I pulled the sensor, and it looks fine. Just a little carbon on it. You would have to be way way rich to have raw gas going out the exhaust.

 

Ok, I got something new I am working on, and trying to figure out. I check the voltage at the pumps tonight, and got 6.8 volts Well; I what I don't get is after some suggestions on this board I wired a second step down resistor(at the front of the truck) in parrallel with the other resistor. So, this should have gave me something in the range of 9 volts correct? Well; from there I tried putting a jumper in the hi/low relay spot as someone else suggested:



Still the same voltage at the pumps. So; I also tried just removing the resistors at the front of the truck and running a jumper wire down there. Still get the same 6.8 volts at the pumps.

How can test for the high voltage which you should have at WOT at the pumps?

Maybe this is my problem; someone please help

 

it's top a secret code name for a Suburu WRX STI, or as Bill calls it a "scooby"

edit: sorry for the hijack Casey..Hope you get it figured out

 

The only way I can think of to measure the fuel pump voltage without being on a dyno is to splice test wires from both sides of the fuel pump power lines and run them into the cab and have someone monitor the voltmeter when you go WOT at some safe street location. The voltage should go up when you splice in another resistor in parallel or jumper the relay, it just does not make good sence that the voltage does not change. Measuring at the wrong place? Jumpering the wrong pins? Must be something like that I'd think.
Charles

 

I don't know; I did the jumper just as in the picture. And what really should have worked is the fact I totally took the resistor out of the circuit. Something isn't making senses here

I can't take it out and test it right now, and probably not for a day or two because the 3 day flood has set in on us

 

Casey, the step is on the ground side. The pumps should have full battery voltage all the time. When you are not at WOT, the ground goes through the resistor and steps the overall pump voltage down. When you go WOT, it switches to the high side relay which directs the pump ground to full ground, and full battery voltage. You might want to check your grounds, sounds like you aren't getting full ground.

 

Can I check the pump voltage by pulling the connector apart and testing the incoming voltage then? I was checking it by unplugging the connector. There are two rows of wires. One row has a total of 4 wires and the other 2 wires. The row with 2 wires which go to the pumps were 6.8 each. In the other 4 there was one that was a normal 12v, but it is for the fuel guage.

 

Have you considered that an exhaust leak might be giving you false lean readings?

 

Casey,
What we have done in the STi world is to run heavy gauge wire from the battery to the relay. The longer the run the heavier the wire. 8-10ga works in most cases. I will find you some flow charts for the Walbro's at various voltage. They drop like a rock as the voltage tapers. If memory serves right at 10 volts the output was less than 50%.

 

A friend of mine with a Buick Grand National told me they are actually running a hot wire from the alternator to the pumps so they can get max voltage.

More I think about it; the more I truelly beleive it's a electrical problem to the pumps. Even to know I am seeing 50#'s worth of FP, I do not beleive it's enough. On my stock pumps I would see close to 60#'s before I started having problems. I gotta get the wiring diagrams, but I beleive I know the general area to start looking.

Now if it would just stop raining

 

Remember presure is only part of what you need. Flow is just as important. The two need to work together at WOT. At idle to partial rpm's it is very easy for the pressure/flow to maintain. Go WOT and everything changes. Fortunately for the Subaru world we can monitor our fuel flow and injector duty cycle. Very easy to pinpoint problems.

Voltage is the key to those pumps.