low power on 1985 Johnsone 90hp V-4

[Rbsgfd578]

First off, I am new to posting on this board but have read it for a while and have gotten some gret info from here.<br /> My problem is I have a 18' Bonito center console with a 1985 Johnson 90hp V-4..Motor starts,idles,and runs good,no skips,missess,or funny sounds.The problem is that it is real slow out of the hole and takes forever it feels like to get up on a good plane. At WOT its only turning 3000 rpms.It just feels like it should be getting alot more power.<br /> The only work I have had done to the motor since I got it was 1 coil was bad and had it replaced and carbs were cleaned real good..Im runnin 50:1 mix, has new Autolite plugs gapped at 40(friend said the plugs are the problem because autolites are junk??)My compression is 120 on all 4..The other 3 coils were checked and had real good fire.<br /> Any help is greatly appriciated..

 

[Goodoleboy]

Re: low power on 1985 Johnsone 90hp V-4

Welcome to the forum!<br /><br />I agree with your friend. Welt sorta autolites are ok in 4 stroke engines.<br /><br />You should have champion L77J4 plugs.<br /><br />Good Luck!

 

[Rbsgfd578]

Re: low power on 1985 Johnsone 90hp V-4

Thank you Goodoleboy..I meant to also ask if there is anyway to add a temp gauge or high temp alarm to this motor,because fo some reason it doesnt have 1 and the 1 thing im scared of on earth is overheating it.It appears the powerhead may have already been rebuilt because it has 2 newer heads and head gaskets..

 

[Goodoleboy]

Re: low power on 1985 Johnsone 90hp V-4

You do have an over heat alarm. Its the horn thats inside your control box. <br /><br />You can test this horn to see if its working correctly.<br /><br />Look on the head and you will see a tan colored wire comeing out of a heat sensor.<br /><br />I check mine by takeing a sewing needle and just stick into the wire just back of the sensor. With key on and the use of a jumper wire touch needle and an unpainted bolt head.<br /><br />Horn should sound off continously, as long as its grounded out.<br /><br />Good luck!

 

[Rbsgfd578]

Re: low power on 1985 Johnsone 90hp V-4

Thank you again very much you have been a great help.Guess tommorow I gonna head out and get me some new plugs and try again..I suppose the gap is right at 40?I have seen other people say it should be 30- 35..

 

[Goodoleboy]

Re: low power on 1985 Johnsone 90hp V-4

Manual calls for .040 ! <br /><br />The new plugs wont be gaped at .040, You will have to set them.<br /><br />Good luck!

 

[Rbsgfd578]

Re: low power on 1985 Johnsone 90hp V-4

Goodoleboy, sorry to bother yo again but by chance is that plug # you gave me(L77J4)the same as a L77JC4? Also I made a mistake in the year of the motor it is an 84 instead of an 85, is the gap still 40 as well.Im getting ready to order me a Seloc manual today for the motor so I can quit having to ask such dumb questions all the time..<br /> Also that you very much for the help you have already given.

 

[Marc J.]

Re: low power on 1985 Johnsone 90hp V-4

Not to interrupt, but I will help too. That's the plug Goodoleboy is referring to. If your motor is VRO equipped, the QL77JC4 or QL82C is recommended. If it isn't, any of the three will work well. Napa is a good place to get them. The Seloc manual is OK, but the OMC factory manual is better. Your local library may have the Seloc. <br /><br />Have you seen your motor turn higher rpms? It could be several things holding you back. Your throttle cable may be misadjusted, you could be way over-propped, or the fuel may be restricted somehow. Your tach should be on "6" and your butterflies should be exactly horizontal at WOT. That's a rather big boat for your motor. A 13.5 X 13 or 13.5 X 15 prop would probably be close to what you should be running. Your motor will live longer if it's propped to turn 5600-5900 rpms at WOT. <br /><br />I hope this helps.

 

[Solittle]

Re: low power on 1985 Johnsone 90hp V-4

If you are maxed at 3,000 rpm I bet you have one or two cylinders not firing. Start it up on the muffs. Take a insulated pair of plyers and remove a plug wire while it is running. If the engine stumbles then the cylinder is firing. If nothing changes you need to check further to find out why.

 

[Rbsgfd578]

Re: low power on 1985 Johnsone 90hp V-4

Thank yall very much..I just had the motor serviced for a coil that was bad,he checked the other 3 and the were firing good..I was just wondering if it was the plugs,because it ran alot better before the coil went out and I changed the plugs..Also the gap is still supposed to be 0.40 isnt it.Ive heard other people say that if you use anything but champion plugs in those motor they will run like crap..<br /> I will check into all the above and I thank you for all your help.