Do LP's run all the time?...

[Mezmorized]

Once the LP has the signal to run, does it run all the time? Or does it run intermittent?

Since it gets the signal to run with oil pressure, I'm thinking it runs all the time. Wiring it up to be live with the key on could be an issue and obviously that's where the oil pressure comes into play.

Right?

Talking about OBD1 here

 

[ak diesel driver]

yes they do. the safety issue your referring to is why you should do the OPS relay mod. 2 diff configurations. 1 acts like stock 2 gives you fuel pressure pre prime with the glows. both these diagrams are for pre prime

 

[JMJNet]

The OPS is supposed to be a fail safe mechanism.

When you are in accident, hopefully, the engine oil pressure goes to 0 and stop the LP so the fuel does not spill.
At least that is the idea.

In reality, yes, as long as the engine is running, the LP suppose to run.
Problem start when LP is not pumping when engine is running due to bad OPS.
Mostly happened in a 95 and before.

The relay mod will remedy it so that the OPS does not have to pass the electric current to the LP to make LP runs in a non-emergency situation.
Makes it more reliable since the OPS is the weak link in this circuit.
It does not have the proper design to pass electric to run the LP.

Hope that makes sense.

 

[Mezmorized]

Ok, that's what I tought. Does anyone have a slightly larger pic of that wiring diagram? When I zoom in, I can't make out some of what is written.

 

[Mezmorized]

I found a pic of the 2 relay mod that I could read. Not the single relay one though.

 

[jrsavoie]

Just do the dual relay upgrade and skip the single. It'll only take an extra 20 minutes, if that. You can check my threads on doing the upgrade to the 95 Tahoe