posted 06-30-2014 08:16 PM ET (US)        

Help with fuel calibration. Will it help? Or, must re-engine? Salmon/tuna season is only 6 weeks away and need help.

Thanks

posted 07-01-2014 08:47 AM ET (US)            

If you are going to spend a lot of time trolling, get a pair of E-TEC 150-HP engines. The fuel economy of an E-TEC V6 at idle speed is amazing. You could be getting 8 to 10-MPG. It will take five hours for an E-TEC V6 to burn a gallon of gasoline at idle.

posted 07-01-2014 01:43 PM ET (US)            

As Jim says, re-power with E-TEC or 4 stroke is the sure way to decrease fuel consumption...in many cases by half. Props and mounting may make small differences. The old carburetor two strokes were magnificent engines for the price when gas was less than a dollar a gallon and fuel efficiency did not matter as much as today.

As another data point, I have a classic 1967 Lyman 16' with 1967 Johnson V4 60 HP. That gets the same 1.4 NMPG the twins on my Revenge get! Talk about using fuel! It runs like a champ but is even worse than the 1989 V4 twins together!

If your figures are correct, you are getting less than half a mile per gallon and something is not right. I would check to make sure all cylinders are firing. It is easy for a V6 to run well with a bad ignition coil...and all the fuel in one cylinder does nothing but disappear in the exhaust. Check your plugs. They should all look the same. If one is clean/no carbon, that cylinder is not firing.

posted 07-01-2014 03:14 PM ET (US)            

Hoosier can you give me model, year of Yamaha's and how and what metering system you use? I looked at Tom Clark's Flosan system and the quote I received was a lot to rich for my blood.

I believe many people, especially in Great lakes area, looked at this boat and like you Jim considered buying it. But probably for the challenge of re-engine it didn't buy it. I and my wife love this boat, to us its better that a WT model yet not quite an outrage.

So whether E-Tec or 4 stroke it will happen. My kids think we need to take one less trip to Hawaii and Disney World per year. That's how we can pay for the engines.

Thanks

posted 07-01-2014 09:00 PM ET (US)            

1992 25' Revenge W/T, with twin 1991 150hp Evinrude's, we cruised 20-25 [knots] and filled twice; 1.7-nmpg.

posted 07-02-2014 01:54 PM ET (US)            

Thanks for all the input. I have a bunch of work to do to find where the fuel is going.

Thanks again

posted 07-02-2014 06:30 PM ET (US)            

Prop pitch is next and will look back on some of Jim's data.

Anything else? I will try about anything short of changing engines this summer. I need to troll but not going to add a bracket if at all possible.

Thanks for the suggestions

posted 07-02-2014 06:44 PM ET (US)            

Second, if you don't already, get SS props. If you are running dinged up aluminum props, it's like driving a car with flat tires... (I suggest reaching out to Tom Clark on ideas and options.)

Third, if your MPG numbers are below 1-MPG you have an engine problem. And you should do the carbs a once over, and check firing on all while at speed.

Lastly if you are doing a tuna run 30nm offshore, trolling with big motors doing 6 to 8-knots, yes, you'll burn some fuel, but not 80 gallons. More like 50 gallons per run. (Running 80nm offshore, you need to wait a few weeks for the fish to be closer runs, period paragraph!)

posted 07-02-2014 07:33 PM ET (US)            

My problem with kicker is where to mount the thing? Maybe have a bracket made to sit on the starboard side, port carries the swim ladder.

Suggestions are always noted and helpful this close to fishing time. I have a slip reserved in the Ilwaco, Wa boat basin for the month of August.

Will take the boat down there end of July no matter what, it can sit there just as well as my drive way.

Thanks

posted 07-02-2014 11:52 PM ET (US)            

Did the people I had who went through the lower units put the wrong props on the wrong engine? Or these the correct ones for each engine.

Another thing about the latest test drive, I went through almost a gallon of Evinrude 50 wt oil over the last 40 gallons of fuel. There is soot in the prop on the starboard engine, not much in the port prop.

I will get to spark plugs Friday.

Thanks

posted 07-03-2014 09:16 AM ET (US)            

Generally I don't think a third engine on the transom is a good idea. That is too much weight in most cases, and probably particularly so if you have the long Whaler Bracket option. Since you already have twin engines, the transom is already cluttered with rigging hoses and cables. Adding a third engine will make that even more congested. Also, adding a steering link for a third engine may be a problem. And finding a way to remote control the shift and throttle of the third engine will also be a problem. Finally, if you need to troll at a high speed of 8-knots, you may not be able to reach that speed with a smaller auxiliary. You may need a 10 or 15-HP auxiliary.

posted 07-03-2014 01:03 PM ET (US)            

Bottom seals were leaking so had local boat shop replace seals and pumps, did the correct props go back on correct engines?

Engine mounting height, top bolt is in top hole of 4 on top of engine bracket, bottom bolt is top of slot on bottom of engine bracket.

Engines are mounted on a Whaler Drive bracket which is a Salt Shaker Marine bracket, attached to transom

WOT gives 4500-RPM and 36.6 mph.

I used a Garmin GPSmap 78sc to get top speed, over a distance of 10.9 miles, I put 40gals in tank and then went [approximately more than] 30 miles and used about 2 gallons of 50 wt oil in ~50 miles.

I am coming to the point where I think I need to change this to a thread titled, "1992 Harsen's Island Walkaround Project" I realize it will take a bit longer than a month to fix/upgrade/change all the stuff that needs to take place before I take it "tuna" fishing.

What say you Jim about the thread change?

Thanks

posted 07-03-2014 01:56 PM ET (US)            

--lowest mounting

--one-hole up

--two-holes up

--three-holes up

posted 07-03-2014 02:16 PM ET (US)            

Yes, my main concern is as you say, "for your boat and your primary concern with its fuel economy."

I had thought Props, oil, fuel mileage, engine height, were part of the equation.

Can fuel mileage be measured accurately with a Flo-scan system without some sort of the "unmentionable" word interface. Do flow meters need a interface to accurately give me fuel mileage? I don't know.

As for your moderation, it needs to happen to keep on subject and I understand that. That is why in a previous thread I asked you if you thought it should be moved, and you did move it. I have asked Hoosier about what he had on his boat to accurately measure said mileage, he told me and I haven't requested anything else about said unmentionables.

Thanks

posted 07-03-2014 04:21 PM ET (US)            

Evinrude XD50 oil is a good two-stroke oil. It is unlikely that use of XD50 oil is to blame in any way for the poor fuel economy.

If you want to measure instantaneous fuel economy, you will need to know the instantaneous fuel flow rate. With the c.1992 Johnson engines you have, the only method to obtain the instantaneous fuel flow rate is by inserting a fuel flow sensor in the fuel line.

Measurement of instantaneous fuel economy will also require measurement of the boat speed. Measurement of boat speed is probably already available to you from your Garmin GPS receiver.

As mentioned earlier, trip average fuel economy can often be different from instantaneous fuel economy at best planing speeds. In the case of these older two-stroke carburetor engines, one often sees that the best instantaneous fuel economy, that is best MPG, occurs at planing speeds, and operation at any other speeds usually produces worse instantaneous fuel economy.

As mentioned earlier, the poor fuel economy at low speeds with older carburetor engines is a result of a loss of fuel charge from the combustion chamber without the fuel being ignited. A significant amount of raw fuel goes unburnt out the exhaust of these older engines when they are running at low speeds.

In your initial article you sought advice about re-tuning your carburetor two-stroke engines to get better fuel economy. As mentioned earlier, this is really not possible. The engines need to run with the fuel-air ratios they have been designed to run with. You cannot apply some post-design, post-manufacturing remedy that will significantly alter their basic fuel consumption characteristics.

As mentioned earlier, there is so much evidence in your data that the engines are not in very good condition. They are burning too much fuel, even for fuel-hungry older two-stroke carburetor engines.

As mentioned earlier, your initial focus on resolving the poor fuel economy should be to check the engines for signs of problems with the cylinder fuel induction or cylinder spark to verify that the engines are operating as designed.

As mentioned earlier by first-hand reports from others who have comparable engines on comparable boats, the fuel economy should be in the range of 1 to 1.5-MPG, not in the range you are reporting of 0.375 to 0.5-MPG.

posted 07-06-2014 09:40 PM ET (US)            

Our 1993 23 Walkaround Whaler Drive with twin Yamaha 150's are mounted one hole up and will turn a WOT of just over 46mph at 5500rpms turning what I believe at 19p Yamaha Stainless props.

posted 08-29-2014 09:40 PM ET (US)            

Thanks for all the help and input.

posted 08-30-2014 11:29 AM ET (US)            

There is no meaningful interpretation to a position reference as "three holes down." From your description, the most reasonable interpretation is you have raised the engine mounting height from the original position to a new position which is best described as "three holes up."

Re the brand and model of propeller you are using: the brand and model are interesting information, but without knowing the pitch (and diameter) much detail is lost. Please pass along the pitch and diameter of the propellers. Also, I suspect you actually have Mercury MIRAGEplus propellers, as the MIRAGE model has not been made for a long time.

Your report of consumption of 40-gallons of fuel in six hours suggests a fuel flow rate of 6.66-GPH total, or 3.33-GPH per engine. However, without knowing the engine speeds being run during those six hours, it is hard to interpret the GPH data.

posted 09-01-2014 11:54 AM ET (US)            

Motors are set as high as possible.

I am experiencing a slight vibration from the starboard engine at low engine speed, at or below 1,500 rpm. This is also the engine the mechanics were not able to replace bearings and seals in because the race appeared to be "welded" in the housing. Speculation on "welding" had occurred because of leaving the power cable left hooked up with engines in down position in the water when at the marina. It appears electrolysis was the cause of the "welding". Mechanics were afraid taking bearing race out would have broken housing.