fuel supply?

[e30leigh]

so just woundering what everyone is running in ways of pumps?

i was gona run a bosch 044 external for the feed pump. but worried the internal lift pump wont be able to keep up?

what has been done? serge tank perhaps with the stock lift pump? or is a larger lift pump required also? im not sure how fast the factory item can pump in order to keep the 044 fed with fuel.

thanks, leigh

[Hey_You]

Check in the DIY section, there is a 044 pump retrofit article that will interest you and answer all your questions.

[e30leigh]

cool thanks man.

[e30leigh]

just had a look. there is a diy walbro 255. its sort of what im asking.

but my real question is should clear up. my car seems to have its fuel pump externally under the car. while our work race e30 has its fuel pump located intank. im not 100% but i thought that the models with the externally fitted pumps still had a small intake pump to lift the fuel out of the tank before the external one takes over. or have i herd bad info?

id look into it myself but have been struggling for the free time.

i mainly need it cleared up if i have one or two pumps? i have an '88 fl 318i m40, if that helps at all?

cos then i can design and start buying the fuelling system.

thanks , leigh.

[bmwguy325is]

Early cars had two pumps. 87/88 can go either way. If your car has the external pump behind the drive it does have the transfer pump as well.

[nando]

The 044 will actually make life easier for the lift pump, since it wont need to build presure, only supply volume. if you look you'll find charts that show the 044 in dual and single config. a dual config will flow all the volume you could ever need, and the 044 will give you the needed pressure. the 044 will piss all over walbro crap six ways from sunday :)

if you want a cheap, not made in china POS upgrade for the in-tank pump, look for a used E46 M3 pump. they do 5 bar stock, and pretty much go right into the E30 pump carrier (late model style, anyway).

[e30leigh]

ill look around for a larger intank lift pump. perhaps a 540 or e46 like you said and use that to feed a surge tank. ill then replace my external feed pump with a bosch 044 to feed the rail. with 6 37lbs injectors i think ill need something decent with a rising rate fuel pressure reg to replace the factory item. i may even modify the factory fuel rail slightly to that the aftermarket reg, perhaps a 1-1 rising rate sard item, can be used without the stock item. itll make the whole system work that much better.

thanks for the info guys.

[nando]

don't mess with FPRs unless you really understand them. Rising rate FPRs are generally a bad idea. 1:1 is a standard FPR which is what you already have. A rising rate FPR increases the ratio as manifold pressure increases, instead of being linear.

[e30leigh]

i understand how they work. the facorty ones arent going to cope with the boost. i need an adjustable one to set the base pressures correctly. and why people would run two in a row is beyond me. one quality adjustable, rising rate reg is all that is needed.

[nando]

why do you need to increase it? the factory regulator is already 1:1. It will already increase pressure with increasing manifold pressure (yes, under boost too). If you've upgraded the fuel pumps, there's no reason to change the base pressure, unless your injectors are slightly too small.

rising rate means the ratio increases with manifold pressure. that means it will go to 1:2, then 1:3, then 1:4, etc. you don't want this. it makes fuel response non-linear, and all engine computers expect it to be linear.

unless you're basically going to "tune" with a FPR, not a custom chip or standalone?

adjustable FPRs are mostly useless unless you have a very specific need. It's better to change the commanded PW inside the ECU if you need more fuel, or get bigger injectors if they're too small. I've had one for years, and it's set at - 3 bar, like stock. :|

[LowR3V'in]

Get a begi if you're going to do it that way.
There's one on ebay right now for $120

[jaywood]

Begi 2025. You can find them used for $100.

[e30leigh]

the factory ones are not built to cope with the pressures of boost. its on the side of caution more then anything to change it. and being able to set the fuel pressure more accordingly has its advantages to fine tune the fueling system slightly. or to compensate for the injector and pump change. 1-1 rising rate is what i will fit. but it goes without saying that a good quality aftermarket reg built for turbo applications is going to function alot better then a 24 year old reg that is built for functioning the controlls during vaccum and ambient pressures only. and with a much lower fuel pressure demand behind it. one could say the factory regs adjustment range is more limited and possibly not up to the task.

[LowR3V'in]

You're just making excuses now.
These regulators have been proven over and over again on many different cars.
Bosch regulators are not NLA. They don't have to be 24 years old.
I don't know why you're saying it's not meant to see boost or this and that.

We're just trying to open your eyes to good info.

[nando]

the factory ones are not built to cope with the pressures of boost. its on the side of caution more then anything to change it. and being able to set the fuel pressure more accordingly has its advantages to fine tune the fueling system slightly. or to compensate for the injector and pump change. 1-1 rising rate is what i will fit. but it goes without saying that a good quality aftermarket reg built for turbo applications is going to function alot better then a 24 year old reg that is built for functioning the controlls during vaccum and ambient pressures only. and with a much lower fuel pressure demand behind it. one could say the factory regs adjustment range is more limited and possibly not up to the task.

they work fine. they don't care about "boost". the stock regulators have been proven hundreds of time with turbo builds.

you don't change your base pressure because the pump or injectors changed - that's nonsense. you change the tune inside whatever you're using to run the engine. the regulator doesn't care what injector size you have and the pump doesn't care what regulator you've got. Besides, most injectors are going to be rated at 3 bar, which is what the stock regulator is.

there is no adjustment "range". it will always keep a 3 bar differential pressure, yes even under boost. it doesn't adjust anything, it's always a 1:1 ratio (3 bar over manifold pressure).