Johnson 90HP - no power

[fattypackard]

just got this boat for a good deal. boat is in great shape....motor, not so much...

its a 1981 Johnson 90hp V4
sounds good on the hose. idles perfect in the water. starts right up.
pushes the boat MAYBE 5 mph. no power at all.

did a compression check. i am assuming my gauge is accurate and i did the check correctly. based on that my readings were Top right cylinder - 60 psi....top left cylinder - 60 psi... bottom right cylinder - 90 psi...bottom left cylinder - 90 psi...

no i know thats not good. all 4 should be around 115, correct?

i spoke to the previous owner, he claims he's been running it and its a good motor. and the ignition packs may be bad. would the ignition packs cause such a big power loss?

also, something else i noticed is that when the motor is running, the bulb is NOT hard. it is soft and squishy. ideas?

should i start looking for rebuild parts....
or a different motor...

 

[kenmyfam]

Re: Johnson 90HP - no power

Basic health check to begin with.
Compression (seems low right now but check again with a different tester if you can to compare)
Spark
Fuel delivery
Spark plug condition.

Could be one or many issues. The results you get will determine what advice everyone gives from there.

 

[fattypackard]

Re: Johnson 90HP - no power

ok, tomorrow i will check the spark first. then pull each wire and see if one or more of the cylinders affects it while running.

also, the bulb is NOT firm at ALL when running.

i will do some test tomorrow and update....

 

[kenmyfam]

Re: Johnson 90HP - no power

Compression should be above 100 psi and within 10% of each other. Testers vary so checking with a different one for comparison is important.
Good Luck and post back.

 

[Barnacle_Bill]

Re: Johnson 90HP - no power

Bulb is not suppose to be firm while running. There is fuel flowing thru it.

 

[fattypackard]

Re: Johnson 90HP - no power

so when the engine is running at idle. the bulb has NO pressure.
also, when i squeeze it, nothing happens as far as rpm etc

 

[kenmyfam]

Re: Johnson 90HP - no power

Does it just have no pressure or is it collapsing ???

 

[fattypackard]

Re: Johnson 90HP - no power

no pressure at all. it must be collapsed because there is NOTHING to even squeeze.

however the engine runs perfect at idle and slow speeds.

just no power at all. cant go past 5 mph. the boat will not plane.

oh, and all 4 sparg plugs are black (fouled?)

again, i'll do some test in the morning and update...

 

[Evinrude Boater]

Re: Johnson 90HP - no power

How many rpms is the engine achieving at wide open? Is the choke closed or stuck?

 

[kenmyfam]

Re: Johnson 90HP - no power

no pressure at all. it must be collapsed because there is NOTHING to even squeeze.

Is it like a vacuum is flattening the bulb ???
Is the tank vented ???

 

[bktheking]

Re: Johnson 90HP - no power

Sounds like you are running on 2 cylinders, check grounds to the powerpack and wiring, check for spark, swap powerpacks if you are missing spark on a bank, if spark appears you may have a bad pack.

 

[emdsapmgr]

Re: Johnson 90HP - no power

The fuel hose bulb will get rock hard when priming it first thing in the morning, for a cold start. Once running, the bulb goes somewhat soft and will stay that way the rest of the day. This is normal. If the bulb collapses, you have a fuel restriction in the line. The compression on the two top cyls is very low and may well affect how it runs. Normal is around 100. You need to check both head gaskets on the top cyls-not real expensive, but could be your problem. When the heads are off, you can inspect the cyl walls and pistons for scuffing (aluminum transfer) and cracked rings. Also, the top carb that feeds these cyls may have debris in the jets, causing a lean condtion to both top cyls-and the consequent low compression readings. You may want to pull the top carb apart and visually check the jets and blow out the internal passages with an aerosol carb cleaner. Checking for good spark on all 4 plugs is a good idea.

 

[fattypackard]

Re: Johnson 90HP - no power

thanks for all the ideas folks! i am going to run out and check all of those things in a bit. will let you guys know what i find out.

 

[fattypackard]

Re: Johnson 90HP - no power

GOOD news!
i tested the compression with a new gauge.
110 on all 4 cylinders.

i checked the spark, top two cylinders do NOT have spark, bottom two do.
so i am thinking the power packs are bad on the top two.
the RIGHT TOP power pack is DEFINITELY bad. the orange wire is broken in half.

i also checked the bulb, before starting, i squeezed it and it doesnt build pressure, but the bulb is cracked and crappy. so i will get two power packs and clean the carbs and put new fuel lines/bulb and hopefully it will run like a champ.

will update after all that. thanks for all the help guys!

 

[kenmyfam]

Re: Johnson 90HP - no power

GOOD news!
i tested the compression with a new gauge.
110 on all 4 cylinders.

i checked the spark, top two cylinders do NOT have spark, bottom two do.
so i am thinking the power packs are bad on the top two.
the RIGHT TOP power pack is DEFINITELY bad. the orange wire is broken in half.

i also checked the bulb, before starting, i squeezed it and it doesnt build pressure, but the bulb is cracked and crappy. so i will get two power packs and clean the carbs and put new fuel lines/bulb and hopefully it will run like a champ.

will update after all that. thanks for all the help guys!

Sounds like you are on the right track. My suggestion is not to buy the "cheap" bulb. Worth the extra $$ for the good one. Compression sounds good now.
Keep us all posted.

 

[fattypackard]

Re: Johnson 90HP - no power

ok another question, to make sure the part i am refering to is the power pack.

correct me if i am wrong, which i may be.

there are 4 power packs on my motor correct? one for each cylinder.
bolted onto the front of each cylinder. with a black ground wire and an orange power wire and the spark pluf wire coming from it?

let me know if that is the power pack or something else. thanks!

also, my motor number is J85TLCSA....i couldnt find the parts on boats.net...

 

[kenmyfam]

Re: Johnson 90HP - no power

Best thing to do is for you to use this link to identify what you are looking at. Plug in your motor make, HP and year. match it up to the model number and select what you need. You will se the parts diagrams and the part identification.
J85 would signify an 85hp to me on the number you posted.

http://shop2.evinrude.com/ext/index.aspx?s1=bf6ad09c53cead335fcfd8a6471c0f7f

 

[mikesea]

Re: Johnson 90HP - no power

you have 2 powerpacks FOUR COILS,probably the coils are your problem,be sure ALL grounds are clean,all connections to the sparkplug as well,often the spring connector to the plug will rust,causing bad connection,coils can be swapped around to test on cylinders that are firing,your eng probably has the connector that the small wire on the coil has a pin,you can push it through (after disconnecting the plug connection)with a needle nose pliers,you might also want to spray wd 40 to help it slide through the connector.most coils problems are connection/ground related,some coils have a seperate ground wire some have a copper band that connects to the block upon securing,dissimiliar metals ,especially like copper and alum can cause corrosion therby preventing a solid ground,report back with your result

 

[kenmyfam]

Re: Johnson 90HP - no power

Your model # J85TLCSA equates to a
Johnson
85HP
Power trim and tilt
Electric start
20 inch shaft
1980 model

Hope this helps.

 

[fattypackard]

Re: Johnson 90HP - no power

yea, the coils must be what i am talking about.
there are four, one on each cylinder.
they are rectangle, with a hard gel looking substance on the outside. with two wires coming out of the "gel". one is a black ground wire that is connected to the block. another is an orange wire going to the ignition harness.

on the top right cylinder, the orange power wire is broken, so i know that coil needs to be replaced. so in order to find out if the top LEFT coil is bad, i can simple plug that coil into the bottom cylinder to see if it sparks?

thanks again!