oil pressure switch delete?

[ktmoutfront]

The stand alone harness should have a trigger wire to fire a relay for the fuel pump. Then the one wire from the pump to said relay. That relay can have static power to it full time. Power out only when the PCM tells it to. The old oil switch wires are useless. Unless you use it for the feed to the pump from the new relay.

 

[ktmoutfront]

Paying for a premium membership will allow pictures to be loaded. Worth the money for full site access.

 

[Blue85]

You are asking for help, but you're not listening to the answer. People are going to start ignoring this thread.

But you have to give your LS PCM control of the fuel pump relay, no matter what you're doing with the oil pressure switch.

need to know how to delete this from the pcm seeking it

It's already been stated that the PCM doesn't seek it. You could attach that switch to oil pressure on the engine and it might get the fuel pump sort of working how you want, except you might have difficulty restarting without cycling the ignition. Again, leaving the fuel pump relay controlled by the stock TBI ECM is not the correct way to do this swap.

"The oil pressure switch serves as a backup for the fuel pump relay to help prevent a "no start” situation. If the fuel pump relay was found to be inoperative, the oil pressure switch circuit should also be tested to determine why it did not operate the fuel pump."

Logically, you would run a wire from pin 9 of the red/green PCM connector (not blue) to the DK GRN/WHT wire at the relay.

The stand alone harness should have a trigger wire to fire a relay for the fuel pump.

If you still don't believe us that you have to connect the fuel pump relay, contact whoever provided the stand-alone harness.

You can post pictures here after you've made a certain number of posts. You can link to pictures hosted somewhere else whenever you want.

 

[Todd6500]

i guess you cant post pics in this forum...... so... let me paint the picture.....

stock 1988 tbi k5 blazer.
stock wiring harness is all taped up to the firewall.
I CONNECTED THE MAIN BUS WIRE TO THE BATT/ALT/JUNC just like it would have been stock.... i did this to maintain all stock lights, fuses, ignition, and yes; fuel pump.
the stock fuel pump housing, has a late 90s high psi fuel pump installed in it now.

new stand alone wiring harness and stock PCM installed for 5.5 ls. VATS cleared. it does start and idle, and respond to throttle.... for 5 seconds...

oil PSI sensor switch has a orange (hot) and a brown (fuel pump?) wire.
the brown and orange run to the fuel relay.
connecting them, the fuel pump runs non stop.
disconnecting them, fuel pump primes and starts.

It seems no-one is quite familiar enough with the system. The pcm turns on the fuel pump via a relay to pre prime the system. The oil pressure switch is in series with the relay's coil power. If there is no oil pressure after the initial pre-programmed time when the pcm removes power from the relay, it opens and the pump shuts off. This is to prevent the engine from running without oil pressure.

 

[Blue85]

It seems no-one is quite familiar enough with the system.

You mean, other than the few people who've already explained it above?

The difference between how the original system is supposed to work and how he has it now, is that the oil pressure switch is not connected to the engine.