Hello!

I just finished a TPI swap on my '85 Chevy Blazer and would definitely appreciate help troubleshooting the gremlins I have. I had this same running setup in an '84 GMC pickup which sat for 10+ years. I pulled the motor and hardware, ECM was trashed (mice), rebuilt the motor and got a new Painless wiring #60102 for the install. Everything is in, wired, connected and I got an 1227165 ECM from a scrap yard out of a corvette.

When I turn the key to the 'on' position the fuel pump comes on and stays on. It should only cycle for 2 seconds then off, but it just stays on the entire time. Jumping A & B on the ALDL connector does nothing, no codes, not even 12. I also remember when keying on and the pump cycles for 2 seconds the SES light should come on until engine start, but nothing. I tried connecting TunerPro RT with my laptop and ALDU1 adapter... nothing. Engine will crank but no fire. I figured with the ECM not even giving me code 12 when I jumper it something else is going on. Since the ECM was a scrapyard pull I swapped it with a reman with the same result. (wasted $$$)

One thing that's irritating about the Painless Wiring kits is you don't get an actual schematic. It's nice that everything is labeled for install but once it's installed, loomed, and tucked away where it's supposed to be it's difficult to troubleshoot. There are two capped fuses in the Painless Wiring harness, one with red wires with a 30 amp which has power, the other is a 15 amp with purple wires and no power. I think this might be the crank wire from the starter solenoid so that makes sense. I didn't check for power on the 15 amp when cranking.

B1 connector at the ECM has power
A6 connector has power when key is in the 'on' position
I did not check for power at C16

I did not connect the oil pressure switch wires to anything, they're tied off.
I removed the fuel pump relay and have power at on the green/white wire when key is on as expected, but it stays on which is unexpected.
I checked for power at on the green/white wire and also the tan/white wire with the ECM removed per another thread to look for voltage that shouldn't be there.

It's like the ECM is only half powered. I don't get it. Grounds are good. I cleared off the paint on the firewall and bolted the ground eyelet there. I measured no voltage drop from there to the negative terminal on the battery. I even ran a wire from the eyelet on the firewall direct to the battery to eliminate any other potential ground issues. No change.

I'm not sure what else to try, but this is super weird behavior. Any suggestions would be greatly appreciated.

-Howdy

 

It's my EEPROM! Not sure what, but something with my chip is no good. Either the chip itself is bad or I programmed it incorrectly. Wrong definition or wrong offset maybe? I'm using a 27SF512 with an adapter. Finally the light bulb went off that maybe I should take my chip out and try the bone stock memcal. The SES light comes on like it should with key-on and the pump primes for 2 seconds then off again.

Now it turns over like there's no spark. I have an MSD 6A box and I'll move on to troubleshooting that next. Getting closer!

-Howdy

 

Good to see progress being made. ....Assuming you're using the harness for the MSD? If so, just take it out of the loop until everything works. Only takes a minute to wire back in. So many horror stories with those boxes.

 

I have no harnesses for the MSD. The original configuration used a computer controlled HEI distributor. Besides the 4 wire connector to the computer, the only wire going to the distributor was a pink one for ignition. I'm using a small cap 7 wire distributor with a blaster 3 external coil. I thought I could use the white wire from the two pin connector from the distributor (tach) as the trigger for the MSD box. Maybe not so simple. The MSD sat in a box for some time, I'm not even sure if it works anymore and will start there with the self-test from the manual in the morning.

If I needed to remove the MSD and use the coil I have as-is I'm not even sure how I'd wire it.

-Howdy

 

Gotcha. I understand. ....my system was up and running just fine BEFORE I added the MSD. There's a $25 harness so you don't have to hard wire it in. ...but if you don't have it, and that's how it's wired now....I understand.

 

I wouldn't use the MSD at all. Why bother when you have computer control over the timing, etc?

If you have problems with spark blow out (unlikely), then reduce the plug gap. We run gaps at .020 all the time to get away with higher boost, etc.

GD

 

I got it! I had a number of problems:

1. Tested the MSD box per the manual and it seems to work fine.
2. The A and B wires on the 2 pin distributor connector were reversed. Fixed that.
3. I attempted to start with the stock memcal which was pulled from a corvette but I don't remember what year. Still no start. I was able to hook up tunerpro though and the dashboard read all kind of crazy values like rpm 6,500 while not running, tps voltage 4.87. (Guessing my definition file doesn't match the data feed) So I went back to troubleshooting my tune and chip adapter. I'm using the 27SF512 chips with GP1 adapter. Verified the file I loaded matches what's currently on the chip. The instructions for the BURN1 programmer states that the chip divet must be towards the handle. Surely this holds true for the GP1 adapter right? No... I had the chip in backwards.

I put the chip in correctly, keyed on, pump cycled for 2 seconds like it should and ses light on like it should be. Tunerpro reported legit values for the sensors. Fired right up. Did a 30 minute break in and a short test drive and it seems to run pretty good. I'll do some datalogging and tuning next weekend.

Thanks everyone for your feedback and input.

-Howdy