TOPIC: '67 80hp dying off at full throttle

Took the Admiral, daughter, soon to be son-in-law out on the Clipper for Mother's Day. She was only run once last year before putting her away and she ran pretty good. I ran the lines dray and fog her to death. Had to pour some gas down the carbs a couple times to get her to fire up before leaving the house. She idled fine but once you got to half throttle she would speed up then slow down and keep doing that. If i pushed her to full throttle from idle, she would crank right up for about a minute then drop back off. i played with the high speed jets but with not much luck. I had freshly rebuilt the carb and fuel pump last fall for the test run and she's sat since winterized. I ran two tanks of gas, with SeaFoam in them but not any better. Any ideas/

Bob

Bob,it sounds like you have a clogged fuel line or (this happened to me) vent on tank was closed. If your using an OMC metal tank,the pick up in the tank might be clogged. Sounds like your getting enough gas to start it and for a short burst of throttle then running lean. jim

Hey Jim,
I used the original tank first then switched to the plastic one. It did start to suck the top down and I opened the vent on the cap but it only got a little better.

Bob

Next time you take it out try letting someone squeeze the bulb on your fuel line while underway and see if that keeps the motor running steady.If it does, the trouble will be from the fuel pump back to the tank. May be the valves or a defective pump diaphragm even though it's new.jim

Hey why didn't I think of that! LOL I'll give that a try and see what happens. Now that I think about it, the bulb really didn't get real hard but the fuel bowl was full.

Bob

If that don't help, might be your float out of adjustment in your carb(set too lean/low). Just throwing ideas at ya,Bob.

???

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" played with the high speed jets "

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I do believe that those adjustments are the low speed mixture needles.

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The high speed jets are fixed and not adjustable.

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Look for issues with the fuel supply.----Vents in tanks. --If an original metal OMC tank check the 2 valves in the tank fitting housing.-All hoses . check install kit in fuel pump too.

Damn CRS, your right Proff, completely forgot about the high speed jets being fixed. Got so used to tweaking the Fat Fifty. I'll check the line from the tank to the cowl fitting and the line from fitting to pump. If nothing comes out when flushed I'll check the pump. Thanks guys. I'll keep you posted.

Bob

Well??? Any news?
I'm always interested in your engine posts, cuz we're running about the same motors and if I have a problem I can always check your posts
Still haven't gotten a chance yet to run my Johnson 100hp on the water. Either too windy or too cold, maybe this weekend.

Sorry Cal not yet. Weather has been iffy so I opted to finish stripping down the Resorter's 350 to go to the machine shop for a quote on the heads and block. I'm hoping to get at it tomorrow or over the weekend. I'll keep you posted.

Bob

Hey waterwings i have the exact same motor and i put a carb off a 1960 75hp on her and now have full adjustment for high speed but i didn't gain that much speed, i think she sucks more fuel now. however when i made her a short shaft i got at least 10 knots or more!
I realize that doesn't help you but wanted to share anyway.

Bob, when I took the AMC 327 for my Sabre to the shop for a fixup the first thing they did was magnaflux the heads to make sure there were no hairline cracks anywhere. They put in new valve springs, reground the seats and valves and new lifters/rods. The lowers were good. He said there was no reason to put in hardened seats and over the past five years I never had any issues. Sadly now she's gone to a new owner.

Thanks Cal good to know. I'm going to see what he says. New 72cc iron heads are $316 each. Depends on how much it will cost to have the existing ones ground cleaned etc. It may just be easier to get now ones and get more horse power at the same time since the existing heads are 76cc smogger heads.

Bob

Like the boat and motor,Matty. The silver/white blends good with your boat.

Well checked the lines and nothing coming out with the gas when I put some through them. Pulled the fuel pump and on of the darn screws was completely loose inside!!!!!!!! Not sure how the heck that happened. The rubber "figure eight" gasket was all stretched and out of shape. That's what I get for using the original OMC kit that's not ethenol friendly. Ordered a new Sierra kit and should be good to go. Stay tuned.

Bob

Thanks Jim, she's my "first restore".

Hey bob, I also used the nos omc fuel pump kit, I haven't had an issue yet but I'm gonna keep an eye on her. haven't run this year yet, hopefully I will be in the water next weekend, I'm gonna keep my fingers crossed lol!
I also run "stabal" in the fuel every time evan if it's ethonal free gas!
Thanks matt

Thank the good Lord we have non-ethanol gas down here. I got so much old junk that needs it,I'd be in a pickle without it.jim

Bob, it's good you found it now while on terra firma. Paddling back to shore is something some of us can relate to and it's not fun

Hey Matt, nice rig by the way. Just keep an eye on it. The one on my Fat Fifty was fine, over 3 years running, so not exactly sure why this one went so quick.

Jim I can get ethanol free but it costs $1 more per gallon, ouch!

Cal, yeah right could have been much uglier!


Bob

matty83 wrote:

Thanks Jim, she's my "first restore".

Hey bob, I also used the nos omc fuel pump kit, I haven't had an issue yet but I'm gonna keep an eye on her. haven't run this year yet, hopefully I will be in the water next weekend, I'm gonna keep my fingers crossed lol!
I also run "stabal" in the fuel every time evan if it's ethonal free gas!
Thanks matt

I cut my oil mix down from 24/1 to 50/1 and added 6 oz seafoam to each 6 gal tank last time out with the 62 johnson v-4 in the aristocraft and it ran perfect. So that's going to be my normal mix from now on.

Wow Bob,a dollar more a gal!!?? It's around $4 a gal down here and that's RIDICULOUS!! The only thing that gets regular ethanol gas is the 98 explorer daily driver(I don't give a shit about)

Yup up here in upstate n.y. it's almost $5 a gallon!
I never tried sea foam jim, herd it's a great product maybe I'll give a whirl.
50/1 is what I'm doing as well, 3oz oil per gallon.
matt

Wow, are you guys getting ripped off on non ETH gas! The Indian casinos close me and a gas station they own real close me, is simple 20 cents more than reg. $3.70 something reg, $3.90 N/E. Plus a nickle a gallon off with a club card, which is free.

Holy crap I'm living in the wrong place i guess. Yes the Sea Foam is great stuff, use it all the time.

Bob

Hey bob, I got my 80horse on the river today and she ran awesome! I guess I got a good kit, hope you got yours running good!- matt

Congrats Matt! Well it just so happens after a rebuilt fuel pump, trying to bypass the cowling connector with a long hose to an inline fuel filter then to the tank hose, no change. Brand new tank hose and cowl connector back on and no inline filter fuel filter and back out but it was worse!!! Actually died at half throttle, back to the drawing board. So now, the heck with it, remove the carb and break it back down. Float with airplane dope coating is starting to peel and a very small piece is in the bowl, crap. Pul all the dope off and there's actually bare cork so I took the 75hp parts motor carb off and took the float out of there Sprayed it with Carb cleaner and get all the old gunk off. Sprayed air down in the needle valve seat and a chunk of black rubber comes flying out of the fuel inlet pipe!!!!!!!!!!!!!! So set the float to correct level put it all back together and try it on the hose. Woo Hoo, runs great on the hose, now off to the river. BINGO, runs like a top and jumps on plane right away!!!!!!!!!!!!!!!! Three hours of running around and we're finally good to go. Still not sure where the rubber came from as the hose leading to it was intact, but no matter, it's running great now. Now I have to check the speed with the GPS, don't trust my buddies mastercraft speedometer, as it said 23! Hell the Fat Fifty did 26 on the GPS and this feels faster, so we'll see.

Bob

A piece of trash in the fuel inlet? Well,I'm glad you found the culprit,Bob. Sounds like your ready to go now!

I am Jim thanks. Not sure where the heck it came from. Maybe when I put the new line on, a chuck came off into the nipple, who knows, at least it's running great and ready for the season now.

Bob

Bob, congrats on winning the battle. Sometimes those little "0" rings on the fuel connector plugs go kapoot, leak and then break off. Glad you found the problem. It's still spring ya know.
Cal

Bob, I've had junk/trash get in the needle seat like that before. Very irritating problem!

Maybe it just picked up a stray chunk of deteriorating fuel line, you know what the durned ethanol does to old lines, eats 'em up from the inside-out!

That stuff is so bad that a few years ago I was using my riding mower and it started to smoke, found out the gas line at the engine was turning to mush before my eyes! Never seen anything like it. I'm getting non-alcohol fuel from my local Cenex station now, the yard equipment runs much better!

Cheers........ed

Thanks Cal.

Ed, the weird part is the lines are brand new. Just installed them last October when I restored it! I know the line was pretty tight gong on the carb nipple maybe it cut a chunk and I didn't know it. Looked fine when I pulled it off though.j Oh well it running and that's all that matters at this point.

Bob

Glad you got her sorted out Bob.

Thanks Mark.

Bob