90 HP Tower of Power horrible fuel mileage

[paulywally]

Just finished rebuilding an 86 90 HP tower of power. Runs awesome. Doesn't idle the best sometimes, but that should be able to be worked out with carb adjustments and timing.

Anyways ran a couple of times now, it will burn a 5 gallon fuel tank in about 45 minutes at about half to 3/4 throttle. Are all these motors that bad on fuel?

I think I'll have to sell it if it is just this bad.


Thanks, Paul

 

[Bob_VT]

Re: 90 HP Tower of Power horrible fuel mileage

Rule of thumb ......... an engine will burn 10% of it's HP rating per hour and holds fairly true on older motors. Your motor will probably burn 9 gallons per hr at wide open throttle.

 

[79Merc80]

Re: 90 HP Tower of Power horrible fuel mileage

I have a 84 90hp Mariner and at 3000 RPM I am burning 5.1 GPH. At 4000 RPM I am burning 7.2 GPH. WOT is 4820 rpm AND BURNING 11.5 gph.

Hope this helps.

Craig

 

[Gomer50]

Re: 90 HP Tower of Power horrible fuel mileage

I have a 1978 90 hp inline 6 and in roughly three hours of having fun, 12 gallons of gas is gone.Back to the dock we go to get to the truck for a second go around.Expect to spend at least 20 gallons of gas for a good afternoon in the sun and fun.I asked the same question about three weeks ago.And I thought my truck got bad gas milage

 

[Chris1956]

Re: 90 HP Tower of Power horrible fuel mileage

Paul, that is not real out of line. What kind of boat are you pushing and what kind and pitch prop. What is max RPM?

 

[swamp-fox]

Re: 90 HP Tower of Power horrible fuel mileage

That sounds about right. I can go about 20nm takes about a hour (with idle zones) and I burn a little less than 6 gallons. Running about 4000rpm '78 90hp. Running at WOT they love gas. There is a spot, when you run WOT if you back off slightly. I don't know the rpm change, but you can listen to the motor sound change. You only lose about 1mph, but I find you get way better gas milage.