Pump cut off

zepfan

If the cut off in a fuel pump is not working, possibly a bad regulator. Would that cause a fuel pump to lose it’s prime? The pump I am referring to is a suntec m# AV2A-7116 installed on a Beckett AFG burner. The burner is on A Rheem furnace installed in 1996. The furnace had a bad ignition transformer that I replaced last weekend. The furnace had not been serviced, or even operated in sometime, so I went ahead and cleaned it out, changed the oil filter, nozzle and pump strainer. The oil filter housing was halfway full of mud, and dirt. Once the burner was restarted, all seemed good. All combustion readings were well within range. The burner ran for two days and then locked out.I went back and there was no oil delivery to the nozzle. Bleed it back off and the burner started right up. One thing I did noticed was that the pump was drawing 3” of vacuum while running, and initially was holding 3” when it was off, once I was finished I did not check the vac. Reading for fear of having to re bleed the pump.This is single pipe setup, with the tank located in the same room as the burner 30’ away, with about 8’ of that up from the tank, then five feet down to the burner. There are minimal fittings from the tank to the burner and I soaped them all down and did not notice any soap being drawn into the fittings. The only thing that I noticed out of sorts was that the cutoff pressure fell below 20%, but did not go to 0, and that when the burner was off the vac. Gauge read 3”. This second trip I bleed the unit three separate times for 15 seconds each, and did not see one air bubble. Could it be that I did not do a though enough bleeding job the first time, the pump is failing, or there is an vac leak that I can find? The oil line is ran exposed in the ceiling, and there is a total of 6 flare fittings. Thanks to all

SuperTech

I'd look for restrictions in the oil line, especially considering how much junk was in the oil filter canister. I would have blown it out if I saw that.
If the pump pressure falls below 20 percent of operating pressure at shut down its probably a good idea to replace it
Blow out the oil line and check the flare fittings.

STEVEusaPA

^^^that. I would add, blow back oil line from pump inlet. Change nozzle, filter, strainer. You should be treating the oil tank if you had that much crap in it.
Other problems could be just poor set up-draft, smoke, air, etc.
If it's not a vacuum leak, you didn't properly bleed. 15 seconds isn't enough.

Big Ed_4

If the oil level in the tank is the same hight of the burner and the vac gauge should read 0 at rest. If the gauge works and showing a reading the oil line is not fully bleed of air .

EdTheHeaterMan

I was taught to prime a fuel pump after a filter change or other fuel line repair this way:
1) operate the burner by jumping the FF terminals. (today we use pump prime on the electronic primary controls)
2) attach a clear hose to the bleed port
3) open the bleed port and allow the oil to flow into a 1-gallon container
4) keep priming until there are no air bubbles for a count of 15 seconds. If you see a smidgen of air... start counting to 15 again.
5) once there is no air for 15 seconds, close the bleed port.
This assures that any air from the oil filter (especially on tank-mounted oil filters 30 ft away) or any high points in the fuel line will be forced thru the fuel piping and purged from the system.

That said... I don't always follow that teaching.... but when I have a problem like this one described above... I follow the teaching of the great Robert Mandell who was the service manager that learned me that way! Sometimes u get 3/4 of a gallon before there is no air.

EBEBRATT-Ed

@zepfan

Check the oil filter gasket and make sure you put a new gasket on the bolt that secures the filter canister. I had one of those drive me nuts once

stevemikel

Agree with check out, maybe replace the filter housing, Generals can sometimes not seat very well in the nut on the bottom of the housing, and always change the washers when changing the cartridge. .

zepfan

Thanks to all that took their time to respond to this. So far, so good. No lockouts this week. The strange part about this is that as bad as the oil filter was plugged, the pump stained was spotless. The filter must have been doing a good job. Take care