HELP! I am not getting any fuel pressure

[Kongfish]

Ok,
Here's the problem I am fighting with, & my equipment.
My Mercury 1990 175 hp Carbureted outboard only runs till the fuel empties from what fuel is in the fuel line & primer bulb & the motor dies. The primer Bulb will be empty, & I can't get the bulb to pull any fuel into the primer bulb at all.
When I remove the fuel line & put the fuel line in a separate portable fuel tank, the primer ball pumps right up.
I have a (in-hull) gas tank, it is plastic looks like around 30gallons. here is a list of new parts i have installed and fixes I have tried to over come this issue.
-New anti siphon valve installed today.
-InHull fuel tank has been siphoned, cleaned, & replaced with fresh fuel (NON ETHANOL) yesterday.
-All new ethanol proof grade fuel lines replaced from carbs, all the way back to fuel tank.
-New fuel water separator, both new filter housing mount & separator filter

So, now what?
2 other questions, does the key need to be in the ON position before the fuel will pump up the primer ball?
What is the correct wiring for the fuel pick up? So I can check that as a possible issue unto itself?

 

[racerone]

The fuel pump on the engine operates once the motor is turning ( if original )----Different if an electric pump is installed.----Have you checked the pick-up tube inside the tank ?

 

[Dukedog]

Tank vented? Did motor run ok on tha remote tank? Take everything added except bulb out of tha system and try it. Some "brand new bulbs" are junk right outta tha box. Water sep/filter before or after bulb. Most cases it works better after bulb. Ideally it needs ta be after tha mechanical pump. Double check all in's and out's on filters/bulb. If all is good and still won't "pull" fuel from tank remove anti-siphon valve and try again

 

[Kongfish]

Hey dukedom,
I just saw your reply, I will give you as much detail as I can on the issue.
All fuel lines are new. Putting fuel line in a different tank and pumping the bulb it will be nice and firm with 2-3 pumps and the motor will run all day long .
I've been told to knock the ball out of the brand new anti siphon valve. And see if that's it.
It was pumping up using the regular under deck tank, I sat at the dock and ran it for an hour at different speeds. Took it home, came back two days later, and I can't get it to even pump up at all. The bulb won't pull ant gas. I can put the motor in neutral, gas it up, and the motor will run like a top. The bulb won't pump up at all but the fuel pump will pull gas enough to allow the motor to run.

 

[Kongfish]

I have not checked the pick up tube, this tank is a bear to get to and to try and access

 

[Chris1956]

Well, it sounds like it is the pickup tube of the tank vent. One or both are partially clogged, I would guess.

 

[Chris1956]

Sorry fat fingers. Should be Pickup tube OR fuel tank vent. Pop open the fuel tank filler. If that fixes it, then the vent is the problem.

 

[Kongfish]

First does this tell you if the vent tube is blocked., I put a rag around the gas filler hole to create a seal and I continued to blew air in the gas tank, it built up pressure and never seemed to be going out anywhere else. When I stopped and moved away the air all seemed to blow back out of the gas filler hole?
Ok,
I will check those,
1.) my vent tubes location. When I open my gas tank lid which is a oblong shaped and when I push the button it flips open, under thear, there's the gas tank filler line.and right above the gas filler tube is another smaller tube maybe, 1/2 inch tube . IS this the vent tube, can I blow compressed air down that tube and see how it acts after that? That is if when I blow air it clears the line of whatever is blocking the line, if anything at all is blocked.
2.) if I pop the gas tank filler tube off , what do I do after popping the tank line loose, the tank is under the deck and the filler hole into the gas tank is located over about 2 foot making it impossible to look into the tank for the pick up tube. I do also have the sending unit I might could open to see in the tank it's straight down but on the inside of the hatch hole under.The deck also. If I pop it off and can see in the tank what am I looking for as far as the pick up tube.?

 

[Kongfish]

No Title

nulls those are inside the fuel pump

 

[Kongfish]

WI mean, when I trouble shoot this, I can remove the fuel line where it goes through the hull. If I drop the fuel line into a secondary can of gas and the bulb pumps up in 2 pumps. Motor runs fine for unlimited time. If I then reconnect that fuel line to its original spot located at where it goes through the hull. It may pump up it may not pump up. If it does pump up. When I crank the motor and run it, the fuel seems to be running till its gone. I assume the fuel in the fuel line is what it's burning, if I give the motor throttle it will pull enough fuel to keep the motor running but once I put it back in neutral, it dies from lack of fuel. So somewhere from my new fuel water seperator, & new mount bracket, & new anti siphon valve. To the gas tank is something that's got to be the issue. I am trying blowing compressed air into the vent line and see if it has any effect

 

[Chris1956]

Kong, You have an easy issue. Just relax. Connect the fuel line to the thru-hull fitting. Now open the gas filler cap and leave it open. Pump up the primer and run the motor. If she stall's due to lack of fuel, the fuel pathway is restricted. If the fuel pathway is restricted, it is either the anti-siphon valve or the fuel screen, assuming there are no other filters, kinks or other obstructions between the thru hull and the tank pickup.

If she runs without stalling due to lack of fuel, close the gas filler cap and see if she stalls. If so, the tank vent is clogged. Remove it and clean it or replace it.