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rang-a-stang 10-13-2018 10:40 PM

GM TBI Fuel pump wiring
I plan to run a oil pressure safety switch (OPSS) in my system. I found a Holley 3 pin OPSS and think it seems to do what I want to do. Attached diagram is a doctored diagram I downloaded from Holleys Website.

This Holley diagram is very different from how the GM TBI system seems to run. The GM TBI system looks like the computer trips the fuel pump relay by sending a signal down the DK GRN-WHT wire, I have read for only a couple seconds when starting (when there is no oil pressure). 12V goes from the ORG wire through the relay contacts and out through the grey wire, then a fuse, to the Fuel pump. When oil pressure comes up, the oil pressure safety switch closes and takes voltage from the ORG line, sends it directly to the GRY line, through the fuse to the fuel pump, and keeps the fuel pump on (basically bypassing the fuel pump relay) so long as there is oil pressure and 12V on the ORG line (Key is in the ON position).

Here is how I would incorporate the Holley OPSS

So my questions are
1) Am I understanding this circuit correctly
2) I believe this to be another version of the Holley switch. Anyone have a better oil pressure safety switch? &pd_rd_r=565eee41-cf5d-11e8-a4cb-8f9c782aa20c&pd_rd_w=l9MrI&pd_rd_wg=TzEkE&pf_rd_i= desktop-dp-sims&pf_rd_m=ATVPDKIKX0DER&pf_rd_p=7d5d9c3c-5e01-44ac-97fd-261afd40b865&pf_rd_r=TNCHCJYVK8VPAGBTWDTA&pf_rd_s= desktop-dp-sims&pf_rd_t=40701&psc=1&refRID=TNCHCJYVK8VPAGBTWD TA

babywag 10-14-2018 08:54 AM

Just use the stock Jeep OP switch, or use a '94-'95 TBI truck OP switch.
Wire per TBI diagram and done.

rang-a-stang 10-14-2018 11:42 AM

My rig didn't have one (engine poorly swapped in from a 73). I have the OP sensor but not a switch. I assumed that was factory. Looking at the 79 diagram I see it now. Rockauto has the original switch for $5.

Thanks for the sanity check.

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