I have a 1982 F250 with the 300 I6. I am having a problem cranking the motor over. Compared to when I first got the truck, it seems like it struggles to turn over when its cold and it will barely crank over when the motor has warmed up and I go to restart the car. The speed of the starter motor will oscillate when cranking, too. But, once the motor starts, it runs as it should. I have replaced the battery (now 700 cold cranking amps, which is significantly higher than the stock batter, tell me if that is not okay), the solenoid, the starter, the and ignition switch. I have cleaned all the contact points for the two battery cable and the cable going into the starter.
My only idea now is that these wires have too high of a resistance. Is there a set amount of resistance that these wires should have? I have tested them and they all come out to about .9 ohm when cold, and 1.1 ohm when warm is this too high and whats causing my problems?
If not, what else do you think could be the problem? Is it a mechanical issue?
Thanks for helping guys, let me know if you need any more information.

 

Here you go:

https://www.ford-trucks.com/forums/1...w-starter.html

 

pull!

BANG!

 

Thanks guys!

 

If the above test indicates the wiring is good, try this: with the engine at operating temperature, attempt to start the engine. If the engine starter drags [turns slowly], then remove the coil wire [from the coil or distributor cap] and try again to start. Of course, the engine cannot start, but if it now spins freely then the resistance might be caused by too advanced ignition timing.

 

my 84 gets harder and harder to crank as it warms and I'm sure it's timing too advanced on mine, as I have new starter/solenoid/cables/battery and cleaned grounds. Zero issues when cold.

 

https://www.ford-trucks.com/forums/1...l#post14663521 This post also mentions pinging from the timing being too advanced. Have you noticed any pinging?

 

Re: All those new parts. After installing all that stuff, did you ever try the voltage drop test (linked above in post #2) as confirmation of a good repair? I can't stress strongly enough how this will isolate such problems. Now I'm as guilty as the next guy that once a repair seems to work, I'm done. I'm typically not going to spend any more time than needed.

But what if the situation was like this?:

Prior to the expensive repairs (new starter/solenoid/cables/battery), the starter system was only operating at 50% capability and the starter cranking speed was often slow. Throw all those parts at the problem and the performance increased to 80%, but maybe there was still some hidden issue. It could be a marginal starter, defective battery, who knows? All you observed was the cranking speed was vastly improved and so it seemed like a good fix, problem solved. No need to investigate further at the time. However, when you need that last 20% of oomph (Sorry for the highly technical terms), the starter system lets you down. With a hot engine, compression is much better than when cold, and 100% effort is needed from the starting system, but unbeknownst to you, you're only getting 80%. But the starting system has all new parts, so nothing can be wrong there. (Excuse me while I start snickering...)

That's why I'd like to steer you back to the voltage drop test. Yeah, I get it, my explanation is overkill and can make one's eyes roll back, but the actual test is incredibly simple. The test does two things. It verifies the battery can supply the massive flow of electrons required by the starter. And it verifies the cables, starter relay, and all connections in between can properly deliver that massive flow.

The test also has you disable the ignition to take any timing issues out of the equation. Think of it this way: Technically, you're not testing the ability of the engine to start. You're testing the ability of the starter system to crank the engine reliably at the proper speed. And once that's been addressed, most actual starting problems disappear. If both parts of the test check good, then your new starter is likely not up to snuff. There's nothing in the test that confirms a bad starter, it's more a process of elimination. Is this a rebuilt starter or a store brand aftermarket unit? Sorry, but a lot of stuff out there is marginal. But I'd definitely run those quick electrical checks first on the rest of the system to make sure the starter is receiving an adequate supply of power under load. Then, and only then, is the starter suspect. If that is the case, don't fall into the trap of getting a free warranty replacement, as any such unit will likely have the same shortcomings. Hopefully you'd get suspicious after the fifth or sixth warranty replacement... You may have to spring for a more expensive unit from a better source.

After that, the only potential issue remaining is engine modifications or problems that require more oomph than can be delivered by a starter system operating at 100% capacity. But since you probably never verified the 100% capability, I'd go back and check that before worrying about anything else.