150 burning fuel

[reggie]

I recently bought a 10 foot sled with a 150 Lycoming it seems to be burning an ungodly amount of fuel. 2 weekends ago I took the boat out for its first real trip since I've had it. In 6 hours I burned 16 or 17 gallons of fuel where a friend's 6 cylinder burned 9. How is this possible I don't see how this engine can even run. It doesn't black smoke or run bad whatsoever, no leaks in the tank it holds fuel any suggestions? Thanks in advance

[scottyroll]

How do the plugs look

[John Fenner]

How does the hull perform? Does it take alot of rpm to get it on plane or keep it on plane? Hulls that run free take less fuel to push around like anything else that is hauling a load.

[reggie]

The plugs are a little black but nothing too serious. The hull is extremely free

[Scarecrow]

Back off the gas pedal, probably a loose nut between the seat and steering stick and next time strap your boat down.

[digginfool]

I recently bought a 10 foot sled with a 150 Lycoming it seems to be burning an ungodly amount of fuel. 2 weekends ago I took the boat out for its first real trip since I've had it. In 6 hours I burned 16 or 17 gallons of fuel where a friend's 6 cylinder burned 9. How is this possible I don't see how this engine can even run. It doesn't black smoke or run bad whatsoever, no leaks in the tank it holds fuel any suggestions? Thanks in advance

I had a very similar experience. I have an 11 foot Don Davis that originally had a 160 on it. I would ride with my friend who had a SV O540 on his 12 foot Benny Webb and he almost always burned less fuel than me; when it wasn't less, it was the same. I eventually put a 540 on my sled and as long as I behave myself, I burn a lot less than I did with the 160. The big difference is the 160 was working hard while the 540 is just loafing along. Of course, engine health and hull set-up, like the above posters mentioned, is certainly worth checking before running out to buy a 540 but it's not inconceivable, especially if you were cruising fast and/or lots of dry where your little motor was working a lot harder than your buddy's 6 cylinder.

[reggie]

I wasn't running hard I ran up on dry a few times but not hard running. And scarecrow what ever you say I'll never trust a man with two first names hahaha

[Gary S]

You have poly on the bottom? What carburater you running?

[460 FULLTRACK]

I have a Big O hull with a 0-320 and I have said the same thing many times. The answer above is correct, I'm running more rpms than a boat with an 0-540 therefore more fuel. My boat is a 13 footer so it's always running about 2200 rpm most of the time. My brother's boat, although a different brand, weighs about the same and he runs 1800 rpm for the same speed with his 0-540. If I get in some thick stuff the rpms go up and I know my boat is working harder.

[reggie]

It does have Polly it's a 10 foot Taylor sled

[reggie]

Ok had the carb rebuilt and it has the correct jets. Put new plug wires and plugs. Went for little ride on istapoka mabye 3 hours no dry running just cruising still managed to burn 10 gallons of av gas. Still no black smoke or anything runs flawlessly what is going on? Way too much fuel carb is a ma4 spa

[GMAC 76]

reggie, when ya say you are just cruising...what rpm are you just cruising at?.....maybe need to add a little pitch to the prop....I think i remember you said the engine run up to 2900 on the trailer which would put it at over 3000 on the water wot...that's a lot of rpm for the 320 to stay economical on fuel

[Bob1120]

I had a 0320 on a 10 foot Taylor hull when I ran the boat over 2000 rpm I burned around 10 gallons a hour. I own a 0360 on a 11 foot sled now and it burns less fuel when cruising the same speed as the 150 boat. The rpm is around 1500 - 1600. The 0320 works harder to cruise the same speed. I was swinging a 68" 4 blade warp on the 032 and now swing a 71" 5 blade warp on the 0360.

[reggie]

Got it to around 2750 on the trailer looked cruising yet

[GMAC 76]

Got it to around 2750 on the trailer looked cruising yet

imo....that should put ya pretty close to where ya want to be on the water at wot

[Scarecrow]

I think new plug wires will make you use more fuel.

[Rich863]

What prop are you running and what is your cruse rpms

[reggie]

66 inch water Walker not sure since I've reset the prop

[JCGator]

I feel like my 170 hp is not very economical on my 10'6" Taylor Hull with poly. I'm usually cruising at 2100-2200 and WOT at 2900. if you look at the gph for your cruise RPM its probably about where it should be on the chart in the operators manual you're just asking for too much from the little engine to be fuel efficient.

[Gary S]

The polymer is hurting the gas milage. It's like adding another person on the boat. Small light boats are just that,small light boats. When you add weight,any weight it affects it.Even more in deep water. You could do what digging did and replace it with a 0540.
I run a 11foot boat with a 0320 and will frog all night on less than 15 gallons. Most nights in the 11 to 12 gallon range. But I don't have poly on the bottom.

[GMAC 76]

reggie, .....don't think the mags or timing would be a major deal in causing excessive fuel consumption but I was wondering if the new plug wires and spark plugs helped with the mag drop test

[Planeguy]

A stock O-320 (150 and the 160 hp versions) has a red line at 2700 rpm and burns close to 14 gph at that power setting. To see 8-10 gph it has to be running 2200-2300 rpm or somewhere between 65% and 75% power. That is from the engine documentation. If this engine can turn 3,000 rpm (110% power) and is spending very much time above 2,200 rpm cruising around, it is little wonder it seems to be burning a lot of fuel. I estimate it could be burning as much as 17 or 18 gph every time it goes to full power (the general rule of thumb would be: the more hp power being made, the more fuel per hp it takes). Of course, I don't think it would last an hour running 300 rpm above red line to confirm my estimate but it wouldn't have to be run very much at full throttle to notice it burns a lot of fuel if I am right.

[Deano]

In all actuality, if you are running at about 3 gals/hrs you are doing better than most.
That's not to say that further improvement is not possible, but not a number to get a headache over.

Just a couple observations that you may or may not find useful. I had a O-290 with angle valve cylinders on it and the fuel consumption increases exponentially as the RPMs start going over about 2200. It was on an old Airgator hull and would slow cruise about 1900 and was great on fuel. At about 2300 it went pretty good and used half again more gas. It had a 68x34 stick on it, so it would only turn about 2750-2800 max, but running like that it could use more fuel than my Cadillac on a 15' Rivermaster.

There are two major things that come into play when you're talking about fuel mileage. The first, is percentage of full throttle. As was pointed out, the smaller engine is working harder to produce the same results than a big engine that is loafing around. The second is amount of wetted surface. To a certain extent, the larger the planning surface is, the less power it will consume to stay on a plane. This was the problem with the old Airgator hull; it was barely five feet wide and acted far to much like a displacement hull that didn't want to get on or stay on top of the water.

I plain, flat disagree with the premise that having polymer is like adding another person on the boat. UHMW is neutrally buoyant, so (while in the water) the only weight you've added is the fasteners. That weight maybe measureable, but is no where near another person. Now running dry, that isn't the case, but that isn't what we're talking about here anyway.

If you are running a 66" Water Walker, you have Cypress blades in a small hub. I believe there is a pretty good likelihood that switching to, or at least trying a medium hub would get you a bit of an improvement. If you can move a little more air at a little less rpms, it would only help your cause. The trade off in such an attempt would be decreased WOT RPMs, but that may only serve to help your cause as well.

[mirage]

Sure wish I could get that kind of fuel mileage.