Crank sensor not ramdonly not reading during cranking?

oldskool442 · Newly Aquired Joined: 26 Feb 2008 Posts: 6

Has anyone had trouble getting their crank sensor to function during cranking?

My car will randomly turn over for 10+ seconds and not get a crank signal. I can actually watch the laptop to see when the crank signal begins to work and the tach shows cranking rpm. Then it fires right up. Happens regardless of if the engine is cold or at operating temp. Happens maybe 25% of the times i go to start it....other times it starts up without an issue.

The only thing electrical near the crank sensor is the CSI electric water pump, which is programmed to turn on over 400 rpm so that can't be the issue during cranking.

I'm using a 1/2" sensor with a 7.25" crank trigger wheel. Initially I had only a .020" gap and thought that was the problem, so I increased the gap to .035" but still have the same problem.

Any ideas?

VeryCoolParts.com · Posted: Sun Sep 28, 2008 3:50 am Post subject:

Run your power and ground wires directly to the battery.
_________________
Wayne Presley
www.verycoolparts.com
Enterprise AL
760-403-6266

oldskool442 · Newly Aquired Joined: 26 Feb 2008 Posts: 6

Would it be a good idea to run 12 gage jumper wires to the battery to see if it has an effect? I'd hate to go through the trouble of doing all that and not solve the problem.

Also, what's a typical gap to run for the sensor? I see in the manual that for my wheel I can run a .070" gap, but I would think that increasing the gap will decrease the signal, where I think I need to decrease the gap to increase the signal. Will an increased gap eliminate some of the electrical noise I may be getting?

RDK · Newly Aquired Joined: 07 Oct 2008 Posts: 1

Maybe I can help.
I had the same issue, fought it for a year(supercharged BBC in Chevelle). Do you have slow cranking RPM or gear drive starter? That was my problem. I replaced my gear drive with a NEW GM long starter & it raised cranking RPM approx 200 rpm.
Fixed!

Later I had my TEC3 updated by Electromotive, I believe it is now the same as TEC3R.They claim improved starting circuits, which appears to be true. I went back to gear starter & have had no more issues. It still cranks maybe 5 sec. before it fires, but is steady everytime hot or cold.