Oil pump failure?

[Nwr161282]

So my boiler has stopped working. I've traced the fault to no fuel coming out of the pump outlet. So I thought OK pump is faulty. So checked the pump drive all good there. I then cracked open the bleed valve and turned boiler on and fuel came out. So that's got me thinking is it the pump, the solenoid or the control box sending the signal to the pump.

Anyone any tips on what I can try next or should I just go for a new pump.

 

[Burnerman]

Guessing this is a Danfoss BFP pump?
Either way, if the pump solenoid isn't getting a signal from the control box or the solenoid coil is goosed, no oil will flow.
John

 

[Nwr161282]

Yes John it's a danfoss BFP11R3 pump. Just away to get my voltmeter out and test. Any idea what reading I should be getting on the solenoid resistance and what pins should I be getting a voltage across from the control box.

 

[Nwr161282]

Looking like control box. Highest voltage I got from control box to solenoid was 1v. Resistance on solenoid was 2.213kohms

 

[oilhead]

Solenoid resistance is spot on. You may have a photocell giving a false flame signal. That could stop the control box opening the solenoid.

 

[Nwr161282]

OK will check the photocell. It was replaced 2 years ago as I gave the burner a major overhaul due to. Intermittent issues. I replaced photocell, ignitors and control box. I replace the Nozzles yearly as part of its service.

 

[Nwr161282]

Photocell resistance when covered =9kohms when exposed to daylight = 200kohms. So looks like photocell is fine. My understanding of the photocell was that when it did not detect flame it allows the electrodes to spake then once it sees flame it stops the ignitors. I did not realise it was connected to the oil pump.

 

[martyndc88]

What process does the burner go through. Doea it sound like it's sparking, does it go through quite a long cycle before locking out. Is the motor spinning ? Have you taken the oil pump out ? Does it turn freely by hand? Is the drive coupling okay ?

 

[oilhead]

If you have a false flame signal on startup, the control box will not open the solenoid.

 

[Nwr161282]

Ok when I was checking the voltage output I stupidly had the photocell out there for it was giving the false flame signal hence no voltage to solenoid. I then tried it with the photocell covered and I got voltage. So I put everything back together and she fired up and ran fine for over 1 hour that includes on/ off when temp was reached.

Everything worked fine again this morning. Then sadly tonight I passed the boiler and it was locked out. So it's back to investigating the issue.

 

[Nwr161282]

So reset and tried to fire up boiler. Boiler went through start up sequence and fired up fine. It then ran for 2mins 40sec before locking out. Took photocell out and cleaned in up (wasn't dirty). Put back together now won't fire up. Oh the joys. Think ill leave it tonight and start a fresh with it tomorrow

 

[martyndc88]

Solenoid dropping out when hot or seized oil pump

 

[Nwr161282]

I've had the oil pump off and all felt free. Checked drive as I know that's a common issue but that is fine. I feel that it's a fuel issue as it did fire up and run for a bit then surly the only reason it would lock out when running is due to no fuel.

 

[oilhead]

Or a solenoid overheating/failing.

 

[Nwr161282]

Haven't had a chance to look at burner yet but might pick up new solenoid any way and try that. I would go for a new pump but I have no way of setting up pump pressure and my heating engineer can't make it till end of next week.