Checked the service manual and did not get anything, can you please tell me what is the normal voltages in low speed (idle) and high speed (boost). I am getting 4volts at idle and 10.9 volts in boost I am thinking that the fuel pump is bad causing the voltage to drop can anybody please verify thanks.

 

How did you measure/log the pump voltages?

 

^ I removed the back seat open up the inspection plate used a digital meter and tested it with a friend driving.

 

Thanks I assume you just tapped on the wires to the pump before the connector.
I remember seeing in the tuning forum section voltage numbers awhile back. Try searching on that section. I'll look for it myself.

 

Depending on the DC resistance of your pump (aftermarket vs stock) you will get different voltates at the pump terminals as lower pump resistance in higher performance pumps will cause the stock fuel pump resistor to drop more voltage with the increased current demands. 10.9v at WOT is quite normal FYI as the stock wiring is quite unacceptable especially considering the 10 foot run that it has to make to get to the back seat of the car.

 

yes I tapped the wires before the connector, I am running a walbro GSS342 thing is I ran a direct from the battery to the pump and when I attached it the pump started grinding when the voltage increased to 11.6 volts my idle felt much smoother and my AFR's at WOT got better. Don't get me wrong but I don't think 10.9 volts is good at all since the pump is rated at 12volts for 43.5psi correct me if I am wrong.

 

So it doesn't grind at 10.9 volts but it grinds at 11.6 volts? I'm sorry, I'm lost on this one, never heard a pump "grind".

 

it sounding like if the gears in the pump is sticking with more voltage not the norma; wining noise associated with the Walbro's, what I did not mention is the reason why I am trying to find out what voltage the pump operates. About 3 days ago while in traffic my car started cutting off I taught it was the IAC screwing up but when I restarted if worked fine, then my afr's started going wack from pull off the car started leaning out until 2k rpm and with my tuned AFR of 11.6 on pump it stated going to mid 12's at WOT don't matter how much fuel I would throw via ecu flash it would still be lean I taught it was a vac line but after changing all it still did the same thing. This is what lead me to pump I also tested the fuel pump relay and its .70ohm the service manual said it should be within .45-.65 value at 20*C but where I live our min temp will be 24*C so I assume this would be normal.

 

the resistance readings of the pump should be around 0.7 ohms. remeber when checking continuity make sure voltage is off. True continuity is .5 ohms or less if its below this its bad and if the readings are too high its bad. If these readings are good the pump is good hands down...

 

^ nice I will test that tommorow and see what the pump reads, but can anybody just measure the voltage before the connector at idle and in boost not only the community.

 

also these pumps are designed to operate on 11 to 15 volts. Your voltage is a little low. try jumping the relay with a jumper wire. If this works your relay might not be energizing.

 

do I just unplug the 2 pin jack and jumper it? or do I have to jumper it with it pluged in? also I found this in the search

https://www.evolutionm.net/forums/ev...ormal-ops.html

scroll down to the bottom it appears that my voltages are way off.

 

update.......... got through the pump was bad and causing the voltage to drop, thanks for all the help.

 

Was this on the originnal stock pump or a Walbro? At any rate you caught it before it blew your motor.

 

^ The pump that was in was a Walbro GSS342 the main reason I did not blow is because I had a AEM UEGO and I was able to catch it when I saw the AFR's going lean.