1984 merc 90hp 6cyl (tower of power) pro's and con's

[edamarino]

and pro's and con's about this motor. seems to run good but has an erratic idle from time to time

 

[444]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

What specifically do you want to know? Mercury made this engine for a LONG time. They are proven, reliable engines. Most common problems they suffer from are from age. So plugged carbs, weakened fuel systems, cracked/deteriorated wiring and the electrical parts only live so long.

 

[Gomer50]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Pros:They run like a bat outta hell when dialed in good.The con:Number 3 piston will go south if she runs too lean and not getting cooled properly.But hey so will every other 2 stroke too.Pretty simple to work on and reliable.Good motor I own a 1978 90hp runs good and loves the gas.If your looking for economy this isnt the one LOL..

 

[79Merc80]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

They're not bad on fuel as long as you keep your hand at about 3500 - 4000 RPM's Here is mine.


RPM ------- GPH -------MPH --------Hous to empty ----------Range -----------MPG
620 ---------1.3 ---------3 ------------13.84 --------------------41.53 -------------2.30
1000---------1.6---------4.5-----------11.25---------------------50.62-------------2.81
1500---------2.3----------6------------7.82----------------------46.95-------------2.60
2000---------3.6----------8------------5-------------------------40-----------------2.22
2500---------4.3---------12------------4.18---------------------50.23--------------2.79
3010---------5.1---------21------------3.52---------------------74.11--------------4.11
3510---------6.1---------26------------2.95---------------------76.72--------------4.26
4000---------7.2---------30.5----------2.5----------------------76.25--------------4.23
4510---------8.8---------35------------2.04---------------------71.59--------------3.97
4820--------11.5---------40------------1.56---------------------62.60--------------3.47

 

[444]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Well mileage depends mostly on the boat it's installed on. My 84 90hp tower of power is on the back of my glastron gt-150 hull which is very lightweight and quick to plane. Fuel mileage when just cruising around at 30mph or pulling a tube at 20 is actually quite good.

 

[79Merc80]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Mine is pushing a 17' Fiberform Waikiki

 

[madgadget]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Love these engines. Had a 140 I6 (later called a 115) on my 16.5ft would often break 50mph on gps!

 

[edamarino]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

well mine is on a 1973 wellcraft airslot. it seems to do about 35mph. but not exactly sure do to no gps, just rough estimate.

 

[jbjennings]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

They're not bad on fuel as long as you keep your hand at about 3500 - 4000 RPM's Here is mine.


RPM ------- GPH -------MPH --------Hous to empty ----------Range -----------MPG
620 ---------1.3 ---------3 ------------13.84 --------------------41.53 -------------2.30
1000---------1.6---------4.5-----------11.25---------------------50.62-------------2.81
1500---------2.3----------6------------7.82----------------------46.95-------------2.60
2000---------3.6----------8------------5-------------------------40-----------------2.22
2500---------4.3---------12------------4.18---------------------50.23--------------2.79
3010---------5.1---------21------------3.52---------------------74.11--------------4.11
3510---------6.1---------26------------2.95---------------------76.72--------------4.26
4000---------7.2---------30.5----------2.5----------------------76.25--------------4.23
4510---------8.8---------35------------2.04---------------------71.59--------------3.97
4820--------11.5---------40------------1.56---------------------62.60--------------3.47

Nice data table! I found it very interesting. I wish I had the same tools to do that with my "new" '98 90hp yamaha, which I'm sure the merc would destroy on top end since the yamaha is just a little 3 cylinder.
Thanks,
JBJ

 

[79Merc80]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

All it takes is a camera (Or pen and paper), GPS speedo, tachometer, and a fuel flow meter. My fuel flow meter includes a tach, hour meter, GPH, and total gallons used. Looks like this.

 

[Chris1956]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Actually I found the L6 motors better on fuel than my newer V6. I moved up to a Merc 135HPV6 from a Merc 1500IL6, and those extra three bbls on the carbs and the extra displacement sucks much more fuel. However, the bottom end power is much better on the V6.

 

[CVX20SPRINT]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

Actually I found the L6 motors better on fuel than my newer V6. I moved up to a Merc 135HPV6 from a Merc 1500IL6, and those extra three bbls on the carbs and the extra displacement sucks much more fuel. However, the bottom end power is much better on the V6.

Really didn't want to hear that.I'm just about to take off a 1500 L6 and replace it with a 150 V6(crank rated).My thinking was that it was almost 10 year newer technology and probably closer to 150 hp,so it theoretically should be a bit better on fuel.

 

[Chris1956]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

You will like the stronger hole shot....doesn't that count?

 

[canoemang]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

I have my 115 I6 On a 1856 Alweld JC, I wish i got as good of gas consumption as that table shows.. I can watch the gas gauge go down at WOT..

 

[CVX20SPRINT]

Re: 1984 merc 90hp 6cyl (tower of power) pro's and con's

You will like the stronger hole shot....doesn't that count?

Yeah definitely a bonus.That and the V6 starts a lot better.Started it on the stand after sitting all winter fogged and it barely rolled over and it was running.The old L6 usually needs a little coaxing when cold.

 

[Luvtohuntandfish]

'84 90hp inline 6cyl merc having holeshot probs. Im thinkin carb probs(has 3 carbs) bogs down in the holeshot 90% of the time n clears up in a minute or so...sometimes longer. Then gets on plane n runs like a raped ape. Need help. Tryin to sell the boat to upgrade to bigger n longer. TIA

 

[flyingscott]

Maybe start your own thread instead of hijacking a 8 yr old thread.