Evo4-8 G4+ Plugin - PWM Fuel Pump control

[EvocentriK]

Hi guys, I am setting up a simple fuel pump power supply & control circuit.

I wish to have 2 or 3 pump speeds to avoid unnecessary fuel heating at idle and cruise. 

I'd like 50% pump DC at 0-5% injector duty cycle and 100% pump DC at 10% injector duty cycle and higher. 

The easiest way I can see to so this is using Injector Drive 5 and changing it from the default Fuel Pump to FP Speed mode. I can set up the FP Speed table to give me the above IDC triggers for the pump DC% i wish to have. Problem is I cannot see what PWM Frequency this auxillary output uses. There is a note in Help saying this is not for use with SSR's as they cannot switch fast enough, but from what I can see these Aux outputs max out at 300Hz. My Crydom DC100D40 SSR can be driven at 900Hz. Will this work for me or am I missing something and the help file is outdated? 

If I used the above method and it was actually being driven at 300Hz via Injector Drive 5, I set Polarity to HIGH, correct? I belive this will give me 0% duty = 100% driven to ground and 100% duty = 100% driven to 12v. 

Following on from that, for simplicities sake I wanted to wire the SSR power feed direct to the battery (car side of 150A breaker at the battery) but take this to be constant 12v. With the way the Injector Drive aux outputs are configured, ie: no freewheeling diodes (right?) this will not result in backfeeding, unless I am missing something...   

If this isn't going to work as I expect (perhaps its driving at 4000Hz or something undocumented) I will need to set up Aux 2 in GP PWM mode to drive the SSR. If I have to resort to this, will this impact the ability to direct wire the SSR to the battery unswitched 12v? Secondly, how in this configuration do I get the pump to prime on key on but then turn off after x seconds? Does Fuel Pump Control have any impact at all when using an aux output like Aux 2 as a GP PWM to drive a controller? 

Thanks in advance 

[ellisd1984]

I'm wanting to do something similar.  I'm using a PWM control module out of a subaru in my celica GT Four, I'm just waiting for a few connectors before I can have a go at it.

Did your car have any sort of speed control for the fuel pump originally?  Mine had a resistor pack fed via a relay that would drop the voltage to the pump at idle & cruise.  I've done away with this but I'm using the those output for my new setup

[EvocentriK]

8 hours ago, ellisd1984 said:

I'm wanting to do something similar.  I'm using a PWM control module out of a subaru in my celica GT Four, I'm just waiting for a few connectors before I can have a go at it.

Did your car have any sort of speed control for the fuel pump originally?  Mine had a resistor pack fed via a relay that would drop the voltage to the pump at idle & cruise.  I've done away with this but I'm using the those output for my new setup

Hi, yes I’ve seen people use Subaru or Jag/Aston fuel pump controllers. I’m wanting to use something brand new and easy to purchase like a high quality SSR instead of a used OEM module from another model of car. I’ll protect it from backfeed with a 40A schottky diode across the SSR pump feed output and SSR ground terminal. 
 

The stock evo system uses a relay to drive either a resistor pack or to energise a 2nd relay for direct voltage feed in an antiquated 2 speed system. Like you I want to do away with all this and simplify the setup.
 

Phase 2 for me is adding a surge tank with the same kind of PWM / 2 speed based pump control for that but I want to get this phase 1 setup working first and prove the design before I do. 
 

 

[Adamw]

You can use the open loop PWM fuel pump control function.  Those crydom and other cheap SSR's generally dont like driving a motor at any more than about 100Hz and some pump make quite a growl at that.  But give it a try.  The note in the help file is comparing to proper fuel pump control modules which would typically work at ~20KHz.

Yes use an ign or inj drive if it is live all the time to prevent backfeed.  However be aware SSR's usually fail "closed" so consider the safety factor if you dont have an isolator or some other easy way to disable.  Dedicated PWM fuel pump controllers are generally designed to fail open, whilst dedicated fan controllers are designed to fail closed.

There is a prime function built in to the open loop fuel pump control function.

[EvocentriK]

4 hours ago, Adamw said:

You can use the open loop PWM fuel pump control function.  Those crydom and other cheap SSR's generally dont like driving a motor at any more than about 100Hz and some pump make quite a growl at that.  But give it a try.  The note in the help file is comparing to proper fuel pump control modules which would typically work at ~20KHz.

Yes use an ign or inj drive if it is live all the time to prevent backfeed.  However be aware SSR's usually fail "closed" so consider the safety factor if you dont have an isolator or some other easy way to disable.  Dedicated PWM fuel pump controllers are generally designed to fail open, whilst dedicated fan controllers are designed to fail closed.

There is a prime function built in to the open loop fuel pump control function.

Thanks Adam, appreciate the input. 
 

I have a 150A main breaker that the SSR supply is connected to if I need to isolate for some reason (pic above). 
 

The FP Speed mode doesn’t have configurable frequency for PWM, what is it set to? 
 

If the SSR doesn’t like >100hz how will this manifest? Heat? Shutdowns?

[EvocentriK]

On 2/28/2021 at 1:57 PM, EvocentriK said:

Thanks Adam, appreciate the input. 
 

I have a 150A main breaker that the SSR supply is connected to if I need to isolate for some reason (pic above). 
 

The FP Speed mode doesn’t have configurable frequency for PWM, what is it set to? 
 

If the SSR doesn’t like >100hz how will this manifest? Heat? Shutdowns?

Hi, just revisiting this for assistance please.

In the manual in the auxillary wiring function table it states FPSpeed is for generalXover mode only. Is that correct? It seems at odds with the explanation of Fuel Pump Control where FP Speed mode is required when using Open Loop Control method via PWM. Problem is, there is no Hz field when using FP Speed, so how do I have any control over the frequency being used to drive the SSR? Thanks 

[Adamw]

In G4+ from memory only Aux 1-8 can do open or closed loop PWM FP speed.  Aux 9-16 and inj/ign drives can only do x-over mode. 

[EvocentriK]

4 hours ago, Adamw said:

In G4+ from memory only Aux 1-8 can do open or closed loop PWM FP speed.  Aux 9-16 and inj/ign drives can only do x-over mode. 

Thanks Adam, I moved it over to AUX2 (which I don't use as I deleted the intercooler sprayer) and it works in PWM mode but lord the pump makes a racket, even at 900Hz drive frequency. Not sure I can live with that, wonder if its harmful to the pump as well. In this mode it appears there's no control over the prime time either - it's a short on cycle only, maybe 500ms. 

I was not able to get Inj drives 5 or 6 (by default those used in the stock setup for Fuel Pump and FP Speed) to trigger the SSR relay even in Test ON mode. I was measuring 0.024v to ground when the Inj drive state was ON, are they not pulled up to 6-12v?