Not running right

[cusoak]

I have a 1995 Johnson 90 hp outboard. Early this summer it developed a problem, when going at full throttle it will run ok and then just die down and stop. Sounds like some one turned off the fuel to the motor. It will start back up with no problem. If run at about half throttle it will run fine
This did not happen all the time.
Not it does happen all the time and the other thing is that at full throttle the boat will not get up to top speed.
Also now it will not idle hardley at all.
One of the things I tried was that when it was trying to die at full throttle I was pumping the bulb to see if I could get it more gas.
That did not help.
Any suggestions on how to figure out what is wrong.
Is there some way I can check the fuel pump to see if it is bad.
Thanks Jeff

 

[rothfm]

Re: Not running right

Begin your troubleshooting at the basics. This could be many things:

Run it on muffs, or better yet-in a barrel. Monitor head temps with an IR gun (harbor freight or similar) to be sure your cooling properly. A strong tell-tale stream only means water is "bieng presented to" the block-It doesnt mean its flowing correctly. You should be somewhere in the range of 140-150 appx. Also ground the heads(2) over-temp connector to be sure your over-temp alarm is working correctly. Also when running at speed, and the issue occurs, check the head temps.

If Temps seem ok, Do a compression test- See the sticky about it. Ensure all are good, and within 10% of each other.

Next: Spark....Get a spark tester, or make one--see the sticky about monitoring spark to ensure they are strong, and in correct time. Again, may be necessary to view while testing at speed. Sometimes electrical components break down at higher speeds/tempatures/stresses.

Fuel: Check all connections, clamps for leaks/air. If this motor sat for any lenght of time, a carb rebuild kit is probably in order.

 

[HenryB]

Re: Not running right

If you can, use an auxiliary gas can to eliminate fuel tank problems. Sometimes a piece of plastic pickup tube will break off and at plane the fuel level is below the pickup tube and stall. As the boat settles the fuel rises to the level of the broken piece. The motor will run until the fuel level is so low that fuel is not picked up.

Also, a plugged up vent will cause problems. Run with the gas cap open to see if the problem goes away.

 

[cusoak]

Re: Not running right

rothfm.
What is the sticky you refer too.
Not sure what you are talking about.
Someone told me about a problem that ocurrs with todays gas and some sort of build up that causes what I am describing. Littile balls that clogs up the fuel system.
Jeff

 

[rothfm]

Re: Not running right

rothfm.
What is the sticky you refer too.
Not sure what you are talking about.
Someone told me about a problem that ocurrs with todays gas and some sort of build up that causes what I am describing. Littile balls that clogs up the fuel system.
Jeff

See the link: http://forums.iboats.com/johnson-evinrude-outboards/top-secret-file-updated-8-1-2012-a-299680.html

Stickys are entries that the mod's post that cant be altered, and deemed such good information-they post for all to use. Usually they are at the beginning/front of a forum. This sticky is also called "top secret"...Give it a look, there is lots of good things in there.

 

[cusoak]

Re: Not running right

Up date on motor
I found that the roller on the throttle cam lever was bad, the outer ring was gone . Took carb off to rebuild and found to be clean onthe inside. Also found a roller the the linkage that was half worn out.
Ck compression and had 105 psi on all cylinders. Bought a spark tester and set it to 1/2" and tested. Spark jumped like crazy.
So I tried to start and it would start but not idle. when pulled back to idle it would die. Checked timming and found that it to be out of time. not at 28 degrees. Not sure at what speed it should run at to be in time if that makes a difference.
I read my manual on timing and seems as thought you need a tool to do it. I could not find where it said how to change timing.
Is there a simply way of doing the adjusting on the timing.
Jeff

 

[cusoak]

Re: Not running right

I was wondering if some one could tell me how the copper tube that runs out of the water pump and goes to the engine block.
Is attached and sealed where it goes in to the block.
I have rebuild the water pump and now after installing the lower unit back on I get water leaking around where the two units connect together.
I also found that the 2 thermostats are stuck open.
Any advice would be helpful.
Jeff

 

[cusoak]

My 1995 johnston 90 hp motor has 3 cylinders that have 120 lbs of compression and 1 that has about 100.
The motor will start and run on muffs and rev up. But when put in the lake it will not, it boggs down and dies.
I have while running pulled spark plug wires off and on 3 of the cylinders that make a difference but on one it does not. It seema that that cylinder is not firing. It is the one with not so good compression.
Any ideas on what might be going on,
Thanks Jeff

 

[jakedaawg]

Time to pull the head and have a look see.

 

[fireman57]

One cylinder is definitely low. You might take three different readings and make sure they are right. If they come out okay it sounds like you have a bad coil on the cylinder that makes no difference.