Fuel Economy - Carbed Outboards

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Texas Transplant

Texas Transplant

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Joined
Feb 24, 2001
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Fort Worth, TX
Okay. I probably already know the answer to this, but I thought I would let some of our experience on the board to chime in. I've got a 95 Stratos with a 150 HP Evinrude on it. Carbed of course.



The motor starts great and runs great. However, I certainly 'seem to notice' that it really is gulping the gasoline. Most of the time when I'm on my home lake, I'm running about 4,000 RPM's (36/37 mph), but really burning up the gas. I had the engine tuned about 3 1/2 years ago, and probably don't have 50 hours on it since then.



Question: Should I replace the spark plugs and/or take it in for a tune up?



In reality, I'm probably simply reacting to several things.



1) My boat sits on a lift on my dock. Therefore, I don't 'top off' every time I go fishing. Therefore, I watch the gauge more.



2) I really can't fill mine up on the lake, due to the location of the filler tube and the poor design of the filler pipe. If I try to fill up 'on the lake' - I would have to put the handle of the gas nozzle underwater, to get it to flow into the fill tube. Again, poor design.



3) Should I look to make sure that I 'trim up better', to get better effeciency? That thought has come to mind also.



Inquiring minds want to know.



Thanks.



Tex
 
I cant see how replacing the plugs could hurt anything although i doubt you would notice and real increase in fuel ecomomy. If its running good i dont see why you would need it tuned up either since it was only done 50 hours ago.



I think you will see the biggest bang by trimming up more/backing off the throttle to keep the same speeds you run now. Just dont trim up too far to the point where it starts to porpose. Having less hull in the water will make it run more efficent. Believe it or not a blueprinted/balanced prop will help a bunch too.



Reality is carb motors are very thirsty. They do run great but they love the gas. When i had my 150 xr6 I never really gave it much thought. Only now that i own an optimax do i ealise how thirsty that motor really was. Just this last weekend i was up north on Winni and with my old boat i would have burned the better part of the 45 gallons my 882 held easily. I would have towed that boat home almost empty. With my z7/ 175 xs i barely used 10 gallons of gas bombing around there for two days. That really showed me how thirsty that xr6 was/is. Even though it loved the gas i would not have bought a new engine to replace that xr6 on my 882, the difference milage would never have made up the cost of a new motor, not to mention i really liked that motor and how reliable it was.
 
I have no hard evidence to prove this but I really believe that the 150 Optimax on my 591 uses less gas than the 50 hp carb motor on my old Tracker. I guess it's a good problem to have but I worry about not using enough gas to keep it fresh.
 
Harpo, i worry about the same thing with mine. Up until sat i had not put a drop of fuel in it since early may. my xr6 it was a once a month deal at least that i was fueling it up. every weekend if i fished bug lakes. I did run it down to almost empty but still it was in there a long time. My service manager at my dealer suggested when i picked it up that i run stabilaizer and quickkleen in every tank.
 
Haven't run any QuickKleen in mine, but given what I've seen recommended here on several threads, maybe I should.



Appreciate the feedback.



Tex
 
That's what I'm going to start doing too. I attempted to syphon most of the gas out of the boat so I could put in some fresh gas, Friday. I bought a syphon hose that has a little pump gadget on the end of it so you don't have to suck it but it wouldn't go down the filler tube. I took the sending unit out but then the dang hose wasn't long enough to reach the gas can sitting on the garage floor and there wasn't enough drop for it to start a syphon with the can sitting in the boat. Finally I gave up and the motor ran fine Saturday but I'm still going to get some of that gas out and run it in the truck. I bought some Quicksilver Fuel Treatment & Stabilizer for when I get the old stuff out. I put some of that in last Fall so things shouldn't be in too bad of shape but I'm going to start putting it in every time I add gas.
 
I always run Quickleen and add Stabil to a tank when I fill it up cause of the distance in between times of nonuse.

I'm going to get the newer Stabil this weekend for the methanol mix.

It's hard sometimes to get "pure" gas nowadays.

I do know it keeps the cylinder tops lookin' pretty good considering the "junk" gas we get!;)
 
I have looked for the new Stabil for ethanol, but can't find it as yet. May try ordering some. I have found that our local Chevron dealers, don't have the ethanol tags on their pumps, so I've been using their gas. However, not sure how much I trust that either.



Tex
 
Ive been looking for that new sta-bil as well since E10 is all we can get around here. Nobody seems to have this new stuff or even knows about it yet.



Tex, the quickkleen wont hurt for sure. I never ran it in my XR6(i ran synthetic oil so carbon was not an issue in that motor) but im told its essential in a Opti to keep any carbon to a minimum.
 
For those of you who have motors dating from before '97 there is an after markey EFI system... In this day and age of the cost of new and the restrictions on "playing" with newer motors these older ones are worth looking into... You can get a formerly carbed 150-200 Merc with aftermarket inject for between $6,000 and $8,000 with a two year (extendable to 5 years) warranty.



If you already have the motor and want it rebuilt and changed it is about $4,500 - $5,500.
 
Ok you Merc guys (me included) go get the MERCURY Fuel Treatment and Stabilizer!! Why would you not put a Merc product in your motor first? Do you not trust them? It is cheaper than Sta-Bil or SeaFoam and it is made (or packaged) by Merc. You can also seperate the requirement and get just treatment or just stabilizer also. I use the combo. I have been 100% happy with it and I have been running e-10 for 5 years. I have never found water in my seperator. Original fuel filter (yes I am going to change it!!) It says right on the bottle of the Treatment and Stabilizer to add it to every tank of e-10 but as a rule, I run it every other tank. Nary a problem.



TOXIC
 
Tox,

that is what i run in my opti now, as well as the quickkleen. The reason im looking for the sta-bil isnt because its cheaper. The new marine formula is designed to help prevent the phase seperation that can occour if the fuel sits, the merc stuff wont prevent that. I dont burn near as much fuel as you do so mine has the potential to sit for a while. Im trying to do whatever i can to make sure i dont end up with alcohol gel at the bottom of my tank.



I have been running e10 for a while too but with my xr6 i was burning it at a rate that phase seperation would not be an issue(i also drained the tank for winter). My opti is a while different story, it hardly burns any fuel. Until Sat i had been running on the same 10 gallons I put in the tank since like May and i have been fishing every weekend( on smaller sub 1k acre lakes)and i have been runing it a good bit. Saturday was only the third time i have put fuel in it since i have bought it. Im not filling it either, just putting in a small amount so i wont have it sitting around forever in the tank. This opti just doesnt use nearly the fuel my xr6 did. Hnestly if i filled it today it would be the last fuel i put in this year.
 
Unk,



I just googled Mercury Fuel Treatment and Stabilizer and went to the results from the Mercury Marine website.



TOXIC
 
Yeah, probably just simply didn't realize it's 'thirst' when I was towing it back and forth all the time. Easy to simply stop and put 8-10 gallons in to top it off. When hanging on the lift, and not able to top off on the lake (problem with the design of the filler cap and filler tube) - I watch it much closer.



Thanks all for the feedback, provided quite a bit of insight.



And yes Glenn and others - it starts immediately and runs like banchee. You could probably eat off that engine. I'll buy gas! :D



Tex
 
Tex,



You might want to try one of those fuel cell, gas tank things on what look like 2 wheelers. Load it into the truck, go get gas and then wheel the gas to the boat and fill it with the hose. I think they hold 10-15 gal????? I see a lot of people with them at the lake.



TOXIC
 
I recently added a hydra foil on my merc 90. I have really noticed the increased fuel economy. I found it on overtons but my local dealer was actually cheaper.
 
Check your local ordinance about filling up at a marina with a portable tank ahead of time. Alot of places it is illegal around here.
 
all I know is it does say on the box that you will get increased fuel economy, my mechanic told me it would and that I should buy one, and I know I can usually run my boat for a weekend on 1 tank of gas. we went down on vacation from thursday to sunday (10 days) with a full tank. I finally put gas in on the following friday and we did alot more boating than normal. but maybe, someone came along and kept adding fuel just so I would think it was helping...... now, I do know it gets on plane much quicker but I also believe it has hurt my speed some. I have a fish and ski and use it for pulling tubes at least 50% of the time it seems like. and no other changes were made. and I am one of those guys who runs the boat full throttle all of the time!



your slam did hurt my feelings a little ;)



just kidding.
 
foils do save gas Glenn, the surging of an outboard porposing uses excessive gas from the prop slip. also the time to plane is shorter so you are not taxing the motor constantly. Unless all you run is WFO when on plane you wont see much of a difference, but if you get on plane and back it down to a cruise speed you will see a difference.



my .02
 
all I know is it does say on the box that you will get increased fuel economy, my mechanic told me it would and that I should buy one
Click to expand...



The first part is theoretically correct. The foil diverts thrust out and back, acheiving a quicker climb onto the hull's pad. Less fuel burned than waiting for the hull to lay over from a bad and/or wrong prop. All of this is done by exerting untold, and definitely not mfr. recomended, force onto a pot metal lower unit, directly impacting the points of contact. (The holes drilled through the cavitation plate, for most foils.) This latter part of the statement leads me to recomend a more experienced mechanic for you. Any tech that advises a foil for a FS hull instead of a properly pitched prop creates cause for concern.



now, I do know it gets on plane much quicker but I also believe it has hurt my speed some.
Click to expand...



Unless you have some unknown hull issues, the addition of a foil cannot impact planed speed running. (Other than sharp turns which have caused numerous rollovers and cartwheels.) The foil is designed and installed at a location that will be slightly above the water's surface after the hull is on pad. If not, the steering and handling characteristics of the hull will be negated by the foil's impact upon turbulence from the hull and pad. (This is severely abnormal and a "scary as HELL" situation!!) You would know instantly when on pad and applying throttle that the foil was submerged. Mr. Toad's Wild Ride at Disney would have little to offer over those conditions. :D
 
Tex - Try using a transfer siphon hose with a 5 gal. gas can. I've used them for years and put 30 gals. (6 jugs) in the boat without spilling a drop. I fill up the jugs then transfer them to my Sportsman to take them to the dock. On the dock, I open one jug, slide the transfer siphon hose ball end into the bottom, the clear end goes into the filler neck on the boat, shake the ball end that's at the bottom of the jug to be transferred, and wait a minute or two while it transfers. I can do 6 jugs in less than 30 min., start to finish. It's well worth it as opposed to filling up on the water.
 
Always, every time. When gas goes in, Quickleen and Marine Stabil goes with it. Cheap insurance to keep the cyl. heads clean and happy!;)
 
I installed a foil on my 200 EFI the first year I boat my boat,(2000 901 Dual Console) to help with my holeshot. I did notice a little better holeshot and also found I could stay on plane about 2-4 MPH slower with it than without.



I don't measure my fuel usage closely. I run it until it's about 1/4 tank and then I fill it again.



RoyC

 
I fill my 520 almost every week. 58 gallons.
 
Ouch Mini..... Do they include lube with that fullup? Or at least a kiss afterwards? lol



Man thats some serious $$ your talking here, WOW!
 
Dayum Mini, the oil companies are going to be running you for President if you keep that up. We might be getting that legal weed sooner than we think.:lol::lol:
 
Big Water = Big Fuel bill!!:lol: I can, if I want to, drop my boat in at Lake Anna and not even crank the big motor and have great fishing all day in one of the best creeks on the lake!! BUT.....Clients don't like that (don't ask me why) so I will usually make a couple of short runs to some of my honey holes no matter what. I can usually get 3 client trips out of a tank. I put fuel in every time I go to the lake just to keep it "fresh". That way I don't have stale fuel by my 3rd trip. I have to gas up the truck every other trip if I don't do any additional driving.



TOXIC
 
I hear that Tox, I fish some big water too and my old boat really drank it down. Its not hard to make fuel go away on big lakes.



I spent two days on Winni in NH which os ~45000 acres and i would gustimate i burned about 8 gallons, my old 150xr6 would have been 40+ with the same amount of running that i did.
 
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