Weird Ignition Problem (Even for an MGB GT)

I jumped into the GT this am to drive to school (I let her warm up for about five minutes first) and made it about a quarter of a mile before the red dash light came on and she died. It was as if I'd just turned the key off. She started right back up and ran for a few seconds before doing the same thing again. I started her back up and drove her home. I'm looking under the bonnet for anything out of the ordinary but, so far, haven't found anything. She's got a Crane Fireball XR700 ignition system that was installed by the PO. She's been running great for the six months I've owned her and now this. :( Anyone out there got any ideas?

Shawn

Check Fuel flow.
Check the plunger on the fuel cut-off switch if equipped.
Check the little black wire in the distributor if it is there... to make sure it isn't shorting when it heats up.

Thanks Peter. :D

Shawn

One other one... check the high tension wire connector between the coil and the distributor to make sure it is tight and grime free.

I had the 73 die in the middle of nowhere yesterday. Ckecked fuel flow,,ok..Replaced rotor button and that's when I notice the coil to cap wire hanging down from the cap.. Plugged it back in a away we went.....

Pull on all you ignition wiring leads, sounds like one may be quite loose.

My guess is the fuel pump. When it shuts down, listen for the clicking or lack there-of. I went through my ignition system top to bottom when I still ran the Crane and found it wasn't ignition in the end. I had the EXACT same problem - the car just shut off like a light switch.

Also check the overflows on your carbs. If either one is restricted it'll act like a kill switch too!

Fuel pump was my first thought, too. If the pump is ticking away, and you've checked the other bits already mentioned, then pull and check the fuel filter. It could be restricted but not completely blocked; that could cause the intermittent symptoms you're seeing.

My pump would just get hot and die. I'd turn the igniton key off to drop power to it, then it would come back on ticking with another turn of the key. Sometimes. Its amazing how fast the float bolws will empty!

If its an SU pump and it is "ticking away" you're not getting any fuel.

When it is fuel, the car will generally chug a little before it finally dies, did it do this or did it just die?

If you have a SU fuel pump, can you here it ticking? Turn your key, is it ticking?

if you aren't sure about this, all you have to do is pull the gas supply hose from the carbs and turn the key, if gas comes out, then rule out any fuel pump problems.

Now if the car didn't kind of chug, then it is more than likely ignition related. Also, the reason I think it is ignition related is that, HOW DID THE FUEL PUMP START WORKING AGAIN, after it died?


My best guess is that you have a loose wire somewhere in the ignition area. Wire from coil to dizzy (small wire), high tension coil wire to dizzy, or your ignition module is going haywire. When the module inside the ignition starts to die, and this only happens after quite some time usually. They last far longer than points/condenser-assuming they've been used regularly and nothing is wrong in your wiring - but when they do finally die, they generally work, then don't work, then work again. It gets quite frustrating, in fact, to diagnose the problem sometimes because of the nature of them working then not working.

B

Guys, I turn on the ignition and I hear ticking at the fuel pump. The car runs 99.9 % of the time but when it shuts off it's like I turned the key off. After I posted this topic today I found a loose and dirty wire at the negative post of the coil. I was just sure this was the problem, but after fixing the connection and a thirty minute ride later she did it again on my way home. I don't know shinola about these Crane electronic ignitions so I don't have much to go on troubleshooting wise. The only other information I can give is the fact that the tach doesn't work when I first start her up. It takes a few seconds before it kicks in and it didn't do that before this problem. According to the instruction manual for the Crane ignition, the tach is hooked to the negative post of the coil. This is why I was so sure I'd found the problem when I found the loose and dirty connection at the negative post of the coil. I guess that wasn't it. Help please, this is my "economy car" that I'm driving 50 miles round trip each day, instead of my truck, to help save fuel (money). I'll check the fuel pump and filter tomorrow. :D

Shawn

Shawn, assuming you're still trouble-shooting when you read this tomorrow - Is it cutting out bump-related? Meaning, if you hit a bump - does it quit? Or does it just die on a smooth road?

Rick, it could be bump related. The road I was on this am is quite bumpy. What are you thinking?

Shawn

I'm changing my mind, is what I'm thinking. This does sound like either a loose connection or a short somewhere in the system.

It sounds like time to follow Brian's advice: Just take a breath and start methodically following the wiring diagram, beginning with the starter solenoid and moving upward. (Just for grins, check the battery post connections first.) Considering you've likely ruled out the pump, there isn't much else but to patiently work your way from connection to connection. A test light or better yet, a multi-meter may become your new BFF.

You might check under the dash, just left of the steering shaft, for tight connections at the triple Lucar connector with the assortment of white wires going to it. This powers the fuel pump, the coil, the tach and a few other things. I had one that was corroded and loose which caused similar intermittent problems.