fuel pump troubleshooting/adjustments
 

The other night,my car cut out while driving. Seems i have no fuel pressure. Recently installed a new fuel pump, have maybe 150-200 miles on it.

Pulled the pump to be sure it was still on hanger and connector was seated, looks good. Next went to manual to locate check connect, was going to jump and trace power, but it's not there. But, looks like all it does is link the check connector prong on the circuit opening relay to ground. So, question:

Can i just connect the checker connector to ground and get power to pump when the key on acc?

Also, looking at the diagram/manual made me think about rewiring the pump,there is a lot of thirty year old wiring and a couple seemingly unnecessary components.First, and certainly not needed, is the resister relay under passenger light/airbox location. Looks like its to regulate voltage, thinking i'm modded enough full power to pump can't hurt. Less sure about the circuit opening relay, but thinking i may eliminate it as well. here is what I am picturing:

Power from the fuse block, normal fuel pump location, to ground through a 4 pin relay to activate relay. power from battery to pump through activated relay(probably a 15-20 amp fuse here). Pump ground to chassis. I realize this would give it power when key is in the ACC position, so considering an inertia switch between fuse block relay activation in case of accident.

I'm sure if this is right, there is a write up, i will look into it; somehow that hasn't occurred to me until now. But i typed it all out, so...opinions? tweaks?

The fuel pump jumper is on the right side of the car, near where the fuel pump resistor is located, and isn't involved with the ecu check connector. Ground it out and it runs the fuel pump with the key on. This is used when priming an empty fuel system.

That fuel pump resistor/relay pack is to help keep fuel pressure low while you're under idle conditions. It does regulate voltage of the fuel pump, reducing output, but is meant for low load conditions. If the engine is under load, the relay attached to the pack goes closed circuit, and the resistor is bypassed. By eliminating this feature, you are adding a lot more recirculated, heat-soaked fuel back into your fuel tank. No good reason to eliminate it, just make sure it is working properly.

No mention in the post that you checked the fuel pressure regulator located under the UIM. If that thing gets blown out, its sure not gonna hold any fuel pressure for you. If you are talking about fuel pressure problem under boost, you might have a bad fuel pressure regulator solenoid on the vacuum spider.

Sanity check, how do you know you don't have fuel, and it wasn't another gremlin that cut your engine?

The check connector(yellow, 2-pin) is not there for sure, in fact that whole emissions harness is gone
https://cimg9.ibsrv.net/gimg/www.rx7...c03ac7f72f.jpg
. I was talking about making a new one at the circuit opening relay(under dash).

I hadn't thought about the hot gas being recycled through though. But the resistor relay looks easy enough to pull and test.

I maybe should have mentioned i went haltech maybe 1000 miles ago, That was my first test, shows 0 pressure. Secondly i pulled the connector at the pump and used a meter while i had my wife turn it over. Last, i had no back pressure when i pulled the pump. And this is why i wanted to use/rebuild that check connect, to trace the voltage and see where i lose without having to crank.

The fuel regulator, rails and injectors were done when the haltech was. i guess i can check if the regulator is bad, wouldn't be the first time something went bad way before expectation.

The complete re-wire just popped into my head while i was looking into where that check connector was, and what to do with it gone.

Well that's an entirely different matter then. A lot going on here.

Where are you measuring your pressure? First, put your pressure gauge on the pump, make sure it is a dead end, and see if the pump itself is putting out pressure. If you are getting any reasonable voltage to the pump, you should be getting some sort of static pressure. Suspect number one.

With the haltech, how are you triggering the resistor pack relay? If you aren't controlling it, then you will want to patch it out.

Thanks for your help, i did get it going.
Unfortunately, i pulled a bonehead move and touched multiple things without checking in between, so i can't say for sure where my problem was. I can say it was either a poor ground connection or a loose connection between the battery and the relay.

My man Pyroman! How can someone check the fuel pressure regulator located under the UIM? The FSM does not mention anything about it. Also I would like to ask where exactly the fuel pressure regulator solenoid is located. Where is the vacuum spider? Is it behind the UIM?

Thanks in advance.