Propane tank won't fill after running on empty

Propane, Butane, LPG, GPL, C3H8, C4H10
Post Reply
shepd
Posts: 6
Joined: Mon Mar 12, 2012 1:39 pm

Propane tank won't fill after running on empty

Post by shepd »

Hi! Unfortunately I ran out of propane on the highway and my car just barely ran at an idle. I checked the dial on the propane tank and it was completely empty (the dial was below the E, even). Had it towed to a propane station, but they couldn't fill it--no propane would enter the tank.

Did something happen when I ran out of propane? It's not completely flat, but I think it's literally just running on fumes, since I can't get much above an idle at this point. Or is it just double-unlucky co-incidence?

Is there anything that you need to know to help answer? I can tell you it's a Manchester tank, fumigation system, and that it's installed based on Ontario standards.

C3H8
Posts: 1129
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: Propane tank won't fill after running on empty

Post by C3H8 »

The very first thing that needs to be checked is the possibility that there is still plenty of fuel in the tank. Check by opening the spit valve on the tank and seeing how powerful the spit is. Loud hissing there is fuel in the tank. You can verify this by putting on a pair of rubber gloves, goggles and long sleeves and loosening the hose going to the lock off slightly. If a white vapour comes out then liquid is available for running the engine.

From this point you need to check the fuel filter to see if it is so dirty it is preventing adequate fuel from getting to the vapourizer. This is unlikely at our current temperatures as the tank pressure should be quite high. It should be checked anyways as the problem you describe certainly indicates a lack of fuel.

You haven't indicated the equipment or the vehicle so I can't offer any other suggestions at this time.

shepd
Posts: 6
Joined: Mon Mar 12, 2012 1:39 pm

Re: Propane tank won't fill after running on empty

Post by shepd »

Thanks C3H8. Next time I will try those things. I have a feeling the attendant last night didn't really know how to operate the pump (and while I know how to, since you need a license, not even the places that know me well will let me touch their equipment). I have a feeling she didn't tighten the connector well enough.

I got the car to the same place that wasn't able to fill it yesterday, and they were successful today. They did complain it was slow filling, but from my experience, it isn't any slower than it's ever been for the past 2 years. :) The 100 litre tank took 83 litres before the shutoff kicked in, so that seems pretty much right on that it was at or near empty.

Guess at this point I can thank my lucky stars it's working again. I managed to get it running on gas properly again too, so that's one less thing to worry about.

FWIW, there is no spit valve on the tank or the fill connector, at least as far as I can see. I think I shall have a better look, though, because such a device would come in handy.

131
Posts: 31
Joined: Sun Jun 28, 2009 7:24 am
Location: Tasmania, Australia.

Re: Propane tank won't fill after running on empty

Post by 131 »

Fair dinkum, you can't fill your own tank? Here the majority of service stations have LPG bowsers alongside petrol and diesel. Rock up, fill your tank, pay the price, drive away.
Cheers,

Mick.

Frank
Site Admin
Posts: 887
Joined: Wed Feb 25, 2004 2:17 pm
Location: Stevensville, ON
Contact:

Re: Propane tank won't fill after running on empty

Post by Frank »

I have sometimes had problems filling the trunk-mounted tank in my car at some propane stations during the summer. My local propane station often has this problem with other cars too and the attendants believe it has something to do with the temperature of the tank, especially with underbody tanks exposed to pavement heat. For these vehicles, they have sometimes had success by hosing down the tanks with water in an effort to make them cooler.

Since the differential pressure between the large storage tank and the vehicle's tank should be close to zero because both should be at about the same temperature, I think the problem with that station is with the station's pump. I think the warm, summertime temperatures cause the station's pump to cavitate, thereby making it impossible to overcome the check valve(s) in the vehicle's fill line. Vehicles with remote fill valves have 2 check valves (one at the fill valve and one at the tank). I recall that when they switched to a different fill nozzle at the dispenser, many of their fill problems disappeared too.

C3H8
Posts: 1129
Joined: Fri Sep 09, 2005 11:23 pm
Location: Winnipeg, Canada

Re: Propane tank won't fill after running on empty

Post by C3H8 »

Let's do a quick review on spit valves (liquid fill indicator) and pumps. By code all tanks in Canada have to have a spit valve. Most provinces don't require it be piped to the remote location if the tank is equipped with a stop fill, however some provinces still demand it be piped to the remote location but allow filling with out opening it. The rational is that a service station can check if the tank is overfilled before they take a vehicle indoors. As we know the gauges are not exactly trustworthy. The only propane vehicles not required to have a spit valve are OEM installed products.

Hard filling of vehicles can be attributed to many things. The most common is either tanks that are substantially warmer than the bulk tank or filling stations with weak pumps. It is quite common to see a bulk tank stay cooler then a vehicle tank. The propane entering the bulk tank cools dramatically when filled and can take a long time to reach outside temperature. The large tank takes a long time to warm up so the pressure is frequently lower then the vehicle tank. Differential pressures can range from 20 to 60 PSI. The propane pump is designed to transfer liquid at equal pressures. High capacity pumps will fill tanks with pressure differentials of about 80 PSI. These pumps are usually 3 to 5 HP. Many of the propane stations that fill cylinders only have pumps that are 3/4 to 1 HP. These pumps can only handle differential pressures of 30 to 50 PSI and are low volume pumps. The lower the differential pressure capability the slower the fill. Throw in code demands of check valves at two locations with remote fills, and the added temperature of reflected heat from the road or hot trunks (boots for our NZ, Aus., and European friends) and these smaller pumps can't overcome the pressure unless the tank is cooled or a spit valve is opened for a long time to cause vapourization in the tank to self cool it. Opening the spit valve wastes fuel and could potentially lead to a dangerous situation. Just some info for thought.

Frank
Site Admin
Posts: 887
Joined: Wed Feb 25, 2004 2:17 pm
Location: Stevensville, ON
Contact:

Re: Propane tank won't fill after running on empty

Post by Frank »

While it's possible that is the bulk tank is substantially cooler than my car's trunk-mounted tank (which is typically parked in my garage), I would expect that, within a week, the bulk tank should approach ambient temperatures. I find that my local station in Fort Erie commonly has trouble filling my tank while the one in Niagara Falls never has this problem and it appears to be a much busier propane station. Often, the Fort Erie station would start filling my tank (very slow fill) but would quit filling (as if full) after maybe 5-10 litres, leaving me still low on fuel. The problem solved itself when the Fort Erie station fixed their dispenser's meter thereby making the Niagara Falls station substantially cheaper.

shepd
Posts: 6
Joined: Mon Mar 12, 2012 1:39 pm

Re: Propane tank won't fill after running on empty

Post by shepd »

I'll have to search for that spit valve then. It isn't anywhere near the fill... And I didn't see anything under the service cover on the tank. Maybe it's somewhere else? Or maybe I need to have a closer look.

Could be heat, hard to say. No way to hose this tank down, it's located in the trunk. It was a different station than I regularly go to where I had the problem. The place I usually go to had broken equipment at the time. Must just be that they don't have the best equipment.

Thanks for the tips, though! When I'm in the US and end up having to fill at U-Haul, who are only really outfitted to fill BBQ tanks, maybe I'll bring some cool wet towels to throw on the tanks. It's better than nothing. Too bad US propane prices are so high!

Post Reply