Z31 fuel pump voltage

[Mastersorbet]

Hi guys

Is there any way to control the fuel pump voltage through nistune? IAW the FSM the ECU gives 13.4V to the pump during priming and cold start. Is there any way to manipulate that?

[Matt]

not sure how you can actually control the voltage. will need to check the manual for the specific voltages and when they are set (ie idle fuel pump voltage is different to when engine is running)

it would require specific code modification and not something i would be attempting to do

[Mastersorbet]

not sure how you can actually control the voltage. will need to check the manual for the specific voltages and when they are set (ie idle fuel pump voltage is different to when engine is running)

it would require specific code modification and not something i would be attempting to do

OK, i'll be wating for it. Thanks

[Matt]

if you move to a moreserious fuel pump setup (eg Bosch 040 or similar) you wont be using that finer control anyway, you will be switching it via relay which doesnt use the pulse output in this case from the ecu

[Mastersorbet]

The reason why I ask is because i have a Walboro 255 installed and during warmup the engine is getting WAY too much gas and after evaluations in multiple areas, all facts point out to the feature that the fuel pump is over feeding the injectors.

[PL]

Sounds like you may need to change your fuel pressure reg to something capable of bypassing more fuel.

Best you monitor fuel pressure to make sure it's not going too high throughout all parts of the load/rpm range.

PL

[Matt]

As PL said

The standard ECU cannot put out that much current to run these type of fuel pumps. You will find the voltage will drop way below the required 12 volts due to the increased current usage if attempting to do so. You need to run nice thick wires from the battery and relay drive it to maintain the voltage levels to the fuel pump

[PL]

Yeah, but in this case it sounds like the fuel pressure is already too high, so voltage at the pump is probably fine.

The only car I ever had this problem with was a Datto 1600 with an SR20 in it. The car builder had done a great job - Bosch 044 pump, big fuel lines everywhere - and big wires feeding the fuel pump too. I had to pull heaps of fuel out to make it run properly. Then I put the fuel flow/pressure rig on it and yep, fuel pressure was about 10psi too high everywhere.

He didn't wanna upgrade the FPR (and didn't really understand what was going on despite my efforts to explain) so I just tuned it for the excessive fuel pressure. One day he'll fix the fuel pressure problem, the SR will lean out and the world will have one less SR20...

PL

[Mastersorbet]

Yeah, but in this case it sounds like the fuel pressure is already too high, so voltage at the pump is probably fine.

The only car I ever had this problem with was a Datto 1600 with an SR20 in it. The car builder had done a great job - Bosch 044 pump, big fuel lines everywhere - and big wires feeding the fuel pump too. I had to pull heaps of fuel out to make it run properly. Then I put the fuel flow/pressure rig on it and yep, fuel pressure was about 10psi too high everywhere.

He didn't wanna upgrade the FPR (and didn't really understand what was going on despite my efforts to explain) so I just tuned it for the excessive fuel pressure. One day he'll fix the fuel pressure problem, the SR will lean out and the world will have one less SR20...

PL

awesom, you understand my situation.

Since i have a walboro 255 that runs a lot higher flow than the original and 440 injectors instead of 260 stock, when the the pump is flowing fuel unde 13.4 V of energy it simply overfeeds my engine.

I had to do something similar and tune the injector feed accordingly so it cant work, but it's not 100% effective, the best way i can get that fixed it is if i can control when is the pump goin to recieve 13.4V.

[Adam]

Wouldn't it be any easier option to just get yourself an adjustable FPR?
(I'm only asking for my own curiosity )

Cheers
Adam

[Mastersorbet]

Wouldn't it be any easier option to just get yourself an adjustable FPR?
(I'm only asking for my own curiosity )

Cheers
Adam

That's agood suggestion but to me the less crap i have under the hood the better. Besides, it is only an inconvinience when the car is warming up, it's just too rich for the first five minutes, after that all works well.