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Walkers
United Kingdom
13 Posts |
 Posted - 07/13/2012 : 12:55:31
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Hi Guys,
I have an old Gilbarco Highline 2 mono with a problem which my usual maintenance guys cannot seem to fix.
I was hoping somebody else has had the same problem and knows how to fix it.
When you start the pump it clocks up to between 0.1 litre and 1 litre before the trigger is squeezed.
If the pump is used again soon after, sometimes it will be ok (stay on 0.00) but sometimes wont be. If you leave it for a couple of hours it will usually have the problem.
It is much worse on hot sunny days (i.e.it will clock up more volume sooner).
When it is clocking up it does sound and feel like it is pumping something so I assume this is not an electronic or pulser fault.
The problem seemed to coincide with a grade change from diesel to premium unleaded.
It had a new schrader valve fitted which seemed to improve things a bit.
It had a new under-pump valve fitted - this didn't change anything
It had a new complete schrader valve assembly fitted. This seemed to improve things a bit but the problem is still there.
There is no sign of a leak.
Any advise would be most appreciated.
Regards
Adrian
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fuelco50
USA
21 Posts |
Posted - 07/13/2012 : 14:05:09
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| Is it a dispenser or a pump |
Jim |
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Walkers
United Kingdom
13 Posts |
Posted - 07/13/2012 : 14:19:55
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Hi Jim,
I think the terminology might be slightly different between England & USA.
I would say both. It is a fuel dispenser with the pump built in.
(Generally called a petrol pump but are properly called fuel dispensers with the option of built in pump. It quite rare to find them here without the pumps built in)
Thanks
Adrian |
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ZMiller
USA
1317 Posts |
Posted - 07/14/2012 : 11:15:00
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SayWhat? The pump unit has a bypass pressure valve that may not be seating or the wrong set spring. The dispenser by design is not to alow meter movement assuming the air elimitator is operating correctly. Is there any indication that fuel is leaking or spitting through the side vent? Yes suction pumps and steel lines everywhere there. Tank and stinger feed setups seem a little strange, overkill and a step back in time when compaired to the United States and your fellow Frenchies in Canada. I was working on an Exxon site there and found it strange to see 10 stingers one for each fueling point in the tank. You do have vapor recovery on dispensers in some areas there (diesel to gasoline doubtful but) what about this one. Remember as well that diesel under vacuum generally does not vaporize and gasoline does. You may have a pump vacuum to high for the .20 less fuel weight and you are seeing small amounts of intermittent vapor fart passed at the meter. Farts here. Farts there too? OR you do have a leak down stream of the meter and just haven't found it yet. I can't remember if you are using foot valves on tank stingers there.
Let us across the Pond where right is right and left is left know if or when you figure it out. |
There are two theories to arguing with a woman:...neither work!
“It's so simple to be wise. Just think of something really stupid to say and then don't say it.”
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Walkers
United Kingdom
13 Posts |
Posted - 07/14/2012 : 12:34:46
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Hi ZMiller,
Many thanks for your reply.
You are right about the setup in England. Most sites over 15 years old have steel suction lines, one for every dispenser/pump with a non-return valve at the tank generally referred to as a popit valve and no vapour recovery on the dispensers.
(newer sites have plastic suction lines with under pump non-return valves instead of popit valves)
This particular pump sits virtually on top of the tank and had a popit valve. As it was thought that fuel might be draining back to the tank this was replaced - made no difference - then an under pump valve was fitted in addition - still made no difference. (The Gilbarco trained engineers had run out of ideas and were trying anything)
The air separator was swapped with another working pump some time ago, they managed to break the side vent pipe so it now vents inside. I have run it without the covers on many times and never seen any vapour coming out of the vent pipe. When it is working it is quite smooth flowing so I thought the air separator must be working.
I have had a good look for leaks and can't see any. When you stop fuelling it doesn't clock up any more, I have waited until the pump times out and it doesn't clock up so I was thinking it couldn't be leaking. Although I guess it could be a leak that only leaks after the pump has stopped.
I will check the bypass spring/valve when I am next on site. It is common practise to pack out the spring with 2 pence coins to increase the flow rate, particularly on biodiesel, I thought these had been removed when it was changed to gasoline.
thanks again
Adrian |
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Kennyl
651 Posts |
Posted - 07/14/2012 : 23:03:14
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| How deep is the tank? Do you have Alcohol or Ethanol in you Gasoline? What is the temp of the fuel? My thought is that you may have vaporization of the fuel during idle time and this bubble (fart a Z called it) is what is causing your jump. |
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termdoc
USA
220 Posts |
Posted - 07/15/2012 : 02:24:39
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Let's not over think this. This is the most common problem with G&B dispeners (or pumps). First, replace the hose, nozzle, swivel and breakaway to eliminate the obvious - cheap, easy....Still have the problem - Put a new meter chamber in and move on.
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hardworking
USA
506 Posts |
Posted - 07/15/2012 : 07:55:49
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Meter creep can only be caused by the pump putting out more pressure than is in the system (post meter). So, that being said, where is the pressure being relieved to? That's the key to finding this problem.
You say you can't find a leak and you've replaced check valves. Strange.
How long of a hose is on the outlet of the pump/dispenser?
Did you have a satellite dispenser? If so, have you checked it out?
A 1 liter creep sure seems to be a lot though. |
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Bob
USA
34 Posts |
Posted - 07/16/2012 : 17:10:25
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| I like the changing the nozzle idea, if your stie is doing prepays the customer may be draining the hose or removing the prewwure form it. A soft wall hose will expand a bit more in hot wheather. |
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ZMiller
USA
1317 Posts |
Posted - 07/16/2012 : 18:59:03
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| Single or dual fueling points at this dispenser pump? |
There are two theories to arguing with a woman:...neither work!
“It's so simple to be wise. Just think of something really stupid to say and then don't say it.”
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Walkers
United Kingdom
13 Posts |
Posted - 07/18/2012 : 11:07:37
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The pump/dispenser is a single grade, single fuelling point, single nozzle (no pre-pay, pay at pump, satellite dispenser etc.), probably the simplest version of a highline 2.
The hose is the standard length, about 10 feet.
The fuel is premium (97) unleaded, 5% ethanol.
The underground tanks is quite small so probably 10 feet to the bottom. Fuel temp is 15C (about 60F)
The amount of meter creep is usually around 0.15L (25pence)but on a very hot day, which is rare in England it went up to 1L.
I swapped the complete hose & nozzle with another dispenser, pumped a 100L out to make sure any air/vapour was flushed thru, left if for 3 hours and it was fine, read 0.00. Thought it was solved. Next day it clocked straight up to 0.15L again.
Today I swapped the bypass valve internals and spring and pumped 100L thru. I will leave it overnight to see if it has helped.
As termdoc said, I am probably trying to over-think this but after doing the obvious I am trying to figure out what else it could be.
I did notice that when I disconnect the hose, it was full of fuel but not pressurised where as the donor dispenser, as soon as I started undoing the nut fuel started to seep out indicating it was under pressure.
I am thinking problem has got to be in the meter but replacing it is a bit of a problem as you have to get them re-certified before you can use them, don't know if it is the same in the USA. |
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hardworking
USA
506 Posts |
Posted - 07/19/2012 : 07:31:40
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The lack of pressure in the hose (when you are taking it apart) is the clue. If you aren't losing pressure to outside the line, you must be losing it back into the tank, or, you have a small underground leak and the under pump check valve is not working correctly.
It sounds to me like you have leaking check valve issues (assuming you did inspect the whole unit for leaks and found none). Does this pumping unit have a factory installed check valve in the unit? Do you only have a check valve under the pump or is it on the tank?
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Walkers
United Kingdom
13 Posts |
Posted - 07/19/2012 : 13:43:52
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Tried it this morning and it clocked up to 0.10Litre.
There is a factory fitted valve between the pump and the meter. This has been replaced twice (once just the internal part, second time the whole unit).
There is also a check valve under pump AND at the tank (only about 2 feet away)
This is no sign of a leak - although as it higher octane gasoline which evaporates very quickly I am thinking there might be a tiny leak somewhere out of sight.
I am probably going to swap the air separator next, don't see how it would help but it is the only thing left except the meter.
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bigbadjohn
Canada
2163 Posts |
Posted - 07/19/2012 : 14:29:18
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The only way you will get meter jump is a leak after the solenoid. If you're not seeing leakage then it's internal. I would guess that the seals and gaskets in your meter that were immersed in diesel for years deteriorated quickly when you switched to gasoline. I would expect that if you tested the calibration of that meter you'd find it reasonably accurate on high flow and way over on slow flow....fuel has more time to leak by seals in slow flow.
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Don't learn safety by accident.
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Walkers
United Kingdom
13 Posts |
Posted - 07/19/2012 : 14:59:03
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hi bigbadjohn,
I am thinking it has to be in the meter (as you said), it is the only thing left to replace. We had a calibration check in May and it was fine, both fast and slow. I would still expect to see a visible trace of a leak. This dispenser doesn't have a solenoid as it is single nozzle, single grade. Don't know if that changes anything. |
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bigbadjohn
Canada
2163 Posts |
Posted - 07/19/2012 : 15:13:07
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| The valve between the pump and the meter is the solenoid. |
Don't learn safety by accident.
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