MSD 6A with Howell TBI hard cold starts

[deano186]

I have a 73 Ford Bronco V8 that I've had an MSD and Howell TBI kit on for years. It works fine except that when the truck hasn't been run for a day or more it is hard to start. If I give it a shot of starting fluid it will fire up immediately and restart again fine until it has set for a day or more again.

The Howell TBI isn't firing the injectors during cranking when this happens. I talked to Howell's tech support and they said it's because the GM ECM in the Howell TBI setup isn't seeing a strong enough signal from the tach output of the MSD 6A box during cranking to get it to fire the injectors.

Originally this wasn't a problem but it developed over time.

I also added an aftermarket Tachometer at some point and it is also running off the tach output of the MSD box and it seems to work fine.

I'm not using any kind of tach signal amplifier and I wonder if the 8920 tach amplifier would fix this problem?

Thanks for any help,

Dean in Phoenix

[msdtech1955]

so, by pass our ignition ,,,and run a stock inductive to see if the problem is still there.

[deano186]

I removed the tachometer connection from the MSD tach output and the Bronco cold start problem went away. Maybe the tach was pulling down the signal too much. The Howell TBI runs off the MSD tach output okay during cranking with the tach disconnected, so I'm happy. I'll just do without a tach.

[msdtech1955]

and was this a oem style tach ?

[deano186]

Originally Posted by msdtech1955

and was this a oem style tach ?

It was a Sun tach that I had added to the truck.

[msdtech27]

the 8920 adapter should give you a stronger signal to run both units, (howell & sun tach)