88 Supra Mariah 454

[Sjsupra88]

Hey all,

I'm Steve- I just bought an 88' Supra Mariah with a 454 and I'm pretty stoked to be apart of the supra community!
She does need some work... as all boats usually do. Actually, I'm pretty sure i bought a floating project. I'm a first time boat owner and while I'm pretty mechanically inclined, I figured I'd see if I couldn't pick some brains on the best way to do things.

My first concern is the floor. Everything seems solid on the Port side of the boat. The Starboard side, under the steering wheel is a mess. Looks like a repair was mickymoused. Behind the drivers seat, there is a couple of soft spots as well. The stringers still felt pretty strong when i checked the bolts on the motor mounts. Obviously its hard to tell anything until the seats and carpet are out.

I also am looking for a good wiring diagram for the boat. when i purchased it, the guy had the wires from the coil and distributor all unhooked, and had it rigged to a motorcycle battery to get it to start.. i should have taken pics but I am super confused how he did it.. I put a new battery in it and i have no power to anything on the dash or to the motor... I looked under the dash and the key switch has some really crazy wiring going on in there...

i guess the big question is... where do i start... ??! I assume pulling the interior and the floor is probably the best to begin this massive project..

any input would be great.

thanks,

Steve

[Cooose]

Hey, welcome to the club.

If you are planning to pull the floor, one thing will lead to another and pretty soon you will be doing a full stringer and deck job.

If you get this far, then you will probably just replace all of the wiring because it's easy to do with the boat in 389 pieces.

If you decide just to tackle the wiring for this season, then you can download a manual from the Supra website that will have it. Choose whatever the oldest one they have up, I think it's 90-93.

Post up some pics when you can. Folks around here are pretty helpful!

[flipz96]

Congrats! I just sold my '88 Mariah a couple weeks ago. Here is a wiring diagram was sent to me from Chris Young. It was really helpful. I used this to rewire my dash.

18531

[michael hunter]

If the main stringers are still ok and the engine alignment is good I would get it running and work out all the running and electrical bugs first. There will be plenty of time in the winter to tackle the floor and stringers.

[Sjsupra88]

Wow Thanks for the Responses guys!
I’m pretty excited to dive into the project. I’ve already begun pulling out a lot of the interior. After reading up on the forums it looks like I need to pull the gas tank to be able to do a full repair on the floor.
Unfortunately the floor under the dash where your feet would go is pretty shot and needs immediate replacement so that’s gotta happen before it sees water.
Hopefully I’ll know more once the floor is out. Since the port side is solid I’m hoping I can get away with only replacing the wood on the one side of the boat. Maybe that’s wishful thinking?

I was planning on doing a wiring replacement anyhow, since that section of the boat seems to be where the wire run is- so a big thanks to Flipz96 for the diagram. Hoping to have the rest of the interior out this weekend, so I’ll post some pics of my progress.

[Sjsupra88]

1853218533
Here are a couple photos. As you can see the area under the steering wheel is definitely in need of attention.

[Salty87]

... Maybe that’s wishful thinking?

We've all been there hoping it's not a total rebuild but the sad truth is...it is. By the time the deck is rotting in the middle of the boat the bottom of the stingers are shot. Your foam is trapping water. Would be throwing good money after bad to piecemeal a patch job.

Another vote to use it for the season if the motor mount bolts are holding firm. Slap some plywood over that area under the diver's dash. It's a low traffic area. You wouldn't be the first or the last to do this (I did it behind the dog house for a season or 3). Save the rebuild for next winter. Of course that's if you were hoping to use the boat now versus working on it for a couple months first.