Fuel consumption

randleman what engine you runnin to get milage like that? and what happened to your stars and posts? I thought you were all fixed up.?
 
Thats very impressive fuel mileage. Are the Johnsons the same dough as the Suzuki's? I havent seen anyone with a Johnson out here but I am starting to see a few more of the suzukis. I hear they get up and move better than most and they are high maitenence. Any truth to those rumors?
 
I have run mine for 4 seasons now, I have changed the oil 3 times.

This winter I will probably put in a new waterpump just because.

I pull skiers w/ no problem, top speed is 39-40.

As for price, I haven't looked lately, 4 years ago mine was 9K for everything, motor, controls, prop, monitoring unit (idiot lights), wiring harness, tax.

I have been very pleased with mine.
 
Slowly narrowing the bugs in the boat, now I'm concentrating on the engines performance while in water.
Right now I need to clean (or rebuild) the carbs and check timing cause it's running way rich, to the point of fouling the plugs.
Photo of fuel consumption at 31mph and rpm.  :-[
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New plugs with 30 minutes run time on them (after being wiped off with a wrag).
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It will quickly do 41mph at 5000rpm (and draw 22.5gph).
I was expecting about 8gph at 30mph.
We'll see when done with the adjustments if it improves. :-/
By the way this wasn't at best trim, speed, etc, etc.
We were just trying the motor's reaction to various circumstances. I'm sure the numbers would have been a little better by picking the best operating range (which was what I was trying to do till it started fouling the plugs).
 
Differnt critter all together, but for refernece, my 88 Merc 150 burns a little under 8 ghp at 4k getting 28-29 mph.

'Slot
 
I'm sure (hoping) these numbers are way out of wack but felt they needed posting in case someone seen or knew something I didn't.
 
if your burning 13.2 gph & doing 31 mph, that's approx 2.3 mpg right. my 95 150 mariner gets 2.3-3.0 depending of load & seas. i don't have a fuel gauge, i just fill up & set the odometer on the gps. if i go 70 miles, it always takes 30 -35 gallons to top it off.
 
Hey tsubaki, those fuel burn numbers aint all that bad for a cross-flow JOHNNY-RUDE. Clean your carbs and try running some standard style plugs in her, those surface gap plugs are for extended high RPM usage. They are notorius for fowling at low RPM's for no apparent reason.

And if you want to talk about a fuel hog, I can bring my flats boat with the XRI MERC into the discussion. All I'll say is she LIKES FUEL!!!! But god will she jump on plane in a hurry and run shallow ;D.
 
That is what I found out about those type plugs in the past.
That is what the book suggested and they were a pain to find here in town.
I'll cross reference the other type and put them in.
I think I had L77JC4 plugs in during the last run, they performed about the same.
Got two carb kits yesterday and the other should be in town Thursday.
Not knowing any real history of the motor rebuilding the carbs will at least give me some piece of mind.
All the coils, wires and one powerpack appear new. The best indication I get out of this motor is it had some problem and they did several things to it to try and improve it.
The thermostat covers have been removed and resealed. One temp sensor had been cut and respliced but not removed, come to find out it was defective. I have all ideas the thermostats are missing. That will be my next venture cause the engine isn't getting much past luke warm.
One more step at a time. :-/
 
If you don't have T-stat's, it will always foul plugs at slow speed's. Been there, done that. T-stats are vital to keeping these engines from fouling. Most people overlook them. Also do the bypass valves and springs while your there.
 
Thanks Theferm, at least I got some ideas now of the possible problems. To top things off I never checked the plug gaps on the L77JC4 plugs, come to find out they were between 25-32 instead of 40 like recommended.
Cleaned and replaced floats and valves in two of the carbs yesterday and found no real contaminations.
Had water lines on two of the floats but no evidence of varnish.
Waiting on the last carb kit.
Might remove the t-stat covers today.
 
Removed the thermostat covers and they are in there.
Going to replace them (& bypass)when they show up.
Also going to run the L77JC4's when I reassemble what I've removed to do this.
Any ideas of all the fouling or running rich? Anybody?
The two "cleanest" ones came from the two top cylinders, the rest were about the same.
 
The intake (flame arrestor) is damp, oily (but not gummed) like most I've seen. Easy to wipe off.
And the recirculating valves? If it's the ones in the thermostate covers, yes planning on changing them.
 
The valves I'm refferring to are the ones that screw in by the carbs and attatch to hoses that run back and hook in by the cylinders. They are mostly for slow speed operation, but it may help.

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I'll look at those before I put the carbs back on.
If you hadn't suggested it I wouldn't have fooled with them.
Thanks
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And 4 more below them, not to meantion the feeder.
 
My mistake, they's 8 total plus the one going to the air damper (intake, breather, airbox, flame arrestor).
2 sets of 4 each are connected together and 1 to the airdamper.
The one into the airdamper was clogged and one to the set of 4 to the upper bodies was clogged.
BACK ORDERED is the last carb kit. Probably Monday.
 
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