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FLDXT

99 17ma fuel tank question...

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Posted in general with no love. Think I've narrowed an issue down to degrading fuel lines. Gonna switch everything out. Only problem is getting to the connection on the tank. The picture below is from an LT18, it has a 42 gallon tank, the connection is in the back of the tank with no access. I'm trying to figure out how behind the sending unit is the end of the tank? My sending unit does not line up with the access in the console so I will need to expand that, but I need to know if an access can be cut in the console floor or it will need to be on the deck to access the back of the tank. Not sure who engineered that but apparently they assumed fuel lines last forever.

 

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So from what I could tell today and using Reel Loco's measurements, the end of the tank with the fuel connection is 10" from the dead center of the sending unit. Pretty sure I can cut an access hole and keep it in the console. I was going to go with a long rectangle hatch and catch the sending unit but I'm afraid it will jeopardize the integrity of the deck some I'll have to address that eventually, probably with a bigger pile hole over the sending unit.

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Tnt emailed me back today. No screen or antisiphon valve in these tanks, there are two baffles. Where the fuel line meets the tank, on the interior there is a piece of hose that hangs down to about 1/8" from the bottom of the tank, this is the pick up hose. Not sure yet if it is accessible through the sending unit hole if it needs to be replaced but we will see.

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Thanks for these updates FLDXT.  I wish I could give you some advice, but I don't have anything useful.  The info you are putting here is going to be useful for someone else though!

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I hope so, this has been a pia that I'd prefer not to deal with again anytime soon. Still trying to figure what kind of access to install where the sending unit is, odd shape and I dont think an 8" or 10" pie hole is gonna cut it.

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FLDX,  I'm afraid I'll have too do the same thing at some point so I'm following your post with much interest, and I really appreciate you taking the time to share as you go along. I can comment on hole over your sending unit that doesn't line up. The previous owner of my 98' 17MA apparently needed to access the sending unit. It appears they removed the round access panel cap along with the frame (same as yours). Then they elongated the hole for access to the sending unit, only enough for access. Then re-installed the same access cover using the same screw holes as before. There is about an inch of open area outside the frame where the cut was made but that can be easily covered. Having said that I never bothered with it, in fact I have a battery tray that sets over the hole, complete non-issue. In regard to the fuel line connection at the tank, I think this is doable without much issue. *** having to cut a hole in the floor in the center console but better than having to get to the other end of that tank (which probably comes next). I looked at mine and that 10" measurement from the sending unit to the end of the tank sounds right. The tank has to end about there as wires and cables from the console enter the bilge just past the end of the tank. To cut the hole, I'd use a rotary tool with the bit set just shy of the thickness of the floor. You can measure the thickness of the floor at the hole for the sending unit. Done properly I don't think the floor will be weakened by this. My biggest concern would be if the fuel line gets stuck while trying to pull the new hose, hopefully it's loose enough and has plenty of clearance for a smooth pull. Good luck, I'll be following this.

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Flats man, appreciate the info, I too have a battery tray that sits over the sending unit. Think I'm gonna get a rectangle hatch to go over the sending unit though. I have a rotozip and a dremel to make the cuts, I'm thinking the 6" pie hole should offer enough room to make the change. I'm gonna take a 3/8" male/Male fitting and make the connection between the old hose and new and hopefully pull through. My two biggest concerns are the internal hose in the tank and getting the sending unit off. I'll keep documenting what I find. I have a new wema sending unit com i'l ng and some enzyme tank cleaner. 

 

Front of my tank is pretty easily accessible through the big hatch in the front, should be an access panel already there to get it the full and vent lines at the tank.

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Sounds like a good plan. Did TNT give any description of what that pick-up hose is made of or how it connects internally? If it's a standard fuel line with a hose clamp, I Just don't see how it could be replaced through that small sending unit hole. Surprised that it's not a solid pipe that's welded in place.

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They did not, I emailed them back and waiting for a reply asking those questions. I think I'm gonna steal your idea about about leaving the sending unit pie hole, I have some 1/4" starboard that I'll cut to fit over the sending unit access.

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This is great info! 

It would be great to know if any 17MA owners had a custom tank made with all the fittings lined up directly under the console pie holes for ease of connection/troubleshooting. If so, posting the specs of that tank and it's fitting holes would be a great help to those 17MA owners who need to replace their tanks in the future. 

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Well there it is....spent the day cutting and replacing fuel lines. Removed a flow sensor and shut off valve out of the system to eliminate some kinks, my racor sits higher than my fuel tank. Nothing look too awful. Pulling the fuel lines isnt bad, not sure you even need to pull them. When I cut the hole above, there were all kinds of goodies down in the hull, wrappers, wire, etc. Pulled the sender also, pumped all the fuel, a little debris on the bottom hit some startron should take care of that, added back about 5 gallons w some startron and smushed it around, jacked the nose up gonna let it sit until tomorrow and pump out. Still dont know what the fitting in the tank looks like. Where the fuel line meets the tank there is a thread fitting, didnt have the fortitude to try it. Unless its connected to this mysterious drop line in the tank, no way to get to it, hoping that's not the issue. As I was sloshing the fuel tank around say my PP hit the ground, blew a fitting with fluid everywhere, always a special little treat. 

 

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when I was cleaning my fuel system...I blew the line from the stern to fuel tank to clean out the pick up valve...sometimes they get some debris around the screen.

a few shots of air will provide  you with some line  cleaning.

dc

 

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1 hour ago, Wanaflatsfish said:

when I was cleaning my fuel system...I blew the line from the stern to fuel tank to clean out the pick up valve...sometimes they get some debris around the screen.

a few shots of air will provide  you with some line  cleaning.

dc

 

According to TNT, there is no screen. Still want to see what's in there.

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50 minutes ago, Wanaflatsfish said:

are you taking out the sender ?

 

dc

 

Already did, you can't see that far forward and I couldn't find a mirror to look in there. I have to pull the sender once more today to drain some fuel out, I'll try to get creative again.

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Great job cutting that hole! That tank is a few inches further aft than I thought it would be. I checked the forward access panel in my 17MA and you were correct, you can access the vent and fill line connections at the tank. I looked in there and was surprised how clean my lines and clamps are, no need to change right now but good to know for the future. I'm thinking about adding an access panel in the center console like you have done and changing the fuel line from the tank to the filter, this thread will make it a lot easier knowing what I'm getting into, thank you!

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