Critique my fuel system
#1
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Critique my fuel system
I thought my fuel system would be good for my goals, sub 350whp@250kpa, but it looks like I'm leaning out up top and MS is showing 120% duty cycle.
Specs:
'96 Miata stock lines
'99 fuel rail
ID1000 injectors
Aeromotive boost referenced FPR @ 70psi base pressure
Walbro 255
Can I just raise my fuel pressure another 10psi or is the Walbro 255 going to start giving up on me? Am I going to need a new pump something like a DW300 or Walbro 400? Or am I getting to the point that I need to think about a fuel rail or aftermarket fuel lines?
Specs:
'96 Miata stock lines
'99 fuel rail
ID1000 injectors
Aeromotive boost referenced FPR @ 70psi base pressure
Walbro 255
Can I just raise my fuel pressure another 10psi or is the Walbro 255 going to start giving up on me? Am I going to need a new pump something like a DW300 or Walbro 400? Or am I getting to the point that I need to think about a fuel rail or aftermarket fuel lines?
#3
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Thanks, Vlad. It looks like 90-100psi is where the 255 starts taking a dive in flow rate. I was hoping I could push it a little harder and get enough flow. Good know the lines aren't necessary though, that seems like it'd be a big expense. I'm sure a $150 pump is getting off easy by comparison.
#6
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North of 300whp, I think a fuel pressure sensor is pretty much a requirement. Between the need for better wiring, the balance between flow and pressure from the pump, and nearing the limit of the injectors, you really need to know what the fuel pressure is doing.
#9
I thought my fuel system would be good for my goals, sub 350whp@250kpa, but it looks like I'm leaning out up top and MS is showing 120% duty cycle.
Specs:
'96 Miata stock lines
'99 fuel rail
ID1000 injectors
Aeromotive boost referenced FPR @ 70psi base pressure
Walbro 255
Can I just raise my fuel pressure another 10psi or is the Walbro 255 going to start giving up on me? Am I going to need a new pump something like a DW300 or Walbro 400? Or am I getting to the point that I need to think about a fuel rail or aftermarket fuel lines?
Specs:
'96 Miata stock lines
'99 fuel rail
ID1000 injectors
Aeromotive boost referenced FPR @ 70psi base pressure
Walbro 255
Can I just raise my fuel pressure another 10psi or is the Walbro 255 going to start giving up on me? Am I going to need a new pump something like a DW300 or Walbro 400? Or am I getting to the point that I need to think about a fuel rail or aftermarket fuel lines?
My advice is start there. If you look at the pump specs (flow vs pressure) you'll see cranking the pressure isn't doing you any favors, and that's assuming you got the HP version. If you don't have the HP version, you need it or a better pump.
#13
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Thanks for the feedback guys. This is on E85, I forgot to specify that.
I bumped pressure up another 10psi (which looks like about the limit on the 255) and it still leaned out so it looks like the pump just can't keep up. I ordered a DW300 that should be delivered today, hopefully that fixes the problem.
I'll have to look into the voltage drop issues. I guess that's the next thing to address if issues continue.
I bumped pressure up another 10psi (which looks like about the limit on the 255) and it still leaned out so it looks like the pump just can't keep up. I ordered a DW300 that should be delivered today, hopefully that fixes the problem.
I'll have to look into the voltage drop issues. I guess that's the next thing to address if issues continue.
#14
Thanks for the feedback guys. This is on E85, I forgot to specify that.
I bumped pressure up another 10psi (which looks like about the limit on the 255) and it still leaned out so it looks like the pump just can't keep up. I ordered a DW300 that should be delivered today, hopefully that fixes the problem.
I'll have to look into the voltage drop issues. I guess that's the next thing to address if issues continue.
I bumped pressure up another 10psi (which looks like about the limit on the 255) and it still leaned out so it looks like the pump just can't keep up. I ordered a DW300 that should be delivered today, hopefully that fixes the problem.
I'll have to look into the voltage drop issues. I guess that's the next thing to address if issues continue.
#16
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Mid 80s are maxed out, but not unsafely so. You can also add base pressure at 350whp without stressing the pump too much. I made ~350whp at ~87psi rail pressure on E85 with a Walbro 255HP and ID1000s.
#17
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A. My pump couldn't hold the pressure I needed it to run for my injectors to properly fuel the car.
B. My injectors weren't big enough to properly fuel the car at the pressure I was running.
Bumping the fuel pressure gives my injectors more flow, assuming the pump can hold the pressure. This didn't fix the problem so I assume the pump can't hold pressure at the flow rate I need and I bought a better pump.
Sure I can lower the fuel pressure to 43psi and the pump will easily hold pressure, but then the injectors can't flow enough and I'm still leaning out. That 2 minutes of extra wear on my pump was the test I used to help confirm the issue.
* Edit - I really miss props. Thank you to all those who have helped out and provided data from their personal experiences. I can't imagine the money I'd be throwing at this car if it weren't for all your help.
#18
My logic is that one of two things were happening:
A. My pump couldn't hold the pressure I needed it to run for my injectors to properly fuel the car.
B. My injectors weren't big enough to properly fuel the car at the pressure I was running.
Bumping the fuel pressure gives my injectors more flow, assuming the pump can hold the pressure. This didn't fix the problem so I assume the pump can't hold pressure at the flow rate I need and I bought a better pump.
Sure I can lower the fuel pressure to 43psi and the pump will easily hold pressure, but then the injectors can't flow enough and I'm still leaning out. That 2 minutes of extra wear on my pump was the test I used to help confirm the issue.
* Edit - I really miss props. Thank you to all those who have helped out and provided data from their personal experiences. I can't imagine the money I'd be throwing at this car if it weren't for all your help.
A. My pump couldn't hold the pressure I needed it to run for my injectors to properly fuel the car.
B. My injectors weren't big enough to properly fuel the car at the pressure I was running.
Bumping the fuel pressure gives my injectors more flow, assuming the pump can hold the pressure. This didn't fix the problem so I assume the pump can't hold pressure at the flow rate I need and I bought a better pump.
Sure I can lower the fuel pressure to 43psi and the pump will easily hold pressure, but then the injectors can't flow enough and I'm still leaning out. That 2 minutes of extra wear on my pump was the test I used to help confirm the issue.
* Edit - I really miss props. Thank you to all those who have helped out and provided data from their personal experiences. I can't imagine the money I'd be throwing at this car if it weren't for all your help.
When I rewired my pump, that bought me a bit of headroom in boost since the pump could pump a bit more up top with higher voltage. Even if you put a new pump in, I recommend it. Thread here where I posted voltage drop data on my 99.
https://www.miataturbo.net/general-m...-1999-a-83478/
[/QUOTE]
#19
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^ Thanks for the link, I was having trouble finding info when I searched.
New DW300 arrived today, DOA. Installed it and it did nothing. Uninstalled it and wired directly to a battery and still got nothing. So more waiting for another one now. Good thing I paid more to get 2 day shipping, blah.
New DW300 arrived today, DOA. Installed it and it did nothing. Uninstalled it and wired directly to a battery and still got nothing. So more waiting for another one now. Good thing I paid more to get 2 day shipping, blah.
#20
^ Thanks for the link, I was having trouble finding info when I searched.
New DW300 arrived today, DOA. Installed it and it did nothing. Uninstalled it and wired directly to a battery and still got nothing. So more waiting for another one now. Good thing I paid more to get 2 day shipping, blah.
New DW300 arrived today, DOA. Installed it and it did nothing. Uninstalled it and wired directly to a battery and still got nothing. So more waiting for another one now. Good thing I paid more to get 2 day shipping, blah.