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470 mercruiser tank half full out of gas

mark_p

New member
"I have a 1979 18' Sea Ray

"I have a 1979 18' Sea Ray with a 470, yesterday while on the lake the boat ran out of gas.I was towed to a gas dock and proceeded to fill the tank, the tank took 13 gallons, I have a 30 gallon tank. The boat started and I was able to drive back to the ramp, which was an hour away with no problems.

When I got home I checked the gas tank vent tube for any blockages, there were none. Then I pulled the pickup tube out of the tank to see if it was damaged or not long enough to reach the bottom of the tank, there was no damage and it reaches the bottom of the tank.

Why would the boat run out of gas with the tank half full ?"
 
May be another issue such as i

May be another issue such as ignition.
hard to diag if not reproducable.
next time check for spark and have
starting fluid handy to verify it's fuel related.

Kurt
 
I know it was fuel related bec

I know it was fuel related because I checked the fuel filter after I ran out of gas and it was empty. After filling the tank we had to use starter fluid to get the motor started.
 
""...proceeded to fill the

""...proceeded to fill the tank, the tank took 13 gallons, I have a 30 gallon tank."

The gas pump shut off automatically? If it did then the VENT was not venting fast enough for the air in the tank to escape. I always SLOW fill my 30 gal. tank.

Mark:

What did the fuel gauge read when it died? What did it read when you "filled the tank...took 13 gallons"?

This issue sounds like a classic VENT problem. Check for a spider nest or other debris in the vent outlet and a low spot or pinched section in the vent line that will hold fuel which then prevents the pump or reduces its ability to siphon fuel from the tank."
 
"The fuel gage hasn't work

"The fuel gage hasn't worked properly in years, I usually get 8 hrs. from each fill up, I had 3 hrs on the hour meter when I ran out of gas. When I pulled my fuel pick up tube I looked in the tank, the tank is full, so I know that I had over half a tank of gas when I ran out, I have also checked my vent line and it doesn't have any blocks in it, could it be that my water seperator filter is clogged. I will be checking that next but I don't know what to look for if it bad."
 
""After filling the tank w

""After filling the tank we had to use starter fluid to get the motor started."

Pump may be failing. Change the fuel separater filter and the mechanical pump filter in the cone. Also change the carb inlet screen. If it has what looks like sand in it, it is dried fuel varnish. The pump will have it inside of it.

Check the semi-transparent hose nipple on the side of the pump for varnish sludge. If it is there just clean it out w/carb cleaner. Now when you start your engine again look for fuel seeping into the clear hose. If you see it and it is dumping into the carb and flooding it you need a new pump.

Pull the anti-drainback fuel valve at the tank where the hose connects and run some carb cleaner thru it.

While you are there just ground the pink wire on the gauge sender and see if the gauge reads full. If it does, spend the $20 for a new sender."
 
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