TBI Swap Fuel only TACH Signal

[chug302]

Hello,
I have successfully installed a TBI setup on my Jeep and appreciate all of the valuable information on this forum. I couldn't have done it without you guys.

My setup is a Fuel Only setup, meaning I'm not using the Computer Controlled Spark (I have a Howell PROM and it is programmed appropriately for this application.)
My TACH signal is connected to the EST Hi reference (B5 purple/white) and it appears to work fine.

My question is this.

Do I need to connect the EST reference (B3 black/red) to anything. It seems like I should connect it to GND.

Any help would be greatly appreciated.

Thanks,

Scott

[Bill usn-1]

Did you install a filter between the coil and B5?

If not then your ECM may not live a very long life.
If you have a Howell filter then your fine.

B3 is a ground reference so yes you can tie it to gnd.

This filter was supposed to work but didn't work for me.
I saw/see no advantage at all to going fuel only.

[chug302]

The only reason I went with the Fuel only setup was because of California emissions. I happened to find someone selling parts of a Howell system and I was able to piece the rest together and still me California's emissions.

I'm going to build a system for my brothers jeep now that mine is working. I will use the full computer controlled timing on his.

I did not install a filter. I have a GM HEI type of distributor and when I called Howwel the said I don't need one.

thanks for your help

[Bill usn-1]

That's good that it's working for you.
I hope it continues.
I would hate to get in the middle of nowhere and burn up the ecm.
Seems odd that howell provided a filter with their fuel only systems and now tell you that one is not needed.
Maybe the 4 pin GM module puts out a nice regulated signal that is small enough for the ecm to handle.
But if you have an HEI distr then you don't even need to do anything but lock your mechanical advance to use the 7 or 8 pin module to have timing control.
it's very easy for you.