I've read countless threads on this site regarding swapping from TPI to Carb. Almost all of them mention the fact that the Oil Pump Primer will de-activate the Electric Pump after a certain amout of seconds, causing a stalled engine.... but how could this be?

I removed the entire TPI harness from the engine bay, installed my Carb, Distributor and new AFPR.... then customized the original wiring to allow the stock electric pump, and oil primer to receive voltage (since they share the same relay) through a 12 volt seperate from the ECM;

Fuel Pump Relay (5 wires):

Thick Orange (Constant to Battery)

Thick Red (Current Feed Shared by both the Electric Pump & Oil Primer)

Thin Tan/White or Orange (To Fuel Sending Unit)

Green/White (12 volt, which originally went to the ECM, but is now wired directly into the fusebox)

Black/White (Ground, which I grounded on the firewall)


After the above, I don't see how the primer has any say.... maybe the ECM (through the primer's input) had some say, but with the ECM removed, both the primer and the pump will now be receiving constant voltage through the relay, from the battery, by way of a 12 volt (key on) source.

If anything, the oil pump primer will now be running constantly until the key is turned off.

Does anyone feel that this is wrong, and if so, could you kindly explain why?

Thanks!

 

I'm not sure what you're talking about with the oil pump primer but, the factory fp relay is powered direct from the battery (as stated), the black wire is relay gnd, green/white +12 from the ECM switches the relay, and usually a heavy gauge tan/white wire is what runs to the FP. There is a small orange wire the runs inside to the ALDL connector for FP test.
The only other thing tied to the FP relay is the oil pressure switch (well that, and the MAF relay) but, isn't something that causes the FP to shut off.

 

the fuel pump primes by the ECM triggering the relay, then shutting it off after 3-5 seconds, then, once the engine starts, the oil pressure switch trips and supplies power to the FP, on my 89, it does not use the OP switch to trigger the relay, it uses the switch to directly supply power to the FP, my car will start without the FP relay, just very long crank time(needs to build oil press. just cranking , to trip the switch)

 

Thanks guys!

It's definitely different with my current set up, and explains why those posts that I was reading were concerned about the Oil Switch.

What I did, was, I eliminated the ECM entirely. Removed the harness, and cut off the leads from the Fuel Pump Relay that lead to the MAF and the ECM.

From there, after leading the green/white wire to the fusebox, and black/white to a seperate ground.... I lead the thicker Orange wire to the battery, and ran the last two (thick red, and thinner orange) down through the fender by the ECM.

The last of two wires bypass the ECM (they did this stock), and connect into a 'clear' connector, with the thin orange wire leading to the ALDL (like was mentioned above).... and the thick red wire leading to the electric pump.

What had me scratching my head, was did the Oil Pump Primer shut off by way of the ECM.... or is it designed to do this by itself (like a stand alone piece)?

With my ignition in the 'key on' position, it sounds as if it's priming indefinitely, and not shutting off..... unless I have a defective switch?

Anyways, thanks for the reply guys!!

 

what oil pump primern are you talking about, if it is wired like that, the pump will run any time the key is on

and if you are talking about running the pump by jumping the pins in the ALDL, there was no special tool, it will run constant, is was designed to test the pump

 

The Primer I mean, is the switch that's to the left of the Oil Pressure Gauge (on my year, the primer & gauge are connected to the right of the distributor).

So utlimately, I wouldn't even need to have the Primer connected then.... I'd just have longer cranking time when starting the engine?

What had me most concerned, was reading that the electric pump was energized by the primer.... and if the primer failed, then the fuel supply would be stopped.

Plus I was reading how if the car was in an accident, that the primer was designed that when no oil pressure was prevalant.... even with the key in the on position, it would dis-engage the electric pump (via the relay) for safety.

But yes, the way I have everything wired, my primer is on constantly. If it's not even needed anymore, I should just disconnect it from the relay, no?