Can this work? I'd assumed it could work just fine... but what am I missing to make that work if I have an FMU and have upgraded my in-tank fuel pump to a Walbro 255 lph?

 

cough stickies cough

 

I was told this set-up would work but you will need a (4:1) FMU also

 

Youll need an FMU to bump fuel pressure.

-matt

 

You may also need a AFPR to bring down base fuel pressure for start up. The 370's (actually 410ish) plus the walbro may dump to much fuel at start up.

 

Cool. about where would I want fuel pressure at start-up? (so as to adjust the afpr)

 

It's something you would probably have to try out yourself to find what works. You may not need an AFPR, but like I said you could have some flooding issues. The walbro is too powerful for the stock FPR and base fuel pressure will bump up about 3-4 psi. Add the larger injectors and you might get too much fuel at start up. If you do have to lower base fuel pressure don't go lower than 30psi. Make sure you also get at least a mechanical fuel pressure guage as well.

As far as the FMU, I would probably do an SAFC instead. You will already be running larger injectors so that will bring down AFR's a bit under open loop. Then you can just use the SAFC to add some fuel where needed. The SAFC will also give you some other features like peak hold of Knock, RPM, and MAF voltage.

 

So you would completely pull the FMU? Hmmm.... how in the scheme of things do I install the SAFC-II instead? Just wire it into my ECU harness? How do I create higher fuel output on boost without a vacuum line to detect changes? I guess I want to make sure I know the key differences for this mechanical--->electronix switchover...

 

I see that you already have the FMU, in that case you might just want to stick with that. I thought you still needed to purchase one, and in that case I would have bought the SAFC instead of the FMU.

An SAFC does not need a vacuum reading, it adds/pulls fuel based on MAF voltage. It can be fine tuned compared to using an FMU. Yes, the SAFC is wired into the ECU.

Although a little primitive, FMU's work pretty well for low boost applications. They just can't be tuned as well since one disk may have you running lean and the next size up could have you too rich. It's harder to dial in AFR's.