new tank caused problems

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phil123

Cadet
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Sep 4, 2010
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6
I replaced a 6 gallon portable for my 35 johnson with an 18 gallon aluminum.
same place on the deck (elevation wise) properly vented and plumbed. Pump the bulb,engine idles for about a minute or so then runs out of gas. tried with fill open checked vent hose . the only thing I haven't checked is the pickup in the tank, is there a filter or sock in these tanks or is the pump or filter on the notor suspect? any suggestions?
 
Vic.S

Vic.S

Rear Admiral
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May 4, 2004
Messages
4,721
Re: new tank caused problems

If there is any obstruction in the pick up from the tank there will be a tendency for the fuel line bulb to collapse or go very soft anyway.

You could have air leaking into the fuel line, anywhere from tank to pump. Connector the prime suspect.

It could be a defective pump but not if it works OK on the old tank.

Pumping the fuel line bulb will keep it going if the pump is faulty or if there is an air leak.
 
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phil123

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Sep 4, 2010
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Re: new tank caused problems

thanks for the reply,
I notice when pumping the bulb, the connector leaks at the motor. The only other suspect is a hole in the pickup tube (the tank is used but guaranteed and looks to be in great shape) When the engine stops, the bulb is as it is when you first connect the tank, Not collapsed but a little soft. The connector will be the first thing replaced tomorrow and then if that doesn't work, remove the tank ( yikes) and remove and check the pickup. Yeah , it worked great yesterday with the 6 gallon attwood tank.
 
Vic.S

Vic.S

Rear Admiral
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Re: new tank caused problems

I notice when pumping the bulb, the connector leaks at the motor.
Click to expand...
Very good chance that's the cause of your problem then.

Should be able to keep things going by gently pumping the bulb if that is the cause

Recommendation on this forum in the past has been to stick to genuine OMC replacements for that connector as some others are not a good fit.
Maybe just needs a new O ring though.
 
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phil123

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Sep 4, 2010
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Re: new tank caused problems

removed tank this am and found a check valve in the outlet. requires a fair amount of suction to overcome it. also the dip tube is 3/8" id. I wonder if I should remove the check valve (there was none in the old plastic tank) and perhaps reduce the id size of the dip tube (14" lift). the 35 doen't require that much fuel it would seem . what do you think? I'd like to remove the check valve and try it out ,however, it's a real tough job removing the tank if I had to do it again.
 
sasto

sasto

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Jun 1, 2010
Messages
3,918
Re: new tank caused problems

Never seen a check valve on a fuel line......but then again there are alot of things I've never seen.
 
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ezeke

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Sep 19, 2003
Messages
12,532
Re: new tank caused problems

Most likely an anti-siphon valve. That's a USCG requirement for built in tanks that are higher than the fuel supply system - prevents fuel from being siphoned out by a fuel leak.

If you have all of the fuel system higher than the top of the tank, you can safely remove them.
 
Vic.S

Vic.S

Rear Admiral
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May 4, 2004
Messages
4,721
Re: new tank caused problems

Remove the valve if the is no reason for it to be there but there's nothing to be gained by reducing the diameter of the dip tube.

The amount of suction required to pull the fuel up 14" will be the same regardless of the diameter although very small diameters of course will restrict the flow rate. Then you'll need more suck.
 
sasto

sasto

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Jun 1, 2010
Messages
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Re: new tank caused problems

ezeke said:
Most likely an anti-siphon valve. That's a USCG requirement for built in tanks that are higher than the fuel supply system - prevents fuel from being siphoned out by a fuel leak.

If you have all of the fuel system higher than the top of the tank, you can safely remove them.
Click to expand...

Good reason. And I would assume that would go for any fuel line that runs below the top of the tank? On a restore (Penn Yan) I have saddle tanks which are about 8" from the top of tank to the pump. Guess I better look into it, thanks ezeke.
 
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phil123

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Sep 4, 2010
Messages
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Re: new tank caused problems

thanks all for the input. problem solved. check/antisiphon removed and all is good
 
sasto

sasto

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Messages
3,918
Re: new tank caused problems

ezeke, thanks for the web site. It appears the set up I have in this boat is in compliance with part C of the law, metallic lines with shut off valves easily accessible. I like the idea of electricaly operated fuel stop valves. Have you had any expierence with them? The boat is for the Admiral, I want the best for her. I have run mostly diesel and am fairly new to gas.
 
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