I have a '92 E350 5.8 with a Freight King box that has been customized for hauling my race cars.

As long as I've owned this vehicle it has been very slow to take fuel causing fuel pumps to click off even at their lowest setting. This year during my dewinterizing I decided to finally address this issue but I haven't exactly located the problem. I believe the tank may have been moved from its original location during the conversion.

I always assumed I had a clogged vent or possibly a restricted filler neck. I pulled the neck down this weekend to inspect and verified the vent is clear. I can blow compressed air in the filler and feel air flow through the vent. While performing this procedure I can hear a metallic clang every time I squeeze the trigger on my blower. I'm assuming there is a flap in the top of the tank which is causing my flow issue. I need some advice from those familiar with this fuel system before I drop the tank. Is the flap I hear in the tank or fill tube? Are there any problems with this flap that I can repair to restore flow? Can I remove it?

Thanks for any help. I just want to gather all the info I can before dropping the tank.

 

There is a metal "flap" at the top of the tank, where the filler hose attaches.

This is the "Anti-siphon" device.

The problem your having, I've experienced also with cube-vans.

If the tank gets too low, below a 1/4 tank, I have to re-fill it slowly.

I also found some pumps (brand stations, like Flying J's) the pumps flow is very high, causing this same problem with the long, almost flat laying filler hose. I go to other stations, and have no problems.

The real problem is the charcoal canister and the vent lines.
There been some write-ups on here about changing it out, and even "re-building" the canister.

 

My 88 E150 was like this, I could never confirm the roll over valve was the problem but it seemed like a good suspect.
Dorman - OE Solutions Fuel Tank Vent Rollover Valve 911-001: Advance Auto Parts
jim

 

Thanks for the reply. Mine is consistently slow regardless of tank level or pump/station. It's been the same every time I have refueled the entire time I've owned it.
I guess it would be worth disconnecting the charcoal canister to see if that helps.

 

That was my thought too. I would like for someone to confirm the e350 uses one. I can't find a rollover valve listed. ( Your link specifically says it won't fit my vehicle..) Thanks.

 

I'd call the dealership or NAPA---no offense to Advance Auto ect but too often their online catalogs are less than correct.

Those times we've had something similar here it's been related to the fuel tank venting system, the one running alongside the larger fill tube with fuel cap at the top.

We've had several investigate and fix this themselves---hopefully they'll reply or someone else recall where those threads are located.

HTH

 

That was my system, JW. About a 3/4 inch hose plus the 3 inch filler hose, connected to steel pipe on each end with gear clamps. NO flap in the gas tanks (dual tank system), and a vent hose on the top of each tank attached to a roll-over valve. The valve is just a ball on a spring weighted to close if the tank goes on end or upside down.

The thing is, the vent hose in the fill neck is 3/4 inch, this thing is maybe 3/8 and goes to the charcoal canister. It was designed to pull vapors from the fuel.

I had a theory that the gas pumps had two sensors, back pressure and excessive fuel feed (in case the pump nozzle fell from the car or the hose got cut). I think it was too much fuel flow that caused the shut off but I could never prove it. jim






1988 front tank E150

 

Interesting you mention gas pumps and possible dislodged hose shut-offs---I don't think there is such a thing. I've seen a fall out and still be running, apparently hitting the ground didn't trip the hold-open mechanism on the handle trigger.

Over-filling does shut them off though---once upon a time they did NOT!

Good repair suggestions on those vents---so far I've never had to deal with that.

 

If you have had this problem from the start of ownership, then the problem would be at the filler hose or the 'anti-siphon' valve not opening.

The charcoal canister and the vent lines would be plugged over time, not from the start.

Another thought is to check the vapor canister purge valve that's mounted on the right side of the Throttle Body. This is what "releases" pressure from the vent system, back into the engine.