'76 Merc 1500 Tower Carb Question

I finally got it going today after all of the pre inspections and such after being stored for a couple of years. Here's my problem:

While priming with the hand pump I noticed fuel started to squirt out of the bottom carb......the primer bulb wouldn't go completely solid because of this.....

I went ahead and started it and it continued to slightly trickle out while it was running. I've taken a picture and marked with an arrow where it was coming out.

Am I missing something?

Re: '76 Merc 1500 Tower Carb Question

float mechanism not sealing off the bowl properly, bottom carb needs the float set properly, or maybe a new needle / seat. rebuild or at least thoroughly clean all three while your at it, dissassemble and blow out all the jets and passages with air. theres only two things that'll kill an inline mercury...running lean or overpropped!

also those look like the backdraft carbs, put a bb in that line that runs over top of the carb throat...someone at Merc back in the 70s had a great idea to make the carbs use a different jet at midrange to improve fuel economy but actually ended up makin the motor run lean and score cylinders or worse!
these are fairly easy carbs to work on check oldmercs.com for parts

Re: '76 Merc 1500 Tower Carb Question

are you suggesting to totally block off that tube or stick a bb in it to slow it down?

Re: '76 Merc 1500 Tower Carb Question

ClassyGlassy said:

are you suggesting to totally block off that tube or stick a bb in it to slow it down?

Click to expand...

Block off .


AK

Re: '76 Merc 1500 Tower Carb Question

I have the same type of carbs on a 1981 90 h.p. so should I put a bb in all three of them.

Re: '76 Merc 1500 Tower Carb Question

since I'm going to have them off and rebuilding them should I just remove the tube all together and use something like a vacuum plug at each end?

Re: '76 Merc 1500 Tower Carb Question

Does someone have .pdf's of the diagrams for these carbs, or a factory manual they can scan for me? I can't afford a factory manual right now and at minimum I need help with diagrams.

PLEASE.......

Re: '76 Merc 1500 Tower Carb Question

Get on the crowleymarine.com web site. Look up the motor on their parts catalog. It has a blow up of the carbs. You have backdraft carbs, which differ just slightly from the other carbs. Invert the carb covers and set the compound float levers until they are parrallel to the carb cover. When the carb cover is right side up the measurement between the float levers (float drop) is 1/4". Make sure the little spring on top of the floats is good. Initial setting on idle mixture is 1-1/2 turns open. Warm motor and adjust top carb first, followed by mid and bottom. Rich mixture gives lousy idle but good acceleration. If too lean, motor stumbles and dies. Bottom cylinder run richer than top, due to gravity.

Re: '76 Merc 1500 Tower Carb Question

could I get away with just replacing the float parts and setting proper float level.....as well as the blocking off the cross-over tube?

My Quicksilver rebuild kits came in today....how do I know I received the right ones? Here's the part number: 1395-5109--1

I'm thinking of just doing the floats since it started and ran well except for the overflow of the bottom carb.

These parts kits are for EVERYTHING and I just don't want to do a complete tear down at this time.