Losing fuel pressure when in boost.
Losing fuel pressure when in boost.
Well, I had my car on the dyno the other day. As soon as my car gets into boost my fuel pressure is plummeting.
My fuel system step up is as follows: walbro 485 fuel pump installed in the stock fuel pump assembly at Dynosty, pte 1200 injectors, -8 feed line which Ys into two -6 lines to the oem rails with -6 fittings welded on. I ran 180 degree fittings and T back together into a -6 line into an Aeromotive FPR. From there it is a -6 line into my flex fuel sensor and back to the tank via a CJM return fuel correction kit. My base fuel pressure is set to 47 psi at idle.
Thatv35guy came over and we swapped his entire in-tank fuel pump assembly into my car. He has the same in-tank setup, walbro 485 and CJM return fuel correction kit. With his assembly in my car my fuel pressure still dropped.
I have a deatschwerks fuel pump relay kit wired in. And I checked voltage at the pump when the car goes into boost and it stayed at 13volts. I also disconnected the vacuum line at the FPR and the fuel pressure still dropped.
What am I missing? What should I check? Any input would be greatly appreciated!
My fuel system step up is as follows: walbro 485 fuel pump installed in the stock fuel pump assembly at Dynosty, pte 1200 injectors, -8 feed line which Ys into two -6 lines to the oem rails with -6 fittings welded on. I ran 180 degree fittings and T back together into a -6 line into an Aeromotive FPR. From there it is a -6 line into my flex fuel sensor and back to the tank via a CJM return fuel correction kit. My base fuel pressure is set to 47 psi at idle.
Thatv35guy came over and we swapped his entire in-tank fuel pump assembly into my car. He has the same in-tank setup, walbro 485 and CJM return fuel correction kit. With his assembly in my car my fuel pressure still dropped.
I have a deatschwerks fuel pump relay kit wired in. And I checked voltage at the pump when the car goes into boost and it stayed at 13volts. I also disconnected the vacuum line at the FPR and the fuel pressure still dropped.
What am I missing? What should I check? Any input would be greatly appreciated!
Well, I had my car on the dyno the other day. As soon as my car gets into boost my fuel pressure is plummeting.
My fuel system step up is as follows: walbro 485 fuel pump installed in the stock fuel pump assembly at Dynosty, pte 1200 injectors, -8 feed line which Ys into two -6 lines to the oem rails with -6 fittings welded on. I ran 180 degree fittings and T back together into a -6 line into an Aeromotive FPR. From there it is a -6 line into my flex fuel sensor and back to the tank via a CJM return fuel correction kit. My base fuel pressure is set to 47 psi at idle.
Thatv35guy came over and we swapped his entire in-tank fuel pump assembly into my car. He has the same in-tank setup, walbro 485 and CJM return fuel correction kit. With his assembly in my car my fuel pressure still dropped.
I have a deatschwerks fuel pump relay kit wired in. And I checked voltage at the pump when the car goes into boost and it stayed at 13volts. I also disconnected the vacuum line at the FPR and the fuel pressure still dropped.
What am I missing? What should I check? Any input would be greatly appreciated!
My fuel system step up is as follows: walbro 485 fuel pump installed in the stock fuel pump assembly at Dynosty, pte 1200 injectors, -8 feed line which Ys into two -6 lines to the oem rails with -6 fittings welded on. I ran 180 degree fittings and T back together into a -6 line into an Aeromotive FPR. From there it is a -6 line into my flex fuel sensor and back to the tank via a CJM return fuel correction kit. My base fuel pressure is set to 47 psi at idle.
Thatv35guy came over and we swapped his entire in-tank fuel pump assembly into my car. He has the same in-tank setup, walbro 485 and CJM return fuel correction kit. With his assembly in my car my fuel pressure still dropped.
I have a deatschwerks fuel pump relay kit wired in. And I checked voltage at the pump when the car goes into boost and it stayed at 13volts. I also disconnected the vacuum line at the FPR and the fuel pressure still dropped.
What am I missing? What should I check? Any input would be greatly appreciated!
Based off what you're describing it sounds like its a problem with the regulator. You're probably not actually loosing fuel pressure but rather not building more pressure when you enter boost... When your manifold pressure increases it's resistance against the injectors to actually push fuel in. If your regulator isn't raising the effective pressure correctly your injectors won't do their job.
You've already eliminated the pump, it could be some sort of feed restriction. But the fpr should close the return line if that's the case...
I would look around for aeromotive fpr assembly instructions and take yours apart. Check that everything is OK/functioning correctly.
What boost levels are you running? And at what manifold pressure is the fuel dropping off? Do you know what the fuel pressure is while this happens?
Based off what you're describing it sounds like its a problem with the regulator. You're probably not actually loosing fuel pressure but rather not building more pressure when you enter boost... When your manifold pressure increases it's resistance against the injectors to actually push fuel in. If your regulator isn't raising the effective pressure correctly your injectors won't do their job.
You've already eliminated the pump, it could be some sort of feed restriction. But the fpr should close the return line if that's the case...
I would look around for aeromotive fpr assembly instructions and take yours apart. Check that everything is OK/functioning correctly.
What boost levels are you running? And at what manifold pressure is the fuel dropping off? Do you know what the fuel pressure is while this happens?
You've already eliminated the pump, it could be some sort of feed restriction. But the fpr should close the return line if that's the case...
I would look around for aeromotive fpr assembly instructions and take yours apart. Check that everything is OK/functioning correctly.
What boost levels are you running? And at what manifold pressure is the fuel dropping off? Do you know what the fuel pressure is while this happens?
When I was checking the car with thatv35guy's pump in my car the map sensor showed 5 lbs of boost. And my fuel pressure dropped to 38psi. It looked like the more boost the more the pressure dropped.
Is it possible that some kind of blockage in the feed or return line could cause my issues? I made my own lines. I was considering replacing them and see if that made any difference.
Thanks for the input. tThatv35guy and I were stumped when we were working on this issue.
I can only assuming you've checked your FPRs vacuum line?
while you're at it check to make sure you don't have any other leaks along your manifold/vac block, etc?
do you smell any leaking fuel?
while you're at it check to make sure you don't have any other leaks along your manifold/vac block, etc?
do you smell any leaking fuel?
I actually smoke tested the car. The only places where I had smoke come out were the air filter and the ProEFI boost control solenoid. It took awhile to get to those two places. So, I'm fairly positive that I don't have any vacuum leaks. And I don't smell or see any leaking fuel.
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You arent running out of pump, or having an internal leak at the pump module, because your not at high enough power yet, and you tried someone elses pump module.
The regulator isnt letting pressure fall, because you tried another one and it didnt help, and its unlikey you have 2 bad regulators. The vacuum line wouldnt even matter... all that will do is make it go up with boost. But even without a vacuum line on the regulator pressure should not be falling from its base setting except perhaps a few psi by redline when you pushing the fuel system to the edge.
Starting to sound like a flow problem, kinked line or other restriction in the feed line. I would say maybe a clogged up filter... but you tried someone elses pump module, so again, that couldnt be it.
The regulator isnt letting pressure fall, because you tried another one and it didnt help, and its unlikey you have 2 bad regulators. The vacuum line wouldnt even matter... all that will do is make it go up with boost. But even without a vacuum line on the regulator pressure should not be falling from its base setting except perhaps a few psi by redline when you pushing the fuel system to the edge.
Starting to sound like a flow problem, kinked line or other restriction in the feed line. I would say maybe a clogged up filter... but you tried someone elses pump module, so again, that couldnt be it.
Last edited by phunk2; Jan 3, 2015 at 07:37 PM.
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You arent running out of pump, or having an internal leak at the pump module, because your not at high enough power yet, and you tried someone elses pump module.
The regulator isnt letting pressure fall, because you tried another one and it didnt help, and its unlikey you have 2 bad regulators. The vacuum line wouldnt even matter... all that will do is make it go up with boost. But even without a vacuum line on the regulator pressure should not be falling from its base setting except perhaps a few psi by redline when you pushing the fuel system to the edge.
Starting to sound like a flow problem, kinked line or other restriction in the feed line. I would say maybe a clogged up filter... but you tried someone elses pump module, so again, that couldnt be it.
The regulator isnt letting pressure fall, because you tried another one and it didnt help, and its unlikey you have 2 bad regulators. The vacuum line wouldnt even matter... all that will do is make it go up with boost. But even without a vacuum line on the regulator pressure should not be falling from its base setting except perhaps a few psi by redline when you pushing the fuel system to the edge.
Starting to sound like a flow problem, kinked line or other restriction in the feed line. I would say maybe a clogged up filter... but you tried someone elses pump module, so again, that couldnt be it.
I'm assuming the car is running lean as you go up?
If not, bad pressure gauge?
Well, great news! The issue has been solved. Basically, I'm an idiot...
I fairly certain that my first FPR was not working properly. When I replaced it I didn't set the new FPR correctly. It was reading 47-48psi at idle. I pulled the new one apart, yesterday, and inspected it and put it back together. I then set the idle fuel pressure to 48-49psi. I went out and got the car in boost, my MAP sensor showed 5. and my fuel pressure went to 56psi. So, a little more than 1:1.
My only conclusion is operator error and I'm an idiot. Hopefully the car will go back on the dyno this week. Then I'll post up a build thread. Thanks again for all the replies!
I fairly certain that my first FPR was not working properly. When I replaced it I didn't set the new FPR correctly. It was reading 47-48psi at idle. I pulled the new one apart, yesterday, and inspected it and put it back together. I then set the idle fuel pressure to 48-49psi. I went out and got the car in boost, my MAP sensor showed 5. and my fuel pressure went to 56psi. So, a little more than 1:1.
My only conclusion is operator error and I'm an idiot. Hopefully the car will go back on the dyno this week. Then I'll post up a build thread. Thanks again for all the replies!
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