AlexLev Posted October 27, 2018 Report Share Posted October 27, 2018 (edited) Was practicing some CPL maneuvers in my Mooney yesterday when I noticed the boost pump wouldn't stay on. The switch, once I flipped it "on," would auto flip to off (and the fuel pressure didn't budge, so I don't think the boost bump was working even while the switch was on). Eventually after a few cycles- the switch stayed in the engaged position, but the boost pump still wasn't working. I'm hoping it's a circuit problem vs the boost bump itself. One of the things that have me think that is it seems the landing light isn't coming on either (and I just replaced it in March so I feel like it didn't burn out). However, there doesn't seem to be a breaker for either (so is the switch the breaker/circuit??). Few Q's: 1) Where is the boost pump in the M20G? 2) Any suggestions on how to troubleshoot this/where to start? @M20Doc: Would appreciate any suggestions on where my mechanic and I can start with this! Edited October 27, 2018 by AlexLev Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 27, 2018 Report Share Posted October 27, 2018 The switch is a CB/switch combination... Boost pumps can be found by their tell-tail drain fitting. Removing the belly panel will expose the pump... Testing CBs is a challenge... the economics point to replacing instead of testing... Often a weak CB switch can be felt... a smooth operating switch vs. a nice click when switching is a hint... Are you pulling 2gs in any of the maneuvers? If the old style rubber panel mounts are aged... the plastic panel cover bumps the switches and turns off the week ones... Be ready to answer questions regarding what fuel pump you have... and if it has ever been run dry, or left on too long... Some are only rated for limited use. Not being very familiar with the CPL maneuvers... Why were you using the electric fuel pump? PP thoughts only, not a mechanic... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
AlexLev Posted October 27, 2018 Author Report Share Posted October 27, 2018 (edited) 13 minutes ago, carusoam said: The switch is a CB/switch combination... Boost pumps can be found by their tell-tail drain fitting. Removing the belly panel will expose the pump... Testing CBs is a challenge... the economics point to replacing instead of testing... Often a weak CB switch can be felt... a smooth operating switch vs. a nice click when switching is a hint... Are you pulling 2gs in any of the maneuvers? If the old style rubber panel mounts are aged... the plastic panel cover bumps the switches and turns off the week ones... Be ready to answer questions regarding what fuel pump you have... and if it has ever been run dry, or left on too long... Some are only rated for limited use. PP thoughts only, not a mechanic... Best regards, -a- Good info! We did pull some Gs in the maneuvers for sure. You're saying that may have caused something to be dislodged? And to answer your question about why we were using the pump, it was on the power off 180s, during the landing checklist I would turn it on. Edited October 27, 2018 by AlexLev Quote Link to comment Share on other sites More sharing options...
Marauder Posted October 27, 2018 Report Share Posted October 27, 2018 Good info! We did pull some Gs in the maneuvers for sure. You're saying that may have caused something to be dislodged? Alex - do you have the rocker type switches or the toggle type? I had one Klixon rocker fail where the little spring broke. The switch cover moved to the right position but the pump never turned on. Sent from my iPhone using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 27, 2018 Report Share Posted October 27, 2018 Use your fingers to lift the panel in front of the pilot... If it moves a half inch back into what looks like a normal position with nice switch clearance... that is panel sag... A few dollar items to fix... the rubber mounts are behind all the acorn nuts... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
AlexLev Posted October 27, 2018 Author Report Share Posted October 27, 2018 Just now, Marauder said: Alex - do you have the rocker type switches or the toggle type? I had one Klixon rocker fail where the little spring broke. The switch cover moved to the right position but the pump never turned on. Sent from my iPhone using Tapatalk Pro Toggle switches. At first when the toggle switch was auto-going back in the down position, I would hear a "buzzing" in the headset when it turned off, which made me think it was some electrical issue vs the bump itself, but who knows? Now when I put the switch up, it stays up, but no activity from the pump itself. It seems like the landing light also is not coming on, and I am not sure if that is related or not / how I would start to investigate. Quote Link to comment Share on other sites More sharing options...
carusoam Posted October 27, 2018 Report Share Posted October 27, 2018 Expect that landing lights wear out the CB switch... mine did... This makes it susceptible to being bumped and turning off... They are temperature sensitive... as they warm up they trip quicker... Their design is old style... higher amps generate higher temps... the high temp unclicks the CB... and releases the switch... The strength of the click was noticeable compared to other CB switches in the panel... Start with a volt meter... is the pump getting electricity? Is your pump rated for continuous operation? Dislodged is too strong of a term... check to see if you have rubber panel mounts... when they are old or loose things move under gravity... those things will move more under increased gravity... enough to bump the row of CB switches... thus turning off the week ones... CB PP logic... Stuff that didn’t work right in my 40 yr old plane... my headlight CB couldn’t stay on... it got replaced... Follow-up lesson on bus bars to follow... Good news... access to the bus bar is easy from the outside with those handy original access panels... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
AlexLev Posted October 27, 2018 Author Report Share Posted October 27, 2018 Wondering if I should order one or two of these: https://www.peerlesselectronics.com/7270-5-20-circuit-breaker -- have a trip scheduled for Friday and would be nice not to have to cancel -- I figure odds are I'll probably need that Klixon Circuit Breaker or a new fuel pump. Quote Link to comment Share on other sites More sharing options...
Marauder Posted October 27, 2018 Report Share Posted October 27, 2018 Toggle switches. At first when the toggle switch was auto-going back in the down position, I would hear a "buzzing" in the headset when it turned off, which made me think it was some electrical issue vs the bump itself, but who knows? Now when I put the switch up, it stays up, but no activity from the pump itself. It seems like the landing light also is not coming on, and I am not sure if that is related or not / how I would start to investigate. Sounds like a failing toggle switch. They are cheap (in aviation terms) to replace. You should be able to remove the switch and connect it to an ohmmeter to see if it has continuity. I also have a 12 volt power supply I bought from Radio Shack years ago to check switches like these. Put in series with a voltmeter and see what it does. Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
Marauder Posted October 27, 2018 Report Share Posted October 27, 2018 Wondering if I should order one or two of these: https://www.peerlesselectronics.com/7270-5-20-circuit-breaker -- have a trip scheduled for Friday and would be nice not to have to cancel -- I figure odds are I'll probably need that Klixon Circuit Breaker or a new fuel pump. My boost fuel pump was making a lot of noise before it died. The breaker you showed is a 20 amp. Not sure what size is in the plane. Sent from my iPad using Tapatalk Pro Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted October 27, 2018 Report Share Posted October 27, 2018 Is your boost pump working? does it make pressure when you turn it on, on the ground, with the engine off? Quote Link to comment Share on other sites More sharing options...
Guest Posted October 27, 2018 Report Share Posted October 27, 2018 From the wiring schematics it looks like it should be a 10 amp breaker/switch. The pump could be failing and drawing more current than the breaker can pass, or the breaker or both. The pump is under the left cowl flap/ exhaust fairing. Pump operation should be obvious, if the breaker trips, I would disconnect the power wire and connect it to a 100 watt landing light bulb, the same draw as the breaker is rated for to test the breaker. If the breaker doesn’t trip you’re down to the pump. Clarence Quote Link to comment Share on other sites More sharing options...
AlexLev Posted October 31, 2018 Author Report Share Posted October 31, 2018 Looks like I need a new Weldon pump. Took forever to track one down today, but I think we got one overnighted. $1285. Ouch. Quote Link to comment Share on other sites More sharing options...
Yetti Posted October 31, 2018 Report Share Posted October 31, 2018 You can get them redone at http://www.aeromotorsllc.com/aeromotorsllc/ 1 Quote Link to comment Share on other sites More sharing options...
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