85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

[ppjmb5]

JUST PICKED UP A 1979 85 HP JOHNSON AND PUT IT ON MY 15FT TRI HULL USE TO HAVE A 60 ON IT THAT DID ABOUT 25 MPH<br /><br />SO I FIGURED THIS WILL BE GREAT THE GUY I GOT IT FROM SAID HE SPENT $600 HAD IT ALL TUNED UP SO I FIGURED I WAS GOOD TO GO <br /><br />PUT THE MOTOR ON, DROPPED IT IN THE WATER AND THIS IS WHAT HAPPENED ;<br /><br />1) WOULD ONLY DO ABOUT 17 MPH (WHY)<br />2) BURNNED THRU A 6 GALLON TANK OF GAS IN ABOUT 15 20 MINS ( <br />WHEN I RAN OUT OF GAS I SWITCHED TANKS AND I RE STARTED IT ,ALL THE TEETH ON THE STARTER BLEW OFF SO I WAS OUT ON THE LAKE WITH OUT A PADDLE ( BAD MISTAKE I KNOW) <br /><br />A BUDDY OF MINE SAID A DIFFRENT PITCH PROP MIGHT DO IT HE KNEW OF A GUY THAT COULD ONLY DO 12 AND ONCE HE GOT A DIFFRENT PITCH PROP HE WAS DOING 45 MPH (THATS KIND OF HARD TO BELEIVE) <br />BOATS IS A 15FT FOUR WINNS CATALINA RATED AT 1100 LBS PEOPLE LIMIT 825 LBS WITH A GOOD 85 HP V4<br />HOW FAST SHOULD IT BE GOING ON AVAERAGE ? <br />PROP IS A 13 3/4 12 PITCH I ALSO HAVE 13 3/4 15 PITCH ARE THESE THE RIGHT PROPS? OR DOES IT SOUND LIKE ENGINE PROBLEMS I CANT BELEIVE HOW FAST IT SUCKED GAS NEVER SEEN ANYTHING SUCK GAS LIKE IT<br /><br /><br />ANY HELP I WOULD APPRECIATE IT PLEASE <br /><br />SO DOES ANY ONE HAVE ANY TIPS ON WHAT I CAN DO <br />PLEASE!

 

[JasonB]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

I have a '76 Johnson 85hp on my 15.5' Glastron Tri-hull and I can run nearly 40. With a full fishing load and 400lbs of people I can still hit 35-36. I can run hard for a couple hours on 6 gal.<br /><br />I would suspect something funny about the prop and make sure all cyls are firing. I run a 13 1/4x15 for heavy loadsor a 13 1/4x17 when by myself for a bit more speed. <br /><br />I have had the power pack go bad on me before and drop a cylinder and the boat would run similar to what you are describing. The carbs are also a bit finicky to get synced up. Is it spitting fuel out of the carbs when running? These are thirsty engines, but not that thirsty.

 

[Bass Runner]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

sounds like you have a needle and seat leaking by, it will run good at idle and come out of the hole good but then it wont wind up, take the silencer off the carbs and pump the fuel to the motor with the primer bulb and see if the carbs overflow if so get some kits (about $15 each) and rebuild the carbs, check the compression should be around 125 + or - 5 in each cyl, i have even seen them down about 90 if they all are close to that and still run good. Your problem is "not" the prop, if anything with that motor running right you will be underproped. check it out. also check the fire at the plugs. pull them and ground to the block fire should be blue and strong.

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

thsnks guys ill try that ,the guy i got the motor off of said they just rebuilt the crab but thats not right ill check it in the morning all cyl our firing each cyl is running between 1600 to 1800 rpm at low idle couldnt check it at high idle only have hand held digital tach .<br />so if it is leaking thru the carb that explaind the gas guzzing but does it also affect it not going over 20 mph? bass runner thats exactlt what its doing will run good at idle and come out of the hole good but then it wont wind up

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

any body got any suggestions why im eating so much fuel and at the same time i cant get over 20 mph????

 

[Bass Runner]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

If you have a carb running over it will eat gas and flood down 2 cyl on that motor, so you only are running on 2cyl thus no power and no top end, did the carb leak when you pump up with the primer bulb? If one carb is leaking fuel it will just sail fuel past the needle and seat as fast as the fuel pump will pump it.

 

[Solittle]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Did you water test the 85 before you paid for it and/or did you get a wty? Sounds like you need to get a complete once over for your motor. You can do it yourself & if you decide to give it a shot you would be doing yourself a big favor by buying the OEM shop manual specific for your motor.<br /><br />By the way the idle is set way way too high. You can damage the gears by shifting at those rpms.

 

[Walker]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Start with the basics. Do a compression test and a spark test on all 4 cylinders. Tell us what you find

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

yes i pumped the primer bulb it was still hard but i can tell fuel was leaking just couldnt see it i did see a small film of gas around one of the gaskets so i took the silencer off and then what the hell i took the carbs off and cleaned them ,put it back together and started it up was running like crap gas just pouring out of the carb i noticed i put the float in upside down so now im getting another gasket kit,plus i got a compresion tester so ill test it and put the carbs back on .ill let you knowwhat happens <br />thanks for all the help guys <br /><br />no i didnt buy the motor yet its from a friend<br />so he said try it out first see if i like it <br />i really need the extra hp so im trying all i can to get it to work (with your guys help)

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

ok going out to try it ill let you know whats up

 

[flech01]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Hey Bass Runner <br /><br />Your link does not work.

 

[Bass Runner]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Originally posted by Bill2127:<br /> Hey Bass Runner <br /><br />Your link does not work.

Here it is web page

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

well i rebuilt the carbs dont see any leaks <br />did compression test two right cyl were at 140<br />two left were at 130 so i took it out for a test ride i still can only do about 20 by myself <br />what could it be it seems that it isnt eating gas as much now but i still cant get it over 20 with just my self on the boat <br /><br />maybee its in the linkage where should i adjust it could be that i feel like im almost there please help

 

[Walker]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Check to make sure the timer base is moving with the throttle. Look at the throttle linkage on the motor and at the top of the linkage very near the flywheel there will be a short link connected to the timer base which sits under the flywheel. Push the throttle all the way forward and see if the timer base is pulled all the way to the stop bolt. The stop bolt is just a screw with a rubber tip on it. You can do this check without running the motor.

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

yes the timer base is moving that littl rubber stop where should that be at <br /><br />i cant figure this out its so frustarting it wont go over 20 i did almost everything evryone told me

 

[Walker]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

Are you absolutely sure the carbs are clean, each and every orifice? There are high speed jets in the float bowls. They are the ones that usually get gummed up and restricted because that's where the last bit of gas evaporates from when motors are left without maintenance.

 

[mike1234tampa]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

I have a 18.5 ft tryhull with a 1975 85hp johnson and I do 37mph WOT GPS with a 17 pitch prop, yes I would say you have the wrong prop, but if that engine ran right, it would be well over 6000 rpm WOT (bad), have a tach?, what RPM are you at, you have good compression, 6 gallons of gas in twenty minutes, 18 gal per hour, my DAD's 32 ft luhrs with twin 318's gets about that, somthing seriosly wrong with that picture, carbs is what I would look at first, thats alot of gas for that engine, I have ownded two 85 hp johnson on boats 18.5 foot, 17 pitch prop is what they both had, I would go with 19 pitch as a starting point on a 15.5 foot, that engine is a work horse, but like I said you need a tach, I see 19 pitch props on Ebay cheep.<br /><br /><br />My last boat was a renken, it had a very flat bottom, 42mph WOT, 5800 rpm, 1970 85hp Johnson

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

my friend paid $600 to tune the thing up he showed me the receipt complete carb re built <br />but i still went and re built them myself yes i took the the high speed jets out and cleaned them too made sure every orfice was clear <br />yes i have a tach i didnt put it on the boat i dont have a harness for it is there a way i can temporey hook up the tach? <br /><br />i heard that the wrong pitch prop really makes a difrance but that much diffrence? i was reading one of bass runner post and he talked about a simular problem with a 70hp that wouldnt getthe speed and stated it was the fuel pump <br />could it be that as well <br /><br />i want this to run so bad its killing me thats all im thinking about latley you guys have to help me bring this baby to life

 

[Bass Runner]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

By the way my motor is a 1974 70hp on a 16' boat with a 80"beam and it will do 50 with 13x19 pitch sst, and it's over reving did you look at the reeds when you had the carbs off? they can get gummed up or the worse sinario is a screw getting caught in one. Did you ever decarb the motor? Unless your boat is water logged it should run around a 17 pitch prop and run around 40mph, get a tach check the rpm, my tach hooks up in the control, a 12 pitch prop is way low unless your boat weighs a ton. The 15 pitch is closer but watch the rpm

 

[ppjmb5]

Re: 85 JOHNSON WILL ONLY DO 12 MPH SUCKS GAS

i got a tch but no harness so is hould get a harness the boat weighs about 1100lbs with people and gear no i didnt de carb it how do you do that? also you stated bassrunner that on your 70 its was the fuel pump how can you tell if the fuel pump is bad so would a diffrence in pitch say from a 15 thats what i have on it now to a 17 would it really make that much diffence