low voltage fuel solenoid?

[NoTrespassing]

Just a question. I have a 4x6 Cub Cadet Big Country with a 20hp Honda engine. The battery has been dying a slow death over the past year but it's never failed to crank over and start. The dash display started showing battery voltage while running the other day. It was fluctuating between 8-10 volts on the display while driving it and giving a red light warning. After driving it off and on all day it failed to start. Then engine was still cranking pretty well and I put fuel in the carb and it fired until the gas burned up. I disconnected the fuel line and the fuel pump was pumping fuel all the way up to a short hose on the carb. After letting the machine sit for awhile it would fire but wouldn't keep running. After charging the battery it ran fine.

I'm going to put a new battery in it and that will fix my problem but I'm still curious why the low voltage is keeping it from running. The fuel pump seemed to be pushing plenty of fuel up to just before the carb. There's too many brackets in the way to see much and I don't feel like tearing into it when I know a battery will fix my problem. Could there be a solenoid between the fuel pump and the carb for some reason that's not opening at low voltage?

Kevin

 

[aczlan]

I suspect that the root cause of your problem is the charging system, not the battery. When it's running, voltage should be around 13 volts, not 8 to 10.

Aaron Z

 

[NoTrespassing]

I suspect that the root cause of your problem is the charging system, not the battery. When it's running, voltage should be around 13 volts, not 8 to 10.

Aaron Z

Yea, that's a very good possibility but I'm still curious why it fires right up with a slight battery charge. It fires when directly supplying fuel to the carb.

 

[RickB]

The fuel shutoff solenoid is often the first component to quit because of low voltage.

 

[Stimw]

If it has the anti-diesel valve/solenoid that could be staying closed with low voltage.
Not sure if Honda uses them, I know Briggs does on some models.
Need to check voltage running with a volt meter. As stated it should be higher running.

 

[aczlan]

Yea, that's a very good possibility but I'm still curious why it fires right up with a slight battery charge. It fires when directly supplying fuel to the carb.

Fuel shutoff solenoid or electric lift pump didn't like running on 8 volts.
What voltage did you get with it running after charging the battery? If it wasn't 13+, the charging system is the problem.

Aaron Z

 

[David_Kb7uns]

Lack of battery maintaining is a sure way to kill electrical parts

David