84 115 Johnson running problem!!! ARGGG

parrisw

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Ok, this problem has only risen since I did a bunch of work to the motor, it ran fine before, I replaced the old VRO pump since it was over-fueling #4, I put in a regular fuel pump, and at the same time I put in a spin on water separating fuel filter, and replaced the thermostats as well. When I first ran it after that, it was a ***** to start and ran very poorly, wouldn't idle and sounded like it was misfiring, was running on muffs, the overheat alarm also went off, so I shut it down and went and borrowed my FIL's box to run the motor in that way, I put it in the box full of water, now it started great and ran fine and never overheated! So I thought all was well with it, and left it for a month, so today I wanted to take it out to run it in the lake and make sure it was fine, so same thing happened today, was really hard to get going, it would fire then die, did that probably 12 times until it would keep running, and it was running rough, so I let it idle for a few minutes, seemed to smooth out a little, so I tried to take off, well, no power wouldn't get on plane. So I just fired up my kicker and fished a little, about 15min later I thought I'd try to start the big motor, it fired as soon as I touched the key and idled great, so I tried to get on plane, it did and ran fine, after a minute it powered out and had no power, I backed off the throttle, 10s later it ran fine again, lots of power would run up to just below 5krpm, I backed out and cruised at 3k, then same thing again, powered out, I backed out of it, and again would smooth out and run fine again, so it will just keep doing that cycle, so I just stopped trying before I fried something, and went home.

I have not done the carbs or plugs in this yet, I know I should, but it ran great before all this work.

Thanks

Will
 

kenmyfam

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Re: 84 115 Johnson running problem!!! ARGGG

What pump did you put in ??? Should have been around a 1982 era replacement premix pump to replace the VRO. You did put oil in the tank ???? eh.
 

parrisw

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Re: 84 115 Johnson running problem!!! ARGGG

What pump did you put in ??? Should have been around a 1982 era replacement premix pump to replace the VRO. You did put oil in the tank ???? eh.

Ya, its the pump that bolts to the block, and takes the pulse through the hole in the block, yes I premixed the gas, I was premixing before I took the VRO off.

Oh, I'm using a external 20L tank, and it was about 1/4 full, I guess a remote possibility is that it was sucking air?? Don't know.
 

kenmyfam

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Re: 84 115 Johnson running problem!!! ARGGG

2 connection pump or 3 connection ???
 

emdsapmgr

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Re: 84 115 Johnson running problem!!! ARGGG

Check the ignition for spark with an inductive timing light when the engine warmed up and is running under load. Any weak ignition system component will run fine when the engine is cold and tend to break down when the engine reaches normal operating temps. If the spark checks out ok on all 4 wires, then go back to the fuel system.
 

parrisw

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Re: 84 115 Johnson running problem!!! ARGGG

Check the ignition for spark with an inductive timing light when the engine warmed up and is running under load. Any weak ignition system component will run fine when the engine is cold and tend to break down when the engine reaches normal operating temps. If the spark checks out ok on all 4 wires, then go back to the fuel system.

If ignition was breaking down when hot, don't you think it wouldn't correct itself till it was cold again, it only acts up for maybe 15-20s then its fine again for another 30s, its like the carbs are starving or something. And this problem is only since working on the fuel system.
 

kenmyfam

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Re: 84 115 Johnson running problem!!! ARGGG

Thanks. But that is the exact same pump as mine, just a different impulse location, can't see that being the issue.

Unless it is not getting enough pulsage
 

kenmyfam

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Re: 84 115 Johnson running problem!!! ARGGG

Did the old VRO pump use a pulse line ??
Have you checked the output of the new pump ???
 

parrisw

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Re: 84 115 Johnson running problem!!! ARGGG

Did the old VRO pump use a pulse line ??
Have you checked the output of the new pump ???

Yes the old vro had a pulse line. it had a nipple that was screwed into the block, I took that nipple out and thats where I mounted the new pump, I can take a pic if you like. no I didn't check the output of the new pump, how should I do that?
 

parrisw

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Re: 84 115 Johnson running problem!!! ARGGG

Here is a few pics.

P1000102.jpg


P1000101.jpg


P1000100.jpg
 

kenmyfam

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Re: 84 115 Johnson running problem!!! ARGGG

Yes the old vro had a pulse line. it had a nipple that was screwed into the block, I took that nipple out and thats where I mounted the new pump, I can take a pic if you like. no I didn't check the output of the new pump, how should I do that?

Run the pump output line into a container and crank it over. Have the muffs on to conserve the water pump unless the motor is in the water already. Pull the lanyard so it will not try to start. measure the amount pumped out in a given time frame (30 seconds is good) and do the math as to what GPH it is pumping. Remember that you are only at around 300 RPM when cranking.
Pump should produce continuous strong spurts. If the spurts taper off during the cranking then there is an issue.
What part number pump did you use ??
 

emdsapmgr

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Re: 84 115 Johnson running problem!!! ARGGG

When the engine dies, what do the plugs look like? Are they wet or dry? Do all of them look the same? Hard starting can be related to the primer solenoid. Is the red lever on that solenoid parallel to the length of the solenoid during normal operation? Did you pull the primer hose of the top carb hose barb and check to see that fuel comes out when the key is depressed?
 

parrisw

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Re: 84 115 Johnson running problem!!! ARGGG

Run the pump output line into a container and crank it over. Have the muffs on to conserve the water pump unless the motor is in the water already. Pull the lanyard so it will not try to start. measure the amount pumped out in a given time frame (30 seconds is good) and do the math as to what GPH it is pumping. Remember that you are only at around 300 RPM when cranking.
Pump should produce continuous strong spurts. If the spurts taper off during the cranking then there is an issue.
What part number pump did you use ??

Ok, I'll try that, I can't remember the part number I used.
 

parrisw

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Jun 8, 2009
Messages
985
Re: 84 115 Johnson running problem!!! ARGGG

When the engine dies, what do the plugs look like? Are they wet or dry? Do all of them look the same? Hard starting can be related to the primer solenoid. Is the red lever on that solenoid parallel to the length of the solenoid during normal operation? Did you pull the primer hose of the top carb hose barb and check to see that fuel comes out when the key is depressed?

The red lever is unchanged, it does work, when it does start, when I push the key the motor RPM picks up.
 

parrisw

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Jun 8, 2009
Messages
985
Re: 84 115 Johnson running problem!!! ARGGG

Run the pump output line into a container and crank it over. Have the muffs on to conserve the water pump unless the motor is in the water already. Pull the lanyard so it will not try to start. measure the amount pumped out in a given time frame (30 seconds is good) and do the math as to what GPH it is pumping. Remember that you are only at around 300 RPM when cranking.
Pump should produce continuous strong spurts. If the spurts taper off during the cranking then there is an issue.
What part number pump did you use ??

Well looks like you hit the nail on the head with this one. I pulled the out line off the pump, stuck the line into a container, pumped the bulb, yup solid fuel coming out, crank the engine, well, lets just say I can pee harder then it came out of that pump, it had just a slight dribble.
 
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