the truth about the walbro 255lph

[turbodsm_125]

ok so i have searched this whole site religously and i want to know what the deal is with running a 255 on a 1g. do i have to install a fpr? i have seen people go both ways on this. car a wise man or vendor clear this up? will it over run the stock unit? my car is a 90 awd. i am currently runing a 14b with an all stock fuel system. i plan to upgrade in the future, but not the near future.

 

[The_EE]

Yes, you need a AFPR with it.

 

[timloomis]

Yes you need an afpr. I was seeing 12psi over stock on the stock fpr with just a 190lph pump. You can run it without one, but idle and being able to tune it correctly will suffer.

 

[daren_p]

ok so i have searched this whole site religously and i want to know what the deal is with running a 255 on a 1g. do i have to install a fpr? i have seen people go both ways on this. car a wise man or vendor clear this up? will it over run the stock unit? my car is a 90 awd. i am currently runing a 14b with an all stock fuel system. i plan to upgrade in the future, but not the near future.

If you searched this whole site religously, then I guess that you should already know that you will more then likely see FPR overrun with a 255 pump as this has been posted to many times to count A search of simply walbro & I saw multiple threads on this exact subject within the first two pages. If you want to be certain, install a fuel pressure gauge & see but as I said more then likely you will have FPR overrun.

 

[turbodsm_125]

pretty much this is the answer i expected to get. is there any one on the other side of this argument who wants to defend there side? how could you run this thing with out a fpr? running the stock set up would i be better off with a 190?

 

[bling5tatus]

Isn't fpr over run a result of running a certain (higher than stock) amount of boost with the stock fpr and a 255 pump?

I have a 255, but I don't use more than 18psi and I do not believe that I am suffering any issues from this, my AFRs are right where I want them all throughout the rpm range.

 

[daren_p]

Isn't fpr over run a result of running a certain (higher than stock) amount of boost with the stock fpr and a 255 pump?

I have a 255, but I don't use more than 18psi and I do not believe that I am suffering any issues from this, my AFRs are right where I want them all throughout the rpm range.

No, this isn't the case, actually the more boost you run, the more likely you won't have over run in these conditions. FPR overrun normally happens at idle & part throttle conditions, so some that have it won't even notice as under WOT conditions where they tune/pay attention to air/fuel ratio etc., over run doesn't usually happen. Put a fuel pressure gauge on & then tell us you don't have FPR over run I have yet to hear from anyone who actually did this say they didn't have an evelated base fuel pressure.

 

[timloomis]

Like I said, my fuel pressure was 12psi higher than stock with a 190 on stock wiring. I found out the hard way that the fuel pressure doesnt rise equally when it's over-ran either, it's not like I was 12psi higher all the way. Made it a pita to tune.

 

[CanadianTSi]

The only car that gets severely overrun is the 2G AWD (due to its fuel return design)

Now the overrun only effects idle and driving around off boost, once you get into boost the fuel pressure rises therefore the problem goes away.

On my particular car anyways I can tune those situations just fine via DSMLink and have the car run a proper AFR with good fuel trims and pass a smog test etc etc. I also drive a car where the problem is the worst. On a 1G the overrun won't be so bad.