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I recently purchased a new secondary rail and Aeromotive FPR to solve my fuel pressure issues. Now my fuel pressure is 20psi while the engine is running, regardless of what rpm it's running at. It also will not rev above 5K, but this could be an ignition issue. I know it needs to be tuned, but I believe the majority of the problem (with the exception of the ever-present oil issue) is stemming from the fuel pressure only reading half of what it should be.
I took some video of the motor running and also took data logs in the event that those will help. But, like I said, it holds steady at 20psi while the motor is running...while the fuel pump is priming it reads about 14psi or so. Engine Running [9MB MOV] So did I just do something wrong in the installation, or what? I should mention that I have messed with the adjustment screw and no matter how I adjust it, the fuel pressure reads the same! WTF? |
what kind of pump do you have?
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Originally Posted by j9fd3s' post='772519' date='Oct 25 2005, 02:15 PM
what kind of pump do you have? Oh sorry, that's important! It's a Walbro 255. |
20 psi is very very low....
try to start your car, and play with the trottle cable and see if your fuel pressure goes up or down, it should slightly go up even with little throttle cuz you would be closer to 0psi. unfortunately, i cant open your vid on my computer :( but how do you have the lines hooked up? fuel pump->primary rail-> secondary rail-> fpr (one of the holes on the sides)->return line (bottom hole)-tank? i have a feeling that the hose inside the tank has a crack in it, or was not properly installed, with a lot of pressure those hoses expand a little, and that little expansion translates to a huge dip in fuel pressure (i know this from expereince). especially as the gas gets warmer. are you sure you hooked it up the walbro in the correct metal pipe? is your fuel pump making a mean whine, or just a mellow hum? next thing is, when was the last time you changed your fuel filter? |
Originally Posted by FikseRxSeven' post='772630' date='Oct 25 2005, 07:41 PM
20 psi is very very low.... try to start your car, and play with the trottle cable and see if your fuel pressure goes up or down, it should slightly go up even with little throttle cuz you would be closer to 0psi. unfortunately, i cant open your vid on my computer :( but how do you have the lines hooked up? fuel pump->primary rail-> secondary rail-> fpr (one of the holes on the sides)->return line (bottom hole)-tank? i have a feeling that the hose inside the tank has a crack in it, or was not properly installed, with a lot of pressure those hoses expand a little, and that little expansion translates to a huge dip in fuel pressure (i know this from expereince). especially as the gas gets warmer. are you sure you hooked it up the walbro in the correct metal pipe? is your fuel pump making a mean whine, or just a mellow hum? next thing is, when was the last time you changed your fuel filter? Thanks for the response Fikse. The fuel pressure, as far as I can tell, does not change at all with throttle position. The fuel hoses are hooked up as follows: Feed --> Primary Rail --> Secondary Rail --> FPR --> return. I didn't replace the hose *inside* the tank but I did replace all of the accompanying hoses as they were cracked. I guess there's reason to believe that they could have cracked shortly after installing them, thus creating the pressure issue. I don't *think* the fuel pump sounds sick, but then again what do I know? I replaced the fuel filter right before installing the FPR. Hope that helps a bit. |
Originally Posted by Dysfnctnl85' post='772778' date='Oct 26 2005, 04:22 AM
Thanks for the response Fikse. The fuel pressure, as far as I can tell, does not change at all with throttle position. The fuel hoses are hooked up as follows: Feed --> Primary Rail --> Secondary Rail --> FPR --> return. I didn't replace the hose *inside* the tank but I did replace all of the accompanying hoses as they were cracked. I guess there's reason to believe that they could have cracked shortly after installing them, thus creating the pressure issue. I don't *think* the fuel pump sounds sick, but then again what do I know? I replaced the fuel filter right before installing the FPR. Hope that helps a bit. you didnt use the stock plastic fuel filter did you? |
pull the vac line off the FPR and your fuel pressure should spike. Dont take the pump out yet, test the pump pressure first. If its resonable, then your FPR is at fault.
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Originally Posted by j9fd3s' post='772836' date='Oct 26 2005, 12:07 PM
you didnt use the stock plastic fuel filter did you? The replacement I got is plastic...does that count? |
i find it weird your pressure isnt changing with throttle at all. Id do what Ronin said, pull the vac line and it definitely should move, if its still not moving id first guess the gauge, then guess the fpr.
kevin. |
Originally Posted by Dysfnctnl85' post='772906' date='Oct 26 2005, 12:50 PM
The replacement I got is plastic...does that count? you need a fuel filter thats meant for fuel injection on the car. efi runs at 50psi and a carb setup runs at 5psi... try a fuel filter for say an fc, or something fuel injected |
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