shoot2thrill
Member
Ive got a 15 gallon tank in my 84 diplomat, its got a 185Merc 3.8L V6. My gas gauge isnt working right....and I was wondering how many hours should I expect a full tank to last??
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How many hours should my tank last??...
- Thread starter shoot2thrill
- Start date
Eaglenva
Member
til it runs empty??? grin
what i did was found a similar boat weight and setup that had specs like at 45 mph it is getting 3.5 mpg. at that rate my 75 gallon tank should last 5.8 hours at high mid throttle. obviously driving style matters a lot so i would cut that way back to like 3-4 hours true driving with the last 30 minutes being near dock. (that is 260+ miles per tank for me). a lot of stop and goes dramaticaly cuts that back.
what i did was found a similar boat weight and setup that had specs like at 45 mph it is getting 3.5 mpg. at that rate my 75 gallon tank should last 5.8 hours at high mid throttle. obviously driving style matters a lot so i would cut that way back to like 3-4 hours true driving with the last 30 minutes being near dock. (that is 260+ miles per tank for me). a lot of stop and goes dramaticaly cuts that back.
Mark
Well-known member
About an hour! Seriously. Outboards burn 1 gallon for every 10 horses at WOT. I/O's only slightly less. At mid range you are looking at an hour and a half tops.
You need to get the fuel gauge working. You can buy replacement pick ups for the tank or a new gauge. There is a good chance it is just a loose wire also. Go trace the wires from gauge to tank.
You need to get the fuel gauge working. You can buy replacement pick ups for the tank or a new gauge. There is a good chance it is just a loose wire also. Go trace the wires from gauge to tank.
daren34
Member
tank
unless it has been replaced you have a 21 gallon tank
you should be able to cruise 4 to 5 hours on that
skiing i would go 3 to 4 and check
fix the guage
you can get a new sender from any marine store (west marine)
your tank is only 12 inches deep
daren
your 3.8 litre v-6 should get good fuel economy
unless it has been replaced you have a 21 gallon tank
you should be able to cruise 4 to 5 hours on that
skiing i would go 3 to 4 and check
fix the guage
you can get a new sender from any marine store (west marine)
your tank is only 12 inches deep
daren
your 3.8 litre v-6 should get good fuel economy
I think I get close to 5 mpg with my 470 (3.7l 4cyl)
I am usually cruising at about 30mph. Occasionaly do a topspeed run and occasionally have to idle through no-wake zones.
I, too, have a 21 gal. tank (I think it is only 6" deep), but I can only get 18 gal. into it before is spurts out the vent pipe
I usually take it out all day long, do about 50 miles, and use only half a tank.
I am usually cruising at about 30mph. Occasionaly do a topspeed run and occasionally have to idle through no-wake zones.
I, too, have a 21 gal. tank (I think it is only 6" deep), but I can only get 18 gal. into it before is spurts out the vent pipe
I usually take it out all day long, do about 50 miles, and use only half a tank.
checkmate DOH!!
Member
my 85 diplomat with the 470 has the same tank---21 gals but seems to spurt the vent a little early too----and havent gotten the needle on the gauge to complete full yet---but this last sunday topped her off and hit the lake with the kids and a friend in his boat---we got on the water around 11am and tubed, cruised, idled, and sped wide open all day long til almost 6pm or so----i still had a little under a 1/4 by the gauge----havent owned the boat long enough to know all the little idiosynchracies (sp?) of the original gauges and all but thought i did pretty well gas-mileage wise---this was also the first weekend out with a new hydrofoil bolted to the outdrive---cavitation and porpoising was almost completely nullified----i also too noticed the increase in mileage on a tank---so far im happy as a pig in u-know-what with the thing on there----and also happy too i chose a check--nothing sts in the water or planes up just like them----incredible boats.... 
Eaglenva
Member
hey shoot2thrill - it looks like not long at all as mark and others said, i dont know if your engine is i/o or sterndrive. below are some test results. if it is outboard it includes GPH. these should be representative. get the gauge fixed is the best idea.
4.0 i/o new today
http://northamerica.mercurymarine.com/_media/pdfs/bhb/sterndrives/4.3L_Crownline180BR_0304.pdf
http://northamerica.mercurymarine.c.../4.3LTKSAlphaOne_FourWinns180Horizon_0606.pdf
outboard 175hp today
these charts includes GPH
http://northamerica.mercurymarine.com/_media/pdfs/bhb/optimax/175OptiMax_Lund2010ProGuide_0906.pdf
http://northamerica.mercurymarine.com/_media/pdfs/bhb/optimax/175OptiMaxL_Bentley243Cruise_0506.pdf
4.0 i/o new today
http://northamerica.mercurymarine.com/_media/pdfs/bhb/sterndrives/4.3L_Crownline180BR_0304.pdf
http://northamerica.mercurymarine.c.../4.3LTKSAlphaOne_FourWinns180Horizon_0606.pdf
outboard 175hp today
these charts includes GPH
http://northamerica.mercurymarine.com/_media/pdfs/bhb/optimax/175OptiMax_Lund2010ProGuide_0906.pdf
http://northamerica.mercurymarine.com/_media/pdfs/bhb/optimax/175OptiMaxL_Bentley243Cruise_0506.pdf
shoot2thrill
Member
Thanks Eagle...and everyone else....Definitely getting the gauge fixed....and its an i/o