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Fuel Pump control issue... G4+ not commanding secondary pumps on.

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Have a fuel control issue that I was hoping to receive some help or tips with:

Fuel system consists of 4 fuel pumps - 2 in tank Walbro 255s, feeding 2 Bosch 044s in line after the surge tank.

Ordinarily, the car runs on half of the fuel system, commanding the secondary 044+Walbro on when boost reaches above a certain level.

The problem I am having is that the G4+ does not appear to be commanding on the secondary fuel pumps when it should. I detect this in logs because when the ECU thinks it commands on pumps 3+4, fuel pressure does not jump as one would expect, and this problem ends up triggering my engine protection which monitors differential fuel pressure as boost kicks in.

Primary fuel 1+2 pumps (i.e  Walbro #1 + O44 #1) are installed under "Fuel Pump" under Aux 7, while fuel pumps 3+4 (i.e. Wlabro #2 + 044 #2) are installed as a GP output on Aux 1.

I tried testing the fuel pumps under "test mode", and they all work, but only when I test pumps 1+2 OR 3+4 in isolation. 

I can command on Pumps 1+2 in isolation without issue

I cannot command pumps 3+4 in isolation... when I trigger them through Aux 1, all 4 pumps run..

If I turn on Aux 1 and Aux 7 under test mode, Pumps 1+2 stay run, but 3+4 stay asleep.

Both halves of the fuel system are triggered off their own relays, so I can disable whichever half of the fuel system by pulling the appropriate one of the two relays.

 

Map on the car is attached.

Here is a link to a datalog - Dropbox Link

 

You will see in the datalog that the fuel pressure doesn't actually increase when pumps 3 and 4 are commanded on by the ECU. Not sure if there is something in PCLink that I am missing that would cause the pumps not to be activated by the G4+ while in use, but allow me to activate 1+2 and 3+4 independently but not together.

Current Map rev 0.5.pclr

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I don't see any problem with the set up.  Why is Aux 7 set to high polarity tho? if it works like that it would suggest there is a problem with the wiring.  polarity = high means it works inverted to normal, so the aux output is off to command the fuel pump to turn on?

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Thanks for the response Adam,

Couldn't say I know why it is set up that way to be honest. It's that way on my previous V88 ECU as well, and I simply carried all the settings over to my current G4+ when I upgraded last February. 

Should I try switching it to LOW polarity, to see if that has an effect?

I can say that the primary fuel pumps are run through a Weldon Fuel Pump controller. Not sure if this is related? It slows the primary pumps down slightly, and when in boost, ECU kicks them up to full speed and turns the secondary pumps on.

Question - Should I not be able to command the fuel pumps on at the same time via PCLink in Test Mode? Or is this a situation where the ECU is only happy to turn on run one output at a time in test mode?

 

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Pardon my ignorance, but would having things set up the way they are be the cause of what I am experiencing? Could the way I have things set up at the moment would be why I can turn on each half of the fuel system individually, but not turn both halves of the fuel system on to run at the same time?

Pumps 1 and 2 (aux 7) are on full time running through a Weldon pump controller, so would it not make sense to send out a 12V signal to run the main pumps when on?

Pumps 3 and 4 (aux 1) come on and off, depending on what the load of the car is like, so would it not make sense to send a grounding signal for when the secondary pumps are needed?

 

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Why do people complicate things.

 

Either just run the pumps all the time, or PWM them via the ecu if you can. All this staging, multiple relays etc etc just adds complications and failure points that arent needed.

A single 255 as a lift pump would be fine as long as there is a decent size surge tank, and you dont expect to see use of a full 600+ for extended periods long enough to actually drain that surge tank to unacceptable levels. Or a single 340 would offer a lot more. No need at all for 2 lift pumps.

 

Unless all the dual everything is some redundancy for essential racing to ensure you can always finish, or an aircraft lol.

 

And typically ecu's do not send out 12v to run pumps. Typically they send out a ground to energise a relay, although if you can invert that you might be able to send out 12v instead. But that is not normal/common for an ecu.

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You need to draw a diagram on how the fuel pumps are setup and another on how the wiring is done. I think there is a lot of confusion here. Also post a pic of the Weldon wiring diagram. I cant find one online that i can read.

I have a funny feeling that the Weldon fuel pump needs to see a POSITIVE to activate. I recommend you start by running the fuel pump speed control method to OFF until you know all pumps work as expected.

 

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Schematic of the Weldon fuel pump controller:

https://www.dropbox.com/s/h1pofregrxrbfiu/IMG_4351.JPG?dl=0

Additional documentation from the literature included with the pump controller:

https://www.dropbox.com/s/ep8m6hx1xpx9qwu/IMG_4355.JPG?dl=0

https://www.dropbox.com/s/or3i0rqj1vmnmxu/IMG_4354.JPG?dl=0

 

Schematic of the car's fuel system to the best of my knowledge. I did not perform the install myself, and just received a brif

https://www.dropbox.com/s/keamf8tl9z8oly6/IMG_4357.JPG?dl=0

 

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The above both seem strange.

 

What does the Weldon controller use as a load reference in order to vary pump speed ? You appear to have only power and a basic on/off trigger reference ?

You show a connection to Aux6, but I cannot see anywhere where you tell us what Aux6 is ?

 

Although the Race part of the controller does look like a simple off/on where 12v would be ON. Almost makes such a controller pointless, even more so when only applied to half of your system. So is your Aux sending out 12v at high load in order to ramp the speed of these 2 pumps up ?

IMO bad design throughout.

 

If you want to PWM the pumps, then PWM them, doing a simple Hi/Lo setup is not that. I think Aeromotive offer a  better controller where you can give it an rpm or other load input for at least some sort of variable speed.

Or just control the pumps via an SSR and PWM them from the ecu.

 

Also, with separately supplied/triggered 044's you will also need a check valve in the output of the redundant 044 otherwise fuel will try and pump back through it.

 

Simple....One in tank 340, simple off/on via a relay ( or if you really must retain the 2x255's, do same for both )

Both 044's PWM'd and run together via an SSR based on engine load ( boost, rpm, whatever you want really )

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4 minutes ago, Stevieturbo said:

The above both seem strange.

 

What does the Weldon controller use as a load reference in order to vary pump speed ? You appear to have only power and a basic on/off trigger reference ?

You show a connection to Aux6, but I cannot see anywhere where you tell us what Aux6 is ?

 

Although the Race part of the controller does look like a simple off/on where 12v would be ON. Almost makes such a controller pointless, even more so when only applied to half of your system. So is your Aux sending out 12v at high load in order to ramp the speed of these 2 pumps up ?

IMO bad design throughout.

 

 If you want to PWM the pumps, then PWM them, doing a simple Hi/Lo setup is not that. I think Aeromotive offer a  better controller where you can give it an rpm or other load input for at least some sort of variable speed.

Or just control the pumps via an SSR and PWM them from the ecu.

 

Also, with separately supplied/triggered 044's you will also need a check valve in the output of the redundant 044 otherwise fuel will try and pump back through it.

 

Simple....One in tank 340, simple off/on via a relay ( or if you really must retain the 2x255's, do same for both )

Both 044's PWM'd and run together via an SSR based on engine load ( boost, rpm, whatever you want really )

It might seem strange for a few reasons which might become apparent shortly. 7 points though - 

1) I did not perform the install. I was able to draw this up based on a brief description of the way it was put together. I was not mechanically inclined to the point of getting into the nitty gritty of wiring a fuel system up back then, but I am being forced to do some learning now. There might be a few details missing within the drawing, and I'm quite sure that there are, given that I drew it up based on what I was told over the phone by the shop that did the job from what they can remember of it a few years back. This is also the reason why my initial post might have seemed very confusing and light on technical information. This isn't my expertise; I'm learning as I go.

2) FYI, Bosch 044 fuel pumps or even Weldon fuel pumps for that matter cannot/should not be run via a Pulse width modulation controller. Not like you can with an Aeromotive external pump and their PWM controller. I looked into it years ago before going with the Weldon controller. 

3) The Weldon pump controller runs the primary pumps at a reduced speed because of issues relating to fuel heating and vaporlock and other less tangible issues I was experiencing due to my location, and the rest of my setup, and how I use the car, etc.

4) At high load, yes, the primary pumps run unrestricted thanks to the Aux 6 output from the ECU. The secondaries are not controlled by the Weldon controller because they are only needed at high loads/boost to provide additional fuel flow only when needed. They don't need to run at reduced speed because they are off most of the time when puttering around town, and only awake when their flow capabilities are needed at elevated boost levels.

5) Yes, both 044 pumps do in fact have check valves installed at their outlets.

6) I apologize - Aux 6 is an output from the ECU that kicks the Weldon controller to run the primary pumps unrestricted under load conditions. ECU does this just prior to turning on the secondary pumps.

7) I do realize that without knowing all the details on my car, you are very critical of it, and don't hesitate to voice it in this and other threads I have created looking for assistance with curious problems, and that's okay. I'm sure that most people on this forum have a lot more technical experience working on these cars than I do, as this definitely isn't my area of expertise, but I am willing to learn and pick up tools that I need to work on things here and there in my garage. Dealing with these issues that crop up forces me to learn more and more about how things work on it. With that said, it is my hope to leverage some of that knowledge you obviously have in spades in coming up with ideas of things I could check on this setup in order to perhaps figure out why it might not be working as intended, or if there is something that was missing that would make it work as should.

I did not arrive at this setup overnight or through some perverse desire to have the most complicated fuel system known to man. It took more iterations of fuel system setup than I care to admit before I had something that not only did the job as far as providing sufficient fuel flow, but also exorcised a few negative characteristics I simply could not tolerate with aftermarket fuel systems that provided the sort of fuel volumes needed to support what the engine setup consists of.

Hope this sheds a bit of light on things.

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2. Your Weldon controller IS a PWM controller. "Controls pump speed with PWM,"

https://www.weldonracing.com/store/14000-Pump-Controller-p56212294

PWM IS the correct way to vary a DC motors speed. ( PWM via SSR is not ideal as they are slower than would be liked, but perfectly viable and far better than any ancient crap of resistors trying to reduce voltage or other such nonsense ). So SSR's are still a good option.

 

Heat, vaporlock....bullshit American stuff. Never seen anything of any such concern on a Subaru in 20 years working at them ( or indeed any other car )

 

Again, don't complicate things that do not need complicated.

Unless you're doing some sort of 24hr endurance racing or something.

Either just run the pumps all the time, or PWM them. I utterly despise all this staging of pumps as it is just pointless.

 

1 single lift pump will undoubtedly be fine, change to a 340 if necessary. And just run the 2x044's all the time. All this bullshit about hot fuel and other nonsense usually comes from idiots who've never logged fuel temperature in their life. So best to ignore them. If fuel temperature is a concern, then log it. If it does get too hot, then deal with it. It's a doddle to fit a fuel cooler.

But unless you have a very small main fuel tank and live in a very hot climate, fuel temperatures will be of little real concern. It's very simple to log, a sensor will be £10-20

And the heat will apply whether there is 1 pump, 2, 3, 4, 5, 6, 7, 8 pumps etc etc. A lot of the heat comes from the hot rails and circulating fuel to/from the engine. Very little comes from the pumps themselves despite what some might claim.

And all this staging, multiple relays, pumps, triggers, controllers,  whatever...they're all just unnecessary failure points. Keep it simple. But a dual 044 should give you 1200hp worth of fuel quite easily...IF you need that

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On 1/5/2019 at 8:36 PM, Stevieturbo said:

2. Your Weldon controller IS a PWM controller. "Controls pump speed with PWM,"

https://www.weldonracing.com/store/14000-Pump-Controller-p56212294

PWM IS the correct way to vary a DC motors speed. ( PWM via SSR is not ideal as they are slower than would be liked, but perfectly viable and far better than any ancient crap of resistors trying to reduce voltage or other such nonsense ). So SSR's are still a good option.

 

Heat, vaporlock....bullshit American stuff. Never seen anything of any such concern on a Subaru in 20 years working at them ( or indeed any other car )

 

Again, don't complicate things that do not need complicated.

Unless you're doing some sort of 24hr endurance racing or something.

Either just run the pumps all the time, or PWM them. I utterly despise all this staging of pumps as it is just pointless.

 

1 single lift pump will undoubtedly be fine, change to a 340 if necessary. And just run the 2x044's all the time. All this bullshit about hot fuel and other nonsense usually comes from idiots who've never logged fuel temperature in their life. So best to ignore them. If fuel temperature is a concern, then log it. If it does get too hot, then deal with it. It's a doddle to fit a fuel cooler.

But unless you have a very small main fuel tank and live in a very hot climate, fuel temperatures will be of little real concern. It's very simple to log, a sensor will be £10-20

And the heat will apply whether there is 1 pump, 2, 3, 4, 5, 6, 7, 8 pumps etc etc. A lot of the heat comes from the hot rails and circulating fuel to/from the engine. Very little comes from the pumps themselves despite what some might claim.

And all this staging, multiple relays, pumps, triggers, controllers,  whatever...they're all just unnecessary failure points. Keep it simple. But a dual 044 should give you 1200hp worth of fuel quite easily...IF you need that

 

Stevieturbo - You are correct regarding the Weldon; my apologies. I knew there was a reason why I ended up with he Weldon pump controller to run the pumps as opposed to using a more crude setup that involved just reducing voltage to the pumps. 

I too thought the fuel heating issues were a non-issue when I resided in the UK. Once I moved across the pond and experienced heat during summer with a fuel setup similar to what you describe running at 100%, and had to deal with my car suffering from fuel starvation issues in hot weather. Then  I opened my eyes and changed my setup. Yes, the fuel system did in fact start off as "simple", with all pumps running at 100%. It was okay in cooler weather, but a different story in  hot weather.

Update:

I figured out the issues last weekend but forgot to post, so here it is...:

1) The wiring on my secondary relay was incorrect. Relay 2 (secondary pumps) was using the same ground as in relay 1, which should not have been the case, as the OEM fuel pump controller uses ground to control when it triggers a relay1 runs its pump. Relay 2 should have been grounded to the ECU AUX1 output all along instead of being wired to receive a high side trigger from the ECU. I have Ducie54 to thank for this one, as I was looking at his labelling for the relays on his schematic, and noticed it differed from mine, so I spent time in the manual for the G4+ to figure out why that was the case.

To control relay 1, the the ECU Aux 7 provides a "high side" drive to the OEM main fuel pump relay, which in turn powered the OEM fuel pump controller. This in turn delivers a switched 12V source to the control side of Relay 1. After reading that area a few times, I concluded that the primary fuel system had to be hooked up as if it were a "solenoid" in the manual, while the secondary would need to be hooked up like a normal relay circuit, with the ECU controlling the circuit by grounding it. On the surface, I think my installer made the error of thinking that both relays had to be wired the same way with only difference being where they were sending their power to, so they did things such as allowing both relays to use the same ground through to the stock fuel pump controller. Problem with this was that "staging" worked by running Aux 7 (primary pumps), and then turning off Aux 7 and simultaneously turning on Aux1 which resulted in all 4 pumps going.... Not ideal at all.

2) The "race" power level setting on the Weldon PWM fuel pump controller had to be triggered through a relay, and not directly from the ECU. I read on a Mustang forum from an employee of Weldon that the Weldon pump controller needed to see an actual battery 12V in order to trigger the pump speed increase of the primary pumps.  The ECU just was not putting out 12V at the pins on the high side output at the pin. I believe it was 10.X volts I was seeing while in test mode without the engine running. So I installed a relay, sent ground to the ECU output so that it can low side trigger it, and wired the rest of the relay up like I did for Relay 2. And just like that, I can now use "test mode" to alternate between fast and slow pump speeds on the primary side!

So now, my fuel system is working and staging as designed. Control logic is as similar to OEM as I can get, with primary pumps running at low speed at low engine RPM and IDC, and then switching to high speed at a certain RPM or IDC, and my secondary pumps kick in full bore at a certain boost level to augment the primary side of the fuel system. This solution ensures little to no noise levels of noise with external pumps with the engine running, low fuel heating issues during the summer months, while maximizing fuel pump life. 

Thanks to all that spent time helping me with this issue, and thanks also to Jason and ScottC @ LinkUSA for spending a bunch to time helping to brainstorm potential areas to look at and try. :)

I'm sure that Stevieturbo might be curious as to why I retain the OEM stuff to trigger off the primary fuel pump relays in the first place instead of ripping all that stuff out to reduce complication... Answer is that the car needs to retain the ability to return to the stock ECU every once in a while for OBDII emissions testing. The fuel system had to be done in a way that the stock ECU could still communicate with the primary fuel system in order to fuel the car, while working as intended with the Link ECU in place. 

 

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