• Hey Guest!
    British Car Forum has been supporting enthusiasts for over 25 years by providing a great place to share our love for British cars. You can support our efforts by upgrading your membership for less than the dues of most car clubs. There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Upgraded members don't see this banner, nor will you see the Google ads that appear on the site.)

MGB no start problem

Share this page

P

prc

Freshman Member
Offline
It's been awhile but just trying to start 1980 mgb , new battery, all accessories work and I heard the fuel pump kick on once but nothing after that. I turn ignition and starter does not turn over, it doesn't even click. I looked at the wiring and it looks good and tight. Any ideas on where to start checking? I seem to remember something in the past about my ignition switch but that could have been a different car. Would that be something easy to check? This thing has been sitting for a couple years but the last time it started right up. Thanks for any help.
Paul
 
my two cents - if power seems right to accessories, but starter doesn't crank ... it's possible the starter ground or power cable is loose and/or corroded.
 
If it has been 2 years it might be the battery. It takes a lot less juice to get the accesories working than the starter turn over. You can test bu taking a jumper and going straight from the battery to the starter - this eliminates everything else.
 
Jpsmit, as mentioned above I just bought this battery today and used it on a different car so I know that is good.
 
Do you have a meter or test light? Meter is better. Did you test the ignition switch and starter relay? Easy access for testing theses components is under the bonnet on the passenger side.
Tight connections don't mean that electrons are flowing.
Wiring diagrams are available at > ADVANCE AUTO WIRE < Use sheet 25, '78 and later from Bentley. The Haynes inspired versions are not the best because Haynes tried to incorporate too many years into one diagram.
 
You can bypass some of the start circuit by disconnecting a wire from the ignition relay and touching the bottom fuse. See John Twist's video on starting a MG under the bonnet. Your car is at the end of the video.
 
Ok perfect. Did that and the engine turns over. So did I just bypass the starter relay or did it prove the relay is no good? I'm still trying to rule out the ignition switch. Thanks
 
You bypassed the ignition switch and the relay. A wiring diagram and a voltmeter are needed. With the ignition switch to the start position, do you have voltage at the input to the relay? Then to the relay output. You ought to disconnect the coil so it doesn't overheat with the ignition switch on.
 
So I put a jumper from c1 to c2 and engine cranked. I then put jumper from c1 to w1 and nothing happened. Shouldn't that have energized the relay to cause it to turn over? I think I have a bad starter relay. Thanks
 
Ok I confirmed that I have 12v at the 2 r/w wires on the relay which is telling me the problem is with the relay. Correct??
If so where can I get a replacement round like the original? Thanks for all the help.
 
Last edited:
The starter relay and the ignition relay are the same part, so you can swap them. If the car then cranks you'll know the relay is bad.
 
I'm looking up relay's and I'm finding a 131-510 and a 131-520 but cannot seem to get any help on the difference between? I currently have a lucas round one about 1inch dia.
 
Thought I would give you closure on this. Went and bought an aftermarket 40A 4 PIN relay at the parts store and wired it up and it's working great. Sorry purists. Thanks for all the help.
Paul
 
Back
Top