Originally Posted by
Mr. Fixit
81-F-150-Explorer and others: I have a similar problem with our '76 F250 - 460 engine. She usually runs fine (except for guzzling the fuel!) but lately is becoming much harder to start when cold. Yesterday she began running real rough and then quit with a strange "run-on" sound - then dead (with a ton of firewood in the back!!!)
I noticed that during the hard starts over the last weeks in the morning, after a good crank and no start, when I turned the ignition switch off, there was a single cough each time.
Could this simply be a bad ignition switch? Is there a way to bypass the ignition switch so that power gets to the ignition system directly?
Unlikely. But not impossible. What it sounds like is the coil colapses and fires (once) when you shut the power to it off at the switch. This is relatively normal. However are you getting spark while cranking? Check the I terminal at the starter solenoid. That is the coil resistor bypass with the ignition switch in the start position. Also check the red wire at the coil in the run position.
Before I begin systematically checking the Duraspark module, coil and distributor, I'd like to eliminate the simple stuff. I will check all the grounds (engine ground strap) due to all the body & frame rust. Are there other ground wires in the ignition system - is the DuraSpark unit grounded through the casing to the body?
No, the DS module is grounded through the distributor base, using a wire. (Black if I recall correctly, away from my manuals)
Also, is the "Blue Grommet" easy to see on the DuraSpark II module?
Very easy to spot. It's the grommet where the wires go into the module. DS-I's can be Red for 1974, green for 1975, etc...
DS-II's can be Blue, Brown etc...
Blue is the most comon and the most simple.