Fuel Primer Bulb Goes Flat

[MrMckee]

Re: Fuel Primer Bulb Goes Flat

I am going to try and find a one piece elbow and pick up tube like my old tank. Like I said before my new tank has the pick up tube built in. I will probably will have to have one made.

 

[Water Plug]

Re: Fuel Primer Bulb Goes Flat

I took a break from my tank today and ran through my head every possible scenario. This problem defies all logic. More food for thought, the boat runs fine when I have a full or 3/4 full tank, but once it hits 1/2 a tank that is when the bulb colapses. Does my pick up tube have a hair line crack?? I say no the bulb would still inflat with air, right??

Hey MrMckee, Slow down and take a breath. When your tank is 3/4 and full the weight (5.6 pounds per gallon) of the gas adds fuel pressure to the lines and it's works fine. There is a restriction caused something being partially obstructed, that's for sure.

Fuel restriction from the tank to primer bulb can be anything from a:
(1) The pickup in the fuel tank patricianly clogged.
(2) The Fuel line that is to small (inside diameter) for the FPH (fuel per hour) for your engine displacement.
(3) The Fuel tank that is not properly venting and creating a vacuum.
(4) A defective anti-siphon valve the is defective.
(5) Fuel flow path is inadvertently reversed, all arrows must point in the path to the engine.

It's time to slow down and breath MrMckee.

In order for an engine to run properly it must receive an uninterrupted and unrestricted flow of fuel. This cannot occur if improper fuel lines are used or if any of the lines/fittings are damaged. Too small a fuel line could cause hesitation or missing at higher engine rpm. Similarly, a clogged fuel line, fuel filter or dirty fuel pickup or vacuum lock (from a clogged tank vent as mentioned under Fuel Tank) could cause these symptoms by starving the motor for fuel.

Check the tank first to make sure it is properly vented, then turn your attention to the fuel lines. First check the lines and valves for obvious signs of collapsed hoses that could cause restrictions.
If there is a restriction between the primer bulb and the fuel tank, vacuum from the fuel pump may cause the primer bulb to collapse. Watch for this sign when troubleshooting fuel delivery problems.

No matter what type of tank is used, all must be equipped with a vent (either a manual vent or an automatic one-way check valve) that allows air in (but should prevent vapors from escaping). An inoperable vent (one that is blocked in some fashion) would allow the formation of a vacuum that could prevent the fuel pump from drawing fuel from the tank. A blocked vent could cause fuel starvation problems. Whenever filling the tank, check to make sure air does not rush into the tank each time the cap is loosened (which could be an early warning sign of a blocked vent).

Hope this helps a little, OUCH my fingers from typing... :/
------
If you only look for the complex,
you will always miss the simple.
Brian~

 

[ccichris]

Re: Fuel Primer Bulb Goes Flat

Hello
Some interesting comments - I had a recent similar problem - I found the problem by removing the pickup assembly - it was a factory mistake - slightly too long (probably for a diff. tank) - when the pickup assembly is screwed down the tube crushed into the bottom of the tank - mine created two nasty kinks which restricted the fuel flow and was obvious. It created a similar situation you are describing. I would assume if it was just slightly long it could essentually jamb at the bottom of the tank without creating an obvious kink but simply smash into the bottom also creating a restriction not otherwise noticed (careful measurements can reveal) . Also - there should be a shutoff valve (blade valve) as part of the pickup assembly - is it all the way open ? Moved down the hose assembly between pickup and primer bulb ?

 

[rickdb1boat]

Re: Fuel Primer Bulb Goes Flat

Good point, Chris. Take nothing for granted.....

 

[ezeke]

Re: Fuel Primer Bulb Goes Flat

I'll take 10 on the vent.

 

[Snowdrggn]

Re: Fuel Primer Bulb Goes Flat

I had a similar situation, when the tank was below half full a fuel restriction would starve the engine for fuel and it would quit. I determined it was something with the tank itself. After driving my self nearly insane over it, I finally figured it out after removing the built in tank. I found a sandwich baggie in it!!! When the tank was at lower fuel levels the baggie would stick to the pickup while running. The only thing I could think of is one of the neighbour's "porch monkies" put it in there in the off season!!!

Food for thought........

Snow.

 

[MrMckee]

Re: Fuel Primer Bulb Goes Flat

A baggie in the tank! I guess I am going to have to take the round sending unit off to see if I can see into the tank. If that doesn't work I will take the tank out. Since I bought a new anti-siphon valve I took my old one and removed the check ball and installed it and low and behold the primer bulb would pump fine. Anyway I have bigger problems now, my motor over heated and blew a head gasket. I took both heads off to have a look and the port bottom cylinder has metal marks in it ( part of the cylinder ) and part of the cylinder looks like somone has been chewing on it. Game over for me the motor is almost 19 years old. I am repowering. I may be able to swing a deal sweet deal with Yamaha. If that doesn't work out I like the E-TEC 115. Suggestions anyone? Thanks to all for their input.

 

[Joe Dirt]

Re: Fuel Primer Bulb Goes Flat

Funny you mention that- a few years back, someone went through and stuck saran wrap into the gas tank filler tubes of abot 10 cars in our condo complex...

Their defense was "well, yeah, we put them on top, but when you filled the tank, YOU pushed it into the tank- that's not OUR fault!

What a**hats. At times I weep for the future...