Engine will not start, please help!

[pistonhead]

Hi Guys
I am new to this Porsche thing and I am looking for some help from my cousins across the water.
Last year I bought a 1975 911 s targa in viper green, great car and we are now best friends, well we were until the other day!
I decided to fix a couple of oil leaks behind the injection system, so I stripped it down, fixed the leaks and all was well.
After a week I cannot start the car, with the cold start lever on the engine fires and revs for about 1 second, it does this on 3 turns of the key, then nothing.
Every one has a different idea on what this problem is, I was told to remove the air box cover and move the flap by hand while someone turns it over, this resulted in the car blowing back and catching fire in the air box, as you can imagine I run around hysterically looking for an extinguisher, luckily it went out on its own, I must try and be a little more organized!!
some one has said the coil?another the plugs? another told me the fuel pump relay?
I am now very confused, if anyone on here could help I would be very grateful, I live in a little welsh village and my nearest Porsche mechanic is 50 miles away, I would have to put it on a transporter, it would cost a fortune, on top of that I have promised to take a bride to the church next Friday, white ribbons and all, she is 6 foot and rather large, if anyone can help at least it will stop me getting a black eye for letting the lady down (when I say lady, I mean, she is a mean tough hill sheep farmer)
So my new fond Porsche friends, Please Help.

[Paulporsche]

Sounds like you have your hands (and your passenger seat) full!

You have to systematically start eliminating possibilities. The previous suggestions of others are all possibilities. I like to start w/simple/cheap things first. Make sure your points, plugs, wires, cap and rotor are all good. Check for spark @ a plug end. If you search you will see how to do this. Be careful as the CDI produces much higher than usual amounts of voltage.

Try another relay in place of the fuel pump (red) one. The black ones will work. Make sure the tines on the end of the relay are splayed a little to make a good connection. Clean the connections. Make sure the fuel pump fuse (I think you have one) is good. Be sure there is fuel in the tank. Check for fuel delivery. You can pull an injector, turn the key, and see if fuel is sprayed into a container. Careful w/ this.

There are large circular connections under the steering wheel. Make sure they are snug. Make sure the connector and fuses in the engine compartment (driver's side, rear of car) are snug.

Ensure you have no vacuum leaks. Make sure the popoff valve (if you have one) reseats.

Usually a backfire through the intake, as you had, indicates a too lean mixture. This could be due to some of the above or an out of spec Warm Up Regulator which may have a too high control pressure, or an incorrect setting.

I'm sure there is more you can do, but that's what comes to mind now. Good luck and get back to us.

[911mot]

Hi pistonhead. Try cleaning the distributor cap inside and out. It's been a bit wet lately....

[pistonhead]

Thank ou Paul and Mot, I will do some more work on your advice, when I have found the problem I will let you know
Thank you both.