Gas

[ccyoder]

1989 Glastron Sierra 195SS sterndrive
4.3L Mercruiser 2bbl with Alpha One outdrive
Alum. prom 14.5d x 19 pitch
600 hours

I'm using, what I think is an excessive amount of gas in my boat, and I'd like to get your opinion on the matter.

I use just shy of a tank, which I think is 17 gal or so, for 6-7 hours at the lake, which includes being docked at the beach for hours at a time. The boat runs fantastic for its age. Bought it this past summer with a new ignition system and carb. No troubles and a great runner.

One thing to note. This engine's normal operating temp is between 150-160 (think) and I'm running around 120-130 at its hottest. So my guage is off or my thermos stuck open, or I have the wrong thermo. At any rate, I guess running cool could lead to excess consumption, but I'm not enough of a gearhead to really know. I'll have the thermo checked during winterization. Until then.......any advice from the folks who know?

 

[QC]

Re: Gas

To comment accurately on this we need to know a fixed distance and fixed speed and fixed RPM. Lots of variables although it does "sound" high . . . My guess is that you should see an average of around 3 - 3.5 MPG. That's 50+ Miles . . . Yes, cold op temps can cause increased fuel consumption, but not double, so that part of this thing is not an order of magnitude type deal.

 

[Robj]

Re: Gas

While I cannot comment on the consumption, running that cool decreases engine performance and increases engine wear. For optimum performance you want your engine to operate at about 160. Piston ring wear at 160 is about twice as much as what you would see at 190. I realize with a raw water cooled engine it won't run at 190, but you can at least run it at the design temp. Check your thermostat and your temp gauge.

Have a great day,

Rob.

 

[Chris1956]

Re: Gas

I had a similar-size boat with that powerplant. I think your fuel consumption is high. Will that motor swing a 21" pitch prop? Mine would, and that will save some fuel for you. Are the spark plugs a light to medium brown? If they are blacker than that, your carb may be slightly flooding.

 

[180shabah]

Re: Gas

Again, we are only guessing cause we don't know how you use your boat, but it does sound high.

Start with the free stuff, pull the plugs for a reading.

Verify proper choke setting and opperation.

 

[wire2]

Re: Gas

For comparison, I burn 32 gal in 8 hours of mostly on plane running, with maybe 18-20 stops for locks and slow zones. In a 19' Glastron bowrider, 4 adults + gear, 5.7 I/O.

 

[ccyoder]

Re: Gas

Thanks for the input.

I'll pull the plugs and see what they look like and report back. Won't be until this weekend though. Haven't run with anything other than the 19 pitch prop. Guess I could give a 21 pitch a shot. Will that be hard on my aging outdrive? I am going to have the thermostat replaced during winterization to get it running at the right temp.

As for how I run it, I cruise at 35mph at 42-2600 rmp (if I'm remembering correctly), but do get a little faster for short periods. I run around 25mph in the afternoon, which is around 3500rpm, when the water gets choppy. And then I crawl through the idle/no wake zones.

On a normal day, we'll cruise around the lake for 15-20 minutes, go dock at the beach for a few hours. Then we'll drive across the lake to get a bite to eat, cruise another 15 or 20 minutes and back to the beach. There are days when we drive more and we do some occasional tubing, but not much. Does this help?

What's killing me is that we have a dock, so I've got to get my gas on the water and they really bend you over at the stations on the water. Last time I got gas it was 3.60 a gallon, when it's 2.79 a gallon at a land station.

 

[John_S]

Re: Gas

What are your wot rpms with the 19 pitch? If you are getting 4800 rpms or less, do not consider going to a 21 pitch. You will be over propped and lugging the engine.

Check your plugs as others have suggested. Black will indicate running rich. While you are at the boat there are a few quick checks you can do if it is running rich: Verify that your choke is opening all the way when engine is at operating temp. With flame arrestor removed observe fuel in carb throat. Dribling in carb may indicate stuck float needle (happened on my Mercarb). Also check your fuel pump sight tube that attaches to the carb. Any gas in it, indicates a ruptured fuel pump diaphram.

 

[QC]

Re: Gas

How much distance are you covering?

 

[HT32BSX115]

Re: Gas

You did not provide enough information in your first post.

Is there fuel on the lake?


Fill the thing up and run around the lake at a cruising speed for exactly 1 hour (NOT Wide Open Throttle) Do it at whatever planing RPM/speed you like to run around at.

Then fill it back up and measure what it took to fill it. [You could also do it for exactly 1/2 hr too but The less time you run it requires you to be more accurate filling it up to the same point]


Any other "guesstimate" is is not going to tell you anything useful.


Cheers,


Rick

 

[ccyoder]

Re: Gas

I'll check the choke operation and the carb. When you say check for dribbling, is that with the engine off? And, sorry, but what's the fuel pump sight tube? Is that just the line from the fuel pump to the carb? Also, FWIW, I've purposely smelled to see if my engine is running rich. If it is, it's not bad enough that I can smell it through the exhaust if that makes any sense. And I'm running around 4800 to 5000 WOT with the 19 pitch.

As for distance, here's my best approximation. My wife and I went out to eat last night at the lake. Hopped in the boat, started it up with a hair above a quarter tank of gas. We idle at I'm guessing 3 mph for 5 minutes through the channel to the open water (.25mile). At open water, I bring it to 35mph and cruise for 10 minutes (6 miles) and spend 2 minutes idling to the restaurant dock (.1 mile). We make this exact same return trip. By the time we got near the dock, the needle was below Empty and I was afraid we'd run out of gas. So, in summary:
.25x2=.5 miles
6x2=12 miles
.1x2=.2
=12.7 total miles on estimated 4.25G is 2.98 mpg

So QC, this sounds about like what you'd expect. The only snag is that don't know what my fuel capacity is, so I'm basing this equation on the assumption that I have a 17G tank. I haven't been able to verify this anywhere and am making this assumption on fill-ups and so forth.

 

[John_S]

Re: Gas

You look for the dribbling when the engine is idling. You can monitor that at the same time you are watching the choke operation as your engine comes up in operating temp.

The sight tube is a clear plastic hose from the fuel pump to upper carb body. You should be able to easily find that with flame arrestor off.

 

[getinmerry]

Re: Gas

Gas guages on boats are notoriously inaccurate. However, your calculations aren't too far off as far as milage goes.

I would refill...run a predetermined distance (better yet, use a GPS to log milage) and refill the tank to find out what actual is.

Chuck

 

[180shabah]

Re: Gas

That gas guage is only to determine..Do I have gas? yes or no?

Everything in the middle is almost as accurate as a guess

 

[ccyoder]

Re: Gas

It's a good idea, but I'm not going to invest the money in a GPS to figure this out. Need that money for gas....; )

I'll do the engine check this weekend and will follow Rick and Chuck's "timed run" suggestion.

As for the carb check, will the dribble be coming from the carb jets or somewhere else? And thanks for the clarification on the sight tube. I know what line you're talking about but unfortunately, mine is no longer clear. The years have made it nearly opaque, so can't really tell when there is gas in there. I wonder if I should replace that.

 

[eriediver]

Re: Gas

A boat that small (to me) I'd put it on the trailer & go to the gas station when I needed gas. I'm paying $3.69 at the marina. Prices have come down but the s.o.b that owns our marina is just gouging us. I get roughly 2 miles to the gal. but that's probably not much of a comparison to your boat.

 

[ccyoder]

Re: Gas

I've thought about pulling it out to get gas on land, but I think about going through all the hassel of pulling it out and straping it down, etc and putting it back in, just to save 10-15 bucks and it just isn't worth the time and effort. Unfortunately, I think our friends at the marina gas stations have figured that out.....

 

[QC]

Re: Gas

Well you should verify all by doing that run from/to a fuel dock, fill up when you start and then again back at the dock. Known distance + known fuel use = known consumption . . . then we'd have this nailed . . .

 

[180shabah]

Re: Gas

.....I know what line you're talking about but unfortunately, mine is no longer clear. The years have made it nearly opaque, so can't really tell when there is gas in there. I wonder if I should replace that.

Definately.

This is the only "fuel line" on your boat that is not marine rated. Just hit the local hardware store for a piece of clear tubing of the same size and swap it out. Should only set you back a couple of bucks.

 

[DayCruiser]

Re: Gas

I've thought about pulling it out to get gas on land, but I think about going through all the hassel of pulling it out and straping it down, etc and putting it back in, just to save 10-15 bucks and it just isn't worth the time and effort. Unfortunately, I think our friends at the marina gas stations have figured that out.....

I just use a 5$ "kerosene" pump and a few 5 gallon cans. Everytime I go out I just filler up. I never go to the marina to get robbed
The gas station is bad enough