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cellison cellison is offline
Join Date: Sep 2002
Location: Johns Creek, GA
Posts: 1,404
Still no start- mmmm

I was hoping i would not have to ask for help / guidance, but here goes.

I had a no start issue about a month ago and I thought I traced to a bad coil (per my resistance readings and no spark at the plug). I read a several good informative threads on the topic and thought this was the issue. I installed a used old style bosh coil off a running 911 and the resistance on it was good. I went ahead installed a new Beru wire set, bosh plugs/rotor/cap as they all were fairly old. I tied to start it about 10 times and still no start. One thing different now is when the car is attempting to crank, on about half the ammempts the tach will read around 4k rpm, but the other attempts it will not read, or then start to read. When the no start first occurred a month ago, the tach would only bounch whenthe key was truned but would not read. I rechecked all the connections (ICU, coil wires etc) and the coil resistance all seem good. The Bosch OEM ICU is humming.

Iím thinking about my next steps in troubleshooting and would like comments / suggestions / tell me if I am off base for those more in the know:

1.) I want to make sure it is not a fuel problem. Both pumps seem to be working.
QUESTION: where is the best place to spray starting fluid in the fuel system to see if it will crank?

2.) this weekend when I have a helper, I will check for spark.

3.) The ICU is humming but I understand it could be bad.
QUESTON: is there any way to test it in the car to see if it is any good? I thought I read there is not a good safe way to do it. I could send it out to be tested and rebuilt if needed.

4.) Regarding the green coax wire from the distributer to the ICU 6 pin connector: I checked the connection to the distributer and it seems good. I believe I should have the single wire to the ICU (no connection mid way) so I didnít look any further at the coax. I want to check continuity. At the connection to the distributor, there is a green wire and black wire.

QUESTION: Do I check continuity on the green connection at the distributer to the 31d connection on the 6 pin ICU connector? Do I check the black wire on the connection to the 31/1 connection on the ICU connector?

5.) My ignition switch did not want to turn a intermittently about a month ago the same day this no start occurred. It would eventually turn and the car would start. The same day it would trun but then the no start.
QUESTION: should this be a non-issue since the key will turn and the pumps will run and the CDI is humming?

Any help / guidance in advance would be appreciated.
79 930 #632
88 911 Cab
74 TR6
88 CRX Si

Last edited by cellison; 07-06-2012 at 10:06 AM.. Reason: clarify
Old 07-06-2012, 09:57 AM
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