MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Variation on an old electrical mystery . . .

When I turn on the key, there is no ignition light and no fuel pump operation, yet there is voltage to the front of the #3 fuse, to the coil, and at the 3-way connector ahead of the firewall.

Since my garage floor is too uneven to jack the car, I'll have to wait for help to push it out, jack it up and check for voltage at the fuel pump itself. In the meantime, any solutions come to mind?
Dan

Check the ground, in the boot, the bolt on the number plate mount, along with the other grounds for the rear lights.
Ken R
Ken Rich

Dan.....This could be one of several things;

1 there is not enough juice in the battery.
2 the earth is poor either on the battery or somewhere in the loom
3 the main power lead runs from the battery to the solenoid, then onto the ignition switch, lights and fuse box. Check that all of these connections are clean and fixed not loose.

HTH
ian holliday

Dan;
I had this problem intermittently on my 76 B. I would pull & fiddle with the wires on the fuse block, and it would start to work. I removed the fuse block, cleaned all the rivet joints, and soldered them front & back. I also cleaned & greased the spade connectors on fuse block, & spade connections on the relay mounted to the rear of the fuse block.The car seems to crank faster since I did this. I have also just ordered packs of new bullet tube connectors from Triple C, and plan on replacing every one in the entire electrical system.
An ink eraser works great for cleaning spade connections. This is the type that has fiberglass strands, like a paint brush, in a plastic tube body. Available at any store by school supplies.

Good Luck,

Pete
Pete Haburt

Dan

Welcome to the world of dodgy auto-electics!

I had a similar problem a couple of years ago. it turned out to be a broken wire at the back of the ignition switch. I'd put money on your problem being a broken wire somewhere, so just follow the wires and clean/tighten/replace any connectors that you come across.

Sorry, this is probably a stupid question but, when you say front of the fuse I assume you mean the output side(ie is current running through the fuse)?

Bob
Bob Everick

For many years, I learned that simultaneous failures are unlikely, although faults stemming from the same root cause exist and are an aid in fault finding.

My 1970 MGB was suffering from: (a) the fuel leak, caused by a split hose from the forward float chamber to the jet; (b) a corroded connector at the firewall on the "white" wire feeding the fuel pump and the #3 fuse from the ignition switch; (c) a fuel pump which had stuck points following a week of non-operation; (d) a non-operating ignition warning light (also on the white-wire circuit) which I have yet to troubleshoot beyond determining that the bulb is ok.

Simultaneous failures do happen.
Dan

Hunt's Third Law - "Don't assume that because you have found one problem, you have found the ONLY problem." - courtesy of Nory.

As far as the warning light goes remove the alternator plug, and with the ignition on, ground the brown/yellow (not the brown!) in the plug. If the lamp lights the problem is in the alt. If not, in the bulb or wiring to it. In most cases the white for the bulb comes from the multi-plug by the steering column.
Paul Hunt

This thread was discussed between 25/02/2002 and 01/03/2002

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.