zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage....he

[phatmanmike]

1976 merc 1150 inline 6<br />1986 bonito 16 foot center console boat<br />700 pounds dry, 1700 loaded<br />21 pitch prop<br />no tach!yet<br /><br />took out in gulf today for trip, 15 miles each way. boat went through (2) 6 gallon tanks, then i refueled and used another gallon. 13 gallons total for 30 miles round trip, 2 miles each way was idle speed only, the rest was in the gulf at half throttle (slowest speed possible to plane boat)<br /><br />at this average, i only got a lil over 2 miles a gallon, and it wasnt even CLOSE to WOT! what gives? maybe im too rich. would my mixture screws have anything to do with this, or are they just idle mixtures only.<br /><br />boat is light weight for this motor, and boat speed caculator says i should be able to hit 59mph at 5500rpm with ideal conditions.<br />2 adults in boat, 13 gallons of gas, 1 group 29 battery.<br /><br />anybody have similar setup?<br />zmoz, achris, chris1956?........

 

[DJ]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

2 MPG is not unheard of. The "slowest speed able to plane" may NOT be the most efficient for your rig. The engine may have been on the edge of lugging. That is a very inefficient mode for an outboard to operate.

 

[tmcalavy]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

How does this compare with fuel efficiency before you redid your bulb/fuel line plumbing? Or, are your fuel pumps working properly? Is is just sucking all the gas it can consume or are the fuel pumps doing their job to regulate flow? Just a thought...they can be fuel hogs though, but still great motors.

 

[ZmOz]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Welcome to the wonderful world of inlines. My 16' Glastron with a 1500 gets 2mpg on a good day. Silly me, I thought the 6 gallon tank it came with would be plenty for the day...

 

[DJ]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Six gallons=one day? Now that is funny.

 

[achris]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Once you're off idle the mixture screws are out of play, you're running on main jets. Did you check the main and vent jet sizes when you had the carbs apart? For that engine they should be <br /><br />Main : 0.072<br />Vent : 0.092<br /><br />for altitudes from sea level up to 2,500ft.<br /><br />The sizes are stamped on the jet itself.<br /><br />Chris...........

 

[ZmOz]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Originally posted by DJ:<br /> Six gallons=one day? Now that is funny.

Yeah, it's a good thing nobody warned me before I bought a boat, or I probably wouldn't have. <br /><br />phatmanmike - make sure you have the right prop, I was getting LESS than 2mpg with old, slightly bent prop. Then I got a new prop of the same pitch and gained about 1mpg.

 

[phatmanmike]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Originally posted by tim Mc:<br /> How does this compare with fuel efficiency before you redid your bulb/fuel line plumbing? Or, are your fuel pumps working properly? Is is just sucking all the gas it can consume or are the fuel pumps doing their job to regulate flow? Just a thought...they can be fuel hogs though, but still great motors.

i still havent figured this one out yet... fuel pump is brand new as is all the inerds of the pump, diaphram kit and all fuel lines new too. i DID notice fuel slowly dripping from the BOTTOM screw of the top carb. the screw directly underneath it, surrounded by "brown paint" . what is this stuff and whats that screw for<br /><br /> tried it with and without fuel bulb. nothing<br /><br />tried it with and without clear inline fuel filter, nothing<br /><br />after both tanks ran empty, i had to get out and walk to shore and carry the tank to a gas station, bought 5 gallons of gas and mixed my oil at 40:1( wallmart super tech oil). AFTER this, we had about 2 miles to go back to the ramp, boat ran great the whole time.<br /><br />all day today it would run fine untill the bulb collapsed. i vented the tank VERY well. i even removed the vent completley. it would just slow down and stumble, very quickly. VERY FRUSTRATING <br /><br />maybe i had crud in the tanks, i dunno. i didnt really run it for too long after the new gas. maybe ill see what i can figure tomorow.<br /><br />please add any and all ideas for me, and thanks for ALL the WAY QUICK responses.<br /><br />m ikey

 

[andrewkafp]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Even my little 50 4cyl gets between 5-7 MPG..Looks like I'm too poor to be a petrolhead.

 

[Chris1956]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Mike, Unfortunately these motors use some fuel. However I think your motor (in this case) was using more fuel than it should. The brass plug (with the brown sealer) on the bottom of the carb allows access to to the fuel atomizer(the brass tube with the pinholes in the center of the carb that connects to the black plastic venturi). If this is dripping, it obviously increases fuel usage. I wuld check all the plugs in the carb for this issue. Also, make sure all plugs are firing at idle. I would expect you would use 10-11 gallons of fuel at cruising speed for the same 30 mile trip.

 

[LubeDude]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Im siding with DJ on this one. You just were not running in that "sweet spot". Dont expect a lot better though.

 

[stant1man]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

I dont think i like the sound of this, thats real harsh fuel consumption Mike! Has this just started to happen or is it the old reality kicking in p<br /><br />Is a 21 pitch prop not a bit over the mark for your boat, i hear these engines are most efficient in the high revs, maybe it was a little too much while you were carrying a load, you should get a tacho m8y and see what rpm your hitting @ WOT.<br /><br />P.S.-Im learning p<br /><br />Stan..........

 

[Mercury140-I6]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

I have a 1979 140 inline 6 on a 16 foot Glastron (96). When I am at the Sea Fair Hydro Races and idleing all day it burns about 12-14 gallons a day gallons a day and I only have a 16 gallon tank.<br /><br />Best economy I can get is right about 4200 RPM. the sound of the motor changes and itsounds like it's not working as hard and is kinda free wheeling it even though I know it's not.<br /><br />Craig

 

[JasonJ]

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

Re: zmoz, achris, chris1956, anybody with an inline merc....real bad gas usage..

I get my best economy at around 4000 as well. I do get better economy than you do, I think I get around 4 or 5 mpgs, I have never figured it out to be honest. I just keep plenty of gas in the tank and don't worry about it. I used to run at a lower rpm, around 3200 rpms, and have since found that it makes a certain sort of gravelly sound up to a certain rpm range (3600-3800), and if I go just past that gravelly sound it suddenly sounds smooth (about 4000), I get noticebly better economy. Beyond that and it goes downhil again. Experiment with the sound, all the Merc inline sixes make that gravelly sound up to a point then smooth out. Just past that transition is the covetted inline sweetspot...