I just got finished installing TPI in my truck and now I have no spark... I used the old vacuum advanced distributor and when I plug it into the old computer there is spark, but when I plug it into the TPI computer there is none. Would yall say it is the computer or the old distributor? I have a new small dizzy with remote coil but it's in a running truck and don't want to pull it just to find out the ecm is bad.
CK5
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TPI and no spark
- Thread starter 85 Jimmy
- Start date
You cannot use a vacuum advance style distributor with FI.
dave w
1/2 ton status
It could be that the Large Cap TPI distributor has a bad module? Any chance that there is a local parts store near you can test the Large Cap TPI distributor module? If the Large Cap TPI distributor module tests OK, then my thinking is the TPI computer is bad.
dave w
dave w
I never tested the TPI module, just the one in the dizzy with vacuum advance. I'll just swap the distributor out since I have one and see, if that doesn't work I'll get a new computer.
Can I ask why I can't use the vacuum advance distributor? It should still have spark, unless the TPI ecm doesn't read the old 3 pin module since TPI with a big hei distributor has a 5 pin module...
Can I ask why I can't use the vacuum advance distributor? It should still have spark, unless the TPI ecm doesn't read the old 3 pin module since TPI with a big hei distributor has a 5 pin module...
dave w
1/2 ton status
I'm thinking the TPI ECM needs the reference pulse from the distributor ignition module to get the spark going. I'm thinking the TPI ECM also needs the reference pulse from the ignition module to enable the fuel pump relay for more than a few seconds.
dave w
dave w
The vacuum advance distributors are a 4 pin module and the TBI is a 7 pin IIRC and the ECM needs a reference signal for spark and also for the fuel pump. Also remember that the vacuum advance distributors have a mechanical advance system as well and you need a distributor with NO advance mechanism at all since the ECM controls it.
dave w
1/2 ton status
Thanks for the update.
Just curious? Did the Small Cap HEI with the remote coil and Large Cap HEI with the internal coil have the same identical electrical distributors connectors?
dave w
IIRC from back when i did my TPI swap on my other blazer the large cap HEI (which i used) plugs directly into the ECM harness. If you ran the small HEI then an adapter harness was required for the external coil.
dave w
1/2 ton status
yep, that's it
dave w
1/2 ton status
Cool,
So what about the connector on the Large Cap HEI distributor that went to the "BAT" terminal of the distributor cap? I'm thinking that somehow the old "BAT" wire gets spliced into the Small Cap remote coil somewhere?
Anyone know of any links on "HOW TO" convert from Large Cap HEI to Small Cap HEI?
dave w
So what about the connector on the Large Cap HEI distributor that went to the "BAT" terminal of the distributor cap? I'm thinking that somehow the old "BAT" wire gets spliced into the Small Cap remote coil somewhere?
Anyone know of any links on "HOW TO" convert from Large Cap HEI to Small Cap HEI?
dave w
Cool,
So what about the connector on the Large Cap HEI distributor that went to the "BAT" terminal of the distributor cap? I'm thinking that somehow the old "BAT" wire gets spliced into the Small Cap remote coil somewhere?
Anyone know of any links on "HOW TO" convert from Large Cap HEI to Small Cap HEI?
dave w
IIRC i just swapped in the correct wiring harness from the ignition module to the ECM. I think i have one in the garage still i can get a pic of later.
