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Discussion Starter · #1 · (Edited)
Here are the specs:

BL fuel kit and BL67 turbo kit:

twin warlboros
aeromotive fpr
750cc injectors
vpc d chip/afc fuel controller

The symptoms:

ever since I had my fuel system installed I have been adding at least %30 or more fuel using the afc to get acceptable A/F ratios on low boost so today I hooked up a fuel pressure gauge to see what is going on.....

fuel pressure does not rise 1:1 with boost. Base fuel pressure is set to 44psi. I set the boost controller to run off of the wastegate spring (15psi) and fuel pressure only rose to 49psi, I was expecting close to 60psi. While flooring it in fifth and watching the fuel pressure gauge I saw the pressure rise to 49psi for a second or two and then actually saw it drop close to base pressure. :ugh2:

Another symptom is that the fuel pressure spikes when I let off the throttle at high rpm and high load, I am not sure if that is normal or not but I want to put out every little detail I can to try and gather some ideas.

When I pull the fuses for each individual fuel pump pressure drops so I guess that is good. What I'm not sure is normal is that fuel pressure drops much more drastically when one of them is pulled vs the other.

Also, every time I drive the car and let it sit in the garage overnight the garage ends up smelling like a gas station.

:EDIT:

forgot to add that fuel pressure drops to zero instantly as the car is shutoff
the fuel gauge also doesn't update until I start driving away from the gas station, it also "lies" to me saying I have well over a quarter tank when there is maybe 2 or 3 gallons left in the tank.

:EDIT:

I've looked for and fixed obvious external fuel leaks at the fpr, etc. I've checked the fuel filter (aftermarket, I have replaced the stock one recently) and it doesn't look clogged or anything.

Thanks in advance for any help, this car is driving me nuts. :blast:
 

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Boost4fun
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Maybe the FPR is damaged somehow.. Sounds to me that way. Try to put some boost on it from an external source like a compressor and check what happens. Is the fuel pressure increasing then or not.. If not it´s most likely that thing is bad.
Gerd
 

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Are you certain that both pumps are functional? I would check both pumps and then the relays/fuses?

vnt :bigthumb:
 

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Yup get your voltmeter back there and look for power to each pump. Then like you said pull each fuse and make sure each one is working. If your pumps are fine you got a bad fpr or pressure source feeding the fpr is blocked or leaking.
 

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Discussion Starter · #5 ·
I tested the voltage to the pumps. I got about 13.9Volts going to each of the wires that feed the pumps. This was tested at the point where the wires go into the tank. Is that the right location to look for the voltage?

Also did the fuse test one more time and got pretty much the same result. Take one fuse out and pressure drops about 10 psi, replace previous fuse and take the other one out and the car will come close to stalling if not stall completely due to lack of fuel.

To add to the problem, I noticed today that somehow my static fuel pressure has dropped about 10psi down to 35psi without me making any changes. When removing the vac source from the FPR the pressure doesn't rise the slightest bit. Attempts at adjusting the the fuel pressure using the adjusting bolt higher than 35psi were unsuccessful . :ugh2:

Bad FPR or is there a possibility that there is something going on at the pump end?

mike91t said:
Yup get your voltmeter back there and look for power to each pump. Then like you said pull each fuse and make sure each one is working. If your pumps are fine you got a bad fpr or pressure source feeding the fpr is blocked or leaking.
 

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SupraSol said:
I tested the voltage to the pumps. I got about 13.9Volts going to each of the wires that feed the pumps. This was tested at the point where the wires go into the tank. Is that the right location to look for the voltage?

Also did the fuse test one more time and got pretty much the same result. Take one fuse out and pressure drops about 10 psi, replace previous fuse and take the other one out and the car will come close to stalling if not stall completely due to lack of fuel.

To add to the problem, I noticed today that somehow my static fuel pressure has dropped about 10psi down to 35psi without me making any changes. When removing the vac source from the FPR the pressure doesn't rise the slightest bit. Attempts at adjusting the the fuel pressure using the adjusting bolt higher than 35psi were unsuccessful . :ugh2:

Bad FPR or is there a possibility that there is something going on at the pump end?
Def sounds like a bad fpr to me, is the vac source free of leaks?

vnt :)
 

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Discussion Starter · #7 ·
yup, vac source is definitely leak free. The fpr didn't even respond when removing the vac source completely.

vntperformance said:
Def sounds like a bad fpr to me, is the vac source free of leaks?

vnt :)
 

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fpr dropping to zero when you tunrn the car off is normal
fp not regulating below 35 is normal as well, the orifice in the reg is too large...
you may have a leak in one of the lines in your tank. do you have two separate lines or a y? how is your regulator set up? (center return in to the side port, one port plugged, bottom to return)?
 

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Discussion Starter · #9 ·
I think you may have misread. I can regulate below 35, easily in fact. I can't raise it above 35 psi anymore. I honestly do not have a clue what it looks like back there as I didn't install the fuel system. From what I understand I think with the BL kit you use two separate lines coming from each pump since I have two fuel filters in the mix. The return is BL style, where one pump feeds one end of the rail and the other pump goes into the fpr before feeding the opposite end of the rail. The center of the rail is plugged. The return is off the bottom port of the FPR.

Morefaster said:
fpr dropping to zero when you tunrn the car off is normal
fp not regulating below 35 is normal as well, the orifice in the reg is too large...
you may have a leak in one of the lines in your tank. do you have two separate lines or a y? how is your regulator set up? (center return in to the side port, one port plugged, bottom to return)?
 

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SupraSol said:
forgot to add that fuel pressure drops to zero instantly as the car is shutoff
the fuel gauge also doesn't update until I start driving away from the gas station, it also "lies" to me saying I have well over a quarter tank when there is maybe 2 or 3 gallons left in the tank.
This could be the float in the tank. Sometimes it will get stuck when you install the second pump.
Good luck.
 

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Boost4fun
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As I recommended it formerly already try to put some external pressure to the FPR (1 bar for testing) and look how the pressure behaves. If there is no major change the FPR is bad. You can also check th pumps by pulling one gas line after the other and check the flow..
It must be one of both causes.-Either a pump or the regulator...
Gerd
 

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Discussion Starter · #12 ·
Gerd,

I didn't have access to a compressor this weekend. That is a great idea though. I will probably rig something up and use a simple bicycle pump to pressure a hose leading to the FPR. The pump test you mention sounds kinda messy, so I will leave that for last! :)


Hefti2 said:
As I recommended it formerly already try to put some external pressure to the FPR (1 bar for testing) and look how the pressure behaves. If there is no major change the FPR is bad. You can also check th pumps by pulling one gas line after the other and check the flow..
It must be one of both causes.-Either a pump or the regulator...
Gerd
 

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Boost4fun
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Yeah, the gas line check is surely a little messy;) Just place the line in a can or so and watch if there is a good flow or not as last thing.
Before that try to pressurize the FPR and see what happens..
Good luck and keep us posted
Gerd
 

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When cars say, "NO MORE!"
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SupraSol said:
Also did the fuse test one more time and got pretty much the same result. Take one fuse out and pressure drops about 10 psi, replace previous fuse and take the other one out and the car will come close to stalling if not stall completely due to lack of fuel.
This should not happen. The car should run just fine with only one pump running it especially at idle.
 

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SupraSol said:
I think you may have misread. I can regulate below 35, easily in fact. I can't raise it above 35 psi anymore. I honestly do not have a clue what it looks like back there as I didn't install the fuel system. From what I understand I think with the BL kit you use two separate lines coming from each pump since I have two fuel filters in the mix. The return is BL style, where one pump feeds one end of the rail and the other pump goes into the fpr before feeding the opposite end of the rail. The center of the rail is plugged. The return is off the bottom port of the FPR.
Running one Walbro, I've had the fuel pressure down to like 18psi. With two Walbros, I can't get the fuel pressure below 40psi at idle. Sounds like one of your fuel pumps is dead/not connected or fuel line came off.
 

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hardtopper
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Hau said:
Running one Walbro, I've had the fuel pressure down to like 18psi. With two Walbros, I can't get the fuel pressure below 40psi at idle. Sounds like one of your fuel pumps is dead/not connected or fuel line came off.

BINGO! just what I was thinking. If you have them y'd in the tank and one is loose then the flow could

1: be pushing your float down and making you look like you have less feul then you do.

2: causing one pump to go to fuel rail and back into tank overworking the pump and not getting all the pressure to the rail(least path of resistance)

3: when the other pump is on there would be no pressure to the rail and the car would die.
 

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I have to agree with the above comments. My gutt is telling me that the problem in the tank.

I went through a identical situation...... Though both of my pumps were functioning properly, I was dropping preasure on the dyno when boost was turned up. The culprit was the little metal nipple/cap that sits on the top of the walbro pump. It had worked its way up my fuel line attatched to the pump sitting sideways blocking fuel.

WEIRD!!!

Goodluck on your hunt for more fuel................
 

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Any news Sohil, I think im experiencing a very similar problem with my car!!!

I was at the light and the car just died and fpr dropped right at 10psi and the car starts and I can hear the pumps but not as loud as usual. Any ideas? Power is reaching both pumps and grounds are good also!
 
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