B7800 crank but no start - basics first fix

[Mudder]

The dreaded crank but no start, with good starter rpm spin but no usual audible “click” from electrical components. Although the battery has been on a Ctek smart charger showing fully charged, I still reverted to a Noco jump pack first to just to rule out a good 12v indication but insufficient CCA (based on atv battery experiences). Sure enough it fired right up. Point being that battery voltage alone can mislead, and fail a load test, so try the simple things first and cross fingers. Regardless still appreciated the many informative threads on similar issues. This was a Kubota battery only 1 year old, on a smart charger during winter.

 

[nyone]

I had a battery once show 12.6v. But when you went to crank it it would drop to next to nothing. It showed next to no warning. It was a napa gold about 5yrs old.

 

[Henro]

Something doesn't quite add up.

You say the starter was spinning at good RPM but the engine only started when you jumped the battery?

Did you notice that engine RPM increased when starting after the battery was jumped? If it was the same to your ears, then again, something doesn't add up. Coincidence maybe?

Perhaps the problem is still awaiting to reappear.

 

[Mudder]

Something doesn't quite add up.

You say the starter was spinning at good RPM but the engine only started when you jumped the battery?

Did you notice that engine RPM increased when starting after the battery was jumped? If it was the same to your ears, then again, something doesn't add up. Coincidence maybe?

Perhaps the problem is still awaiting to reappear.

Thanks for your reply. Observation with the jump pack was return of the single audible click at the first key-on position.

Suspecting the click was a fuel solenoid or similar relay, which required just a bit more electrical voltage and/or amps to activate.

Yes the starter may have spun a bit faster, but (subjectively) it seemed fast enough given 19 years of ownership. A 2004 model purchased new.

So guessing just either a weak battery, a solenoid/relay at early stages of failure as you mention, or a combination of both. Seems if there was enough power to spin the starter, the solenoid would not be so sensitive as to not activate.

Reason for the OP was viewing numerous “crank but no start” posts that focused on replacement parts, with no mention of a battery CCA load test/status first.

 

[Mudder]

Update with fix. After several months the intermittent problem got worst. Fixed with stop fuel solenoid relay and solenoid replacement.

Follow up with fix- B7800 no fuel stop solenoid activation. Crank, no start.

After months of intermittent crank but no start with no fuel stop solenoid “click”, finally fixed it by replacing the relay, ACA12115 (CA1a-12V-A-5) located inside the dash and beside the tachometer cable. Checked all grounds and even got a new battery. The solenoid passed a bench test with...

www.tractorbynet.com