How far can a fuel pump pull?

dvndog

Seaman Apprentice
Joined
Mar 11, 2006
Messages
31
I recently had a couple of posts about the carbs on a 84 90hp johnson with vro and a problem with motor quiting like running out of fuel. And this has been happening on and off all summer it would come and go but after 10 or 15 min it would act up and bog or stall but always restart. Today I tried pulling the gas from my kicker motor tank which is right in the back of the boat within 3-4 feet from the motor, and the motor ran great not missing idling good @ low r's and did not die. Now the real tank for the big motor is in the front of the boat, Installed a 26 gal fuel cell and put it in the bow and ran new line all the way to the back of the boat aproxx 12-16 feet away. Is it possible for the motor having not enough pull on the pump and the siphon form the tank to satisfy the motor. Could it starve for fuel occassinally?

Any Ideas would be great.
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: How far can a fuel pump pull?

i could depending on where the line is run. also could be an air leak, or stop up vent on the tank. have you tried pumping the bulb when it does this.
 

Walker

Captain
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Jun 15, 2002
Messages
3,085
Re: How far can a fuel pump pull?

The only problem with long fuel lines might be too small of diameter giving too much friction loss in the flow, but the volume of flow is so small that I doubt you'd have a problem there. Elevation, not distance, is what would cause a problem. If you were trying to lift fuel may 6 feet or more you might have issues.
Are you sure you don't have some line restriction or maybe a kink?
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,226
Re: How far can a fuel pump pull?

How about an anti siphon valve?
 

dvndog

Seaman Apprentice
Joined
Mar 11, 2006
Messages
31
Re: How far can a fuel pump pull?

I was also thinking if the motor was starving for fuel due to an air leak or what not, does the fuel pump still pump the same amount of oil, and is this why I was burning twice as much oil. I have not torn into it yet because I just moored the boat at camp and will not be back until the weekend.
 

iwombat

Captain
Joined
Jul 12, 2006
Messages
3,767
Re: How far can a fuel pump pull?

If you've got an air leak the fuel to the VRO will be frothy. Same volume - more air. The VRO mixes per volume. More air in fuel -> more oil per same amount of (un-frothy) fuel.

Hope that made sense.
 

ezeke

Supreme Mariner
Joined
Sep 19, 2003
Messages
12,532
Re: How far can a fuel pump pull?

Someone was asleep in science class, not to mention physics. It is not a question of distance so much as the height.
 

mikesea

Lieutenant Commander
Joined
Oct 1, 2006
Messages
1,830
Re: How far can a fuel pump pull?

I agree with the problem being an air leak,kink ,bad tank vent or fuel pickup,here is a great site someone posted beforehttp://continuouswave.com/whaler/reference/VRO.html
 

Barnacle_Bill

Admiral
Joined
Feb 8, 2004
Messages
6,469
Re: How far can a fuel pump pull?

I had a 17' center console with a 90 Johnson. The tank was in the bow with 3/8 line ran to the motor. No problems even after it sank but we won't go there.
 

flywheel90

Recruit
Joined
Jul 23, 2007
Messages
2
Re: How far can a fuel pump pull?

had a simular problem, check your bottom of your gas tank for debris, mine would idle and troll fine but debris would obstruct the thimble type screen on the sypon hose when at WOT. i turned the motor off and the hose would lose suction and debris would fall off, until the next time.
 
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