Hello all,

I had made a post earlier about how my porsche isn't starting but I have new information now so maybe it will help out with finding a solution!

- CDI box is humming perfectly fine
- Spark was tested by unplugging a sparkplug wire and grounding a new sparkplug to the intake (sparks fine)
- fuel pump fuse and relay are both good. (tested the fuse by checking continuity between the two ends, tested the relay by putting into where the horn relay is and honking the horn, it works fine)
- fuel pump outlet tubing was taken off, while turning car over a little stream of fuel comes out (nothing more than a stream of ****)
- replaced the fuel pump, car still isn't starting, I'm assuming the pump is flowing much more but I'll check tomorrow

Am I missing anything that I should be checking? Does this sound familiar to any of you? Any possible fixes? Thanks a lot in advance.

 

i have a 78 so not sure how different it is , but if you take out the air filter do you have a pop off valve in there ( ( a plastic check valve bonded into the air intake. If so make sure it is seated and sealed properly.

also with the ignition on and that air cover off , reach in and under the air plate and lift it slightly. If it is like my car you should instantly hear the pump run and injectors dumping fuel. if you don't hear anything this may be your problem.

If you do hear the pump running it may be time to do some pressure system checking with CIS fuel gauges.

 

With the previous fuel pump I tested lifting the plate, and I legit would hear nothing but some chatter from relays and what not. I’ll test with the new fuel pump and I’ll also unhook one of the injectors just for good measure and see how things go. Thanks for the reply.

 

I'm curious which hose you disconnected to measure fuel flow with your old fuel pump.

Also keep in mind that when you lift up on the plate, fuel will flow out of all six injectors. Don't hold the plate up for long or you could fill each cylinder with fuel.

I would pull all the injectors and place them in separate jars. This is a really good CIS video, the fuel injector test starts at the 25 minute mark, but I would watch the entire video:

Mark

 

yeas i was gonna mention this , but forgot... personally i would get 6 small identical containers. ( baby food jars for example ).. put an injector in each one , lift the plate for a while... now compare containers on a lever surface. all containers should have the same amount of fuel.

PS eat the baby food first .. i find the banana one particularly tasty

 

I GOT IT RUNNING! who ever wired the fuel pump on this car used the brown for negative and black for positive, so the new pump was just pumping backwards (I think).

Thanks a lot for your help. as for the tube that I removed to check the flow of the fuel pump, it is the tube that goes from fuel pump to the inlet that goes to the distributor.

As I was starting it up after having wired the pump properly, the car was hesitating to start, but it felt sooooo close. I went out back to push up that plate in the air box just to double check that the pump is indeed working and voila, after trying to start it once more it worked out.

There is ONE final issue that I must take care of (in terms of fuel lines) the line that goes from the tank to the pump (or in my case from the tank to a fuel filter then to the pump) has a hole in it, would you happen to know what diameter is needed for this?

 

great to hear you got it working, not sure of the line diameter.

 

That hose is 11.5 mm ID. You can get it from Belmetric in that size. If you want to try a local store, 1/2-inch is too big, but you might be able to get a 7/16-inch to fit.

See this thread: http://forums.pelicanparts.com/porsc...line-size.html

Mark