5.3 fuel pressure issues
Thread Starter
Teching In
Joined: Mar 2017
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5.3 fuel pressure issues I finally got a DBW pedal to work, I haven't mounted it yet but thats no big deal. I wonder if you can help with my new problem though. I got the motor in and running. It is a 2005 5.3 with flex fuel injectors and a mild texas speed cam. Texas speed tuned my computer for the cam and injectors. It will start up and idle like a champ as long as you want it to. If you touch the throttle petal though, it will rev slightly then fall on its face. You can smell it running very rich. I first thought the problem was the 02 sensors were too close to the end of the open headers (I'm running the Racing Innovation shorties). I put 18" of flex pipe on the end of the collectors. Still have the same problem. I hooked up the fuel pressure gauge today. When you turn the key on, it goes to 70psi, which I think is way too high, then bleeds off when the pump shuts off. It also holds the 70psi while its running. I have a Walbro 255 in my tank going through stock fuel lines to the stock Sonoma fuel filter then to a Corvette style filter/regulator. I am wondering now if I have a leaking injector since the pressure leaks down so fast. But why is the psi running at 70? Any ideas are very much appreciated.
Fuel pressure From what I understand some of the aftermarket fuel pressure/filters are not very good. You may try another brand to see if the pressure comes down. Get the TORQUE app, install it on you phone or tablet and link it with a bluetooth adapter plugged into the ALDL. You can monitor your long and short range fuel trims to see what's going on. When I did my DBW it would run just fine in the garage but fall on it's face under load. Turns out there was a compatibility problem with the tune/APP/TAC.
Thread Starter
Teching In
Joined: Mar 2017
Posts: 6
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my fuel system consists of a walbro 255 in my tank running to a WIX fuel filter/regulator. That goes to the motor from there. The return runs from the filter to the tank, all using factory lines except the line from the filter to the fuel rail, it is new. I have been connecting the fuel pressure gauge to the passenger side frame rail.
I am not familiar with the TORQUE app but it might be something I need to look in to. Will it work with OBDII vehicles? My Sonoma that the 5.3 is in is a 98 model.
I am not familiar with the TORQUE app but it might be something I need to look in to. Will it work with OBDII vehicles? My Sonoma that the 5.3 is in is a 98 model.
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70 psi fuel pressure when your tune is probably based around a 58psi base pressure is something you gotta fix first before you get much farther. IMO the corvette stye set up is nothing but trouble.
with the scanner you will look for diagnostic trouble codes first
then you will look at throttle position values or voltage. 0 volts is closed throttle. 5v is wfo.
with the scanner you will look for diagnostic trouble codes first
then you will look at throttle position values or voltage. 0 volts is closed throttle. 5v is wfo.
Thread Starter
Teching In
Joined: Mar 2017
Posts: 6
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Well I got it figured out. It wasn't fuel pressure or dbw pedals or anything like that. It was the tune. For anyone needing a computer tuned, I wouldn't recommend TEXAS SPEED AND PERFORMANCE. I paid a lot for their mail order tune and it wouldn't rev past 1500rpm. I then had to pay another tuner to come to my shop to tune it. If your in the upstate SC, Charles Barber is the man for tuning. It runs like a champ now!
