EFI ignition gremlin.. help please.

[67EB_in_619]

Ok.. so my truck fires up fine. idles good.. runs and drives great.. until WHAMMO - it cuts off. It isnt losing fuel pressure. It dies like you switched the key off.

Here is what I have done and determined:
Swapped dizzys and TFI modules (not convinced Rich Porter is a good brand.. some cheap stuff in there.. about to go buy a autozone replacement)

Swapped coils
Bypasses the ign switch
Swapped in new relays
wiggled every wire I can find
Swapped ECUs (same tuning chip though.. I might try to run it without the chip and see what happens)

The harness was new 12yrs ago - Ryan McCormick harness.. and its in good shape.. havent hacked it up at all.

I have determined that the EEC relay is keeping power when it dies
I have determined that the coil is keeping power when it dies

I dont know what to try next and the 50th celebration is next weekend.

Help!

 

[67EB_in_619]

forgot to subscribe...

 

[EFI Guy]

Bad chip would cause fuel pump run on condition.

I have heard of certain vintages of RJM / RF harnesses having the spade connectors spread and not make good contact to the TIF module. That's a quick easy check.

 

[67EB_in_619]

Tif or tfi?

 

[garberz]

That was the issue with Kevin's Ron Francis harness. The female spade connectors weren't making good contact with the male spades on the TFI. Same issue at the Mass Air meter. If you wiggled the harness, it would shut off, or when the temps came up.

Mark

 

[garberz]

We depinned the TFI plug and gave each female spade a gentile squeeze till it made a tight connection with the TFI module. We did the same to the Mass Air, and he hasn't had any of those issues since.

Mark

 

[67EB_in_619]

I will double check the TFI connector as well, but I think I might have found it.
It ran fine without the chip - well, it actually ran crappy until I introduced a vac leak, but it didnt shut off... chip back in = died.. repeat.. So I pulled the tune selector cable out of the chip which means it should default to position zero (my normal tune) and it ran good. Idled without dying for 20m.. then drove it 20miles.. no issues.. I will drive it around again today some more, but I am thinking the selector switch was junked up and confusing the chip.

I will tweak the TFI plug just for good measure... I am dragging this pig to the 50th either way!!!

 

[garberz]

I will double check the TFI connector as well, but I think I might have found it.
It ran fine without the chip - well, it actually ran crappy until I introduced a vac leak, but it didnt shut off... chip back in = died.. repeat.. So I pulled the tune selector cable out of the chip which means it should default to position zero (my normal tune) and it ran good. Idled without dying for 20m.. then drove it 20miles.. no issues.. I will drive it around again today some more, but I am thinking the selector switch was junked up and confusing the chip.

I will tweak the TFI plug just for good measure... I am dragging this pig to the 50th either way!!!

Nice to hear you've got it pinned down. See you in a few days.

Mark

 

[nvrstuk]

Glad you found it!!

What software tune are you running?

EFI guy strongly suggested to me to not put in a selector switch for different tunes because the switch will/can cause problems. I'd never heard of this being a problem before but glad I listened to the expert! I have a couple buddies that have selector switches on Tweecer tunes- I'm running Moates Qtrhorse.