90 ford e150 5.0efi dual tank club wagon stalling while driving issues. recently vehicle will not run....cranks but no start. bench tested ext. pump ok. checked shrader valve and no gas. today have gf koeo so i can listen to in tank pumps (ok) and when examining the engine area smelled gas and notice leaking from shrader valve (after koeo test on pumps i disconnected battery and examined engine area and smelled gas). bubbles up and slowly pours down the threads of the valve. I can press on the valve and release more gas, but after pressing it will continue slowly coming out down the threads. I would have to assume a bad needle inside the valve....can I use one from a tire rim? also, where did this pressure come from or build up at because as I said it didn't have any gas at it the other day. I think the selector valve (mechanical) is damaged and gas is sitting in that building pressure and occasionally it pushes it out to the ext pump. I dunno. but the question is why is it leaking and why is it leaking when the other day it didn't even have any gas there?

 

Here is an easy way to discover if a schrader is leaking. Try spitting on your finger and rub it into the port. It'll bubble up just like soap solution, and it's right at hand.

 

90forde150 5.0efi dual tank club wagon 110k. van cuts off while driving...dies. With the help of Hanky I have narrowed it down to the mechanical selector valve being damaged and a problem with the shrader valve. I had previously pushed on the valve needle and no gas came out after having primed the pumps via koeo a couple times. I koeo to check for humming from the in tank pumps as well as the external pump.....sounded good. anything electrical that has to deal with the fuel system as well as the ignition has been checked and is operational. so the other day after having koeo testing the fuel pumps, I disconnected the battery with intentions of messing with the fuel system when I noticed a smell of gas. checked shrader valve and leaking slowly down threads....first bubbling then leaking. I take the valve off and remove the valve core and it appears to be fine. I compare it to several other valve cores I have from tire rims. I notice no difference in the valve cores from tire rims other than the color of the plastic gasket on the core (black and red on ford and gm and the shrader valve core is white). I put it back together and try starting van....cranks, no start. I press the valve needle in and air comes out then gas. I again try to start and nothing again. press valve gas comes out, try it again. This time it tried to start. tried turning it again and it again attempted to catch but didn't. Turned key off and then again shrader valve starts leaking. Can I use a valve core from a tire rim in place of the apparent faulty valve core in the shrader valve? It fits, looks exact with the exception of the color of the gasket. and if this valve core is faulty would that be enough to cause a stalling out issue with the van? I know the fuel is under pressure but perhaps the valve core is bad causing poor pressurization of the fuel resulting in stalling while driving usually during low acceleration or while decreasing speed? I haven't ever notice any gas leaking from that area during operation of the van but could that be because the injectors are sucking the gas down and the shrader valve doesn't have enough pressure on it at that time to cause gas to leak but if it is faulty enough that it would cause pressure to decline causing the stalling out? somewhere along the rails, the shrader valve, perhaps the fuel pres reg and the mechanical valve selector lies the problem. thanks for any assistance

 

I would not recommend using any other valve core except the one that belongs in there,
A valve core from a tire is not made to stand up to unleaded fuel and if you have the wrong core in the fuel system you are asking for trouble with a possible really bad fuel leak and potential for fire. Don't do it !
It's too bad you don't have the cap that covers the schrader valve, because until you could get the proper core that might keep the valve from leaking as a temporary measure.
I'm wondering how all that air is getting into that fuel rail.
There is supposed to be a check valve in each of the in tank fuel pumps to prevent drainback. Did you ever check the vacuum line going to the fuel pressure regulator?
It should be dry and have no gasoline in that line.
I don't want to throw you a curve here,but if air is getting into the fuel system it's like running out of gas and the injectors cannot inject air . Since the entire fuel system is supposed to be under pressure it might be a good idea to invest in a fuel pressure gauge that goes over that schrader valve and see whats going on if you haven't already done so.

 

Ill just get another shrader valve core from the junkyard tomorrow. when the gas is going to the injectors it is under pressure, right? with a damaged shrader valve core could air be sucked into the injector rail resulting in the van stalling/dying while driving? would that be a symptom? or is that possible? I know the fuel in and return lines coming from the tanks going to the mechanical selector valve to the external pump and to the filter up to the pressure regulator appear fine without any leaks. the rear tank hose (return) where you fill it up at had a hole in it awhile back which was replaced, but the filler hoses and return hoses look ok. I'll grab a fuel pressure gauge tomorrow as well and check that. whats the psi on this...60? thanks again....im indebted to you.

 

The specs I show for a 1990 van auto trans 5.0L are 35-45 psi.
Don't be reluctant to ask for assistance . It would be different if you had the manuals and resources and I remember very well what it's like working without the specs.
Just always be careful and respect that "gasoline" it has no feelings. I hope you are using some kind of gloves to protect your hands from direct contact with gasoline. It "ain't what it used to be" ! Many years ago I remember reading a quote about washing parts in gasoline. It stated, whoever is doing it won't be doing it long.
The composition has changed dramatically, so please be careful working around it.
We would like to think with 35 psi no air could get into the system, but in passing an opening that permits air to be drawn in does allow air to enter and drives the tech nuts.

 

good morning. I obtained three schrader valves the other day and already placed one on the van and plan to check it today to see if it starts. I don't believe the leaking schrader valve is causing the van to die while driving but I do believe that the mechanical selector valve is perhaps bad. and I want to delete that all the way off the van. What is the purpose of that selector valve? If it wasn't attached, wouldn't the tanks still operate normally, or is that selector valve like a reservoir....similar to the reservoir inside a carb.? I know that the tank selector switch only turns on or off the pump you are selecting and those pumps are what makes the shutters open inside the selector valve to pump the gas through it where the external pump takes over to pump it up to the injectors. I'll be back later today with my findings regarding the schrader valve and will again check all hoses and lines from both tanks up to the fuel rail. thanks folks

 

Just think if you didn't have the selector valve , tank 1 would be pumping into tank 2 instead of the hi pressure pump. Believe me , they wouldn't have spent the money to put something in there if they did not have to !

 

OK, good morning. new schrader valve isn't leaking now. no gas up to the fuel rail either tho. Is there a delete procedure for the selector valve? Can't I just unplug the selector valve and run the fuel return line and the delivery line to the external pump and the return line coming off the fuel rail? and just delete the rear tank (disconnect electrical connectors, plug hoses)? This theory is my mind would elminate the selector valve and have the van just running from the front tank. I plan to remove the rear tank anyway because of a damaged bumper smashed almost under the back of the van. I know that the selector valve is like a reservoir but I also seen other ford trucks which don't have selector valves I just don't know how the fuel system operates without a selector valve.....do those ford trucks that dont have that valve still, in some cases as applicable, have an external high pump?
In any event, I am off to the junkyard to grab two or three selector valves (just in case the first or second is faulty too) and as soon as Im home I'm taking mine off and gonna check out the insides to see whats going on in there.
Thanks Hanky....didn't think about the lack of a selector valve pumping gas into the other tank but I planned to delete that rear tank anyway so that wouldn't pose to much of a problem.
At least (with your help) I have brought it down to the selector valve since everything else checks out. I'll let you know my findings tomorrow. Thanks again.

 

There is always time for a little bit of humor. I'll bet you and the junkyard owner are on a first name basis by this time. Looks like you are heading for the homestretch , Give it hell !