Fuel Questions

[BiGGinZ]

The car is a 91 eclipse turbo. It has a 255 Walbro Fuel Pump, 550 injectors, and a safc. Do I need to get an afpr? Want to run 18-22 psi on the fuel set-up. I was wondering because I thought maybe because of the safc I don't need an afpr. I will be running this psi on a 16g turbo. Thanks.

BiGGinZ

 

[ICGerms]

You shouldn't need an AFPR...it's nice to have the extra bit of control, but it's not really necessary.

 

[andymoraitis]

You shouldn't need an AFPR...it's nice to have the extra bit of control, but it's not really necessary.

Sorry but that's not correct. The 255 will heavily overrun the stock FPR causing you to run incredibly rich. The AFC may correct for the injectors and modify the airflow, but the stock FPR overrun will end up washing down the cylinder walls with fuel.

Andy

 

[BiGGinZ]

I have two completely different answers. Can someone (like oldman) come in and clear things up. I think I will need one but I am not sure. I will eventually get one anyways but I am wondering if it is something I need to do in the next month. If I do need one, any install guides? Thanks.

BiGGinZ

 

[DSM_Aruba]

Since your running at high boost levels, I would recommend you to go for an AFPR. If you're going to install a Fuel pressure gauge with the AFPR, look for the liquid filled gauge. You can get one very cheap at slowboyracing.com

 

[DSMvroom]

I'm no wiseman but from my gathered information from reading about AFPRs, the 255, and the 190 from this site, VFAQ, and DSM.org I've concluded this regarding your question . . .

the 255(high or low pressure) will overrun the stock FPR whenever the RPMs are below ~5500rpm (i need someone to correct this number because im pretty sure i'm wrong, but it is somewhere up there). An AFPR is required to be able to handle and stabilize base fuel pressure during these times.

An AFPR is not required for the 190.

Because you have an AFC, I do not know how much of my first conclusion stays true.

 

[ICGerms]

Sorry but that's not correct. The 255 will heavily overrun the stock FPR causing you to run incredibly rich...

That's not true. I put AFPR's on three different 1G's, all with 255lph Walbros, and none of them REALLY needed to have it...fuel pressure only went up a maximum of 6psi, and that was only on one of the cars. The other two increased 3psi and 4psi, respectively. ALTHOUGH, other 1G owners have reported that they DID need an AFPR because the 255lph fuel pump was overrunning the stocker. I don't know why the difference, but this topic has come up several times on other boards. The 2G's don't seem to be as fussy and/or inconsistent when an aftermarket fuel pump is added.

 

[BlackbirdOfPrey]

The correct answer is.....

Its different for every car.

Some cars may be able to get away with not having an aftermarket fpr, but some may need it worse than a .05 cent hooker. It is entirely dependant on the car. It is nice to have an extra degree of adjustment, but you might not need it, the only way is to find out and log runs. For the most part a 190 you wont, but with a 255 you may or may not need one. Sort of the same idea as someone boosting 15 psi and blowing a head gasket, and someone boosting 25 psi and being fine on the stock one, its a DSM, who knows>?

 

[oldman]

Yes, 255 will overrun the stock fpr and yes every car is different and will react differently with overrun but you can be sure it's there. Can one live with it? Yes, just like you can live with venting the bov or running 550cc and 2G mas (for 1Gs) without a safc. Is it good for the car? No!! Since this is a performance site and we like to stick with facts and numbers and part of my job is to advise the new comers to do it right, my answer to the original poster would be "Yes, you need an afpr for the 255".

 

[oldman]

If I do need one, any install guides?

http://www.vfaq.com/mods/FPR.html

 

[BiGGinZ]

Thanks oldman and everyone else that replied. I will be getting one whenever money permits me to.

BiGGinZ

 

[CanadianTSi]

I don't understand why so many people get the 255

The 190 will support all the horsepower the mojority of people on this site will ever make and it doesn't overrun the FPR...

 

[BiGGinZ]

I don't understand why so many people get the 255

The 190 will support all the horsepower the mojority of people on this site will ever make and it doesn't overrun the FPR...

My car already had it in it when I bought it.

BiGGinZ

 

[steve]

the 255(high or low pressure) will overrun the stock FPR whenever the RPMs are below ~5500rpm (i need someone to correct this number because im pretty sure i'm wrong, but it is somewhere up there).

It's not directly related to any RPM.
Overrun is caused by the fuel return port (orifice and valve) not being able to return all the excess fuel back to the fuel tank to maintain the correct fuel pressure. Any time the excess fuel drops below the ports flow rate the pressure drops back to what it should be. That can be caused by a reduction in the pump flow or by the engine using the extra fuel.
Fuel use is engine load based. You use much less fuel at 4k free reving than you do going up a hill or under boost, so when the regulator stops overrunning is going to depend on how much the engine is using at any given point. If you think about it you'll note that the FPR can drop in and out of overrun all over the place.

Steve