My '86 F150 with a 302/AOD will start when it is cold but not after I have driven it long enough for the coolant to get up to normal operating temperature. (I get a single click from the starter solenoid, but no crank.) When this happens it can be jump started.

The battery has been tested for voltage and CCA and checks out OK. It gets over 14 volts when running. (I also had the alternator bench tested and it was OK.) The battery cables were looking a little ragged so I went ahead and replaced all 3. (BTW, NAPA had the best fitting cables.)

The starter solenoid did fail not too long ago and I replaced it.

What am I missing?

Thanks!

 

Is it EFI or Carb ?

 

I would start by looking at all of the major cable connections. Are all of them connected to bare,clean contacts? Are all of the grounds bare and clean?

 

EFI.

I cleaned the battery grounds and starter connection with a wire brush prior to installing the new cables.

Are there other grounds I should focus on?

 

Tested battery voltage when trying to start the truck. It went from 12.6 to 8.6 across the battery posts, and at the posts from the battery to the starter solenoid and the solenoid post that goes to the starter. (I did this before work, and couldn't get under the truck to test it at the starter. I doubt it would be different there, as that cable is new.)

I've read elsewhere that the starter can develop an internal short that can present this way in regards to both the battery voltages and the difficulty starting at operating temperature.

 

Well if you replaced everything else what else but the starter could it be right?


I take it you are using the key to start it what if you jump out the solenoid with just the key turned to on will it crank over?
Dave ----

 

Jumping the solenoid has no effect. (A few weeks ago when the truck wouldn't start, jumping the solenoid did get it to start. That's why I changed it.)

What makes me think it is not the starter is that it can be jump started. Perhaps there is some resistance in the starter that gets overwhelmed by the added voltage of the jump start?

 

So even jumping the sol still does not do anything and everything between batt to starter has been replaced but the starter.
Then you add more power thru just starting and it cranks me thinks bad starter.


Besides how much is a starter?
Dave ----

 

Good point. I'll put a new one in on Saturday.

 

Chasm*18, I have copied from your initial post: "When this happens it can be jump started". You stated later that the battery tested good, but I still wonder about it. FuzzFace2 pointed out that everything between the battery and started has been replaced.

 

I appreciate your response. I have had strong suspicions about the battery. I had it tested with a meter that reads CCAs and it tested within spec. (I know that sometimes the battery can read full voltage and not have the CCAs to crank the starter, but with full CCAs my understanding is that the battery is indeed good.)

My understanding is that battery voltage shouldn't drop below ~9.6 volts when trying to start the engine, and if it does that indicates too much resistance in the system. Mine goes down to 8.6V.

Thanks again for your response. I appreciate your thoughts.

My guess about being able to jump start it is that there is resistance in the starter that is increased when it is warm. The starter is located close to the exhaust and gets warmed by radiant heat. The resistance can't be in the brand new battery cables. The increased resistance is overcome by the increased voltage provided by the jump start.

Another guess is that there is resistance between the starter and the engine block. (The starter is grounded by that contact.) After I take the starter off I will see if cleaning those areas makes any difference.

 

I removed the starter. There wasn't too much gunk behind it to stop it from grounding.

I had it bench tested at Auto Zone. It failed. I was happy to hear that. (If it would have passed, I was still contemplating putting in a new one, since the problem was intermittent and the starter sometimes worked.)

I installed the new starter and it seems to have fixed the problem.

Thanks again for all of the responses.