I've narrowed down my problems to fuel pressure, because the gauge I purchased couldn't even READ the pressure coming out of my pump because it was so crazy high(Walbro 255). I have a 13b Cosmo motor with 550cc primaries in a KGParts fuel rail and 1680ccs in the stock secondary rail. The stock FPR just doesn't appear to be doing the job.

I also have a T04R turbo and NPR intercooler, and Haltech E6X, if that helps at all!

So what should my fuel pressure be?

 

i believe it's the same for all forced induction rotaries, 40 psi. a friend of mine is having this same problem and we are trying to figure out how to get it back down. let me know if you find a solution please. thanks.

 

40-45 Static is typical, 50-60 under boost depending on actual boost. Mine sits at about 60psi at WOT. Carl

 

I'm running 50psi base...

 

50psi, so I need a better gauge! I think I'm going to get an FPR just to be safe, I don't think it's wise to run only the secondary rail FPR at this point, but I could be wrong.

The engine will only run for about 15 seconds with the injectors "off" in the Haltech (to me this means the fuel pump isn't pumping, in turn not keeping the lines pressurized), and not at all with the injectors on. It *appears* that the fuel pressure keeps rising until the motor can no longer run and sometimes backfires with spark only.

That's probably super-convoluted but I'm trying to make sense of what's happening!

Thanks for the responses and if you have any other ideas I'm open to them.

 

fuel pressure could be your problem

most find 40 psi at zero vacuum works for them. that would be approx 33 at idle, say around 15 inches hg.

some run higher fuel pressure so the pump has a headstart in dealing w, for example, 20 psi of boost as fuel pressure at 20 psi should be approx 60 psi.

a key consideration is that if you are properly tuned at X fuel pressure and you raise your fuel pressure say 10% you will be very rich and will absolutely need to retune your base fuel. anytime you change fuel pressure you will need a global base fuel adj.

ideally for aggressive street and occasional track you should run as low a fuel pressure as you can as it will be easier on all components... if you are racing only you might just run a bit more pressure and turn down the base fuel map.

either way, get a gauge and an adj FPR.

good luck,

howard coleman

 

I ran the stock fuel pressure reg on the seconday rail for a year with no problems. This isn't to say your's isn't bad. Get a gauge and see for your self.