944 Race Car No Start

Troubleshooting a no start condition on my 944 Race Car

After the race at Indy, the car has made a few short trips in and out of the trailer but that is it. In preparation for the next race, I pulled it into the shop.  When I later went to move it onto the lift, it would not start.

I first swapped the DME relay.  No start. I then replaced the DME with a jumper. No start.

I put an inline spark tester https://amzn.to/2OExuoF on plug number one and I got a flashing light so that meant I had spark. That told me the reference sensors were working.

I then connected an LED https://amzn.to/2MuhnHm to one of the injectors.  It flashed as expected telling me the injectors were firing.

I then had to figure out a way to test the fuel pressure since I do not have the right fitting for the end of the fuel rail.  I ended up using a short section of ⅜ fuel hose. I slipped it over the threads of the test port and slipped the other end over my gage.. I held both ends with hose clamps.

The fuel pressure was perfect at 36 psi.  I also took a sample and checked for water. The fuel looked fine.

I then removed the number one plug and installed the compression tester. The compression looked good telling me the timing belt was still in place.

I notice that the inline spark tester looked weak when it flashed so it tried swapping a coil https://amzn.to/2MuhuCM from the parts car.  No change.

I tried putting a spare spark plug directly into the coil wire and grounding it.  I got a tiny spark.

Later I retried this test with the plug from number one and got no spark.  I noticed the plug looked dark so I cleaned it up with some brake cleaner and a brass brush. https://amzn.to/318PaLC I got a bit more spark. I reinstalled that pug and tried to start the engine again. I got a few pulses but still not a run.

I removed the second spark plug and repeated the cleaning procedure.  When I tried to start the engine it got even more pulses, but still no run.

So I pulled the remaining two plugs and cleaned them.  The car started right up. As I revved it a time or two the engine cleared right up and idled smoothly like nothing had ever been wrong.

I suspect that running the engine the last few minutes at Indy with a dying battery and then just a few short hops in and out of the trailer since the race had fouled the plugs.  While this is a common problem on our RX7, I never suspected it to be a problem on the 944. I am glad it was a simple solution and I got it fixed before a race weekend.