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Discussion Starter #1
For what it’s worth, it occurred to me that someone may be interested in this. I was going to put it in the tech forum but it seems nobody ever goes there.

When I 2003 got my 1100 Spirit and put it away for the first winter I had to crank it for a long time in the spring. Same would be true for running out of gas.

I dug into this and found that Honda has a safety circuit on the fuel pump that only pulses it while cranking so it takes a long time to fill the carb. Once it is running the fuel pump has full power and is controlled by the pressure switch. I did not like cranking that long. It’s hard on the battery and starter.

I located the hot wire to the fuel pump and installed a mini pushbutton from the hot wire to 12 volts. In the spring I just pushed the button (with fuel and ignition on) until the fuel pump stopped on the pressure switch when the carb was full.

It then started instantly just like you rode it yesterday.

I think the Honda engineers would have been smart to run the fuel pump when the starter button is pressed. That would result in a much faster start after a carb runs dry.
 

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Thank you for sharing this info ARH,
I`ve read here on HSN technical forums that the "kill switch" flipped repeatedly off-on-off-on does the same as the push button you installed...
I may have dreamed this ~ but...;)
 

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Discussion Starter #3
Thank you for sharing this info ARH,
I`ve read here on HSN technical forums that the "kill switch" flipped repeatedly off-on-off-on does the same as the push button you installed...
I may have dreamed this ~ but...;)
That may be true. It never occured to me to try that. I don't have the bike any longer so I can't.
 

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I`ve only had to use this feature one time,
This was from my stupidity of Not checking if I was on Reserve (or forgetting it?) when I left the house... ;)
 

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This is a very well known phenomenon with the late model Shadow line. However, there seems to be a few facts in error.

First off, there is NO pressure switch anywhere in the fuel system of these scooters. The fuel pump runs until the pressure comes up to design pressure, and then it simply stalls out until the pressure drops enough to allow the pump to run again. No pressure switch.

"I dug into this and found that Honda has a safety circuit on the fuel pump that only pulses it while cranking"

The above quote is accurate. The below quote is not. Kinda.

"I think the Honda engineers would have been smart to run the fuel pump when the starter button is pressed."

As correctly noted, the fuel pump pulses any time the engine is cranking. Any time. This includes the time the starter button is pushed. As long as the engine is turning whether by fire or by the starter...the pump is getting a pulse signal to run. So, yes the Honda engineers were smart as this is exactly what they did.

Now, not all Honda's along with many other makers sleds use the fuel pump relay. Instead they energize the fuel pump any time the key is on, but utilize a tilt angle sensor to kill the fuel pump. Both are only safety devices to kill the pump in the event of a crash.

You can jumper the relay to fill a dry fuel system...though I think it's over kill. How often do you run out of gas? In the four years I owned my Spirit I ran out once. And I learned not to do that again.

For the times when service or storage required that I deal with a dry fuel system..I simply put some low air pressure on the gas tank. Either by cupping a hand around the filler neck and then blowing by mouth, or with an air chuck from my compressor. Either will fill the carb bowls fairly fast with no excess starter cranking. Just beware that you don't put more than a few (5 to 10) psi on the system. You don't want to blow off fuel lines.
 

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I've only run out once and started cranking then stopped and used the kill switch and after doing that 5 or 6 on and off I hit the starter and it fired right up, So no need to wire in a button, Just use the kill switch and try not to run out again LOL.

Dauntae
 

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Discussion Starter #9 (Edited)
This is a very well known phenomenon with the late model Shadow line. However, there seems to be a few facts in error.

First off, there is NO pressure switch anywhere in the fuel system of these scooters. The fuel pump runs until the pressure comes up to design pressure, and then it simply stalls out until the pressure drops enough to allow the pump to run again. No pressure switch.

"I dug into this and found that Honda has a safety circuit on the fuel pump that only pulses it while cranking"

The above quote is accurate. The below quote is not. Kinda.

"I think the Honda engineers would have been smart to run the fuel pump when the starter button is pressed."

As correctly noted, the fuel pump pulses any time the engine is cranking. Any time. This includes the time the starter button is pushed. As long as the engine is turning whether by fire or by the starter...the pump is getting a pulse signal to run. So, yes the Honda engineers were smart as this is exactly what they did.

Now, not all Honda's along with many other makers sleds use the fuel pump relay. Instead they energize the fuel pump any time the key is on, but utilize a tilt angle sensor to kill the fuel pump. Both are only safety devices to kill the pump in the event of a crash.

You can jumper the relay to fill a dry fuel system...though I think it's over kill. How often do you run out of gas? In the four years I owned my Spirit I ran out once. And I learned not to do that again.

For the times when service or storage required that I deal with a dry fuel system..I simply put some low air pressure on the gas tank. Either by cupping a hand around the filler neck and then blowing by mouth, or with an air chuck from my compressor. Either will fill the carb bowls fairly fast with no excess starter cranking. Just beware that you don't put more than a few (5 to 10) psi on the system. You don't want to blow off fuel lines.
Fine on the pump stalling. That may be the case, but I would expect the pump to have an internal PS.

The safety circuit is a retriggerable oneshot. When you are cranking it is pulsing. Once the engine is running the pulse rate is high enough to keep it on solid. I verified this with a scope. I see no reason not to run the pump on solid when the start button is pressed. I disagree with your take on that one. I Don't see a safety issue there. The oneshot stops the pump if the engine dies. The kill switch also stops the pump. Unless they are worried that the start button will stick on in a crash. So when the start button is pressed and the engine has not started the pump is pulsing and it will take a long time to fill the carb. Using the start button to overide the oneshot would fill it quickly.

My complaint is not running out of fuel, it is starting in the spring when the carb has dried up.

It sounds like when the kill switch is turned back to run it triggers the oneshot to pulse the pump. I would have simply used this feature if I knew about it. My thumb would probably get tired though.
 
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