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Post by Colin McA on Aug 14, 2009 19:38:34 GMT
I am looking for some inspiration.
Due to a incident relating to my electric fuel pump I want to know whether it is running or rather not running. My normal method is to listen but if there is background noise I can't be sure.
I am sure there must be something like the alternator warning light that comes on when there is a failure? I was thinking of wiring in a relay to the earth side of the pump which would switch a lamp when there was no flow of electrickery.
I am looking for some good ideas here. the simplest would be the best.
I only want the lamp to be on when the pump is not pumping and the ignition is switch on.
Colin
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Post by Phil Nottingham on Aug 14, 2009 21:34:15 GMT
There is a simple electronic circuit that can do this from parts from Maplins - I am electro-mechanical only so the old relay type using a simple 2 pin flasher unit with a 5 pin relay may work in series with an earthed warning light but only if the pump will draw sufficient current which I doubt.  What is the point though - if the pump stops working the engine will stop - this the warning! If you just want to know the pump is receiving current - and the warning lightonly comes on when it is not a cheap low current relay approx 50p with NC contacts will work - dead simple to wrire up. Alternatively wire a buzzer |
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Post by Smallfry on Aug 14, 2009 23:27:56 GMT
Unless you have some sort of low pressure sensing device or a fuel pressure gauge (dont know ifthey go down that low) I cant really see how else you could do it.
You can easily make up something to check if the pump is getting electric feed, but this will NOT tell you if the pump is actually working (pumping)
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Post by Colin McA on Aug 15, 2009 14:28:52 GMT
What happened was I was heading to the monthly meeting and was low on fuel, when there was a loss of power I thought it was the fuel so pulled the reserve and the car did pick up.
On the way home 12miles or so it happened again when I was on the motorway so I put the reserve back in and had enough fuel to get to the petrol station.
I thought that was the end of the problem but about a mile or so later it died again. I was able to get to the side of the roundabout which during the day is very busy so I was luckily it was late.
At I couldn't quite hear, due to the road noise and the aeroplane taking off.
The short answer is that the connection at the pump wasn't the best and the supply cable had got melted on the exhaust at some point affecting the supply to the pump which is next to the reserve tap.
I have sorted out both problems but it led me to this.
If I supply the pump via one of fuse positions and a fuse blows I would lose the pump.
If the wire gets damage enroute to the pump I will lose power but the wire at the supply will still be live.
If the engine stops running I would not known that it is due to the pump until I start to diagnose.
Hopefully the pump will be fine for now but I like the idea of the non-running warning lamp.
Colin
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Post by johnwp5bcoupe on Aug 15, 2009 18:14:47 GMT
What happened was I was heading to the monthly meeting and was low on fuel, when there was a loss of power I thought it was the fuel so pulled the reserve and the car did pick up. On the way home 12miles or so it happened again when I was on the motorway so I put the reserve back in and had enough fuel to get to the petrol station. I thought that was the end of the problem but about a mile or so later it died again. I was able to get to the side of the roundabout which during the day is very busy so I was luckily it was late. At I couldn't quite hear, due to the road noise and the aeroplane taking off. The short answer is that the connection at the pump wasn't the best and the supply cable had got melted on the exhaust at some point affecting the supply to the pump which is next to the reserve tap. I have sorted out both problems but it led me to this. If I supply the pump via one of fuse positions and a fuse blows I would lose the pump. If the wire gets damage enroute to the pump I will lose power but the wire at the supply will still be live. If the engine stops running I would not known that it is due to the pump until I start to diagnose. Hopefully the pump will be fine for now but I like the idea of the non-running warning lamp. Colin Colin I have found from the begining with the Facet even before the need for fuel reserve the pumps speed picks up like it is being starved of fuel and if I pull the reserve it slows down push the reserve back in and back to normal then it speeds up again  so I now keep the tank at least 1/4 full and no problem as you know my pump is way below the tank so gravity should feed the pump  |
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Post by Smallfry on Aug 16, 2009 0:39:16 GMT
Welcome to the crappy world of Facet pumps.
Gravity does NOT feed the pump on any P5 because the tank outlet is at the top. Once the pump has been turned off for a while, it has to SUCK the petrol back up to top the the tank outlet, and obviously if the fuel level is low it has to work a whole lot harder. You should get a sort of syphon effect when its up and running and there are no air leaks, but again, one the fuel level is low, you get an intermittent gulp of air when going round corners or over bumps etc, and these pumps are not good at coping with this.
And the main problem with Facet pumps (apart from questionable reliability) is that they are good at PUMPING, but not very good at SUCKING.
For these pumps to work well, they should be near the tank, and ideally, have the tank outlet at the bottom.........you could cobble something up using the drain plug.
Another possibility is to use a swirl chamber like they use on rally and race cars............but I have not looked into this to see if its feasible yet.
But as you dont let your car get less than a 1/4 of a tank it shoudnt be a problem really (you dont do you ?) At 15 to 20 mpg its a bit silly...............after all, you wouldnt want to be stranded ?
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Post by johnwp5bcoupe on Aug 16, 2009 6:23:03 GMT
Welcome to the crappy world of Facet pumps. Gravity does NOT feed the pump on any P5 because the tank outlet is at the top. Once the pump has been turned off for a while, it has to SUCK the petrol back up to top the the tank outlet, and obviously if the fuel level is low it has to work a whole lot harder. You should get a sort of syphon effect when its up and running and there are no air leaks, but again, one the fuel level is low, you get an intermittent gulp of air when going round corners or over bumps etc, and these pumps are not good at coping with this. And the main problem with Facet pumps (apart from questionable reliability) is that they are good at PUMPING, but not very good at SUCKING. For these pumps to work well, they should be near the tank, and ideally, have the tank outlet at the bottom.........you could cobble something up using the drain plug. Another possibility is to use a swirl chamber like they use on rally and race cars............but I have not looked into this to see if its feasible yet. But as you dont let your car get less than a 1/4 of a tank it shoudnt be a problem really (you dont do you ?) At 15 to 20 mpg its a bit silly...............after all, you wouldnt want to be stranded ? Sorry I dont agree try disconnecting the feed to the pump once it is primed and see if it flows freely I drained my tank that way when I fitted the new O ring in the tap, apart from that the pipe to the pump is always full from the tank and the pipe to the carbs is always full. Have you siphoned petrol out of a tank using a rubber hose putting your finger over the end once the flow has started as long as the outlet is below the fuel level it will flow will it not? no matter how high the loop maybe if you are on the last dregs of either the main or reserve you will get a slush effect as the car moves about and the pump will struggle as it pushes better than it pulls by the very nature of how the pump is designed so the higher the fuel level in the tank the better the gravity flow! I agree the Facet likes a good pressure and works better under these conditions but fitting it in the boot next to the tank will not help as you will loose your reserve unless you fit 2 of course! and it will be worse on the pump on start if the delivery tube has drained as it will still have to suck on nothing apart from fumes at least under the car as I have said it has the benefit of the delivery pipe which should be full as priming source once started GRAVITY helps.I did think about a one way fuel valve in the tank but it all seems to work for me! "Silly I am not" 1/4 full as a minimum is fine for me as I carry a can at all times and over a run of 1100 miles I had a return of 22,23 and 25 mpg on full tank tests using BP Ultimate also using the throttle sensibly and depending on the type of driving roadwise  |
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Post by Phil Nottingham on Aug 16, 2009 10:12:59 GMT
Actually the petrol syphons out. The Facet pump is far more reliable than SU's and teh mechanical pump anyway and it is easy to cehck it is receiving pwoer. working or pumping petrol in the very unlikely event of failure. It is not usual to fuse the supply though for safety.
Mine is mounted low at the front of the car so it is asstisted by the syphon effect too. In its 10 years I have no problems with it aprt from noise outside the car it is quiet
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Post by johnwp5bcoupe on Aug 16, 2009 10:24:32 GMT
Actually the petrol syphons out. The Facet pump is far more reliable than SU's and teh mechanical pump anyway and it is easy to cehck it is receiving pwoer. working or pumping petrol in the very unlikely event of failure. It is not usual to fuse the supply though for safety. Mine is mounted low at the front of the car so it is asstisted by the syphon effect too. In its 10 years I have no problems with it aprt from noise outside the car it is quiet The noise I dont like either Phil but at least the pumps work! the fuel will only drain back to the level of the fuel in the tank Phil I have tried this on several occasions if the tank is full the pump slows down quicker but there is always fuel in the pipe to prime it as long as it is mounted below the tank. |
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Post by Phil Nottingham on Aug 16, 2009 14:22:36 GMT
Mine will drain the tank via Reserve and it sucks very well without problem as I found out once when engine stopped and took almost 14 gals to refill
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Post by Colin McA on Aug 16, 2009 21:18:35 GMT
So how about the warning lamp then!!!! |
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Post by johnwp5bcoupe on Aug 17, 2009 5:32:20 GMT
So how about the warning lamp then!!!! What warning light is that Colin Do you know the current of the pump? if not I will measure mine! you need to know if the pump is working not just if you loose the volts  I will email you |
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so I now keep the tank at least 1/4 full and no problem as you know my pump is way below the tank so gravity should feed the pump 
I will email you