Mitsubishi MT18D solenoid problem

[pdflat]

I previously posted about a problem with my tractor starting, then cutting out after a few seconds. I had some replies, and investigated the possibility that the fuel line was sucking in air.
I have just noticed that the problem is the fuel shut off solenoid, which normally pushes in when the ignition is turned off to shut off the engine, and which now is pushing in just after the engine has started and so prematurely cuts out the engine. If I manually hold the plunger out for about 10 seconds after starting it stays out and the engine continues to run perfectly till the ignition is switched off. So I'm confident that here is the source of the problem.
My question is, is there a way of telling whether the problem requires a new fuel shut off solenoid, or whether the problem is with some wiring, e.g. the wire that connects the solenoid to the ignition switch? Incidentally the fuse for the dashboard indicator for fuel level and engine temperature keeps blowing. Is this likely to be related?
Any help would be very much appreciated

 

[PILOON]

Fuse blowing suggests therein lies the problem. eg a short in solenoid wireing.
I'd pull the wire leading to the solenoid and actuate it directly from the battery (or other source) as a test to prove the solenoid operation. If the solenoid then operates as it should then simply replace that lead from the switch to solenoid.

That solenoid will be normally closed and wants power to open it.

 

[pdflat]

Thanks very much. I'll give that a go today. There are two wires to the solenoid. Is one positive and the other earth? They are identical. Does it matter which is which for the purpose of testing directly from the battery?

 

[PILOON]

A solenoid is basically an electromagnet so it wants current to flow thru the coil to pull or push open or closed the valve.
In your case power will open the valve as OFF is non powered or relaxed position.
For testing either will do the trick.
If OK you should actually hear a click or clack as it operates. Also touching with fingertip you would feel it as it opens.

If as I suspect solenoid is OK you could wire up as in test a switch to power up(with fuse in line) until such time as a permanent fix is accomplished.

Chances are good that somewhere a hot wire has chaffed and is shorting to ground which is why fuses are blowing.

 

[pdflat]

Thanks Piloon,
It's all sounding eminently possible that I will be able to fix this one myself, so long as I can find the short circuit.