7.4 merc won't start after winter storage

timharper89

Petty Officer 1st Class
Joined
Jun 24, 2018
Messages
263
It comes out because the gas expands in the heat. Only way to stop it is don't fill it so full
What annoy in the winter? Isn't it recommended to keep the tank full to avoid condensation? Or empty, but i have a 75 gallon tank that would be difficult to time correctly for an empty tank.
Fed Regs says the fuel tank sender and fittings must be accessible. I had a 1995 rinker 232 and mine was same way, lucky for me but I never needed to get to.
Hopefully i don't need too either.
Right now lets hope its just bad gas or fuel pump.
shouldn't be gas since i put stabilizer and fresh fuel in the fall.
Disconnect the rubber fuel line at the filter. Get another piece of fuel line and a gas can. Connect fuel line to filter housing and stick other end in the gas can. Fill the filter full of gas and then try to crank it
this is what i was going to do if starting gas in the carb failed
Wear safety glasses
Oops...I know better
 

San_Diego_SeaRay

Petty Officer 1st Class
Joined
Nov 9, 2014
Messages
342
Got it started by spraying gas in the intake with a spray bottle. Ran beautifully for 10 minutes until I turned it off. Accelerator pump maybe? Carb need rebuilt?

IMO the fact it ran for 10 mins is a solid indication that everything from the gas tank to the carb is working properly. I'd focus on the carb at this point.

Even though my accelerator pump doesn't work, after I get it started and it's warmed up the boat starts up like a champ; no problems whatsoever.

I bet if you tried to restart your boat right now, it would fire right up.

Lastly, I hope you have it on water muffs. Otherwise, you're looking at a new impellar at a minimum.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,371
did you ever check the oil level inside the pump body where it bolts up to the water pump
 

tpenfield

Moderator
Staff member
Joined
Jul 18, 2011
Messages
18,237
Perhaps that was water standing in the intake? Not sure if you smelled gasoline while doing all the cranking.

Rebuild the carb would be a good thing. . . or just get a new one.

with any no-start situation it is back to the basics . . .

Compression, Spark, Fuel.

It sounds like you didn't have fuel getting to the cylinders. As I recall my carb 454 was a bit difficult to start at the beginning of the season or if it had sat for a while. It seemed that my anti-siphon valve was a bit leaky and the fuel would drain down. Took a bit of cranking to get it re-primed.
 

timharper89

Petty Officer 1st Class
Joined
Jun 24, 2018
Messages
263
Hope it was just a fluke
Me too. I might rebuild the carb anyway just to be sure. Is it possible the fluid in the intake was the remnants of fogging oil or something? It definitely smelled similar to gas but a little different. I wondered about that
 

timharper89

Petty Officer 1st Class
Joined
Jun 24, 2018
Messages
263
IMO the fact it ran for 10 mins is a solid indication that everything from the gas tank to the carb is working properly. I'd focus on the carb at this point.
This was my assumption.
Even though my accelerator pump doesn't work, after I get it started and it's warmed up the boat starts up like a champ; no problems whatsoever.
I think I will order a rebuild kit. It can't hurt.. unless I mess something up😬
I bet if you tried to restart your boat right now, it would fire right up.
Yeah we did it again, and that's exactly what happened
Lastly, I hope you have it on water muffs. Otherwise, you're looking at a new impellar at a minimum.
Uh yes. Almost forgot though😬
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,186
On the picture of your fuel connector at the anti syphon valve looks to missing a hose clamp. Usually there are two clamps.
 

cyclops222

Commander
Joined
Mar 21, 2024
Messages
2,197
If as soon as you crank the starter motor. That big chokeplate swings WIDE OPEN or more than a 1/4" to 3/8" open. It will cause a LEAN COLD hard to start mixture. If the idle speed and idle mixture have been set with a warmed up engine ? The engine may be too lean and slow to start when cold.
lots of tweeks to get a engine starting and idling when cold.
What state are you and the boat in ?
DO NOT REBUILD the carburetor. It is fine when warm. Lets get the choke system correctly set up.
 

Grub54891

Admiral
Joined
Jun 17, 2012
Messages
6,186
I dislike those pumps myself. Had one customer's boat and it quit while moving it from the slip, windy day. Lucky people were around to help with avoiding squishing other boats at the docks and getting it back to the slip. Belt broke. That little belt works hard running the fuel pump and seawater pump. Also seen a few that went south from lack of maintiance. People don't know about servicing them. Don't know what Mercury was thinking when they designed them.
 

04fxdwgi25

Chief Petty Officer
Joined
Mar 25, 2022
Messages
596
Agreed that's a crazy design. Would have been better with a crank mounted impeller and normal fuel pump!
You are right, but the later model Gen GM motors don't have a fuel pump boss / drive, as everything went to electric fuel pumps in the auto world.
 
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