remote cut off fuel pump power

My girlfriend has a sixteen year old son who she bought a 2003 Mustang V-6. (I know, bad idea). Anyway,  she is having a hard time controlling him with this new car.  He takes off, doesn't mind her and she's worried about him getting in to a wreck or worse.  She hasn't been able to take the keys from him and they have awful fights between the two.  She asked me how to disable the car without him knowing.  I said that's easy.  Just open the hood and pull the 20 amp fuse that powers the fuel pump.  Presto, that worked perfect and he didn't suspect a thing and couldn't figure out why the car wouldn't start. Problem is that the car has to be unlocked for her to open the hood and pull the fuse when she once.  So that got me thinking.  How can she disable the car with no keys whenever she wants and without him knowing.

All that takes me to this question.  Instead of pulling the fuse, I thought I could rig a remote start keychain controller with some sort of relay that would cut off power to the fuel pump whenever she wanted.  I thought about cutting the power to the ignition or starter but I think the kid would have a friend that would figure it out eventually.  Cutting the power to the fuel pump would keep his head scratching.  The mother wants to lead him in to thinking that the car has an intemittent fuel problem and will cost a lot of money to fix.

So with this idea, would anyone recommend to get a cheap remote start keychain controller, the right relay switch and and how to easily wire this in to the car. I'm fairly good with wiring and such.  Just need a cheap solution that would cut the power on and off to the fuel pump (just like pulling the fuse) remotely.   Thank you in advance if you have any good ideas.  Car Toys said they could rig something up for like $200.  I know I can do it cheaper.

Might be better killing the ECU, or some essential signal required for it to start. Also if pulling the fuse, it'd be worth substituting with a blown equivalent. (Missing fuses are easy to spot...) IMO problem is the mechanism. If it were to be a security kit solution, how does he start when far away? Will it be in valet mode until he returns home? If a simple relay solution (whether remote or concealed reed switch etc), then for safety it should be energised to prevent starting. Will that drain the battery? Hence why a lower draining solid-state solution (to cut or short some essential signal) is probably best. But consider the "fail-safe" aspects - if he can't start in the snow or desert or train crossing... You essentially want the equivalent of a wheel lock. This is really an issue that should not be solved by disabling the car. (He'll just park it somewhere else anyhow...) But maybe others have suggestions....

She just wants to control the starting of the car when he is at home.  He usually locks the car in the driveway. Today, she was able to pull the fuse because he had to go to alternate school for being in trouble and he left the car unlocked.  He got home, tried to start the car and it wouldn't start.  His first thought was he had a hole in his gas tank (Go figure, he's sixteen).  He's bright but not that bright when it comes to cars.  He didn't run the battery down which is what I was worried about.  Anyway, his drugging friends came over and they all think he has a fuel pump problem which is expensive to fix.  That's perfect, he just needs to think the car is unreliable and that it will require his mother's money and time  to take it to a real mechanic to have it checked out.

He'll be in this alternate schoold for bad kids for the next few weeks, so I will have to take a day off and rig this thing up with the car unlocked and he won't notiice a thing.

And no worried about snow or otherwise.  We live in Houston.  He's home a lot of the time and she wants to disable it there when he is being beligerent and not respecting her authority.  He is the type of kid that is running all his friends around on her gas money.  Usually, he picks them all up and brings his friends to his house so they can party and get high.  This is a single mother with a out of control sixteen year old.  She is scared of him.

This problem runs deeper than I think any of us know how to handle and I feel the car problem is just a symptom. Lifestyle, friends, even giving him the car in retrospect. Yes it snowed in Houston when I worked there. Why do you think only starter cut is recommended?

I'd disable the car and spend the money sending him to advanced driving. Or steal and trash the car. Anything else is IMO just delaying the inevitable. And playing tricks could place him in debt and lead to worse problems.

A "for sale" sign would probably be a cheaper, more effective fix. Or cutting off the gas money. :)Kevin Pierson

This is probably well beyond our expertise to advise except as I said before the car isn't the problem, the lad has to change at least his fiends and his lifestyle or your troubles have only just started. He can't be allowed to control his mother like this. Once more I agree with KP but as I said that's only the start

Here is your cheap remote disable solution. 1 Ch Remote Relay As others mentioned, for safety it should be implemented as an "active" override and not a passive one. They make 2ch models too, interrupt the starter wire on one channel and an IGN wire on the other and you can alternate between a Crank No Start and a No Crank No Start "failure"... Nobody likes chasing intermittent problems. Keep in mind the relays on that device are only rated to 3A, so you will want to drive a 30AMP automotive relay with this device. Unless you interrupt the fuel pump relay for example or something similar.

That cheap solution looks perfect.  $12.00 and a little time to install it.  Looks like it just takes a constant power battery wire and ground and the fuel pump wires.  I haven't seen the part yet so it's hard to tell but it doesn't look too complicated.

I'm a little confused what you meant by having a 30 amp relay driving the device.  How would you wire in that 30 amp relay with this if I was coming off the wires from the fuse box for the fuel pump.  Can you elaborate a  little of that?

 Thanks for everyones advise and you're right, the best solution is to just take the car and just sell it.  Everyone has told her that including me.  Having said that,  I understand she is dealing with a hard teenage situation with a kid who is smart with a lot of potential but has been screwing up by smoking weed and running with the wrong crowd lately.  He was a good kid just a year ago believe it or not.  Kids change so quickly at this age and if you've raised a teenager you know there are trials and tribulations.  My son went through something similiar at that age (not near as bad) and now he is in the Army doing great.