Hi, my name is Ed. Welcome to Just Answer!.

Problems of this sort are usually caused by a tank venting failure, although there might be a physical obstruction that someone... um... placed in your fill tube. Sorting out which it is might require some disassembly, but the timing of your fuel backup could tell us something.

A physical obstruction will produce an almost immediate backup, shutting the pump off within a second or so of beginning the refuel process. The fill tube is pretty small in diameter and can't hold much volume, so a piece of debris big enough to lodge in the tube will cause shutoff within about one-Mississippi or less.

Venting problems tend to take a bit longer to back fuel up. You have two crucial vent tubes... a small one that crosses from the top of the tank to the fill tube and a large one that connects to the tank top as well, but vents through the vapor canister, which collects fuel vapor and holds it to prevent hydrocarbons from venting to the atmosphere as vapor volume in the tank is displaced by liquid fuel.

There isn't much that can go wrong with the smaller hose... even if broken it won't produce filling problems as you've described. The space above your tank on the 04 Ram 1500 is also considerable, so it can't be crushed during tank installation.

It's likely that your large vent will be to blame, but you will need to do some diagnosis to find out where the restriction lies.

This system uses what's called the onboard refueling vapor recovery (ORVR) system and the vent valve at the top of the tank is simply called the ORVR. Its job is to seal the vapor (evaporative) system when fuel is added and the tank becomes full. Once sealed, vapor pressure builds and eventually causes fuel to back up in the fill tube... shutting the pump off. Because a fair amount of pressure needs to be developed, I'd expect this sort of problem to allow several seconds of full-speed fuel fill before shutoff.

If the ORVR is mechanically stuck in the tank top or if the vent tubes are restricted for any reason, you'll get the sort of difficulty you've described. To sort it out... is it the ORVR or something else... slide under the truck on the driver's side about 3 feet forward of the fill tube and locate the vapor canister.

The vapor canister is the black plastic box suspended from the inner frame rail, which can be identified by the two large rubber hoses connected to it. Disconnect the hose that feeds to the canister from the tank and attempt a fuel fill. If it makes all the difference, returning fill times to normal, it means you have a restriction after the point that you removed the hose. No change means the ORVR is stuck and tank replacement is needed to remedy the situation since the ORVR is plastic-welded to the tank and isn't serviced separately.

But good results from disconnecting the hose means your problem will be external to the tank and may still involve the canister, hoses, NVLD (leak detector) or the vent filter at the end of the line. Sitting in high water levels can cause water to get past the filter and can even saturate the canister, causing a hydrolock that's considerably stronger than the pressure exerted by refueling. Continued hose removal in sequence from the canister to the vent to sort things out if you find improvement by disconnecting the canister.

I'd expect there to be an evap leak code set (and MIL illumination) with water entry and it really doesn't happen on the 1500 models. It's most likely the ORVR... which means tank replacement unfortunately.

Let me know if you have any questions. I'll be glad to help.

Thanks,
Ed