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Go EFI Pulse Width Modulation Instructions With Pictures

Did you know that you can control the pulse width modulation (speed) of your fuel pump with your hand held controller? Your system comes shipped with the fuel pump control pwm set for frame mounted pumps. If you are using a fuel command center (fcc) you should change the speed of the pump. To do this follow these steps.

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38 comments on “Go EFI Pulse Width Modulation Instructions With Pictures

  1. Will the system work blending E-85 and methanol AKA Alcohol? I will be using a 82 mm turbo on a 347 ford for dragracing. Will the o2 sensor lean out too much or not enough to run in the seven’s in the 1/4 mile?

    1. E85 reduces the HP capacity of the fuel injection system by 30%. Methanol pushes the loss to around 50%. This would make the HP capacity fairly low and most likely wont work for an engine making around 650hp.

  2. I have a FiTech `1200HP. My fuel system has a Walbro 450 LPH pump in the tank. Pump is controlled by the FiTech unit. Can I use the pulse feature on my setup and not run the pump at full blast all of the time?

    1. Refer to the pump manufacturer for that. The EFI will PWM a fuel pump up to 15 amps but not all pumps work with PWM.

  3. I am running an aeromotive a-1000 fuel pump with a 100 micron and a 10 micron filter. I have 10an feed lines and 8an return to my fuel cell. This system worked fine with the f.a.s.t. ez efi version 1 multiport kit. I read a review on summit racing saying your fuel pressure regulator couldn’t handle the a-1000. Is this true? I have the a-1000 external efi regulator. If I were to use this before the inlet to regulate the flow down, would that solve the problem? I am running this on a 545 bb ford with a single turbo. Thanks!

    1. The fuel pressure regulator in the FiTech throttle body is capable of flowing up to 340 LPH. Any fuel pump over that flow rate will require an external bypass regulator. Also the A1000 draws a lot of amperage and will also require a relay to be powered.

      1. Does Fitech offer or recommend a particular relay for for A-1000 users. Giving the pwm control voltage a solid state relay would be in order- correct? If so most user are sceptical as to what relay to purchase. I , myself have only limited understanding and experience with the mechanical relay. The SSR is new to me. I’m almost certain that I speak for many. I really want to take advantage of the pwm ability that my system offer.

        Are there any recommendations ? Btw you guys make a great system. Thx in advance

        1. I have no recommendations because we have not tested with SSRs…

          What I can say is our PWM feature operates at 1000hz so I would check with whatever SSR you are looking at and see what it can cycle at. Also verify amp draw from the pump and if the A1000 can ultimately be PWM operated.

  4. I have the 400/basic EFI from you and I have a external fuel pump with return. How much pressure should it be getting? Right now it’s @ 55psi. Too much?

    1. This pressure in fine for the system to run.

  5. I am running a 40003 fuel center. The primary pump is stock to a 40 micron filter to fuel center then out to your filter is this to mush restriction?(420 Hp motor)

    1. A pre-filter is recommended. Your setup is what we like to see.

  6. I would like to use the GO EFI 4 600hp to replace the Ford CFI system in my Country Squire. It has an in-tank fuel pump that maintains 39psi. Will this be enough to satisfy the GO EFI while the engine is in stock condition? (’85 302 smog era engine) I realize I’ll need more fuel as I perform upgrades. Eventually my high compression 351W will go in and I will add a bigger pump.

    1. You need a fuel pump that can run higher pressures. The EFI system runs at 58 psi.

  7. How do I find ‘Go EFI PRO Tuning’ on my handheld? It is not listed at #6 of the Main Menu as instructed in Step 1 of setting Fuel Pump PWM. I have an in-tank 255 lph Walbro pump, not a rail mounted pump. For my Hand-Held Main Menu #6 is ‘Display Set-up’ I cannot find ‘Go EFI PRO Tuning anywhere on my menu’s.
    I am assuming the PWM would be the same between the Command Center and the Walbro in-tank?

    1. You need to go to Display Setup first and mark PRO Calibration to SHOW. It will then show the Go EFI Pro Tuning in the Main Menu.

  8. How many amps can the Go-EFI 4 safely supply for the fuel pump? I have an in-tank Walbro 255L pump and your pump power wire doesn’t seem very substantial. My other option is to use a standard relay instead but believe I’ll lose the PWM feature. As I understand the system that means the pump will run full speed all the time. Is this a problem? Which do you recommend, a relay or direct wiring with PWM from the EFI? Thanks.

    1. Your pump is perfectly fine to hook straight to the EFI system. It will work with pumps up to 15 amps.

  9. tank is in the back of the vehicle. thinking of using a walbro gss340 will a bigger wire need to be used along with a relay? I have the same go efi 4 as above. would really like to not have to worry about another relay if i don’t have to.

    1. A Walbro GSS340 can be used with or without a relay for the fuel pump.

  10. My fuel pump is a Walbro GSS340 which is not pwm capable. Is there any advantage of running it with a relay off of the Fitech, or just as good to run it with switched power separate from the Fitech? I am wondering if maybe a safety advantage. If I use separate switched power, I use an oil pressure switch to turn the pump off when the engine stops. Will the Fitech kill the pump when the engine stops?

    1. You can use a relay with the fuel pump. This is taking the load off the ECU to drive the pump.

      When the EFI looses a RPM it shuts off the fuel pump so it is useful to have the EFI turn on the fuel pump relay.

  11. I have a30008 mean street bought a year ago there is no pro tuning section on the hand held is there an update for this as looking on the forums there is a lot that im missing if so can you let me know where to find it as want to set up fcc thanks

    1. Some systems have different features on the handheld. For Pro Tuning you must turn it on in display setup on the main menu.

  12. I have a 85 corvette,Im going to replace the tune port with the fitech go 400.would I have to do anything to the fuel system ?

    1. The Go Street EFI operates at 45 psi so be sure your pump can support this pressure.

  13. Hey,

    I am running the Fi Tech EFI8 with twin 62mm turbos on a SBC 372″. I have it running good, but I am installing an additional fuel pressure regulator per your advice in the FAQ tech columns with a Aeromotive A1000 fuel pump on relays. My question is what do you recommend the additional regulator to be set too? It will be mounted just before the unit inlet with a fuel return line T’ed into the units return line and back to the fuel cell. I was guessing about 58 psi or so?

    I am also installing a Aeromotive Fuel pump controller due to the Fi Tech not able to handle the amp draw of it and it now running off on 30 amp relays. if this changes anything with the regulator pressure. Thanks for the help!

    1. 58 psi is the correct pressure to set the regulator at. No matter how you power the fuel pump the regulator will always maintain the fuel pressure.

      1. I am using the FiTech orange fuel pump signal wire as my fuel pump power/ ign source signal on my Aeromotive pump controller. This FiTech ECU is trying to use its PWM and reduce the fuel pump voltage sent one this wire. How do I get my ECU to give a flat clean 12 volt signal here? Basically zero fuel pump modulation from my FiTech ECU so the Aeromotive can control the pump. Settings to do so?

        1. Set PWM to 100 and it will no longer use the feature.

  14. hi I have a fitech 1200 poweradder system I’m having trouble with the pwm control I have an areomotive a1000 fuel pump that I have regulated with a return style regulator before the throttle body the problem I have is right now I have the external regulator set to 40 psi if I turn it up to 58 as told the injection needs it causes the EFI to want shut the fuel pump off after idling for a time and than it stalls sometimes it even wants to run the pump erratically to where the fuel pressure is to low to run the engine while driving at speed if I adjust the regulator back down to around 40 psi engine runs fine with no issues I have tried to adjust some of the settings for fuel pump control under pro tuning but have had no luck resolving the issue for now I have just been running system at 40psi any advice on this issue would be appreciated thanks.

    1. When using a large pump like the Areomotive A1000 you need to not only run an external regulator you also need to power it with a relay. The FiTech ECU is not able to PWM pumps that draw more than 15 amps.

  15. I have a 1969 Camaro with a stock 307. I have fitted your throttle body and fuel command center (yes i set the PWM to 40) along with a ready to run MSD Distributor and Blaster II Coil, and have had the car running for about 3 hours now. After running for 20 minutes it was perfect. The idle was perfect, there was no rich smell in the exhaust, the fan was coming on and off like it’s supposed to – it was running beautiful!
    A couple days ago I went to run it and now it starts and runs for about 3 to 5 seconds and then dies. Does that every time. If I catch it before it dies it will keep running but at about 3500 rpm and runs real rough.
    It threw a code P0335.
    I had the “KEY” wire connected to a temporary wire coming from the battery as the car is still in pieces so I rewired it to the ignition switch circuit. Now it still does exactly the same thing only now it’s not throwing any code.
    Next I jacked up the screw on the drivers side, reset the TPS in the ECU and ran it again – does the same thing only at a higher idle. I set the screw back to where it was.
    I’ve reset the Learn with no change.
    I reset it to stock calibration, went back in and changed the PVM, cubic inches, fan settings, saved it, disconnected it, reconnected and ran it and still no change.
    When my wife came home I had her start it so that I could watch the gauges on the command center – it’s barely making 30 psi, then dropping to 20 psi and that’s when it dies. Just out of interest I was poking around with the test light checking to make sure I had voltage to everything, and when I put it on the negative of the coil (which also has the blue wire) it cycled the fuel command center.
    We re-started the car with the test light on the negative the hole time and it still died, but as soon as it died it re-primed.
    What should I try next? Should I connect a hot to the positive on the fuel command to see if that keeps it running?

    1. When you hooked up the test light to the negative of the coil you sent a signal to the EFI for RPM. This made the pump turn on. Check RPM on the dashboard while cranking and see if the system sees the RPM. If it doesn’t there is something up with the ignition system like the module or coil are going bad.

      1. I isolated the wiring and still no change. I put power directly to the pump and started it and it stayed running. After about 2 minutes running i took the jumper off and it stayed running. Now it seems to be running alright! At the moment I have the diff out, so when it goes back in I will run it again and hope that it runs ok. If not I think the fuel command pump is faulty. FYI I also have a fuel injection pre-filter between the mechanical pump and the fuel command pump. There is nothing wrong with the distributer or coil – they are MSD and are brand new – their stuff never goes bad. i am using the MSD ready to run chevy MSD with the extra grey wire for tach feed. Should I connect the blue wire to that grey wire instead of the negative on the coil??

        1. Hook the FiTech blue tach wire to the MSD grey tach wire.


    1. The PWM should be at 75.

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