Strange starting problem on a '78
06-02-2013, 04:30 PM
#1
Rennlist Member
Thread Starter
Strange starting problem on a '78
Hi folks. I hope you can help me in this.
I friend has a '78 turbo and has a intermittent starting problem.
Starter runs, but engine does not fire. One day it starts normally, the other it doesn't. He has been stranded on gas stations as well, suddenly no firing at all. No sign.
It smells gasoline and it runs very rich if it eventually fires. I suspect there's no problem with fuel feed.
In my world, engines run if they get fuel and ignition sparks. Not on this one.
This has been done so far, but to no avail:
-Both fuel pumps modified with modern fuses and wiring
-All fuses and connections in the fuse box have been checked
-New and modern ignition box is installed
-New coil and changed all the high voltage wires
-New and modern ignition cut off relay is installed
I've observed the following when it is failing to start: The ignition cut off relay is getting +12V feed, and it's feeding the ignition box too. I saw good sparks on one of the cylinders when the starter was running.
Then, while we're doing tests, suddenly it fires normally, and I cannot do any more measuring until it fails again. That might take a week or two. Very annoying. I've pulled and tweaked on all wires in both the engine compartment and fuse box location to no avail, we can't get it to fail or stop when it's having a good day.
As far as I can see, there's about only one thing left to change in the ignition circuit, the magnetic angle sensor in the distributor. Could this be faulty, thus the sparking, but maybe at a completely wrong time/angle?
I have hit the wall on this now, any tips on where I could continue searching?
Cheers from,
Tore
I friend has a '78 turbo and has a intermittent starting problem.
Starter runs, but engine does not fire. One day it starts normally, the other it doesn't. He has been stranded on gas stations as well, suddenly no firing at all. No sign.
It smells gasoline and it runs very rich if it eventually fires. I suspect there's no problem with fuel feed.
In my world, engines run if they get fuel and ignition sparks. Not on this one.
This has been done so far, but to no avail:
-Both fuel pumps modified with modern fuses and wiring
-All fuses and connections in the fuse box have been checked
-New and modern ignition box is installed
-New coil and changed all the high voltage wires
-New and modern ignition cut off relay is installed
I've observed the following when it is failing to start: The ignition cut off relay is getting +12V feed, and it's feeding the ignition box too. I saw good sparks on one of the cylinders when the starter was running.
Then, while we're doing tests, suddenly it fires normally, and I cannot do any more measuring until it fails again. That might take a week or two. Very annoying. I've pulled and tweaked on all wires in both the engine compartment and fuse box location to no avail, we can't get it to fail or stop when it's having a good day.
As far as I can see, there's about only one thing left to change in the ignition circuit, the magnetic angle sensor in the distributor. Could this be faulty, thus the sparking, but maybe at a completely wrong time/angle?
I have hit the wall on this now, any tips on where I could continue searching?
Cheers from,
Tore
06-02-2013, 04:44 PM
#2
Burning Brakes
Join Date: Apr 2006
Location: Central Washington State
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Read this entire post; it should give you some points you perhaps haven't thought of or checked out.
http://forums.pelicanparts.com/911-9...snt-start.html
http://forums.pelicanparts.com/911-9...snt-start.html