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Excessive smoke

J

justmyluck

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"New to the forum and need hel

"New to the forum and need help. I have a 1996 7.4 (not efi) mercruiser (gen6) and have excessive smoke at start up, smells like gas and is not real black. Seems to be fine after 5 minutes. I believe it is the choke from what I have read here. Is the choke something I can adjust or is it time to call a mechanic? Engine fires right up and runs fine after the smoke clears. thanks for any help"
 
"[b]"Is the choke somethin

""Is the choke something I can adjust or is it time to call a mechanic? "

If you have to Ask,..... Chances Are,....
You otto call your Mechanic in......."
 
"Bill,
This does sound like

"Bill,
This does sound like a Choke Issue BUT....
Be careful about trying to diagnose the problem. A Mechanic could simply do what you diagnose, then charge you and not solve the problem!
It may be a better idea to take the boat to someone that you can trust and state what the problem is and then ask if this could be a choke issue?
Before you take it into the shop check to be sure that something is not disconnected (possibly the wire if it has an Electric Choke).
If you are mechanically inclined then get a repair manual and give it a go. Take notes so that you can get it all back like before and make small adjustments, but this move could cost you more i9f you get it far out of whack!"
 
"A digital camera works great

"A digital camera works great when you are doing any disassembly. The photos can be viewed on a almost any TV, not only for reassembly but for close inspection of a critical part. HDTVs give the best view of your pics. Guy"
 
"Thanks for all of the info.

"Thanks for all of the info. I think I am going to get the manual, read that, and then decide if I want to make any adjustments. I have some basic mechanical skills but usually know when its time to call for help. I really hate to change anything because the boat runs great, but dock neighbors won't appreciate the smoke out. Thanks again. Glad I found this forum."
 
"Bill;
I will try to help.
F

"Bill;
I will try to help.
First, I am assuming its a 4 bbl Quadrajet, with electric choke. You'll need the cover and spark arrestor off.
The choke butterfly blades are the front top set on the primary barrels. With the engine cold, they should JUST be closed. You can check and adjust this by loosening the 3 screws around the black heater element housing (where the wires connect) and rotating the housing left and right. When the blades are just closed, tighten the screws.
Next, as soon as the engine starts, the choke blades should open to a spacing of about 1/8 to 3/16 of an inch. There is likely a small diaphragm pot hooked to the choke shaft thru a linkage that is supposed to open the choke this little bit when it starts. If they are not opening, this is your problem.
As the engine warms up the choke heater housing should get warm, and within about 4-5 minutes the choke should be open wide (straight vertical). If this does not happen, your heater element is likely shot.
Hope this helps,
Rod"
 
"OK, I started the boat over t

"OK, I started the boat over the weekend with carb/choke exposed. Before starting the choke was barely(but completely) closed. It opened slightly(3/16 ") after starting. Excessive exhaust smoke & smell started immediately. If I manually opened the choke then the smoke almost went away. It took almost 15 minutes for the choke to open completely (at idle) and boat ran fine at that point. Any suggestions as to why it is smoking so badly at start up? Thanks Again its a 7.4 merc, 1996, 550 hours. Complete tune up last year."
 
"Sounds like Mr. Choke is set

"Sounds like Mr. Choke is set a bit rich. I usually adjust mine on the lean side. Might require restarting it a few times, and use of the "fuel injection hand" on the throttle (pump, pump, pump), but it works better set on the lean side.

JEff"
 
"Bill, why not just back the c

"Bill, why not just back the choke setting off a little and try it out? You can't hurt anything, and you will quickly see if it solves the problem.
Does the choke heater housing get warm after a few minutes of running? Usually the choke should be completely wide open in only 5 minutes or so.
If your idle jets are adjustable, they may be open a bit too much. You could try closing them by turning them CW with a screw driver. This should be done fully warmed up.
Rod"
 
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