won't start

[Norman]

!979 "B". I am getting no power to the starter. Battery and ground is good. Starter new. Ignition switch new. Battery new. All accessories work. Not an electrician so any advice as what to check will be a great Christmas present. All I can think of is bad relay, bad coil, fuses all work. Thanks

nnormann99@yahoo.com

[Norman]

Oh and I have electronic ignition

[Vic Butler]

There are 2 relays on the offside inner front wing. The starter relay is the back one. They are identical. Check there's power going to it with the key in the start position. One of the brown wire is the power. There are 2 on one terminal.
Further thought. Is the starter the correct one? The rubber bumper MGB's have ballast resistor ignition and there is an extra terminal on the motor that goes directly to the coil to bypass the resistor. If the starter doesn't have this terminal the engine won't run but in your case I wonder if the starter is wired correctly. There are several terminals on the solenoid.

[Norman]

The starter fits so I guess it is the correct one. On the solenoid there are two large connection. For the positive terminal and three brown wires. Could it be that I have connected the positive to the wrong terminal? Also, the three brown wires are also connected to the terminal that comes from the battery.

nnormann99@ yahoo.com

[Vic Butler]

The incorrect starter will fit but it doesn't have the connector on it that goes to the coil.
I'll study the wiring diagram later and report back if no one else has come up with an answer. It's an unnecessarily complicated set up.
Further thought. Is the new starter motor the original large Lucas type or is it one of the lightweight hi torque type or what? Many of the aftermarket ones don't have the connector to bypass the ballast resistor. Many dealers incorrectly state that the pre engaged motor is for 1968 to 1981 cars when it's not. Rubber bumper MGB's have the one with the extra connection. Who supplied it?
You didn't dislodge any wires when replacing the rubber boot?
Edit. I've had a look at the wiring diagram. On the starter solenoid there are three heavy brown wires on one terminal, two go to the alternator and one to the battery. There's a thin brown wire on the same terminal that goes to the light switch. The thick brown wire on the other terminal goes to the starter motor.
There are two small terminals. One has a white/red wire that is the feed from the starter motor relay on the offside inner wing and the other has a white/light green wire that goes to the ignition coil bypassing the ballast resistor. It is this connector that is often missing on replacement starters. On the diagram the latter terminal appears to be between the two for the brown wires but that may not be the case in reality. The white/red feed wire terminal appears to be out on its own.
That's about the best I can do without seeing the setup.

[Charles Farran]

Norman,

Your first post implied that the starter did not turn over when you switched the ignition switch to the crank position rather than just the ign position.
The main + cable should be attached to the main post on the back of the solenoid along with 3 other brown wires. Assuming you have the original ballast wiring then there are 2 further terminals , one of which connects to the feed from the starter relay on the inside wing. The other terminal supplies a full 12V to the coil when the starter is being cranked (& only then) to create a better spark to the ballasted coil. (This terminal on the solenoid is marked IGN & when live under cranking shunts the resistor out of circuit).
Getting the starter motor to turn simply needs a + supply to the first of these additional terminals with the - being supplied by the earth lead of the battery to the chassis which when reaches the body of the starter motor via the engine block which should also have an earth strap connecting the block to the chassis. (On my 1980 car this is a connected to the chassis on the bulk head under the oil pressure hose mounting bracket and the rear of the block on the bell housing).
Assuming all the wires are connected correctly as above , with the car in neutral , you can carefully try using a test wire connection from the brown fuse post in the fuse box to the the starter relay (front one). Remove the W/R wire from the relay. Place one end of your test wire on the exposed terminal (best to sue a crocodile clip or spade connector taking care not to touch the body of the car & touch the other end to the brown fuse post. If the starter doesn't turn, then the problem is at the solenoid end. If it turns, then replace the W/R wire to the relay & remove the W/N & do the same test with the other end of the test wire on the brown fuse post. If the starter doesn't turn then the relay is faulty - if it does then it suggests there is a fault in the supply from the ignition switch. (You will not have a high current going through your test wire as the high current under cranking is supplied directly from the main post on the back of the starter solenoid & via that solenoid on the starter motor itself).
(I have had to do this on my car so know it works).
Cheers,
Charles

[Charles Farran]

Apologies, the rear relay, nearest the fuse box is the starter relay!
Cheers, Charles

[Charles Farran]

In my earlier posts i described the colours of the wiring. I know that some wiring diagrams indicate slightly different colours(WR & WN seemingly varied from time to time & you may find them to be the same colour each side of the relay) & of course if a PO has interfered with / chopped & changed the wiring then be aware of this. (If the loom has not been interfered with then the colour combination of the wire at the solenoid end should be the same as the wire coming from the relay end). The relay should be earthed by the black wire which is attached to the body work by a screw on the inner wing part hidden by the brake servo further back from the fuse box.
If the relay works you can then check the feed from the ignition switch. Remove the W/N lead again (assuming this colour on your car is appropriate (see above comment) from the relay and connect a test bulb lead to this with the other end attached to a suitable earth on the car. If you then turn the ignition key to the crank position, then the bulb should light up if the ignition switch is correctly connected up & working - if not then you need to look at that area for a solution.
Cheers,Charles

[Vic Butler]

Interesting Charles. I've never had to replace the starter motor on mine so all my comments are based on theory. I had thought of fitting a high torque starter but in view of this and earlier posts where the connector to bypass the ballast resistor is nearly always missing I'm leaving well alone.
"If it ain't broke don't fix it."