Gas Drinking Mariner 45hp

[SKYCRANE]

I have a 1986 Mariner 45hp (s/n 0A917774) with two WALBRO carbs. Mounted on a V17 Bass Tracker. Went out today to do some fishing but ran out of gas. Traveled just under 20 miles on the water and used 10 gallons of gas, if it haden't been for a friendly passer by with spare gas I would have been stuck. Poured in another 5 gallons, traveled 6.8 miles back to dock and used all but about 1/2 gal. of that fuel load.
Anyone got any ideas??? I have the factory Service manual, but no help there.

 

[achris]

Re: Gas Drinking Mariner 45hp

That does sound a bit high. Rule of thumb is that the engine will, at full throttle, use HP/10 gallons per hour. What speed are you doing at WOT (Wide Open Throttle)? That will give you a ball park figure for miles per gallon. 45hp on a 17 foot boat is probably stretching the friendship a little. Also what RPM are you getting at WOT? If it's too low, then you'll use heaps more petrol (gas is what we use to light bbqs) than if it was set up right. I think the WOT on those engines is 5000-5500, but check the book.

Chris................

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Cool day, semi smooth water, was running an average of 23 to 25 mph, if the dash tack was right (and I think it is not) it indicated 5000 to 5100 rpm. But as the day went on water got fairly heavy so had to do a bit slower, 15 to 19 mph.
As for the boat/motor match up, it was the original motor on the boat when bought new, I bought it second hand but the person I got it from had the original paperwork when he bought it from a dealership.
I do know I need to adjust the idle, seems to be a bit low. Changed out the carb bowl gaskets but did not mess with the floats, they looked to be in good shape. Prop is a 13 pitch but need to measure the dia., I know that will have some to do with it.
But what does not compute, is that a buddy of mine has a 17 ft Lund with a 40hp on it and we go all day on a 6 gal. tank and still have plenty of gas at the end of the day.

Thanks...
Curtis...

 

[DJ]

Re: Gas Drinking Mariner 45hp

Leaking (holed) fuel pump diaphram comes to mind.

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Thought of that too DJ but there are no visible signs of fuel on the carbs, unless it is all internal.
One thing that I did notice while on the water with the engine shut off was a stream of raw fuel floating in the water coming form the prop exhaust.

Thanks...
Curtis...

 

[DJ]

Re: Gas Drinking Mariner 45hp

Curtis,

You wouldn't see it in the carbs. it would go directly into the crankcase.

 

[Laddies]

Re: Gas Drinking Mariner 45hp

If your carbs are WMA series carbs and they have inlets without springs on them or a incorrect float level they will burn fuel faster than 2 men can carry it.

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

U R right they are WMA carbs, but the front choke plates are one piece, not the split style. I just put new gasket kits on both carbs, the fuel diaphrams looked good on both but changed them all anyway, the floats are set at 5/16 as per the service manual, not sure if it will do much good or not. I also reset the idle screws to 1 1/2 turns out to do a idle reset on the motor, the boat tach is not working so good so will go out and buy a handheld tach from autozone along with a timing light to check that also. other than that I am still confused as to how that small a motor could use a total of 15 gallons of gas in under 30 miles of travel. Sevice manual is not much help in the troublshooting department.

Thanks...
Curtis...

 

[Laddies]

Re: Gas Drinking Mariner 45hp

Does the engine have the spring loaded inlets in it? Thats the most common problem with excess fuel use, followed by the inlets leaking at high speed the 44cu. in. engine is normally a miser for fuel so you do have a problem. Is the bottom clean and flat many boats develop a hook from sitting on the trailers.

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Laddies, not sure what you mean by spring loaded inlets. If you mean the choke plates, they are the one piece type, they are not a two piece with the spring loaded flap. I am not so sure if these are even the right carbs for this motor. They are both WMA Walbro carbs with a date stamp of 1985 and the motor is a 1986. I know I have run out of ideas, rebuilt the carbs, reset idle speed, and they still use fuel like mad.
As for the hull, it looks to be pretty straight, I have full length runningboards on my trailer that run the full length of the hull so it will sit straight and level.
I would like to say THANKS for all the help that has been sent my way from all you folks in the boating world.

Thanks...
Curtis...

 

[Laddies]

Re: Gas Drinking Mariner 45hp

Heres a picture http://www.iboats.com/Sierra_18_729...8954704--**********.441683751--view_id.174832

 

[Holeshot458]

Re: Gas Drinking Mariner 45hp

SKYCRANE
I just purchased a 1988 V17 Bass Tracker with a 1988 45hp Mariner also. I had it out this weekend and went through six gallons of gas in about 10 miles. I think that is rather high too. So I am very interested in the answers you get to your problem.
I noticed, what looked like, raw fuel in the water coming from the exhaust too. Makes me think that it could be holes in the diaphram of the fuel pump like DJ was saying. Does that make sense?
Hope you don't mind me butting in!

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Not a problem Holeshot, maybe we can both find out what the fix will be. As I stated above I installed new diaphram kits in both carbs, reset the idle best I could without a tach. I ran the motor in a makeshift tank (large trashcan) so I could have a load on the motor in forward gear and came out with the same results. Used just over 1/2 gallon of gas for a 10 min. run at idle.
Had to break down and take it to a local shop to see if they could figure it out, if so I will post the results for you. If not, then not sure what my next move will be short of buying another motor. Can't afford to carry a ton of gas just to go fishing.

Thanks...
Curtis...

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Laddies, yes that is the style of fuel inlet I have. The springs are attached permanent to the inlets. When I put the gasket kits in I inspected them before I checked the float measurement and they both looked good, no deformed tips and the seats looked good also.

Thanks...
Curtis...

 

[Holeshot458]

Re: Gas Drinking Mariner 45hp

Sorry you were unable to come up with anything. Hopefully your local shop can figure it out. I'd be very interested in what they have to say.
Thanks.

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Okay folks here it is in a nutshell. Boat shop said top 2 cylinders have very low compression, they are still firing but not burning all the gas just letting it pass through the exhaust(hince the raw fuel in the water) which causes a large fuel flow rate and why I used so much on a short distance run.
The fix was posed it two ways. $2500 to rebuild the motor or get a new or used motor to replace it. Looks like I will be looking for another motor just can't afford a new one so will be looking for used. Just my luck to buy a boat that the seller filled me full of BS. I did run the motor before I bought the rig but you can only tell so much without taking it on the water. Learned my lesson well.
For all of you that gave input for my problem I Thank You Very much and my your rig run fast and long and the water be glass smooth for you.

Thanks...
Curtis...

 

[Yepblaze]

Re: Gas Drinking Mariner 45hp

I don't know your mechanic, nor have I read every word in this thread.

But from what I have read.

Get a second opinion.

 

[hkeiner]

Re: Gas Drinking Mariner 45hp

As previously suggested, be certain that the compression is bad before getting another motor. You can do a compression test yourself very easily. The boat does not have to be on the water and a compression gauge is not expensive.

Another thing you might do before replacing the motor is to decarb it. Perhaps the rings are stuck and can be loosened up to restore compression. It is a long shot, but worth a try.

Following are some FAQ threads that might be of help too.

http://forums.iboats.com/showthread.php?t=188767

http://forums.iboats.com/showthread.php?t=158076

 

[Holeshot458]

Re: Gas Drinking Mariner 45hp

Very sorry to hear that.
But, like the other posters have said, I would check the compression myself or, at the very least, get a second opinion from another shop.
I have since rechecked my records and it looks like I ran more like 20 miles on six gallons. So, while not great, its not as bad as I thought.

I hope you can come back again with some better news.
Good Luck!

 

[SKYCRANE]

Re: Gas Drinking Mariner 45hp

Thanks for the info. I will be out of town for the next 3 weeks working on helicopters in Ft. Rucker AL. But when I return I will do a good de-carbon on the engine then recheck the compression. Who knows might just do the trick. I would like to keep the motor that I have so if this works it will be great.

Thanks again...
Curtis...