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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 |
wait, since i cant open the video, what kind of car is this we're talkin about again?
i doubt its the regulator, as previously suggested, even if you take the screw off the regulartor, pressure will not go down to 20psi. martin |
Originally Posted by j9fd3s' post='773009' date='Oct 26 2005, 07:30 PM
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 Wow, that's a pretty ignorant mistake for me to make! I bet that's exactly what the issue is. Fikse this is my Cosmo -> FB swap. |
lol i agree with j9fd3s then..... filter is too constricing, i bet your walbro is whining like a cat with its tail under your front tires
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yep id definitely say its that filter then.
kevin. |
i helped my friend install a TII motor into an 82, and we used a gsl-se fuel filter in the car. fuel pressure was at 40 (before other issues came along, rusty fuel tank). so you might want to take a look inside your tank too, make sure that the thing is not rusting and clogging your pickup filter, and eventually ******* up your injectors and eventually your motor.(tahts what happenned to his car).
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Originally Posted by FikseRxSeven' post='773185' date='Oct 27 2005, 12:05 PM
i helped my friend install a TII motor into an 82, and we used a gsl-se fuel filter in the car. fuel pressure was at 40 (before other issues came along, rusty fuel tank). so you might want to take a look inside your tank too, make sure that the thing is not rusting and clogging your pickup filter, and eventually ******* up your injectors and eventually your motor.(tahts what happenned to his car). and it was definitely carbed before hand? i dont remember when the carbs went away https://www.nopistons.com/forums/pub...IR#>/smile.png kevin. |
At least one of Aeromotive's regualators comes with two springs. One for low, carb pressures and another for high, FI pressures. If your's came with two springs and it has the wrong one in you may have the carb spring bottomed out and it simply just won't make any more pressure. Also, is it possible you just bought the wrong regulator? What is the model number?
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Thanks for the advice guys. I installed a fuel filter from a TII and was able to adjust the fuel pressure just fine.
It idles a lot better with lower fuel pressure...I actually have to put my foot on the throttle to keep it idling with 50psi of pressure. Does that sound right at all? It still doesn't like to rev but it needs some tuning I'm positive haha. I'll work on getting it rolling now and then getting it to a dyno. |
Originally Posted by Dysfnctnl85' post='774200' date='Oct 31 2005, 07:23 AM
Thanks for the advice guys. I installed a fuel filter from a TII and was able to adjust the fuel pressure just fine. It idles a lot better with lower fuel pressure...I actually have to put my foot on the throttle to keep it idling with 50psi of pressure. Does that sound right at all? It still doesn't like to rev but it needs some tuning I'm positive haha. I'll work on getting it rolling now and then getting it to a dyno. if it ran "ok" with 20psi of fuel pressure, and then it doesnt with 50psi, its prolly too rich with 50psi. |
Fuel injectors work the same no matter the fuel pressure, so if your pressure is lower, and the injector opens for a millisecond, it's just squirting in less fuel than if the pressure was doubled
Sounds to me like you should increase the pressure and back off the injectors. You base map for idling is too rich at the proper pressure. So, if the pressure drops, and you haven't touched the fuel map, it will be closer to the proper ratio, so it idles better. |
Originally Posted by ColinRX7' post='774326' date='Oct 31 2005, 03:41 PM
Fuel injectors work the same no matter the fuel pressure, so if your pressure is lower, and the injector opens for a millisecond, it's just squirting in less fuel than if the pressure was doubled Sounds to me like you should increase the pressure and back off the injectors. You base map for idling is too rich at the proper pressure. So, if the pressure drops, and you haven't touched the fuel map, it will be closer to the proper ratio, so it idles better. the whole idea behind a fuel pressure regulator is to keep the relative pressure the same between the intake and the fuel rail. |
Hmm well I'm all backwards then
You understand what I'm getting at though right? I wasn't thinking with the intake pressure input, I was picturing an aftermarket adjustable FPR with no vacuum input.. |
Originally Posted by ColinRX7' post='774370' date='Oct 31 2005, 07:15 PM
Hmm well I'm all backwards then You understand what I'm getting at though right? I wasn't thinking with the intake pressure input, I was picturing an aftermarket adjustable FPR with no vacuum input.. ah ok, like my mercedes. |
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