Porsche Repair: Unable to start 1983 928, engine cranks, fuel injection system

Question
Dear Dave,
I just inherited a 1983 928 that has been sitting idle for at laest 5-6 years. I replace the battery and the engine cranks fine but does not want to start. Any tips to where to start?

Thank You, Dave Chan

Answer
Hi Dave...well the great news is you've got a very cool car.  But...there are only about a gazillion places to look for a no-start after the car's been sitting that long.

I really doubt the problem's in the electrics but just to make sure you should verify you've got a spark.  The easiest and safest way to do tis is to put a timing light on the car and act as if you were timing it.  If the light pulses near the timing mark you're in pretty good shape.  The other way is to pull a spark plug.  If you don't already know about this technique write back and I'll be happy to explain, but I need to throw in some cautions.

If you have spark the next place to look is fuel delivery.  I assume all the 6 year old fuel has evaporated so you added new fuel.  The first place to test is at the fuel line that enters the engine compartment from the rear and snakes up towards the fuel injection system.  Somewhere in that couple of feet of line there will be a connection from hard line to rubber.

If you've been cranking and if there really is fuel, then at that connection you have a lot of fuel pressure.  Enough to make a mess of your eyes if you crack that connection open.  First de-pressurize the system by removing the gas cap and listen for a vaccuum sound.  Then you can carefully open that fuel line connection.  If clear fuel comes out and creats a small puddle that's actually a good thing.  Use a jar for the next step.  Replace the fuel capo and turn the key so the fuel pump activates and you should get a gush or two of fuel in your container.  If so, that's good, so stop and put everything back together.

If you have spark and if you have fuel and if the engine is cranking and sucking in air, the car will start.

UNLESS, drumroll...the residue from the evaporation of 6 year old fuel (the residue is better known as crap, crud, gunk and other colorful names) is everywhere new fresh fuel is trying to get.  One obvious place is the little teeny hole at the bottom of each fuel injector.  I'm using that teeny hole as an example...actually there are many places crap, crud and gunk could be blocking the normal fuel path.  What this means is quite a big job of taking little  things apart and cleaning them.  I'd suggest not doing that yet.

Why don't you do the spark and fuel tests and write back to me..,and we'll go from there.

One day soon you will be lookin' cool driving that 928.

Dave