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MG MGA - wiring gremlins

Hi,

I'm putting my car back together after sending it off to the paint shop. Some of the wiring got knocked loose and I've been trying to get it right again. My horn worked, but now when I've put all the wiring back, it doesn't. (I tested the horn, it works.) When I turn the key, the ignition light comes on, but the fuel pump doesn't. There was a loose wire by the fuel pump that I'm not sure what to do with (see picture). The starter works, but not the wipers.

Any ideas? I've attached a couple of pictures and everything appears to be okay. The fuses looked okay, too, though the contacts were rusty on one of them.

Thanks,

Darian


Darian Henderson

Here's the other picture:




Darian Henderson

I believe that is a ground wire for the fuel pump.
John DeWolf

I'm sure you're right, but the pump was working before without it. Maybe just a fluke?

Thanks,

Darian
Darian Henderson

Was the resilient mounting pad in place previousley? If it is installed it would isolate the pump body from the chassis, which is why the ground wire is required. Fresh paint would also isolate the pump even if you still don't have the pad in place. It may have grounded through the fuel line previousley.
John DeWolf

There was no pad, and it has fresh paint, so that probably explains it. I'll check tomorrow about the pump, but do you have any ideas about the horn and wipers?

Thanks,

Darian
Darian Henderson

Was the dash recently painted on the underside? The horn has a switched ground that connects into the instruement panel grounding system. I think the wiper switch is also connected into this ground system. If it was painted then you should scrape some paint off where the ground system (black wires) connects to the body metalwork. I can't remember exactly where that is.
John DeWolf

A meter or simple continuity tester will help you ferret out a lot of these gremlins. If it worked before, and now doesn't, sounds fishy. Poor grounds would explain a lot of it. It also helps to be able to test for power at the ends of the wire. For example, test for 12v at the fuel pump lead at the pump end would direct you either toward the pump itself or bad ground if 12V present, or to the other end of the wires if 0V present. In any case, there is not much to the wiring so you will ultimately prevail.

Dennis, Az
Dennis

Thanks again,

I tested to see if I was getting a current to the fuel pump. I was, so I pulled out the best friend of the SU pump - the hammer. Now it's working...

I'm all for originality, but if this is a pattern of things to come, will any replacement fuel pump do?

Thanks,

Darian
Darian Henderson

Yes, any fuel pump that stays under 5 psi pressure. If it isn't for concours show, see here: http://mgaguru.com/mgtech/fuel/fp201.htm
Barney Gaylord

Thanks. I saw the link. So, for example, this one should be fine, too.

http://cgi.ebay.com/ebaymotors/ELECTRIC-FUEL-PUMP-BRAND-NEW-UNIVERSAL-12vol_W0QQitemZ330142663402QQihZ014QQcategoryZ33555QQrdZ1QQcmdZViewItem

Darian
Darian Henderson

This thread was discussed on 06/07/2007

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