84 Skipjack sport main fuel tank issue

ericdehaven

Newbie
Jun 11, 2021
2
0
46
90008
Name
Eric DeHaven
Boat
skipjack 24 sport cruiser
Hey everyone, I am a bit new here but was sent over by Skipjack and excited by the community.
I have an 84 sport cruiser that has been updated with a big block chevy / penta twin prop outdrive (along with many other modernization updates etc)
I am having a fairly bad issue with the main fuel tank and hoping someone here can chime in.
The main in-hull tank is the original unit, and at some point by the previous owner had regular ethanol blend pump gas left in the tank for a period of time. who knows how long and why they would have done that without stabilizer.
When I got the boat it had the dreaded green sludge built up around all the brass fittings in the tank.
I have since rebuilt the carb, changed all the fuel rails, lines, filters, etc..
My 2 20gal saddle tanks work fine.
I replaced the main tank pickup with an aluminum / rubber based unit as well as fully drained and flushed the main tank best I could. I do not get any more green sludge when get fuel from the main tank that I can see in the filters or tanks when I pump it out.

However here is my issue.
When I run the motor at cruising RPM (3000) and switch to the main, I get loss of fuel pressure. even though I can get flow from the lines using an electric pump in testing no problem.
I have cleared the vent hose and verified that we are getting proper venting, I have even tried running it with the fuel cap off to test for vacuum issues.

I have 2 theories.
1. the tank is just shot and needs to be replaced. cut the deck ($1000) remove tank (massive blood sweat and lots of tears) new tank made ($1600) and re-glass the deck.
2. Fuel delivery issue. So we are coming out of a 3/8in pickup hose to a 3/8" fitting, 3/8" fuel hose to a filter separator (new unit and 3/8" in 3/8" out) to a fuel shut off 3/8" in/out and then to a 3/8" tee where it joins with the 2 saddles (on a separate selector shut off). Total fuel line run is maybe 3.5ft
I am running a standard marine chevy mechanical fuel pump and a regulator set to max 6psi. This works fine with the saddles that have much longer fuel runs but running 5/16 or possible 1/2" fuel line cant remember.
By regular measure this should be fine, the motor is probably 350/400hp with a 4 barrel holly so should be fine with that fuel line..

I am very afraid this is theory #1 and I will just do it if I have to but would love to find a way to save the tank and not cut the deck of my very good condition jack..
Any suggestions would be much appreciated
 
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skillett

Almost A Member
Jun 11, 2009
118
22
Oxnard, Ca. U.S.A.
Name
Doug
Boat
25' Skipjack Sportsman
I agree...replace the tank. I have an 85 sport cruiser and just completed replacing the tank. It was an 1/8" aluminum, now a 3/16". The tank last 35yrs...my old 24 fly had a steel tank that also lasted 35yrs...its time. I have pictures of what I did...if you have questions...my new tank was 1800.oo
 
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Dragon

It is what it is...
May 24, 2006
423
298
SLO Co.
Name
Paul
Boat
22' Pro Sport CC / 20' Skipjack Open
You have a 37 year old boat...Your ready for a New Tank...
 
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Windy Bay

Member
Aug 2, 2008
404
165
Elkton, OR
Name
Larry
Boat
2 Skipjack Sports Cruisers both under construction
I do not envy you. I have 2, yes 2 sportcruisers. 1 is a 1980 and the other is a 1990. On the 1980 the fuel tank was leaking. when I got it, it had been out in the rain for quite some time. So, I cut the deck, pulled out the tank. Then discovered the stringers and transom were gas soaked, along with water soaked. Replaced stringers, transom, and the board that runs along the Keel. had a new tank built, put the tank in the hole, and that is where I stopped. I could not get the deck to crown the way it did before I cut it. And if I had it to do over again I would cut the deck a different way. My advice is replace it sooner rather than later. Have a professional cut the deck (unless your really good with that kind of stuff) . Getting the tank out was not that hard. Cut the foam, put a chain hook in the sending unit hole, and lift with something. I used my tractor bucket. Came right out
 
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ericdehaven

Newbie
Jun 11, 2021
2
0
46
90008
Name
Eric DeHaven
Boat
skipjack 24 sport cruiser
Thanks all, I have decided to pull it and get a new one made. I am in Ventura CA and Skipjack themselves referred me to a local glass guy who will cut the deck and re-glass after I replace the tank for $1000. I found a few local shops in Ventura that can do the tank in 2 weeks using the old one as a reference. So I think this is the plan at this point..
I also sprang a small water leak at the back of the motor this weekend, (only when the engine is running) thinking its the exhaust y pipe so looks like I have to pull the motor at the same time. So guess its going to be a good time to do the tank to. ugh, well at least we use the hell out of the boat so its all worth it.

Skillet any pics you have would be greatly appreciated! DM me and I can give you my email address if you dont want to post here.
 
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Feb 1, 2019
9
3
73
Port Hueneme
Name
David
Boat
Sancha
Thanks all, I have decided to pull it and get a new one made. I am in Ventura CA and Skipjack themselves referred me to a local glass guy who will cut the deck and re-glass after I replace the tank for $1000. I found a few local shops in Ventura that can do the tank in 2 weeks using the old one as a reference. So I think this is the plan at this point..
I also sprang a small water leak at the back of the motor this weekend, (only when the engine is running) thinking its the exhaust y pipe so looks like I have to pull the motor at the same time. So guess its going to be a good time to do the tank to. ugh, well at least we use the hell out of the boat so its all worth it.

Skillet any pics you have would be greatly appreciated! DM me and I can give you my email address if you dont want to post here.
Hi Eric

Not sure how to DM you. I have an 25' Skipjack Fisherman which was built in 84 and have been considering changing out the tank. It was repowered in the 90's with a 41p diesel but I don't have any information about the tank. I would appreciate it if you would forward the contact information for the guy who agreed to pull the tank as well as the guy who is building your new one. I live near you (Hueneme) so there's a good chance that I can use the same people.
 
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SkipJack Boats

Advertiser
Advertiser
Jul 8, 2020
237
193
65
Oak Hills, CA
www.skipjackyachts.com
Name
Michael Englebrecht
Boat
25 ft Skipjack
Hey Eric, glad you made it here. When I need info on a older boat these guys are amazing.

Any boat that gets older will eventually need tank work.

Our friend Tom who post on here pretty often and who I consider brilliant, told me a story about a possible nightmare story about his bout was being launched and he didn't have just a leak but all his fuel was sloshing around the bilge of his boat.

Being the smart guy he is he had checked by inspecting by opening the hatch and looking in the hatch. The thing to do if you like living. In my 50+ years of owning boats this has saved me at least twice.

I would change it if I were you. If the original tank definitely. If you need help or advice I can come to to your boat and help. Doing some of these big jobs yourself (with experienced friends) help get to know and understand your newest family member and will make you a safer boat owner. It not brain surgery but not easy either. We all learn to enjoy keeping our boat safe and maintained. It's part of the hobby.

Call me if you need some help.

BigMike
 
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