Performance enhancement-Johnson GT 150

DJ_Callahan_27 · 03-11-09, 08:32 PM

I have a 1984 Johnson GT 150. It runs great and flys on the 1984 Pro Craft 1750 bass boat it's on now. But it only gets about 1 MPG of fuel. OUCH.... Is there anything that I can do to improve this? That being said, if I can't improve the MPG what can I do to improve power and speed? The reason I ask is because I'm thinking of putting this motor on a bigger boat. Thanks guys

DJ

Captmikestarrett · 03-11-09, 08:46 PM

Another Great White Hope motor..

Not understanding your question totally.. OK had to read it again.. more power will shorten life of motor.. If it works nice leave it alone..

Capt Mike

DJ_Callahan_27 · 03-11-09, 09:07 PM

Ok, will this motor do alright on a 19' bass boat?

woody · 03-11-09, 09:13 PM

Quote:

Originally Posted by DJ_Callahan_27

only gets about 1 MPG of fuel. OUCH.... Is there anything that I can do to improve this?

Yeah haha, dont run it at WOT(wide open throttle)

~Mark

DJ_Callahan_27 · 03-11-09, 09:27 PM

I don't, I open it up to get on plane then back it down just a hair

bamabassman · 03-11-09, 09:33 PM

you are kidding about the 1 mpg aren't ya? hahaha, as for as pushing a 19 footer, i would think it would depend on the boat for real. it won't do as good as it does on the rig it's on now. and it may shorten the life of the motor pushing something larger. wait for a few others to read this thread and hear what they say ok? i ain't no expert on this.

DJ_Callahan_27 · 03-11-09, 09:48 PM

I wish I was kidding. But thats about what it gets maybe a hair over but less than 1.25 for sure. I'm looking for a 18' or bigger bass boat just for the added room on the deck and storage. Guess I just hoping it will work on a larger boat.

woody · 03-11-09, 09:54 PM

I was just kidding DJ. Actually WOT describes my driving habits.

I'm no motorhead but there are plenty of them here that can help ya out. Just give them a chance to respond.

~Mark

bingham · 03-11-09, 11:32 PM

haha 1.25 or less? if i were you i wouldnt think about getting a bigger boat you already have bad gas mileage!!! id probably try getting it cleaned out or get a new motor!!! just not enuf mileage for me

1FASTLASER · 03-12-09, 08:49 AM

I really think you need to redo your math on paper. If that moto is running as good as you say it is then you should prolly be around 4mpg. 4 is a much more realistic figure. Mow this does depend on how well of a setup you have. I am very familiar with the 1750 hull. I WOULD LOVE to own one. Anyways gimme some figures on how you are running and lemme see ifn I can pinpoint a problem. Are you on a jackplate,do you have a stainless prop,what are your wot rpms and what is real time speed (not speedo GPS speed).........with answers like these I should be able to pinpoint your problem.

DJ_Callahan_27 · 03-12-09, 02:17 PM

I bought this boat last year. Didn't get it to the lake as many times as I hoped to last year. When I bought it the motor wouldn't idle without loading up and would die or you could idle it up to burn yhe excess fuel. I was told to run seafoam through it and change the plugs. After running a 11 gallons of fuel with seaform and changing the plugs it will idle all day now and runs alot smoother. The MPG that I am reporting comes from the former owner of the boat. He also owns an 1989 Pro Craft 1750 with a 150 rude and says it gets about the same. As for speed, I don't have a clue. Speedo isn't working and don't have GPS at this time. Tach is also not working on the boat yet. It has an aluminum 3 blade prop. It does have a jackplate and I think it is the problem, I think that it is set to low but I'm not expert by not means not even close. Laser hope this helps

bamabassman · 03-12-09, 04:50 PM

ok, now laser is gonna sk ya to take some pics. take a few measurements and so forth. LISTEN to him and do EXACTLY what he says ok? he will help you get it set right. follow his directions, and you'll be ok.

zooker · 03-12-09, 05:51 PM

tin prop? thats part of the problem with a tin wheel your spinning alot of rpms, more than you would with a ss prop.. a 150 on that boat will likly run in the mid 60's stock..

laser is on 4 mpg at wot on a carbed moter is about right..

get a stainless prop first and fix the tach..then let us know..

zooker

JB · 03-12-09, 05:55 PM

Quote:

Originally Posted by woody

I was just kidding DJ. Actually WOT describes my driving habits.

I'm no motorhead but there are plenty of them here that can help ya out. Just give them a chance to respond.

~Mark

LOL I can testify that woody is WOT all the time, plus an expert boat handler

I bet we weren't on plane for more than 8 minutes while going from spot to spot on the meat route at brookville lake rofl....he's fast.......

03-11-09, 08:32 PM	#1
DJ_Callahan_27 BassFishin.Com Active Member Join Date: Jul 2008 Location: Southeastern/Ky Posts: 155	Performance enhancement-Johnson GT 150 I have a 1984 Johnson GT 150. It runs great and flys on the 1984 Pro Craft 1750 bass boat it's on now. But it only gets about 1 MPG of fuel. OUCH.... Is there anything that I can do to improve this? That being said, if I can't improve the MPG what can I do to improve power and speed? The reason I ask is because I'm thinking of putting this motor on a bigger boat. Thanks guys DJ

03-11-09, 08:46 PM	#2
Captmikestarrett BassFishin.Com Super Veteran Join Date: May 2006 Location: Accokeek MD Posts: 3,315	Another Great White Hope motor.. Not understanding your question totally.. OK had to read it again.. more power will shorten life of motor.. If it works nice leave it alone.. Capt Mike __________________ Capt Mike Starrett light tackle guide Potomac River http://www.indianheadcharters.com

03-11-09, 09:33 PM	#6
bamabassman BassFishin.Com Premier Elite Join Date: Jan 2008 Location: cedar bluff, alabama Posts: 15,292	you are kidding about the 1 mpg aren't ya? hahaha, as for as pushing a 19 footer, i would think it would depend on the boat for real. it won't do as good as it does on the rig it's on now. and it may shorten the life of the motor pushing something larger. wait for a few others to read this thread and hear what they say ok? i ain't no expert on this. __________________ so many lures, so little time.

03-12-09, 08:49 AM	#10
1FASTLASER BassFishin.Com Super Veteran Join Date: Aug 2005 Location: crossett,arkansas Posts: 2,777	I really think you need to redo your math on paper. If that moto is running as good as you say it is then you should prolly be around 4mpg. 4 is a much more realistic figure. Mow this does depend on how well of a setup you have. I am very familiar with the 1750 hull. I WOULD LOVE to own one. Anyways gimme some figures on how you are running and lemme see ifn I can pinpoint a problem. Are you on a jackplate,do you have a stainless prop,what are your wot rpms and what is real time speed (not speedo GPS speed).........with answers like these I should be able to pinpoint your problem. __________________ Laser's rule with Merc's doing the pushing..........KEEP THE WETSIDE DOWN AND THE DRY SIDE UP!!!!!!

03-12-09, 04:50 PM	#12
bamabassman BassFishin.Com Premier Elite Join Date: Jan 2008 Location: cedar bluff, alabama Posts: 15,292	ok, now laser is gonna sk ya to take some pics. take a few measurements and so forth. LISTEN to him and do EXACTLY what he says ok? he will help you get it set right. follow his directions, and you'll be ok. __________________ so many lures, so little time.

03-11-09, 09:07 PM	#3
DJ_Callahan_27 BassFishin.Com Active Member Join Date: Jul 2008 Location: Southeastern/Ky Posts: 155	Ok, will this motor do alright on a 19' bass boat?

03-11-09, 09:27 PM	#5
DJ_Callahan_27 BassFishin.Com Active Member Join Date: Jul 2008 Location: Southeastern/Ky Posts: 155	I don't, I open it up to get on plane then back it down just a hair

03-11-09, 09:48 PM	#7
DJ_Callahan_27 BassFishin.Com Active Member Join Date: Jul 2008 Location: Southeastern/Ky Posts: 155	I wish I was kidding. But thats about what it gets maybe a hair over but less than 1.25 for sure. I'm looking for a 18' or bigger bass boat just for the added room on the deck and storage. Guess I just hoping it will work on a larger boat.

03-11-09, 09:54 PM	#8
woody BassFishin.Com Super Veteran Join Date: Mar 2008 Location: Jonesville, Indiana Posts: 3,597	I was just kidding DJ. Actually WOT describes my driving habits. I'm no motorhead but there are plenty of them here that can help ya out. Just give them a chance to respond. ~Mark

03-11-09, 11:32 PM	#9
bingham BassFishin.Com Active Member Join Date: Feb 2009 Location: Cottondale, AL Posts: 323	haha 1.25 or less? if i were you i wouldnt think about getting a bigger boat you already have bad gas mileage!!! id probably try getting it cleaned out or get a new motor!!! just not enuf mileage for me

03-12-09, 02:17 PM	#11
DJ_Callahan_27 BassFishin.Com Active Member Join Date: Jul 2008 Location: Southeastern/Ky Posts: 155	I bought this boat last year. Didn't get it to the lake as many times as I hoped to last year. When I bought it the motor wouldn't idle without loading up and would die or you could idle it up to burn yhe excess fuel. I was told to run seafoam through it and change the plugs. After running a 11 gallons of fuel with seaform and changing the plugs it will idle all day now and runs alot smoother. The MPG that I am reporting comes from the former owner of the boat. He also owns an 1989 Pro Craft 1750 with a 150 rude and says it gets about the same. As for speed, I don't have a clue. Speedo isn't working and don't have GPS at this time. Tach is also not working on the boat yet. It has an aluminum 3 blade prop. It does have a jackplate and I think it is the problem, I think that it is set to low but I'm not expert by not means not even close. Laser hope this helps

03-12-09, 05:51 PM	#13
zooker BassFishin.Com Premier Elite Join Date: Jan 2004 Location: denton nc Posts: 13,441	tin prop? thats part of the problem with a tin wheel your spinning alot of rpms, more than you would with a ss prop.. a 150 on that boat will likly run in the mid 60's stock.. laser is on 4 mpg at wot on a carbed moter is about right.. get a stainless prop first and fix the tach..then let us know.. zooker __________________ the godfather.. aml in remission since 7-20-09

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