SO here it the deal. While in the middle of tuning my car we realized the fuel pressure was droping when hitting boost. SO i changed my fuel filter, checked the fmu and did a few other things that did not fix the problem. SO i assumed it was the walbro 255 in the tank. SO i buy a new pump install it and the car is still doing the same damn thing. When i start the car up i have 40+ psi but after driving for a while (1/2 hour to 45 minutes) it gradually keeps dropping until eventually the car dies like it ran out of fuel. Turn the key off and on a few times and i get some pressure built up to drive a little further. ANy ideas on what it would be. I think:
#1 losing voltage at the pump
#2 fuel pump solenoid is going bad
#3 pump is overheating
#4 car is just trying to piss me off
Also I can not get the fuel pressure to rise with the cartech FMU but i think that has to do with whatever the other problem is. Car also has over 3/4 tank of gas. Any help is much appreciated
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was this setup ran and tested before??
or is this during an initial tune?
how bout a pic of how you have the FMU setup.
sorry for the late reply, i was on my honeymoon. But nothing has changed on my fuel system in at least 2 years and it was fine before, thats why i am stumped
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My eco runs at 60psi, my wifes is around 55psi. Thats at idle.
Its either your FPR or your return.
If the pump is bad it will just DIE.
-Chris
check your voltages during the condition. make sure you have battery voltage (+) &(-) when this is occuring.
IamRascal wrote:My eco runs at 60psi, my wifes is around 55psi. Thats at idle.
Its either your FPR or your return.
If the pump is bad it will just DIE.
Yeah as of right now i can not even get the fuel pressure to even go above 40psi.
Yeah today since i finally got some time im going to start checking the voltages. I believe i should be getting around 12volts at the pump, does that sound correct?
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it should be 12 volts and the pump relay and at the pump. I see your boosted maybe your factory regulator is bad or going bad. I've seen some case when boosted causes a factory regulator to go bad pretty quick. Did you try pinching your return line closed with a set of vise grips to see if you pressure would go higher. You also said the fmu won't raise pressure either. This is in boost right?
It might have something to do with the fmu. Not sure if the one you have is similar to the procharger sells with some of there kits but the one that was on my t/a when i bought it wouldn't raise the pressure either. After i took it apart the diaphragm on the boost side some how got a slit in it and separated off of disk that pushed on the plunger type thing inside.
Also just curious did this problem just happen when you were tuning or before? Or did you notice it before hand and it gradually got worse?
Blown Phoniex wrote:it should be 12 volts and the pump relay and at the pump. I see your boosted maybe your factory regulator is bad or going bad. I've seen some case when boosted causes a factory regulator to go bad pretty quick. Did you try pinching your return line closed with a set of vise grips to see if you pressure would go higher. You also said the fmu won't raise pressure either. This is in boost right?
It might have something to do with the fmu. Not sure if the one you have is similar to the procharger sells with some of there kits but the one that was on my t/a when i bought it wouldn't raise the pressure either. After i took it apart the diaphragm on the boost side some how got a slit in it and separated off of disk that pushed on the plunger type thing inside.
Also just curious did this problem just happen when you were tuning or before? Or did you notice it before hand and it gradually got worse?
Ok i have completely gotten rid of the factory FPR. I makes no difference with it there or not so i have the cartech FMU doing the regulating and correct i will not raise during boost. Fuel pressure actually drops. Have not tried pinching my line shut but i will give it a try later. Last night i took all my fuel lines off and blew them out just to make sure there were no restrictions put it back together and now the car holds 40 psi at idle until i hit boost which it would not do before. Before it would fire up to about 34psi and then just gradually drop while idling. But yeah i think its the fmu now. I notice last night when i tore it apart the diaphram did have two little slits in it so i just but some electrical tape on them just to see if it would help(it know rigged but just seeing). But i started noticing the fuel pressure issues during tuning so later today im going to reflash the factory tune and just change my injector constant to what i need for the 550cc injectors and take it for a easy spin. Thanks for the help and any more opinions are needed
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any more opinions? I just rebuilt the fmu with everything and still can not get the pressure to rise. Checked voltage every where but at the tank and they all checked good. Im changing the fuel filter to a wix tonight to see if that helps. but any more things/ideas to look at would be great.
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