i was wondering do i need to run a bigger fuel pump if im using a FMU?

 

The correct way to do it is to not use an FMU.
THe second best way to do it is to run an inline pump (like Airtex).

 

have u considered to run the afc hack instead of the fmu

 

and if u need one i have one, brand new never used. 100 bucks

 

run my crackhead 3bar apexi hack! Depends on how much boost you plan to run. I'm running a bigger in tank fuel pump, FMU, 440 injecters, and the apexi hack to make sure I've always got enough fuel. To be safe, run the FMU.

 

A secondary fuel pump will increase the volume of fuel flowing through the rail, but it won't raise the fuel pressure as much as the FMU will. More fuel pressure = more fuel the injectors spit out.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DXturbo &raquo;</TD></TR><TR><TD CLASS="quote">i was wondering do i need to run a bigger fuel pump if im using a FMU?</TD></TR></TABLE>

Depends on how much boost your runing and what size of injectors your using.
If your going to run a fmu i highly recomend going with a intank 255lph high pressure fuel pump (walbro/holley) makes one that works good for that set-up.

There Is nothing wrong with using a fmu (in response to the post that stated that a fmu was the wrong way of doing it) if it's used smartly.
Where are you located in wa?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">There Is nothing wrong with using a fmu (in response to the post that stated that a fmu was the wrong way of doing it) if it's used smartly.</TD></TR></TABLE>
So there is nothing wrong with running fuel at 12 times the psi that the lines are built for, is that safe? I dont think so . Its just the last thing I would do. You can choose to run unsafe fuel management if you want to. Thats not my problem.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4gen &raquo;</TD></TR><TR><TD CLASS="quote">
So there is nothing wrong with running fuel at 12 times the psi that the lines are built for, is that safe? I dont think so . Its just the last thing I would do. You can choose to run unsafe fuel management if you want to. Thats not my problem. </TD></TR></TABLE>

what the hell are you babbling about???whos running 480psi through there lines?if your running 6psi with a 12.1 disk it is almost 3x the normal psi.....not sure where u got 12 from man..

 

there really isn't anything wrong with running high rail pressure. That's why honda gives you a fuel pressure regulator on the end of the rail. If it wasn't safe, they wouldn't have done it.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4gen &raquo;</TD></TR><TR><TD CLASS="quote">
So there is nothing wrong with running fuel at 12 times the psi that the lines are built for, is that safe? I dont think so . Its just the last thing I would do. You can choose to run unsafe fuel management if you want to. Thats not my problem. </TD></TR></TABLE>

That's ignorance. Last time I saw were rated maximum 300 psi on all Honda fuel lines (pressure side). You are more worrying about the injectors getting stuck open instead of anything else. Anything lesser than 85 psi is fine.

 

wow thanks for all the replies! the turbo forum is so helpful and informative.
anyhow, the only reason i will be using the FMU is cause i got it for free until i can afford a standalone ie... AEM or hondata.

i will only be boosting 7-8 psi max until then... so will a holley intake 255 and the FMU be sufficient? or should i throw some 440 DSM injectors in there too?

THANKS EVERYONE for the replies!


Modified by DXturbo at 9:04 AM 6/24/2003

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Type-GS-R-Turbo &raquo;</TD></TR><TR><TD CLASS="quote">there really isn't anything wrong with running high rail pressure. That's why honda gives you a fuel pressure regulator on the end of the rail. If it wasn't safe, they wouldn't have done it.</TD></TR></TABLE>

what r u talking about? "thats why Honda gives you a fuel pressure regulator on the end of the rail" please explain that to me.

140psi fuel pressure is all kinds of bad. Bad for the injectors, bad for fuel pumps, and bad for the regulator. but FMU's work. they work good up to 7psi w/ an inline and are cheap and simple.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DXturbo &raquo;</TD></TR><TR><TD CLASS="quote">i was wondering do i need to run a bigger fuel pump if im using a FMU?</TD></TR></TABLE>

I had to run a bigger pump with my FMU. My 91 Si couldn't pump enough fuel. I added a walbro pump and it was fine. I'm running an FMU with walbro pump on stock injectors at about 7-8psi and am fine. Sure its far from ideal, but it hasn't been a problem thus far. The setup will be changed soon, but if you're looking to run this to get you by until you get something better, I personally wouldn't worry about it. You should be fine (depending on other factors of course).

 

Stock Injectors
Stock Fuel Pressure ~45psi
12:1 FMU disk ratio

at 7 psi, it will do 45psi ( base fuel press) + (12x7psi) = 129 psi of fuel pressure at WOT with the aboved setup.

This is pretty much the max I'd push out of. period. The stock intank pump even with 255LPH walbro and inline will not be able to handle any higher than this.

stan

 

thanks flamenco-T. how can you tell what size disk it is? the FMU came with the SOHC Apexi turbo kit. since i have a set of dsm injectors and resistor box should i just put those in too?

 

if you have a DSM injectors, which are 450cc, I'd get a lower ratio disk like 8:1 or so.

stan

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 4gen &raquo;</TD></TR><TR><TD CLASS="quote">
So there is nothing wrong with running fuel at 12 times the psi that the lines are built for, is that safe? I dont think so . Its just the last thing I would do. You can choose to run unsafe fuel management if you want to. Thats not my problem. </TD></TR></TABLE>

The great thing is, you even got my whole entire quote..... I'm proud of you for doing that much...now back to topic. I said if used smartly... a 12:1 and 8psi is not smart.. i repeate NOT SMART.........
if used within reason it's still a good way of providing more fuel. If you were a smart fellow you would realize that fuel pressure 12 times that stock amount was not safe......................&lt;-----------(let me provide the arrow to show the the period)...........I'm runing 80psi under full boost...thats 9psi of boost... does that = 12x's stock to you???????? didnn't think so...

Try reading all of the reply before you make yourself look like an idiot.

 

Yes, I do agree with you, I should've been more precise in my translation of FMU use. Good up to 7 psi, just most of my friends are running more, sooo, FMU isnt a path they can choose. Thanks.

 

LOL. It could never be 12X the fuel pressure and plus if your running a turbo on a honda your adding what ever amount of boost over what the engine was designed to run. So why not do the same with the fuel.

if you want run some bigger injectors that way you can use a smaller ratio fmu and keep the pressure lower.