frustrating fuel pressure issue

[Murray_Calavera]

6 minutes ago, BK said:

Though so, 10psi change is not normal and sounds very restricted. What possessed you use one of these on stock lines ?!

For example our white 32 has the same 525lph with AN8 top hat fittings, AN8 supply and return lines with an FPR1200 using PWM.

Changes about 4 - 5 psi

Stock Nismo pump  stock reg on 5/16 lines changes about 3-4psi in my 33.

Previously I had the stock FPR and a very similar sized pump and same lines, it didn't do the 10psi drop. 

Because I haven't had any issues with fuel supply at the top end and the change only appeared to happen with the change in FPR, I thought it was a product of that regulator and not an issue. 

Short version, everything has been fine so far, so I thought everything is fine lol. 

[GTSBoy]

54 minutes ago, Murray_Calavera said:

Short version, everything has been fine so far, so I thought everything is fine lol. 

Yeah, it's not fine. Might be worth a little dig to see if it's going to come unstuck at some point and ruin your day.

[Murray_Calavera]

3 minutes ago, GTSBoy said:

Yeah, it's not fine. Might be worth a little dig to see if it's going to come unstuck at some point and ruin your day.

What am I at risk of happening with how things are at the moment?

[GTSBoy]

1 hour ago, Murray_Calavera said:

What am I at risk of happening with how things are at the moment?

Who knows? depends what's not right. The real problem is that it is currently working even though something is not right. That means that you have something else not right to compensate. So, you might at some point in the future make a change to something that you would have no reason to suspect would cause a lean out and destructo, but because of what you have now being twisted in some way, puts you at risk of unexpected destructo.

[joshuaho96]

25 minutes ago, damnonrs said:

What’s a fpcm?

this is what the fuel pressure does plugging it in and out. It raises when you unplug it

IMG_7522.MOV 55.85 MB · 0 downloads  

 

https://www.gtrusablog.com/2020/01/fuel-pump-control-module-fpcm-on-nissan.html

It's a switched resistor on the ground that slows down the pump at idle. It's possible that this module isn't behaving and is a source of your fuel pump problems. You can check this by seeing fuel pump voltage at idle and seeing how it transitions.  In the ECU map if your FPCM is still hooked up you should have a map for determining which of the 3 distinct fuel pump speeds should be commanded depending on fuel flow requirements.

[damnonrs]

41 minutes ago, joshuaho96 said:

https://www.gtrusablog.com/2020/01/fuel-pump-control-module-fpcm-on-nissan.html

It's a switched resistor on the ground that slows down the pump at idle. It's possible that this module isn't behaving and is a source of your fuel pump problems. You can check this by seeing fuel pump voltage at idle and seeing how it transitions.  In the ECU map if your FPCM is still hooked up you should have a map for determining which of the 3 distinct fuel pump speeds should be commanded depending on fuel flow requirements.

Awesome, I’ll look into this on Monday. Thank you for your feedback so far! 

[BK]

6 hours ago, Murray_Calavera said:

Previously I had the stock FPR and a very similar sized pump and same lines, it didn't do the 10psi drop. 

Because I haven't had any issues with fuel supply at the top end and the change only appeared to happen with the change in FPR, I thought it was a product of that regulator and not an issue. 

Short version, everything has been fine so far, so I thought everything is fine lol. 

If you put a pressure gauge at pump outlet and one at rail, at load I think you'd be surprised how much differential there is, like 20 - 30psi difference with lines that small and so much flow. I would not be surprised to see your actual pump pressure at idle at 60psi with your setup with only 40 at rail. This leads to all sorts of stupid shit like fuel heating, pressurising the fuel tank, splitting fuel tanks and obviously stressing the fuel pump causing premature failure.

Seems to be classic example of too much pump for the lines

3 hours ago, damnonrs said:

Awesome, I’ll look into this on Monday. Thank you for your feedback so far! 

Again with fuel module, piss it off and go proper battery feed to pump. Your situation really just looks like a stuffed reg.

Fuel line upgrade should still be a high priority though - you can never go too big.

[Murray_Calavera]

10 hours ago, BK said:

If you put a pressure gauge at pump outlet and one at rail, at load I think you'd be surprised how much differential there is, like 20 - 30psi difference with lines that small and so much flow. I would not be surprised to see your actual pump pressure at idle at 60psi with your setup with only 40 at rail. This leads to all sorts of stupid shit like fuel heating, pressurising the fuel tank, splitting fuel tanks and obviously stressing the fuel pump causing premature failure.

Seems to be classic example of too much pump for the lines

Again with fuel module, piss it off and go proper battery feed to pump. Your situation really just looks like a stuffed reg.

Fuel line upgrade should still be a high priority though - you can never go too big.

This is the pump I'm using - 

https://aeroflowperformance.com/af49-1057-525lph-e85-hi-flow-fuel-pump

It has a 3/8" barb outlet and the line supplied in the kit matches that size, so -6 sizing. 

Where I had to make up fuel lines, it's -6, the same size as the pump outlet. 

I would think that if this pump 100% for sure needs a larger sized fuel line, why is the outlet of the pump and the line supplied by the manufacturer -6? 

I've been running with a pump this size, with the same lines, for over 3 years now without any hiccups along the way. The last time I maxed out my fuel system, it was my 740cc side feeds, pressure was never an issue. 

Having said all that, I could log fuel temperature and pressure at the fuel hat (no idea how I would put a pressure sensor on the pump outlet, but that is -6 anyway so there is no reduction between the outlet and the hat). 

I'm not massively keen to log these extra channels because I can't understand the value in doing so, but if the powers that be can see value in it, it can be done. 

[BK]

3 hours ago, Murray_Calavera said:

This is the pump I'm using - 

https://aeroflowperformance.com/af49-1057-525lph-e85-hi-flow-fuel-pump

It has a 3/8" barb outlet and the line supplied in the kit matches that size, so -6 sizing. 

Where I had to make up fuel lines, it's -6, the same size as the pump outlet. 

I would think that if this pump 100% for sure needs a larger sized fuel line, why is the outlet of the pump and the line supplied by the manufacturer -6? 

I've been running with a pump this size, with the same lines, for over 3 years now without any hiccups along the way. The last time I maxed out my fuel system, it was my 740cc side feeds, pressure was never an issue. 

Having said all that, I could log fuel temperature and pressure at the fuel hat (no idea how I would put a pressure sensor on the pump outlet, but that is -6 anyway so there is no reduction between the outlet and the hat). 

I'm not massively keen to log these extra channels because I can't understand the value in doing so, but if the powers that be can see value in it, it can be done. 

So its not an actual Ti / Walbro then. Hey mate, can you do me a favour and clamp test the current draw of this pump ? I question the specs attached to it as they vary wildly from and actual Walbro 525lph F285. Aeroflow is claiming 460lph at 3 bar with 5A current draw !

I call bullshit as that current draw for that flow is exceptionally good - too good to be realistic for that style of pump. Either it doesn't flow what they claim or it draws WAY more current than listed. I personally wouldn't trust the specs of the Aeroflow Walbro knockoff to a real Walbro at all. No way you are getting that sort of flow from such low current draw.

The actual Walbro 525 specs in comparison are 460lph at 40psi and draws around 18A at 13.5v. Before PWM on the white 32, I clamped it at 13.7v idling at 40psi and it did indeed draw at least 17.5A inline with Walbros specs.

[Murray_Calavera]

4 hours ago, BK said:

So its not an actual Ti / Walbro then. Hey mate, can you do me a favour and clamp test the current draw of this pump ? I question the specs attached to it as they vary wildly from and actual Walbro 525lph F285. Aeroflow is claiming 460lph at 3 bar with 5A current draw !

I call bullshit as that current draw for that flow is exceptionally good - too good to be realistic for that style of pump. Either it doesn't flow what they claim or it draws WAY more current than listed. I personally wouldn't trust the specs of the Aeroflow Walbro knockoff to a real Walbro at all. No way you are getting that sort of flow from such low current draw.

The actual Walbro 525 specs in comparison are 460lph at 40psi and draws around 18A at 13.5v. Before PWM on the white 32, I clamped it at 13.7v idling at 40psi and it did indeed draw at least 17.5A inline with Walbros specs.

When I bought the pump, I was told by the supplier that it was made by Ti / Walbro and rebranded as Aeroflow, so I just took that at face value. I was told it was identical to a Walbro 525. 

I just threw a clamp on it, so at idle and battery voltage at 13v, it's pulling 14.3A. 

[BK]

32 minutes ago, Murray_Calavera said:

When I bought the pump, I was told by the supplier that it was made by Ti / Walbro and rebranded as Aeroflow, so I just took that at face value. I was told it was identical to a Walbro 525. 

I just threw a clamp on it, so at idle and battery voltage at 13v, it's pulling 14.3A. 

So that's at your 33psi idle at full vacuum ? If so seems more in the ballpark as it's still around 16A on the Walbro specs at 30psi

How good / calibrated is your DC clamp meter ? Fluke ?

[Murray_Calavera]

1 minute ago, BK said:

So that's at your 33psi idle at full vacuum ? If so seems more in the ballpark as it's still around 16A on the Walbro specs at 30psi

How good / calibrated is your DC clamp meter ? Fluke ?

Yep, that's my 33psi full vacuum idle. 

I had to by a clamp to do your test, so it's a brand new one of these lol 

https://www.supercheapauto.com.au/p/sca-sca-clamp-meter---digital/343253.html

[damnonrs]

19 hours ago, BK said:

Again with fuel module, piss it off and go proper battery feed to pump. Your situation really just looks like a stuffed reg.

Fuel line upgrade should still be a high priority though - you can never go too big.

is there any write ups on doing this for the 34 gtr? i know 33 and 32 are different

[BK]

43 minutes ago, Murray_Calavera said:

Yep, that's my 33psi full vacuum idle. 

I had to by a clamp to do your test, so it's a brand new one of these lol 

https://www.supercheapauto.com.au/p/sca-sca-clamp-meter---digital/343253.html

Yeah probably not that accurate compared to a $400 Fluke DC true rms clamp but will at least give you a ballpark idea. Make sure you zero it everytime.

Only reason I asked was that your current reading is closer to a Walbro 460lph F274 at 30psi, being around 13.5 - 14A. Anyway we know the published specs for the Aeroflow are wrong.

[BK]

36 minutes ago, damnonrs said:

is there any write ups on doing this for the 34 gtr? i know 33 and 32 are different

The factory fuel pump control module is a piece of shit that never really gives your fuel pump full battery voltage, so you definitely should do it. The 34 is exactly the same as 33 in the boot, it's only the 32 that's in the back seat body trim area. Essentially all you want to do is physically unplug and remove the FPCM and switch battery voltage direct to the fuel pump. Ghetto way to do this without the upgraded battery wiring is to just remove the module and wire the fuel pump negative wire directly to earth.

They all work on all GTRs the same, having 3 pump voltage settings. You only get full pump voltage on cranking and full load, and then there is a medium load and idle / low load settings. Roughly speaking this translates into pump voltages of roughly about 8v, 10v, 12v. Even at full voltage setting the pump never actually gets the full 13.5v - 14.2v battery voltage because of the module earthing the pump negative through its small circuitry and the very inadequate factory wiring causing significant voltage drop.

That's another thing contributing to your problems - Bosch 044s, and any fuel pump really, HATES low voltages under 12v. An 044 makes horrible noises at 10v - it will not flow properly and will actually damage them.

[damnonrs]

1 hour ago, BK said:

The factory fuel pump control module is a piece of shit that never really gives your fuel pump full battery voltage, so you definitely should do it. The 34 is exactly the same as 33 in the boot, it's only the 32 that's in the back seat body trim area. Essentially all you want to do is physically unplug and remove the FPCM and switch battery voltage direct to the fuel pump. Ghetto way to do this without the upgraded battery wiring is to just remove the module and wire the fuel pump negative wire directly to earth.

They all work on all GTRs the same, having 3 pump voltage settings. You only get full pump voltage on cranking and full load, and then there is a medium load and idle / low load settings. Roughly speaking this translates into pump voltages of roughly about 8v, 10v, 12v. Even at full voltage setting the pump never actually gets the full 13.5v - 14.2v battery voltage because of the module earthing the pump negative through its small circuitry and the very inadequate factory wiring causing significant voltage drop.

That's another thing contributing to your problems - Bosch 044s, and any fuel pump really, HATES low voltages under 12v. An 044 makes horrible noises at 10v - it will not flow properly and will actually damage them.

i will hard wire it for now until my problems are resolved and get it dyno tuned again. i'm just worried about fuel temperature running the pump at 100%, is that a problem or its ok to just have it on full blast at all times

[Murray_Calavera]

1 minute ago, damnonrs said:

i will hard wire it for now until my problems are resolved and get it dyno tuned again. i'm just worried about fuel temperature running the pump at 100%, is that a problem or its ok to just have it on full blast at all times

I run my pump full throttle all the time, 3 years so far so good. 

[robbo_rb180]

23 minutes ago, damnonrs said:

i will hard wire it for now until my problems are resolved and get it dyno tuned again. i'm just worried about fuel temperature running the pump at 100%, is that a problem or its ok to just have it on full blast at all times

the only time heat heat is an issue generally is circuit racing, stupid hot days (40+C) or running multiple pumps full time.

[robbo_rb180]

2 hours ago, Murray_Calavera said:

When I bought the pump, I was told by the supplier that it was made by Ti / Walbro and rebranded as Aeroflow, so I just took that at face value. I was told it was identical to a Walbro 525. 

I just threw a clamp on it, so at idle and battery voltage at 13v, it's pulling 14.3A. 

Even my aeroflow dealer won't recommend their pumps. I have had 1 fail in a car I bought. They are getting better but yeah wouldn't be using them.
Always buy genuine for that kind of thing.

[BK]

3 minutes ago, damnonrs said:

i will hard wire it for now until my problems are resolved and get it dyno tuned again. i'm just worried about fuel temperature running the pump at 100%, is that a problem or its ok to just have it on full blast at all times

We drove 1500km straight on the white 32 before the PWM setup and a 525 pump at the full tilt, with AN8 lines though. Should be ok for what you want to do as the 044 flows about 2/3 of one of these and draws less current than the Walbro 525 by a fair bit. They do tend to cavitate though without the use of a good outlet check valve like the Speedflow ball one.

A better pump than what you have now without going to very high current draw Walbros would be something like the AEM or DW 340lph intank pumps. They flow more than the 044, are quieter and draw pretty low current so would be the first logical step for a pump replacement. You go Walbro pumps you need pretty decent pump supply wiring, like minimum at least 6mm2 cable or 10awg. That said, that should still be the minimum cable size for a fuel pump feed on any fuel pump supply for voltage drop reasons. I run 10mm2 or 8awg for good overkill.