Crank and start, crank and shut down(3 sec) crank and no start

[WorkInProgressK]

Originally Posted by Camibox

Update: So I replaced the CPS. I didn't test the new one before I replaced it but tested the old and had no continuity between any of the pins (all read OL). Went to start the car and cranked but didn't try to catch. Saw the tach rise slightly but realized I never heard the fuel pump. Pulled the relay and put in a switch to test. Fuel pump activated. tried the car and it fired right up. 4 times and fired up every time. Wife says "Huh, bad relay". One of the first thing I did was replace the relay but it couldn't hurt, right. Replaced the relay and 3-4 more tries, no issue. We'll see how it goes when we try again tomorrow. BTW, I did test the relay I removed and it activated when I put voltage to the coil.

Called it. glad it was just that. Then again having a having a bad CPS may lengthen starting but not prevent you do drive. CAS is a must.

Best DIY testing method is starting with the cheapest issues first. If it doesn't help keep working at it.

[Gelbster]

Originally Posted by WorkInProgressK

Called it. glad it was just that. Then again having a having a bad CPS may lengthen starting but not prevent you do drive. CAS is a must.

Best DIY testing method is starting with the cheapest issues first. If it doesn't help keep working at it.

The weakness in our relay test was that nobody insisted on wiggling the coil pins during the resistance test. The relay tested perfectly.
It is possible that the loose pin was caused by an overheating coil in the relay or arcing contacts ? Hence the suggestion to feel if it got hot.
Anyone got a circuit diagram for the fuel pump fuse - just to close the loop ? The 5th pin, the small one is the oddity.
http://www.pelicanparts.com/cgi-bin/supertech/catalog.cgi?action=frameset&return-url=/cgi-bin/supertech/catalog.cgi%3Faction%3Dframeback%26page%3D529&catalog-url=http%3A%2F%2Fwww.pelicanparts.com%2Fcatalog%2F SuperCat%2F1048%2FPOR_1048_FULFUL_pg2.htm%3Futm_so urce%3DSuperTech%23item8

[WorkInProgressK]

Originally Posted by Gelbster

The weakness in our relay test was that nobody insisted on wiggling the coil pins during the resistance test. The relay tested perfectly.
It is possible that the loose pin was caused by an overheating coil in the relay or arcing contacts ? Hence the suggestion to feel if it got hot.
Anyone got a circuit diagram for the fuel pump fuse - just to close the loop ? The 5th pin, the small one is the oddity.
Pelican Parts

Well I did say to bypass the fuel pump relay entirely. But you are right that you would not have know what was at fault on the relay unless you opened it.

Wow, that tab. It just looks like porsche decided you couldn't use a standard 30 amp bosch relay which i am certain is identical inside. Their solution is to change one tab to a smaller one and turn one 90deg.

If you have a soldering iron, you could open it up and re-solder the joints.

[Gelbster]

Originally Posted by WorkInProgressK

Well I did say to bypass the fuel pump relay entirely. But you are right that you would not have know what was at fault on the relay unless you opened it.

Wow, that tab. It just looks like porsche decided you couldn't use a standard 30 amp bosch relay which i am certain is identical inside. Their solution is to change one tab to a smaller one and turn one 90deg.

If you have a soldering iron, you could open it up and re-solder the joints.

But it is not a 4 pin relay so the 5th ,small prong must be NC ?I agree ,it would be interesting to dissect it and observe the reason it failed.

[WorkInProgressK]

Originally Posted by Gelbster

But it is not a 4 pin relay so the 5th ,small prong must be NC ?I agree ,it would be interesting to dissect it and observe the reason it failed.

Well the difference between a 4 pin vs a 5 pin is just that the 5 pin allows 2 functions: normally open or normally closed. Once you have decided what type of relay you need you can trim off the 5th pin, which Porsche did. That one is a normally open considering the function and the schematic on the side of the relay.

[Camibox]

Well opened up the relay. The "loose" prong was not an issue, but, one of the connections to the relay coil was just laying on the connection but not soldered on. Glad I bought 2 when I ordered

[geraintthomas]

Glad you've sorted out the problem bud, it's gut wrenching when you get a problem like this. Happy days!

[Gelbster]

Originally Posted by Camibox

Well opened up the relay. The "loose" prong was not an issue, but, one of the connections to the relay coil was just laying on the connection but not soldered on. Glad I bought 2 when I ordered

Always good when a thread concludes with finding the fundamental cause of a problem.Thanks for sharing.