Johnson 90 hp a weird one

[cyclops222]

A J90TLETS motor is a original pump drive motor.
Have you removed each sparkplug to see if it is clean and free of oil and black carbon ? A failing cylinder can act like your engine.
Have you verified that you are using the correct sparkplugs for a NON jet pump engine ?

 

[That old Mercury]

If there is foam inside the cowling -----What does foam inside cowling look like.---Any pictures?

For a 93 model the sound deadening foam looks ok.
Some a little dark stained , no appearence of it falling apart.
If i make it to the boat tomorrow will get a picture. I been busy looking for an invisible coolant leak on Wifes ford focus !
Thats another story in it own lol
Thanks

 

[That old Mercury]

A J90TLETS motor is a original pump drive motor.
Have you removed each sparkplug to see if it is clean and free of oil and black carbon ? A failing cylinder can act like your engine.
Have you verified that you are using the correct sparkplugs for a NON jet pump engine ?

I removed them at the lake when it was acting up. All plugs a little damp and using my remote starter
And a copper wire for ground on all the plugs they were all firing.
They are new and i bought the same type that was in it.
I am assuming the old ones were correct.
I carry every tool i can think of when running a New to me boat.
Only thing i forgot was my multimeter
Thanks

 

[That old Mercury]

Check the reed valves.

I dont have any fuel spitting back out of the carbs .
I was leaving checking them for a last option .
I am doing going to do the cheap check items first.
Thanks for the advice

 

[cyclops222]

You must check what plug number is to be used in that converted Jet Pump to normal prop engine. And install a new set of 90 hp normal prop plugs.

 

[That old Mercury]

You must check what plug number is to be used in that converted Jet Pump to normal prop engine. And install a new set of 90 hp normal prop plugs.

 

[That old Mercury]

Hi
When i pull up parts list for my motor the parts breakdown always shows a foot and prop.
What indicates that it was orginally a jet drive?
Spark plugs that were in it
Champion QL77JC4
I went with exact number but got NGK
Thanks

 

[cyclops222]

The J at the beginning of the model number is for a jet pump drive.
Many Jet pumps were somehow converted to a normal prop drive by D I Y people

 

[racerone]

Are you 100% sure that the J in front is for jet drive.----I thinks a J after the HP is for the jet version !

 

[cyclops222]

Do a web search of both J version #s. If you think we are wrong.

 

[racerone]

I know that the J in front is for JOHNSON.----The E in front is for EVINRUDE.

 

[cyclops222]

You are right about the letter sequences. J.D.Powers lists the Jet drives as
J90JLETS or E90JLETS.
Thank you for correcting me. So he does have a Jet Drive converted to a standard prop drive. Crowley has a listing for both the Jet and standard prop versions.

I am having a bad day I researched with the incorrect # I added the J to both Numbers Sorry for the confusion.

 

[That old Mercury]

You are right about the letter sequences. J.D.Powers lists the Jet drives as
J90JLETS or E90JLETS.
Thank you for correcting me. So he does have a Jet Drive converted to a standard prop drive. Crowley has a listing for both the Jet and standard prop versions.

I am having a bad day I researched with the incorrect # I added the J to both Numbers Sorry for the confusion.

Thanks for the knowledge.
So with it being a jet drive in the past now i have to worry with it being plugged up with mud and sand

 

[That old Mercury]

Thanks for the knowledge.
So with it being a jet drive in the past now i have to worry with it being plugged up with mud and sand

UPDATE
Check temp sensors all showed OL
So none are bad, grounded them all to block and did not hear an over hear alarm.
Checked plugs two lower cyclinders plugs are a little wet.
I probably have the float setting off.
Checked compression , all 4 at 120 psi.

 

[That old Mercury]

UPDATE
Check temp sensors all showed OL
So none are bad, grounded them all to block and did not hear an over hear alarm.
Checked plugs two lower cyclinders plugs are a little wet.
I probably have the float setting off.
Checked compression , all 4 at 120 psi.

View attachment 398544

Also ran motor on muffs cyclinders were too hot to touch.
Tell tell water cold to the touch.
Water coming out propeller cold
Water coming out of ports right above foot was only warm.
Water that i have not noticed before pouring out around the gearshift rod or between lower unit mating surface, so i have to pull lower unit and see if its the tube leaking or what ever it is.
Will put in new water pump. Hopefully the tube is not corroded.

 

[racerone]

Perhaps you are not aware that the water from the tell tale does NOT circulate through the block.----It should always be cool / cold !

 

[That old Mercury]

Also ran motor on muffs cyclinders were too hot to touch.
Tell tell water cold to the touch.
Water coming out propeller cold
Water coming out of ports right above foot was only warm.
Water that i have not noticed before pouring out around the gearshift rod or between lower unit mating surface, so i have to pull lower unit and see if its the tube leaking or what ever it is.
Will put in new water pump. Hopefully the tube is not corroded.

This boat was rewired and temp gauge never got over 100*
This is the only place the water was slighly warm.
I am assuming thermostats clogged and water only circulating through the poppet valves. But the water is leaking bad between the lower unit
Only place water slightly warm

 

[That old Mercury]

Perhaps you are not aware that the water from the tell tale does NOT circulate through the block.----It should always be cool / cold !

On the models even new ones i have owned the water would be warm , i have even seen steam before on other boats i have been behind .

 

[racerone]

The water from the tell tale does NOT circulate through the block !!!!-----If you see steam from the tell tale there are major issues in the cooling system !----

 

[racerone]

It should be easy to figure out what is wrong with this motor.----But I am stepping aside.----Good luck with it.