Sluggish Start (no start) round 2

[jgnobis]

Hello all. I’m starting new thread as my last one had two issues I was chasing down and I need to just focus on the biggest one right now. I’ve been unable to troubleshoot my issue since the fall due to surgery but am now back at it.
I’m trying to get to the bottom of a sluggish power no start situation. When ignition switch is turned on and I hit the starter button, I get a very sluggish turn and the engine won’t start. I’ve done a number of troubleshooting steps while measuring voltage.

• Batteries - I have measured volts at the battery when trying to start. 12.3-13.x (depending if charger is on or not) and drops down to around 10 volts when hitting the starter button which I would expect, and then goes right back up to 12.4 volts when I let go of the starter button. I have not used a load tester on the batteries but they are behaving within normal volt ranges I would expect when starting.
• Solenoid/Starter - Volts at the positive solenoid bolt prior to trying ignition is at 12.4 and above and then drops all the way down to low 4 volts when the starter button is initiated. Battery reading drops down to around 10 volts as stated above.
• Using a remote starter button on the solenoid to bypass the starter at the panel, I get the same readings. 12.x before and 4.2ish volts when hitting remote starter button.
• With ignition switch turned off at the panel but having a jumper cable from positive coil to positive solenoid, I get the same readings.
  Then, even more strangely, after doing this troubleshooting for a while, the power will just drop at the solenoid to 3-4 volts for a couple minutes. I turn off ignition (or remove jumper), wait for a bit and it seems to resolve itself. Volts at the battery never drop throughout this occurance.

I’m completely perplexed. It's got to be a short somewhere right? I'm wondering if I need to completely isolate the coil, starter and battery from the rest of the wiring to the panel? Or potentially could it possibly be the solenoid? Or just start replacing panel switches and wiring one at a time and rewire the whole panel and electric to the engine… which is no small feat given space constraints.
Thinking of finding a local electrician here in Seattle to help me at this point. Any additional advice is appreciated.

[Dave Neptune]

The first thing I would do is check the connections on the big wires from the battery connection to the solenoid and then to the starter. Also check the battery ground connections. If no joy then do a load check on the battery or batteries. A battery can have a poor connection on the inside that shows voltage just fine but will not flow the juice when under load.

Also check the big wires by moving and bending them, sometimes water will encroach and oxidize the wires to almost nothing and little power can flow. If there is a weak spot that may just be it.

The panel wiring should be fine from what you stated however if the batteries check fine and the wire connections are good could well be the solenoid.

Did you check the voltages on both sides of the solenoid? If the load side drops lower than the feed side get another solenoid.

Dave Neptune

[hanleyclifford]

Do you have the early or late (Delco) starter?

[jgnobis]

Do you have the early or late (Delco) starter?

Late model

[hanleyclifford]

Late model

That means you can easily have a look at the connectors inside the solenoid. Sometimes they can be cleaned up. Your voltage drop to 4 volts is disturbing.

[Sam]

Good advice, I would just add that an unloaded battery at 12.4 seems to me to be a weakened battery, maybe around. 50%. Could be additional factor to the sluggish start.

[hanleyclifford]

Good advice, I would just add that an unloaded battery at 12.4 seems to me to be a weakened battery, maybe around. 50%. Could be additional factor to the sluggish start.

Yeah, it's hard to get useful measurements if the battery is not fully charged. A fully charged battery should read 12.6 to 12.7 volts at rest.