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MG MGA - Convert Positive Earth Fuel Pump to Negative Earth
|One for D.W. DuBois, I suspect. I need a Neg earth fuel pump, but there is a massive 12 week delivery time with most sellers out of stock. I have a spare, unused, SU Positive Earth fuel pump; can i convert something inside so it can be used Negative Earth?|
|If it has points and a diode, reverse the diode|
|Colin - Send me a picture of the top of the pump with the end cover removed and I can tell you exactly what to do. Send to SUfuelpumps@donobi.net Cheers - Dave|
|Colin, Have you tried the MGOC spares dept, Telephone order Lines: +44 (0) 1954 230928 & 231318|
I bought a new neg earth pump from them 2 weeks ago and they were the best price. You don't have to be a member.
|As i recall, this positive earth pump is a 'pointless' type.|
Photo attached. Is it as simple as swapping round the Red & Black wires?
|"Is it as simple as swapping round the Red & Black wires?"|
Yes, but you may have a hard time with the lead length. You can purchase a dual polarity arc suppressor from Burlen Fuel Systems to replace the existing diode - P/N CZX 1004 the price is £4.33.
"As i recall, this positive earth pump is a 'pointless' type."
The only polarity sensitive pumps today are the all electronic versions. All of the dual polarity, points style pumps use the above quoted arc suppressor. Cheers - Dave
|Colin - I bought a negative earth fuel pump last week from MGOC - ordered Tuesday and delivered the next day. (Part No. AZX1331). Price was £114.05 |
I suggest getting the packing rubber as well (AAA260). There are no fibre washers included - mine leaked when I connected the unions, so I put on a couple of washers to cure it.
|D J Hill|
|Dave, If i read your full words correctly, as i (i think) have an electronic pump it is polarity sensitive. Hence i need to modify it. It has Red tape around it, indicating Positive Earth.|
Do i also need to swap the small wires that appear to come out of the innards of the pump to the terminals of the Red & Black wires or just the diode wires? I only ask as the Red & Black wire length of the diode looks like it will transpose OK.
|Colin - I may have misled you. The picture you posted is of a points style pump with a diode/resistor assembly for arc suppression that is wired for positive ground. If you can switch the leads of the diode/resistor assembly around, the pump becomes negative ground. If you get the varistor that I gave you the P/N for and install it, you pump becomes dual polarity - in other words, it will work for both negative or positive ground.|
"Do i also need to swap the small wires that appear to come out of the innards of the pump to the terminals of the Red & Black wires or just the diode wires?"
You just need to swap the red and black wires from the diode/resistor assembly. The other wires go to the coil, which doesn't care which way it is wired. Cheers - Dave
Thank you. Wires swapped and pump whirring away (no fuel yet) on test.
The lead length was OK.
This thread was discussed between 25/06/2015 and 26/06/2015
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