1973 Aquasport gas tank issue and accessories..

[Dbartlow1]

Hi guys! I’m dan and I’m brand new to this forum and boat ownership. I recently bought a 1973 Aquasport 196. It has an older 115 evinrude outboard. The boat is in pretty good shape not major issues. I plan on restoring and customizing it this winter. I have run into a issue right off the bat. I filled the boat with gas before going out since my gas gauge isn’t working. Ran the boat for a few hours then headed in. Went out the next day thinking I had plenty of gas since it’s supposed to be a 50gal tank. Sure enough about 30 mins in the boat stalled out and was completely empty. A friend towed time to the gas station. I filled it up but it only would take about 24 gallons. Does anyone know of an issue that would restrict it from filling properly?? It definitely hasnt had a tank replacement. Can anyone help me out with this?? I’m lost here. Lol. Also where can I find emblems and new rear vents and any other original parts??  Thanks in aft for your help!!!

[hudsport]

welcome, do you smell any gas fumes, any gas residue in the bildge area? using 24 gallons in a few hours points to a very bad leak?

[Capt.Joe]

Welcome to the forum, Dan! It sounds like to me you may have a leak somewhere. I only think that because I have a 150 etec with a 35Gal tank. When I run my fishing charters I burn about 10-15gal throughout the day.

If there isn't a leak, it's possible that the fuel pick up line isn't completely submerged in the tank. It could also be a venting issue. It's hard to tell without seeing the tank.

I hope this helps!

[boatnamesue]

Does anyone know of an issue that would restrict it from filling properly?? It definitely hasnt had a tank replacement.

An obstructed vent wouldn't allow for a full tank fill up....but you'd know if the vent was obstructed for a number of reasons, the most obvious is fuel would spit out the fuel fill inlet due to a pressurized tank.  Despite a number of responses here mentioning possible fuel leak, I'd be shocked to learn it was a leak that you didn't notice because the smell would be hard miss.  But just in case it is a leak...if you trailer your boat then back it down a decline and open the hull plug.  If you've got a leak you'll see/smell the confirmation.  You stated the original tank has not been replaced.  How do you know this?  Unless this hull has been dry stored with a dry tank for over 20 years I find it highly unlikely that tank is original....45 years.  Nah.  I reckon it's been replaced with a tank having less capacity than the original tank.  Only one way to know is to put your eyes on it.

[Fish Head]

Another good reason to inspect the tank if you think it is original would be to make sure the foam surrounding the tank is not waterlogged or holding any amount of water. If original chances are you might have some crevice corrosion that needs some attention before it gets to far gone. Lots of good posts on remounting a tank on this site without foam!

[RickK]

An aside.... the standard size tank for the 170 was 27 gal.  Maybe the original owner downgraded the size of the tank?  Being a 45 y/o boat doesn't necessarily mean a bad tank - in my '71 170 the tank was above the floor so it was still strong (and still is sitting in my yard). About '72 they were moved to under the deck, so anything is possible.

[hudsport]

good point Rick

[RickK]

Typically the fuel burn for a motor is HP/10 at WOT. So that 115 could burn 11.5 gph at WOT - so if the tank is indeed a 27gal, you could burn through it in a couple hours, if you run wide open all the time. If you slow it down to a comfy speed (28-30) the burn rate should drop to about 6 gph.

[boatnamesue]

...and speaking as an owner of a 170 with a 2 stroke 115hp and 27 gal tank, I rarely break 4100 and even more rare run at wot.....I ran 30 miles today and burned 8-9 gallons.  Amazing how the old cliche of 2 strokes being fuel hogs doesn't hold up when you cruise at 3/4 throttle or less. 

[RickK]

The same formula works even on the newest motors.

[boatnamesue]

The same formula works even on the newest motors.

...ain't that the truth

[wingtime]

My 250 Etec sips the fuel at low and mid range rpms.  Get up to WOT and she jumps up to about 22-24 GPH so still close to the gal per 10 hp rule.

I had a 1100  two stroke Kawasaki Jet ski in the late 90s.  That thing was a rocket.  Had a 14 gallon tank.  WOT fuel burn was 14 gals per hour (135-140 hp) at 64-65 mph.  So in theory you could go 65 miles on a tank at full speed.  Even with that fuel burn I could ride it all day on a tank of fuel.  You rarely ran it at full throttle for very long...  was too hard to hold on for that long!

[Dbartlow1]

  Hi guys!! Thanks first of all for all the feedback!! There is definitely not a fuel leak. I was definitely running full throttle, so I could of been burning way more than I should of. The tachometer isn’t working, but I’m replacing it this off season. I’m also going to be doing some restoration to the boat as well. So when I remove the console I’ll be able to pull up the panel and check the fuel tank to see what the deal is. I don’t think it was replaced but I guess it’s possible. I’ll update everyone once I get it opened up! Thanks again for all the feedback you guys are awesome!!