What are the symptoms of a bad oil pump?

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Old 11-30-10, 06:54 PM
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What are the symptoms of a bad oil pump?

I have a Beckett "SR" burner on my old Lennox furnace. After changing the felt filter it wouldn't fire anymore. Must have knocked something loose and plugged the nozzle (.75 80degree B)to where it didn't have a good spray pattern. Replaced nozzle but still won't light off. Pulled cover off pump and strainer was so plugged I don't know how any fuel got through it. I cleaned and reinstalled but forgot to open the supply valve before trying to light it. It made some horrendous sounds. Once I realized what I did, I opened the valve and it still wouldn't light. I pulled the nozzle assembly out and turned it on to check the spray pattern and it was not wide enough to reach the electrodes (which I filed to a point on both, then reset at 5/32" apart, 1/16" - 1/8" in front of nozzle, and 7/16" from nozzle center to tip of each electrode). I don't have a pressure gauge and can't buy one right now as I am unemployed, so my question is: if the pump can't put out the 100 psi it is rated for, how will that change the spray pattern of the nozzle? Will it become longer and not as wide as it would with full pressure? Could I have caused the pump strainer to collapse when I forgot to open the supply valve and maybe that is restricting flow to the nozzle? Should the cone of the spray be in fact touching the electrodes?

Btw: pump is a Sundstrand, 2-stage, 100psi, 1725rpm, 2 pipe system, and I don't believe air is the problem at this point.

Any help would be appreciated...
Rick
 
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Old 12-01-10, 03:03 AM
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Did you bleed it out ?? I know two pipe system can able be self bleed but open up the return line pipe fitting just a crack to see if you have fuel flowing if not then pretty sure the pump is toasted due the age but fuel pump failure is not widespread if the tank filter was change every year.

Move the electrodes about 2mm ahead it will catch the fuel stream and light off.

If the pump is not running at 100 PSIG the spray pattern will go smaller and more courser and possiblty flame out depending on which nozzle you used.

I will suggest that the fuel pump to be replace make sure you get the same speed , rotation and PSIG rating and get few new filter cartage as well you may need to do that anyway.

5/32 gap IMO it may be little too wide so knock it down a notch { 1 /32 or so } but before you get too far with this I know Grady may have few more details that can help you with it.

And make sure you mark the nozzle size and pattern so you will know the next time you need a nozzle.

{ you may have to post the furance model number and Grady can able look up to make sure you are using correct nozzle }

Merci.
Marc
 
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Old 12-01-10, 01:11 PM
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System seemed to bleed fine. My new nozzle was replaced by taking the info off the old one. But if Grady has access to the original specs to verify that would be great. I got the electrode specs from the guy that has worked on this furnace before. The furnace is a Lennox model OF7-140M; 1.00 GPH; 112,000 BTU/HR according to the tag inside. The tag also says it's a Lennox oil burner but mine says Beckett on it. Maybe it was changed at some point? Is that why the nozzle on mine is only .75 GPH maybe?
 
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Old 12-01-10, 04:38 PM
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Burner

Beckett doesn't list your furnace in their OEM data base. Your electrode settings are "textbook" & should be fine.

Something you can do is to check the flow out of the small nozzle line. Simply disconnect it from the nozzle assembly & direct the flow into a suitable container. The stream should be solid & clear red. If that's all good, remove the nozzle, connect the assembly to the nozzle line, & again direct the flow into a container. This will help to flush any loose debris from the assembly. Install a NEW nozzle, reinstall the assembly & try it ONE time. If still no fire post back & we'll go further.
 
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Old 12-10-10, 08:51 PM
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Been a little busy with some other things but back on the furnace now. I stole a gauge off a broken air compressor and adapted it to fit the pump and checked the pressure. It was pretty steady at about 115 psi but had occasional fluctuations between about 105 psi and 115 psi. I had already cleaned out the strainer before. I will now flush the nozzle tube and see if there is any debris in there. I had already put on a brand new nozzle but I suppose I may have ruined it by not cleaning out the tube first? I don't see any debris on the gold nugget nozzle filter like I did on the old one, but I suppose it still could be partially plugged, right? I will get back to you once I have flushed the tube and retried. Also, anyone know how to access the combustion chamber so I can clean up all the unburned fuel that has been dumped in there from all of my previous attempts? I would prefer not to burn down my house if I ever get this thing to light off.
 
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Old 12-10-10, 11:32 PM
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To get into combustion chamber is pretty limited in most case but some can get into by inspection port or remove the oil burner gun then you can able reach inside of the combustion chamber however let me warn you the combustion chamber it may have brick liner or other delicated materals so you have to becarefull when you try to clean out the combustion chamber.

I know most peoples do is let it run for a while to burn off any excess fuel I know furnace will get hotter than normal ditto with flue stack and it will make funny noise along the way but before you do this let Grady give you couple safe pointers before you do this produrce.

If you really smell fuel oil or diesel fuel in combustion chamber I know it will take extra time but remove the burner gun and take a rag and go to bottom of combustion chamber and let it soak { do not try to wipe up much as possible unless you have brick liner other types of liner are senstive to rubbing and can break apart }

Only do this produrce if you have frequent lock out on this this is crictal if you have old honeywell or sentry burner control which they have 45 second lock out.

I will leave this part to grady he will know couple more tricks for your furance.

Merci.
Marc
 
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Old 12-11-10, 05:14 AM
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It is entirely possible you contaminated the new nozzle. It is also possible you are not getting enough, if any spark. Have you checked the ignition transformer? How many times have you reset the burner without ignition? Most of the old Lennox furnaces had a fire clay chamber depending upon how old the furnace is.
 
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Old 12-11-10, 03:40 PM
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I am not sure how many times I have hit reset without it lighting over the course of this issue...maybe 10? I guess I will use some rags to dab it as dry as I can through the blast tube hole. I would guess the furnace is from the mid-1960's. Transformer seems good. I have seen the spark across the electrodes and it seems strong and whitish. What I noticed when checking the spray pattern of the new nozzle was that the "cone" of atomized oil didn't seem to come in contact with the electrodes. This was while it was out of the blast tube so there was no air blowing around it. Wouldn't the atomized oil have to actually come in contact with the spark to light off? Again, I may have already contaminated the new nozzle at that point. Could just a small amount of debris in the nozzle alter the cone shape enough to keep it from firing? It seems like the cone isn't wide enough. What's the difference between a "B" nozzle and a "W" nozzle?
 
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Old 12-11-10, 04:29 PM
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You don't want the spray to hit the electrodes. The fan will blow the arc into the spray.

A 'B' nozzle is a solid spray whereas the 'W' is "semi-solid". This will show you the actual difference. Oil Burner Nozzles

Having pushed the reset button 10 times without ignition, it's time to call a pro. Be sure to tell him/her EVERYTHING for your safety & theirs.
 
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Old 12-11-10, 11:23 PM
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Don't write me off yet Most of those resets were before I opened it up and started learning how these things work. I understand it so much more now and I want to follow through with it. I still need to clean out the nozzle tube and replace the nozzle again and give it one more try before calling in the pros I will follow up after I do that.
 
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Old 12-12-10, 01:46 PM
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Something I don't remember being mentioned is the ignition transformer. Have you tested it to be sure you are getting a good strong spark?
 
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Old 12-12-10, 06:03 PM
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when my grandpa got a new boiler, i took the oil burner off and took it apart. in the spray head, there was a huge chunk taken out of the spray head!
 
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