Mine definatley dumps fuel back to the tank, if the tank is below 1/2 or so, when I turn on the pump, that's how I know when the carb is full, I just listen for the fuel to start pouring into the tank....

 

let me get this straight. The fuel seperator goes bad and in return in sucks(syphons) all the fuel out of fuel bowls. How can this happen? Another way to look at it is, your telling me that if you take a hose and hook it up to the fuel inlet on the carb. that you can suck (syphon) all the fuel out of the bowl. Good luck! Folks don't try this it home it was only a demonstration in theory.

 

Inwywind, this just came to mind. Since you result to starting fluid to start it up I would say you must crank it over alot. With this in mind make sure your fuel pump is getting power while your starting. Not in the run mode on the igniton, but the start mode (cranking the engine). Then give us an update when you can. Seems to be alot people with this problem.

 

Which valve? No instructions, Do you have a part number?

 

220KF150: I know, the drainback thing makes absolutley zero sense, there should be no way that the fuel can go past the needle and seat the wrong way and out the top of the fuel bowl, but, if I went out right now and tried to start up my F250(which last ran 2 days ago) without turning on the fuel pump, it would crank all day and not start, heck, if I went out now, pulled the air cleaner and cycled the throttle, there wouldn't even be enough in there for the acellerator pump to do anything.
I have no fuel leaks, and this truck has done it with both carbs I've had on it, the stock Holley and this Edelbrock which was brand spanking new when I bolted it on. This issue was part of the reason I changed the carb, the Holley had leaking issues(truck caught fire no less than 3 times thanks to it...) which I thought was the reason for this whole thing.
But, still to this day, after the truck sits overnight, the fuel pump runs a good 15-20 seconds before the carb pressurizes(I have a guage at the carb, after the bypass valve) and the return line starts dumping gas back into the tank.
Evaporation definatley doesn't come into play in that short period of time, espically at -40...

I've gotta find my 86 shop manuals again... My 84 manuals say that the pump is a 26GPH unit with an operating pressure of 39 psi, but, I know 86 is different(uses a different pump.) Even with my return line clamped off, the pressure never gets beyond 10 psi.

As for the valve, my installation instructions read as follows:
"Some late model Ford 460 engines are equipeed with a hot fuel bypass unit. It is necessary to replace the stock unit with Ford #E3TZ9N176B(with blue dot) which has a 0.040" orafice"

 

First off this is another great thread on a common problem. Inwywind, you may have 2 problems here. One is the common problem of the carb. bleeding down, evaperation or whatever, in which empties fuel bowls. Try turning it over for about 15-30 seconds, stop, give it a few squirts w/ the accelerator, and then try. It should fire. If it doesn't you may want to look at carb. to see if fuel is squirting out when you move throttle. If no fuel (this is the second problem), probably means that fuel pump is not working in the starting mode. Might be something as easy as a relay. Since it happens every two weeks, it'll be awhile with an update. Hope its helped ya!

Ok, 82F150SWB, since I got you thinking about the syphon thing. Here is the answer. The needle and seat sit in air. The bowl vent sits in air. The front bowl vent sits in air. You'd be sucking air. Ok?
I understand your fuel delivery problem to the carb.,but that pump should be plenty to fill bowl up. And I'm interested in what your gauge says after the check valve. But here is the kicker, my carb. is the original same as yours, but mine is on a 351W w/ mechanical fuel pump. I've had the same problem of bowls drying out. Took me along time to figure it out. Rebuilt the carb. a few times. Still didn't fix it. I put up with it until one day the choke was giving me a fit, burned wire, and I noticed that it was dripping fuel on the throttle plates without the engine running. So I rebuild again. Didn't fix it. There it was dripping and me pulling out my hair while I try to figure why. The problem was that pressure built up in the bowl was forcing fuel out the idle ports. The TVI on the front bowl didn't work. So I changed it. Went to the back bowl TVI, didn't check it because the hose was full of fuel, but I did replace it. Fuel isn't suppose to go in here. There was fuel remanants all the way to the canister. I cleaned her all up and haven't had the problem again. Anyhow, if you find some time check it all out. By the way, it would really drip if the engine was warm and slow down as it cooled.
The fuel pump is a low pressure pump for an '86, I think about 5psi.

 

I threw away the stock carb 3 years ago... The carb on it is a 750 CFM 1411 Edelbrock.
My issue was that it would suck the fuel bowls dry at WOT. It would not rev past 2500 rpm in 4th gear @ WOT, period, it'd go into a very bad lean surge, to the point that the engine would shut off for a few seconds and the demand for fuel on the carb would deminish enough that it could get enough in the bowls to run for a few seconds. Of course, my pressure guage is under hood, but, with the way the engine was acting, and the fact that if I backed off to 3/4's throttle or less, I'm fairly confident that fuel pressure was dropping to zero. Also, the less load on the engine(lower gears) the higher the RPM before it would do this, third would pull 3500, second and 1st there was no issue bouncing it off the limiter at 5500 rpm.
Changing the valve fixed this, but, with the higher pressure at the carb(due to more volume) my off camber performance took a dive, It runs much better at angles with 4 psi than it does with 6-7

 

220k-f-150,
My '83 F350 w/460 and Holley 4180C-4V (10,000 lb. GVWR) has almost the same symptoms of two problems. Problem 1, fuel drains back to tank--most likely a check valve problem (or lack of a check valve in pump, not sure which). Problem 2, dry float bowl after sitting for a couple of days can't be same as yours since my carburetor has no TVI, no vent hoses,and no carbon cannisters (and never did). Both float bowls are vented directly to atmosphere at all times so no way can pressure build up in float chamber. Since truck hadn't been started in a week, today I took the air cleaner off and jiggled the throttle; only one very puny spray out the acellerator pump nozzle. Ran the fuel pump direct from battery to fill everything, then returned wiring to normal. Engine started in about three crank revolutions. Removed the carburetor from the engine being careful to keep it level and not spill any fuel from the float chambers. Sat the carburetor on bench propped up on two bricks so I could see the underside. Put paper towels under it and after about three hours there was a wet spot on towels. Fuel was dripping out the passage that provides vacuum to the power valve at rate of about one small drop every 18 to 20 minutes. Removed the primary float chamber and metering block; as far as I can tell the only way fuel could get from the float chamber to the power valve vacuum passage would be due to a faulty or unsealed metering block to main body gasket. I measured the thickness of the gasket (uncrushed part) with a micrometer and compared with an old (I think) original Holley gasket removed when I first rebuilt the carburetor. The original measured 0.005" to 0.007" thicker in comparable locations. I'm going to try to find a real Holley gasket and see if it stops the leakdown. This may be why it also seems to run too rich at idle.

 

Piffery1, your on to something there. I had that kind a problem on an old 650 and it was that the metering block was warped.
I thought all these Motorcraft Holley's had the vent. I haven't seen one without it. Shoot even the old Motorcraft carbs had them. Anyhow, those vents with the TVI solved my draining. I think. Might of been something else I did that I didn't know I was doing. Ha!

 

Believe me it can happen. Vapor locked in Grand Island, NE in three digit temperatures towing my 5th wheel. Took 3+ hours to cool down so we could restart.

Talking to Ford dealership mechanics it was a big problem on these old trucks, even with the "hot fuel option" which was designed to keep fuel circulating and cooler. There was even a recall where an insulated jacket was installed over the fuel line. One of the guys had a few of these jackets left over so hopefully I'll never have that problem again.

Big engines working in high ambient temperatures generate a lot of heat. On another triple digit temperature trip I had the fuel in the front tank literally boiling! I now empty that one first, then run the rear.

 

ClydeSDale,
If it was "vapor lock" why didn't you just "hot wire" the pump (like you do after its been sitting awhile) and purge the lines of vapor? My best guess is a heat sensitive ignition module may have been the problem.

 

Piffery, that gasket work for you?

 

220k-f-150,
Don't know yet, couldn't find a new one locally other than in a complete kit. Put the carburetor back together with the old gasket I had originally removed because I'm using the truck this weekend. If I have to order a gasket I'm going to try to get one of those premium ones that are reuseable either by Holley or Walker. I know they make them for 4160's and others, but I haven't found one for 4180's.

 

220k-f-150,
I just ordered Walker # G1047BL Metering Block Gasket and # G1046BL Fuel Bowl Gasket from Southwest Auto Parts Supply. These are the Premium No-stick gaskets for the 4180C carburetors. Once I receive and install the gaskets I'll post the results. http://www.swapsupply.biz/ is their website. That's where I obtained the proper power valve for this same carburetor. They have almost everything for Holleys.

 

Thanks for all of the input guys. What I have done that appears to be working very well is raised my fuel filter up higher than the carb inlet, meaning it was caused by drainback. Raising the fuel line farther away from the motor is also a good way to reduce vapor lock (that is what I did for my old 360 that vapor locked frequently). I am still planning on changing the valve 82F100SWB mentioned as getting more fuel to the carb faster seems benificial, man this motor sucks fuel. I am also going to add a button to prime the system easier. Being able to run the pumps from the solenoid is great and makes it so I like this fuel setup.