Hello, my 305 TPI is runing with only 2,4,6,8 cylinders working, the whole driver's side is not working. I do have ignition in the spark plugs but it runs very rough and when I unplug the injectors on that side, nothing happens for better or worse. When I unplup the spark plug wires one by one, there is spark but no change either. Is there some kind of "shared ground" on those 4 injectors? I have no SES light on or codes advisory. It's been parked but I start it once a week or so. I didn't start it for a couple of weeks 'cause of the hurricanes here in FL but it didn't get damaged by water or anything like that. A couple of days ago I started it and it worked fine, the whole 8 cylinders were working fine but it started to act up again. I started it a couple of hours ago and it is still in 4 cylinders. Please help me! Sorry for the long letter.

Thanks, David

 

could have a bad computer

 

Thanks Vortec, could it be a bad conection in the computer?

 

The injectors are all grounded through the ECM. Each bank has it's own fuse...check them both. INJ1 should be the fuse for the 1,3,5,7 bank and INJ2 should be for 2,4,6,8. If the fuses are both good, you probably have a wiring problem like a loose connection in the harness. Check for voltage at the dead injectors with the key on...if +12v is present then the power side wiring is good and you'll need to use a test light to check for a ground pulse signal from the ECM (engine must be running.)

 

If the other bank is firing normally then it isn't a bad computer. There are 2 wires to drive the injectors (one for each bank,) but there's only one transistor in the ECM, and it runs all 8 injectors. The only way the ECM could be the problem is if it has a bent pin in the harness conenctor.

 

Thanks for replying so quickly guys. Please tell me where are these fuses located?

 

Fuse box above the driver's feet.

 

Ok, I'll go and check those fuses now. I'll let you know in a few minutes. Thanks again.

 

Thank you so much guys. It's fixed!!! I checked the fuses and they were both fine. I actually interchanged them and same thing. I took the #1 spark plug and it seemed fine. So I started thinking about the computer. So I tapped under the dash where the computer is located and it worked perfectly fine. I am guessing that moisture probably got a hold of the computer connections, but it's working fine now. I'll take the covers off one of these days and check and clean all connections there. Thanks again!

David

 

When you go to check it, check the terminals in the wiring harness connector as well. If one of them is bent or backing out it can cause the same problem.

 

Ok, I'll check that as well. Thanks again!