Installing Howell TBI with HEI Distributor - Bare Minimum - No Emissions
To start, I have searched for 3 days and can not find what I am looking for. I installed an HEI distributor, it has built in coil. So I removed the Ignition Control Module, old coil, etc... Well the wiring was an absolute cluster to begin with and once the HEI was installed, it did not start, just turned over... I had the Howell TBI kit on the way anyways, so I decided to just go ahead and start removing everything in prep to install the FI system. I removed the old ECM and the wiring harness. I then cut all the wire in the engine bay so that it is still connected to the harness at the driver side firewall and draped over the side of the jeep. The wiring was so far gone that I would rather just reconnect and label everything.
What I need is a engine bay wiring diagram for the '89 4.2 L (auto trans) with Howell TBI and HEI. I have the off road Howell kit as I do not need emissions equipment and I want to eliminate everything that is not necessary. I have looked everywhere and can not find it. The Howell instructions tell you how to hook up to the duraspark ignition system, well I removed that thing as I do not need it anymore....
I have emailed Howell twice with no response. Any help would be much appreciated.
05-08-2012 11:57 AM
Have you tried contacting the manufacturer of your HEI system?
They would know best how to connect it.
01-15-2014 07:41 AM
I know this is an older thread but does anyone have a wiring diagram for installing the Howell TBI kit with a HEI distributor? Getting ready to start on mine, the included instructions don't describe what to do with a HEI set up.
01-15-2014 02:10 PM
All you need for the HEI is a wire that is hot when you turn on the key. The keyed 12volt hot wire goes to the place on the distributor marked bat. The other connection is for the tach. You can use your old coil negative wire on that connection. They really are that simple to wire up.
01-15-2014 05:27 PM
I was undr the impression the TBI computer gets its RPM signal from the distributor, so you would have to use a HEI system from a TBI engine, like a 4.3L V4, and adapt it to the Jeep HEI distributor.
5. AFTERMARKET IGNITION SYSTEMS: If you are running an aftermarket ignition
system (MSD, Mallory, Jacobs, etc.), you might not have a coil signal that will
trigger our built-in tach filter. If your engine will not start, and you have one of
these systems, contact Howell Engine Developments at Ph 810-765-5100 for
So if you cannot get in touch with them, well, keep trying.
OR, on page 3 at the top:
THIS SYSTEM IS BASED ON THE PRODUCTION GM (Chevrolet or GMC)
THROTTLE BODY FUEL INJECTION AND ELECTRONICS, USED FROM 1986-91,ON
4.3 V-6 ENGINES. ALL BACKUP SYSTEMS AND “ON VEHICLE” DIAGNOSTICS
FUNCTION SIMILAR TO THOSE MODEL YEAR PACKAGES. THIS SYSTEM DOES
NOT CONTROL SPARK TIMING AS ON GM ENGINES BUT RELIES ON A TACH
SIGNAL FROM THE JEEP ELECTRONIC IGNITION FOR RPM INPUT TO THE ECM.
RPM input to pulse the injector.
Find the HEI tach output, and connect it to where the Duraspark setup connects to the harness of the TBI computer....
Negative side of the coil should suffice.
01-16-2014 03:39 AM
2xs, you may very well be correct. I was just thinking of the straight up wiring on a GM HEI. I know nothing about the Howell set up.
01-16-2014 09:33 AM
Thanks to you both. I'll get back to you after I take another look under the hood. I thought I eliminated the Duraspark when I put in the DUI HEI set up but maybe there's still some parts in there.
01-16-2014 08:14 PM
I called Howell.......it's as simple as connecting their white wire to the negative side of the distributor which should be the tach lead. Their purple and orange wires go to the solenoid and/or starter for power supply (in run and start modes). And yes, I did eliminate the Duraspark when I installed the HEI distributor. I'll make up a diagram if this all works out.
01-16-2014 08:51 PM
Im glad it all worked out, please post up the diagram, Ill make sure it gets shared as needed.
05-10-2015 11:04 AM
Originally Posted by mckinley4371
I'll make up a diagram if this all works out.
Did you ever get a diagram made up? Would sure like to see it!