Electric Fuel Cutoff

[CISE]

I have been having fuel delivery issues lately. And am getting ready to pull the tank and check to see if I rebuilt the petcock correctly (if something can be put in wrong I can do it).

At the same time I am going to replace all the vacuum limes since I am in there.

Also, in the past I purchased the electric cut off valve and had wired it in, but then took it off because it became very VERY hot to the touch.

So, since I will be in there any ways, I thought I would re-install if someone could let me know what I did wrong the first time. With only 2 wire leads I thought it was just one lead to the accessory power and one to the ground. Is that correct?

Any help would be appreciated (and yes I am one of those idiots with more tools than mechanical smarts. Generally as long as I have the service manual I can follow it and do things fairly well – but obviously I am doing something wrong here).

Thanks for your help all!!

[old grouch]

I am no expert on these machines by any stretch.  I have a DanMark electric shut-off on my 99I/S.  As I recall, you are correct as to the wiring of it.  Don't think it matters which wire goes to the power and which to ground, but guess it could.  Wire it one way, not connected to the fuel line and see if it opens when power is on and closes when power is off.  If not, reverse the wires & try again.  As to it getting hot, I have never touched mine while or shortly after the engine was running, but based on where it is located, betweeen the carbs, on top of the engine, I expect it does get quite warm.  The intake runners get too hot to touch, and they have to have more airflow around them than the DanMark.  Course they are attached to the heads, so....Just my thoughts, maybe someone with more knowledge on the subject can jump in here.  Stan

[3W-lonerider]

that solenoid will get hot, it is an electric solenoid and it's going to build up heat holding the valve open..so yes that is gonna be normal. and it does not matter which wire goes to ground and which goes to positive.

[MarkT]

I noticed the same thing, but checking it with a meter, resistance seemed to be normal.  I assumed while gas is flowing through it, it's not as hot as it is when you just connect to 12v without gas flowing.

[Bobbo]

Also, in the past I purchased the electric cut off valve and had wired it in, but then took it off because it became very VERY hot to the touch.

So, since I will be in there any ways, I thought I would re-install if someone could let me know what I did wrong the first time. With only 2 wire leads I thought it was just one lead to the accessory power and one to the ground. Is that correct?

The only way it would matter is if there was a diode across the input leads.  It is common to use a diode as a flyback on solenoids, but not a necessity.  Usually, if you connect it the wrong way, it won't work and will blow a fuse.  A resistance test won't necessarily tell you if there is a diode.  You would need a diode tester.

[5_19]

Just checked one and the Dan-Marc solenoid has no diodes. Its resistance is about 10 Ohms (9.5 Ohms with one meter and the other meter read 10.5 Ohms). I think if it get to hot to hold for very long, that's normal. TJ

[Bobbo]

Just checked one and the Dan-Marc solenoid has no diodes. Its resistance is about 10 Ohms (9.5 Ohms with one meter and the other meter read 10.5 Ohms). I think if it get to hot to hold for very long, that's normal. TJ

That's almost 20 watts.  If it is a small solenoid,  it would get pretty hot.

[John Schmidt]

Like MarkT mentioned, it's not as warm when the bike is running due to the fuel having a cooling effect. I had my bike running once with the tank & airbox off while I was trying to clean out the jets by spraying some bearcat pee in there while running. Out of curiosity, I checked the solenoid and while running....yes, it's warm but not intensely hot. I shut off the fuel source and it didn't take long for it to get fairly hot, the bike shut down about that time so don't know if it gets to the point you can't touch it. I've had my elec. valve in place for about three years with nary a problem.

[Bobbo]

Solenoids have an "activation" current and a "holding" current.  The activation current is the power needed to overcome the spring return (if it has one) and the standing inertia of the plunger.  The holding current is the power needed to keep the solenoid in the powered position.  The holding current is usually much less than the activation current, quite often half or less.  To lower the power, and temperature used by the solenoid, you could add a parallel resistor/capacitor to the circuit.  This lets the solenoid see full current for a second or two while the solenoid activates, but cuts the current down during the holding time.  The resistor is sized to match the holding current, and the capacitor is sized to the time needed to activate the solenoid.  I don't know if anyone is concerned about the heat and power usage of the solenoid, but they can use this method to reduce both.

[Ricky-D]

All good reasons for not using the electric cut-off!

The heat transfer to the gasoline lessens the density of the gasoline and therefore decreases the performance of the motor!   Have you never heard of the ice cans used at the drag races to cool the gasoline attempting to increase fuel density and the motor's performance? Duh!

And regarding forgetfulness about turning the gas off. Well maybe it's time for a new paradigm!  Maybe those should start to consider extended care facilities and get off the road totally!

Sheesh!

***

[CISE]

Thanks for the feedback everyone .... when in doubt I ask questions.

As to getting ready for extended care because I forget to turn off the fuel ... nawwwwww ... when I forget where I put the bike MAYBE .... (But since I have forgotten to put down a side stand at a gas stop, to use the clutch when coming to a stop, to put gas in the tank, and to forget what state and or country I was in on a bike ride .... methinks just forgetting does not mean I shouldn't ride)


IMHO of course

 

[John Schmidt]

All good reasons for not using the electric cut-off!

The heat transfer to the gasoline lessens the density of the gasoline and therefore decreases the performance of the motor!   Have you never heard of the ice cans used at the drag races to cool the gasoline attempting to increase fuel density and the motor's performance? Duh!

And regarding forgetfulness about turning the gas off. Well maybe it's time for a new paradigm!  Maybe those should start to consider extended care facilities and get off the road totally!

Sheesh!

***

Sheesh is right young feller, how's things up there on that pedestal. Your inference is uncalled for, unless we can all assume you've never accidentally bumped the kill switch and later tried to start the bike, or forgot to turn on the fuel, or any number of other things any normal biker will do in his/her lifetime of riding.

As for ice buckets at the drags, yes, as effective now as back in the early 50's so must be "old school." As for lessening the bike's performance, it's so slight as to not be an issue. Mine will still put me against the backrest and pulls hard throughout the rpm range. Now, if I were to be running at the strip....yes, different story. But for our normal daily usage, as I said....it's a nonissue.

[5_19]

The heat transfer to the gasoline lessens the density of the gasoline and therefore decreases the performance of the motor!   Have you never heard of the ice cans used at the drag races to cool the gasoline attempting to increase fuel density and the motor's performance? Duh!

I read/translate  ............. better fuel milage?! Let's ride.

[Mr.BubblesVRCCDS0008]

Some people have a very high opinion of their opinion. I don't have that same out look, John I too feel that the slight increase in fuel temp by the cut off could be not be measured at all. Also I know bearings do wear out even if they're install correctly. Enough said.