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Discussion Starter · #1 ·
I checked my coil voltage with two different volt meters and got 7 volts starting and 4 volts running. I tried a different ballast resistor and got same readings. I clipped meter leads to the two coil post. I think the coil is original, so may be 34 years old. (They don’t make things like they use to.) In earlier posts it says it should be 12 volt starting and 7 running. I replaced the coil with one from auto zone and I get the same volt readings. I don’t know if I am checking it right or what is going on.
 

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There is not a 100% correct voltage, but both should ideally be higher then what you are reading.

The starting is the one that worries me the most. I would start with measuring the battery voltage, then check at the starter relay, check both before and while cranking the engine. Also check the coil with the key on, and watch it while starting. Does it jump up at all? With those numbers, we could tell you better which way to look.

Another thought, how are you hooking up the meter leads? It should be black to ground, or the batteries negative. And red to the positive side of the coil. Measuring across the coils terminals will give you a lower reading. The negative side is not a ground, so it will read something above ground, if that makes sense.
 

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Discussion Starter · #3 ·
I will check again. I did put negative on the coil. I will try it n battery ground
 

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Discussion Starter · #4 ·
Ok checked with ground on battery now I get 7 in run and 9 1/2 - 10 in start. It cranked so fast there wasn’t much time to see the crank setting. Meter hooked to the battery showed a little over 11. I have been having a problem with rough idle and takeoff from stop if the truck sits for several minutes idling. Thought it might be vapor lock or coil overheating while it was not moving. I put an insulation sleeve on the metal fuel line from the pump, a new fuel filter, and pulled the heater hose up so it is not touching the fuel line.
 

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What is the condition of the wiring itself? You can have perfectly functioning components yet still have issues if the wiring has corrosion or high resistance. This includes connections.

Bucky
 

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Discussion Starter · #6 ·
I try to clean and tighten up connections when I replace parts. I did not see anything that looked bad, but with 33 year old wiring there could be. I have owned the truck since it was a year old and have kept it mostly stock.
 

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from the starter relay to the coil [ key in start position ] should be full battery voltage , key run should be 7 to 9 volts

 

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Discussion Starter · #8 ·
Thank you. I will trace the start wire from the relay and check the condition of the wire and connectors.
 

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to diagnose it , unplug the "BROWN" starter power wire , have someone hold key to START position / with your multi-meter on the Neg battery , now check in order - battery power - Large RED wire on solenoid - PINK wire on solenoid - PINK wire at ballast - PINK before and after the connector at the back of the right valve cover - the PINK wire at the coil Neg = EVERY reading should be the same or close to the battery voltage
 

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Discussion Starter · #10 ·
Thank you for that procedure explanation. I will try it and see what I get.
 

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Discussion Starter · #11 ·
Ok I cleaned the starter relay connections with electric connection spray and a small wire brush. Pulled the starter brown wire off the relay. The battery was 12.5 volts, the terminal with the pink wires to the coil and ballast resister showed 11.5 volts. The coil was a little over 11 volts. Is this normal readings or is the problem in the starter relay since it was a 1 volt drop that close to the battery? The run voltage at the coil was 7 volts
 

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A new relay may increase the voltage, but I would not bother. it should still start fine at 11.5.
 

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Discussion Starter · #13 ·
Ok thank you.
 

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What problems are you having that set you on this hunt?
 

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What problems are you having that set you on this hunt?

Ok checked with ground on battery now I get 7 in run and 9 1/2 - 10 in start.
 
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