhythmic shake. But when I had it at WOT it ran smooth but not having a tachometer the only thing I could measure in the difference is speed. My speedometer is digital and gps measured which at its best ran 33kts. It eventually wouldn’t go above 27kts though it sounded the same.

One month ago it began to randomly die at idle after running WOT. It always started right back up. 3 weeks ago I launched started tied it off and ran up my truck. Came down, got in, untied, motor died and I couldn’t get it to start back up again. Ultimately it was a bad cut off switch. But learning as I go. And I seem to be good at doin part replacement jobs throwing new parts and never getting to the issue. Work Summary

Still Need Cutoff Switch and have disconnected the single wire on the power pack that connects to the black and yellow wire.

Finally needed a new starter and it spins the flywheel great now!!
New spark plug wires - not OEM and I believe they are nickle not copper.
New Power Pack
New Control Cables
New Spark Plugs but thought I asked for the Champion QL77JC4 but guy gave me NGK BZ7HS 10 yesterday. Video is from after putting those in. Not sure if this makes a difference.

I two of the fuel line 3 way union connectors had broken due the installing and taking of the carbs. I rebuilt the whole assembly with new T connectors and 5/16 lines. No leaks and primer bulb gets solid

New fuel pump.
New inline fuel filter

I’ve taken off and Cleaned Carbs 3 times and they all have a new gasket, new floats, they are calibrated level but I have issues with getting it to the 3/4 gap when turned upside down. Has a new float, and float valve seat assembly. Each has a new nozzle gasket.
What I do need that fell apart is the Airbox Gasket
*Also - the Orifice Plug that sits behind the drain plug
Of the float bowl on one of them is stuck and found to be mostly gone. What is left is the furthest in portion of the jet so fuel still must travel through the same hole size but again the majority of the Orifice plug is gone. Not sure if this would cause what goes on in the video.
yes I’ve soaked, pinned with wire, sprayed with high volume carb cleaner, and used compressed air to blow out holes.

What the video doesn’t show is it dies. And it’s difficult to start. I have to lift the throttle advance arm at the controls and I have to engage the electric primer

I experienced some bogging in my initial tests last week and pressing in the electric primer Did make it smoothen out. Last night it did make it better but not till after pushing it in for 3 to 4 seconds and only for a minute.

New Gas 50:1 mix (VRO Deleted)
Compression measured Monday at 92 on all three. I read on here that another person was in the 90s and some said it was too low whilst others said for this age and it being 2stroke that it was ok. The other advice i read for the other guy was to test again with a different gauge and this time it read 94 on all 3. Keeping in mind I couldn’t start it so it wasn’t warm. But it’s been super hot here and I measured it when it was over 100° outside temp.

First 2 Videos on the water The motor sounds muffled and echo’y, if you will. I did not hesitate on pushing throttle down or do it slowly. Nor did I pull it back at any given point.

Second two videos detail out what I just now notice about the spark plugs.
Thanks in advance for all the help.

 

[flyingscott]

What is your compression? Spark jump a 1/2" air gap?

 

[racerone]

Cleaned the carburetors 3 times ?----Likely not a carburetor issue then !!----Don't worry about oil at the plug holes.---Don't worry about the sparkplugs.----Compression is too low.----Remove cylinder head.---Easy and a head gasket is cheap.----And does tell tale fitting come off the side of the engine block or off the top of the engine block ??

 

[flyingscott]

That motor sounds like it is running on 2 cylinders

 

[Fisherg3]

What is your compression? Spark jump a 1/2" air gap?

Compression was 92 on all 3 the first check and 94 on all 3 at second check. I can’t answer the jump or gap.

 

[Fisherg3]

Cleaned the carburetors 3 times ?----Likely not a carburetor issue then !!----Don't worry about oil at the plug holes.---Don't worry about the sparkplugs.----Compression is too low.----Remove cylinder head.---Easy and a head gasket is cheap.----And does tell tale fitting come off the side of the engine block or off the top of the engine block ??

Yes because the last week it’s been bogging and when I press in the primer solenoid switch at the key it gets better and everything I read on here says if it gets better it’s the carbs are dirty still.
If I understand your tell tale sign to be the head gasket fitting is off the side of the block. And so I’m changing out the head gasket?

 

[racerone]

There was a service bulletin in 1994 to move tell tale fitting from side to the top of the block.-----Water pump kit 0432955 has the details.

 

[Fisherg3]

There was a service bulletin in 1994 to move tell tale fitting from side to the top of the block.-----Water pump kit 0432955 has the details.

Ok thanks

 

[brodmann]

Instead of using the choke when it bogs down, have a helper try pumping the primer bulb and see if that makes it pick up and run better. Sounds like a fuel delivery problem to me. That might be causing you to drop a cylinder for a second or two. If the "orifice plug" as you call it is all broken up, are you sure there's no pieces of it in the hole? That's actually a jet. The hole goes in through that jet and up through the bottom of the bowl. See if you can fist a wire in and up and run it through a few times to make sure it's clean all the way through. If you spray carb cleaner does it come out into the bowl?

 

[Fisherg3]

Hey Brodmann. Thanks. So I had my boy squeeze the primer bulb while running and that didn’t change anything. In fact the bulb feels fairly solid. I can squeeze it but it’s not loose.

I know it’s a jet behind that bowl plug screw. Orifice Plug is what the name of it is on the parts ordering diagram is why i called it that. I’ll see if I can stick a wire through it. And get back to you.
Thanks again.

 

[Fisherg3]

Yes because the last week it’s been bogging and when I press in the primer solenoid switch at the key it gets better and everything I read on here says if it gets better it’s the carbs are dirty still.
If I understand your tell tale sign to be the head gasket fitting is off the side of the block. And so I’m changing out the head gasket?

Ok checked out the tell tail and yes it is on the side and bottom. I can change that fairly easy. I just didn’t think that would have anything to do with my current issue.

Went to go see if I could order a powerhead gasket set but the guy said “do you expect it to be like new? 94 consistent compression is good. There’s something else. Maybe coil or stator related.”

 

[jimmbo]

Which Cylinder, is the Fuel Pump getting its Pulses from?

 

[racerone]

The electric primer valve is working as designed.----That means there is pressure from the fuel pump.----Some will argue.----I suggest you remove cylinder head and inspect cylinder walls.----Head gasket is cheap.

 

[brodmann]

The next time you take it out on the water and it has these problems, once you get back home, take the spark plugs out and see if they look the same. If one looks different than the other two, I'd look into that carb again. take out the drain and see if gas is present in all 3 carbs. With the screws out, pump the primer bulb and make sure gas flows out of all 3 carbs. It certainly sounds like a fuel delivery problems to me, or it could be one of the coils is breaking down at high speeds.

 

[Fisherg3]

Which Cylinder, is the Fuel Pump getting its Pulses from?

Im not sure if I know that answer but I do know the pulse tube that goes from the fuel pump to the motor block had a one way valve on the bottom of the motor. I don’t know if this is correct or not, but the fuel pump has an open hole on that has a pulsating air that comes out of it. It’s loud enough for me to hear it despite the sound of the motor and I can feel it if I put my finger on it. I never heard that sound with my last fuel pump. In sounds much like a train steam engine.

Here’s a picture of where the pulse tube attaches down by the shift rod thingy.

 

[Fisherg3]

The electric primer valve is working as designed.----That means there is pressure from the fuel pump.----Some will argue.----I suggest you remove cylinder head and inspect cylinder walls.----Head gasket is cheap.

Ok but I don’t know what to look for on the cylinder walls. I also determined All 3 fuel bowls are filled with fuel. But the “the checking to see if fuel pump is bad is to simply loosen the screws used to attach the pump to the bracket only a few turns. In doing so just one complete turn fuel leaks. But it doesn’t if it’s tight. Just the steam engine sound. Actually my moms old pressure cooker sound.

 

[racerone]

That is NOT a one way fitting at all.-----It is the pulse limiter ( flow fuse ) for the VRO pump.----It should be removed.----And if air leaks out the back of the pump you have the wrong pump installed!

 

[Fisherg3]

Just for the sake of all things I’m not a mechanic. I get

That is NOT a one way fitting at all.-----It is the pulse limiter ( flow fuse ) for the VRO pump.----It should be removed.----And if air leaks out the back of the pump you have the wrong pump installed!

all my info here or on YT. This is my first year so please bear with me. I was told it was a one way valve from the guy at the shop. If I were to remove it then what do I put in its stead? This is a 3cyl calling for 3 hoses on the Fuel Pump. It was hard enough to find this one. All
Of the others say they won’t ship it here.

 

[racerone]

Find a better shop.-----Repeat----It is not a one way valve !!-----It closes if too much air goes through it.----It is a flow fuse to protect the VRO from going " boom " so to speak.----Install a simple fitting.----Get the correct pump or plug the hole at the back.----All easy in my opinion.----I know what a 1990 model 70 looks like !

 

[Fisherg3]

Better shop is an understatement and perceived business idea. No one around here works on motors older than 1999. Ok,

As far as the pump goes there are not any that I can find that mention anything different than another. The ones that look like I need look just like the one I’ve got. They say “does not work on 60° application and this is for a v4 or v6”. If I search for one with my serial number it only brings up the VRO unit. The VRO “replacement” don’t call out my year or model. In fact say it’s only for VRO replacement on “whatever year” and none that are mine. I guess I could plug the hole. With what? Pictures where the air pulses out. Circled in red.