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My 79 B was down all last year with a clutch fluid issue (still in progress). Went to start up this year with a new battery and starter was operating intermittently/randomly. (I Cycle the key until starter decides to activate). Also discovered that I have no fuel flowing at the carb after 3 years of starting up right away in the spring. Are these two issues possibly related? Ideas on where to start troubleshooting?
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MGB Starter and fuel issue
- Thread starter gudfood
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dklawson
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The two problems are probably only related because the car sat for a while.
When you turn the key to the run position can you hear the fuel pump running or is there silence?
For the starter, a '79 would have a starter relay in addition to the solenoid on the starter motor. When you turn the key to the start position do you hear a soft click from the starter relay energizing? Do you hear a louder click from the solenoid energizing?
Have you measured the battery voltage yet?
When you turn the key to the run position can you hear the fuel pump running or is there silence?
For the starter, a '79 would have a starter relay in addition to the solenoid on the starter motor. When you turn the key to the start position do you hear a soft click from the starter relay energizing? Do you hear a louder click from the solenoid energizing?
Have you measured the battery voltage yet?
dklawson
Yoda
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If you need a wiring diagram for your car, copy the PDF linked below. The later model MGBs are covered on the last couple of pages.
http://www.advanceautowire.com/mgb.pdf
When trying to start the car do you have any status lights on the dashboard?
Which fan is making noise? Is it a shop fan or the cooling fans on the car?
The car's cooling fans should not run when the key is turned to run unless the temperature switch is closed. Since your engine isn't running (and therefore not hot) the cooling fans should not be running.
The following is just a quick overview of what should happen.
You turn the key to the START position. The white/red wire on the ignition switch should have 12V on it.
When the white/red wire has 12V on it, the starter relay should close with a soft click.
When the starter relay closes, the starter relay should supply 12V to the white/brown wire going to the starter motor solenoid.
When the white/brown wire has 12V on it, the solenoid on the starter motor should fire with a loud click.
Then the starter motor should spin the engine.
With the help of an assistant (and a multimeter) you can measure where and if you have 12V on the starter circuit. You'll want to measure between ground the the white/red wire and then ground and the white/brown wire.
http://www.advanceautowire.com/mgb.pdf
When trying to start the car do you have any status lights on the dashboard?
Which fan is making noise? Is it a shop fan or the cooling fans on the car?
The car's cooling fans should not run when the key is turned to run unless the temperature switch is closed. Since your engine isn't running (and therefore not hot) the cooling fans should not be running.
The following is just a quick overview of what should happen.
You turn the key to the START position. The white/red wire on the ignition switch should have 12V on it.
When the white/red wire has 12V on it, the starter relay should close with a soft click.
When the starter relay closes, the starter relay should supply 12V to the white/brown wire going to the starter motor solenoid.
When the white/brown wire has 12V on it, the solenoid on the starter motor should fire with a loud click.
Then the starter motor should spin the engine.
With the help of an assistant (and a multimeter) you can measure where and if you have 12V on the starter circuit. You'll want to measure between ground the the white/red wire and then ground and the white/brown wire.
Thanks again Doug! Starter is functioning today. Tested connection at starter, in the trunk/boot and I have power to the pump. The cooling fan is wired for constant run, not off of the radiator switch. Might convert to a belt driven fan? Disconnected the electric connection for now so I could hear what's going on
dklawson
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I'm glad things are working today. Do you think just probing around got an electrical connection working? Maybe there are some connections that need a bit of additional cleaning and a light coat of dielectric grease during reassembly as a bit of protection.
It's your car so it is your decision if you want the fans on all the time. You can always wire in the factory switch later if you want to. If you want an adjustable switch, the company Derale makes one with an expansion bulb/sensor. Mounting the sensor can take a bit of creativity. I have one on our GT6 and the sensor is secured to the radiator header tank. The Derale products are sold by places like Summit Racing. However, other vendors probably sell the same kit for less.
https://derale.com/product-footer/electric-fans/fan-controllers/adjustable-controllers/16769-detail
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