'72 Mercury 7.5hp blue band carb probs

[wm_son]

Newbie here and glad to have found this site! Learned quite a lot from a 2012 post from bigminiandy related to the exact same motor. My ser# is 3277955. Recently acquired and not getting fuel to plugs. It sat for years. I was hoping someone might have a parts explosion of the fuel system including the carburetor. Or possibly a brief synopsis of the steps I need to take to cure this. I'm thinking carb kit and remove all gum (parts soak). Any tips are greatly appreciated. Thank you.

[haventaclue]

Welcome to the forum and to insanity of old Mercs,proud owner of a 1969 Merc800/80HP .
Definitely a carb kit,exploded view, http://www.crowleymarine.com/mercury-ou ... /457_8.cfm .
Soak the carb overnight in carb cleaner,blow through passages with air
Spray some WD-40 or some lube in around the pistons and the top and bottom bearings before trying to start,spray through the carb inlet and let lube run down to bottom bearing,flip her upside down to get the top one,she's been laying up a long time.You'll also need to replace the impeller.Good luck

[wm_son]

Thank you Haven't. Love your signature btw, so true and hilarious. I'm headed to the shop and will report back this weekend with success. Thanks for the impeller add also. I was raised on a circa '55 50hp Merc, short shaft, on 14' Alumnacraft. It flew and pulled many a fat skiiers (me one of them). My baby was a 10hp Hurricane on an 8' hydro. Plenty of fun stories there. At some point I will join CMBA. This site has so much information, and I've read many of the posts; I can see myself spending quite a lot of time here. Can't wait to dig in!

[wm_son]

Soaked, cleaned and reassembled all carburetor parts. I did get it to fire and even run for 10 seconds which makes me feel good, but both gas lines (p/ns 21 & 22 of attached link) are dry rotted. Curious if anyone has made their own lines using existing brass fittings, otherwise I need to cough up $80. Just a thought, thanks. Great parts site Haven't; appreciate that.

http://www.crowleymarine.com/mercury-ou ... /457_7.cfm

[haventaclue]

I bought a couple of feet of fuel line from the local Auto shop,removed the brass fittings from the old ones,the threaded end pulls out,and used pipe clips to hold them,I used the crimp type but the spring clips are just as good and easier to remove the pipe any time.Modern fuel deals better with all the ethanol that is added to petrol these days,10% in our local Applegreen these days,I believe the powers that be are trying to get it up to 15% in the 'States.Stupid really,diluted with ethanol you need more to get where you're going,meaning more emissions,meaning more profit for the oil companies.That's my opinion,for what's it's worth

I was raised on a circa '55 50hp Merc

Nice,I'm a sucker for old Mercs

[wm_son]

Great, I'm headed for some clamps and line. And yeah, ethanol is a whole nuther book. I'm a logger, and we have to take quite a few precautions when dealing with anything +10% for our saws. And you're right about efficiency. Oh well, on a better note, I used to pound many a Guinness. Lived in Germany and Boston for a few years and they love them some Guinness. Now I drink water and coffee. I'll chime in hopefully early this week to give you good results on the 7.5. 10-4, clear.

[wm_son]

Update: was able to cut collars on crimped ends of brass fittings, leaving a bit of a ridge, and soldered new nipples. Replaced gas lines, and all lines and fittings are tight as a bass drum in a St. Patrick's Day parade. Still not getting fuel. I'm thinking fuel pump. Is there a way to test? If not, I'm assuming I need to order all new parts for the pump. Correct? Thanks.

[haventaclue]

Pull the pump,check diaphragm for pin holes,maybe it would be a good idea to rebuild it anyway. Pull the fuel line from the carb,pump primer a couple of times to see if fuel is getting to carb.
If you have fuel,put the carb back on,try again.If no fuel,you may have a bigger problem,worn top and bottom seals,loss of vacuum due to crankcase seal gone.I hope not.Good luck.

[wm_son]

Awesome, thanks. Glad you included vacuum info, something I was thinking also. I remember rebuilding fuel pump on the old 50 back in the 80s, so I'm somewhat familiar. I live SE of Chicago and we're getting their blizzardy weather. May be a few days on this one, but we're getting closer. Really appreciate the advice.

[wm_son]

Great news from the town of Leesburg. I dis and reconnected the fuel line from the gas tank and walla, she purrs like a kitten. Didn't have to dig back in to her or nuttn. Wow, what a joy; she's even spittn water and didn't get hot. I do however have a new leak in the plastic line that carries fuel/air and goes from the bottom jug and runs along the left side of the block and connects to the top jug at a t-valve(behind the side coil). This s/b an easy fix, I think. Please let me know if I need to take any precautions here. Also getting tiny water leak at fitting exiting top of block. I think I can get by with teflon tape on this one or simply tighten the fitting.

Interesting tidbits here: 1. when she first started purring, drops of water were trickling from impeller discharge hole (rear cowl). Shut off, fired back up and got consistent stream. Prolly will still replace impeller like you suggested. 2. Crowley Marine must have updated their website as I'm no longer able to search explosions for 1972. At any rate, I've never had problems with this particular line (stated above) and was curious about its function. Is there another good parts site for vintage motors? 3. Yesterday, I could not access the CMBA site until late evening. I was always redirected to a site EasyCGI (web mgmt site). Not sure if anyone else had the problem. Happy boater here, well ice is 10" thick so it will be a few weeks. Bis spa:ter.