Won't stay running, BS3 equipped

[jpwalt1987]

Hey guys, I have been fighting a problem with the car not wanting to stay running. I thought that I had some bad gas at first but I drained it out and switched to another station. car seemed to be better for a little while but it is now acting the same way. I have a GEN 1 Big Stuff 3. I can increase the base volumetric efficiency to about 50 and it will stay running. That puts the AFR at about 10.5:1 at idle. You would think that it would be blowing black smoke at that AFR but it isnt. I have the base FP set at 45psi vacuum off and it drops to about 38 with vacuum on. I am starting to lean towards a fuel pump going out. It is an older paxton pump similar to the A1000 and -10 line to the fuel rail with 95 lb/hr injectors. It only has about 1200 miles on it. It was running fine and then one day...BAM run like poop!! I have good fuel pressure though, that is why am not sure about the FP being bad. I am trying to think of other possibilities but am kind of running out of ideas. anyone? JW

 

[jpwalt1987]

Forgot to mention that the cursor is moving properly with changes in MAP and the car will stay running if you keep hitting the throttle. TPS is good,no vacuum leaks, 5 gallons of gas, filters are clean. Could it be that the Fuel pressure is there but not the volume? I dont see that being a problem at idle though. JW

 

[jpwalt1987]

some progress...so to speak

Well I got a chance to do some testing today and have narrowed it down and eliminated some things. Fuel pump and pressure are spot on. I jumped the FP relay to make the pump stay on all the time. Pressure is rock solid. I pulled the plugs out and they were fouled out. Put in some new ones. Added 5 gallons of gas from a different station to the tank. I changed coil pack with one I know to be good. no change and NO SPARK now. Here is what I think is going on. The spark is/was soo weak that it could only fire a rich mixture. (rich is always easier to fire than lean) Therefore after the cranking fuel was taken away it would die only to restart and run on a super rich mix (10.5:1)after adusting the VE table. Now that I have no spark I can start tracing the ignition system. I got a known good coil pack and a known good ignition module and still no spark. I cleaned all the grounds for the BS3 at the battery and checked for loose connections at the proper places...all good. I will check the crank sensor tomorrow and the injector pulse and a few other things that I am sure to think of when I cant sleep tonight! Any other suggestions?

 

[norbs]

Well you could buy a msd distributor, digital 7 box and a msd hvc 8251 coil. YOU should be able to get spark at the module without the ecm plugged in even. Check the cam sensor and crank sensor. Make sure the ignition module is grounded or it wont work good run a ground strap off the 3 bolts to the bottom to the firewall. Check voltage at the coil pack pin M,N or something like that.

 

[jpwalt1987]

Well you could buy a msd distributor, digital 7 box and a msd hvc 8251 coil.

If I had a cool $1000 to drop I probably would but that is kind out of the budget right now. I also want to keep the A/C without hacking up the brackets like I have seen to fit the distributor. I hope I dont have any broken wires to chase but that is a big possibility also. Thanks,JW

 

[jpwalt1987]

It Runs!!!

Well after some serious thought and studying a wiring diagram I went ahead and checked my fuses. I found the CCCI fuse blown. Then I realized I had left the key on when I changed the coil and module out. Thats where the no spark came from. I believe that I was correct as far as the weak spark only firing a rich mixture and then dying when the mix would be leaned out. Basically I had a bad module and coil. Not suprised seeing as though they were very old and this motor asks alot from them. I had GM coil so that was free, But the module was $179 @ O'Reilly auto parts. Borg Warner brand. Now I am off to do some real tuning instead of chasing BS. :biggrin: JW