bosch fuel pump setup..

[renxun]

I have an issue of fuel running abit lean when i boost at 1.5bar...i have all the hardware neaded but the main ting lack off is my fuel pump wasnt supplying enough..

however with a limited budget i couldnt afford myself a bosch 044 for the time being... but still can go for a bosch 910....currently im using one 910 to suck fuel frm tank to my surge tank and another 910 to supply fuel towards the fuel rail and below is the question i would like to ask....

1) can i actually set another xtra 910 pump in front of the current 910? meaning to say that it is connected in "serial" connection ... one after another to increase the fuel feed...i have this idea after making a survey to the mercedes service centre and noticed that alot of mercedes came with such setup... will it be able to help ?

2) can i connect 2 pumps in a "parrelel" connection? meaning to say both pump take fuel individually frm surge tank and then the delivery of both individual pumps meets together in one hose and direct to the rail......i saw pl done this setup..

both i dont know which could help... i do wish i can afford either walbro 255l/h external or the bosch 044 pumps but my current situation only enable me to get another 910....how much would it help in both of the setup above? thanks in advance for any feedbacks..my bad english .. hope u guys can understand wat im trying to say..

[bansheebuzz]

You should not use an efi pump to pump fuel from you main tank to surge tank. Get a low pressure high flow pump for this job.

You can run pumps in parallel

A rising rate fuel regulator might solve your problem of running lean as boost increases

[renxun]

low preassure high flow pump? wat would be the pump example be?

so meaning to say is i run pumps in parrellel it could solve the fuel feed?

rising rate regulator do u mean by those sard adjustable regulator?

y mercedes run pumps in serial connection? mind enlighten me on this?

[thechuckster]

low preassure high flow pump? like a cheap facet pump or other pump designed to feed large carbis not an EFI system


run pumps in parrellel? might not solve the problem but it will flow more fuel up to the engine. Doing this would require you to get another pump to feed fuel from the tank to the surge tank.


rising rate? no, the sard is a plain adjustable regulator that tracks manifold pressure/vacuum changes at a 1:1 ratio. Malpassi make a rising rate regulator, for very 1psi over atmo, the fuel pressure increases 1.7psi. Search for 'RRFPR' or "rising rate fuel pressure regulator" to find threads on these items.


merc pumps in serial? damn good question...are you sure you weren't seeing a EFI fuel filter just downstream of the EFI pump?

[renxun]

real thanks alot pal.... i guess now i had a picture wat i should do next....

however another thing i would like to know ...when i have the rrfpr fitted , how would i know if my fuel pump wasnt supplying enough fuel...? i have bigger injectors...

[bansheebuzz]

you need to put an efi fuel pressure gauge inline and load up the car on a nice steep hill, if fuel pressure drops then your pump system is no good. You will prob have to take it to some1 unless you want to buy expensive gauges.

No you cannot run efi pumps in series.

[MWP]

What size are your fuel lines, surge tank fittings?
They could be limiting flow.

As others have said, running a 910 before the surge tank is bad.
Use a Holley Blue or a Carter Black pump (or similar), they are good for ~450HP.

[DX20VT]

Lots of cars run fuel pumps in series like the merc's.

The good old VL commodore did it.

There is a reason for it too.

A high pressure High flow fuel pump will not suck fuel, the must be gravity fed or pressure feed.
To do away with this you can fit another pump in tank like the VL.

The thing is though,
it does not increase the total flow in the system.
If you removed the lift pump and placed the main pump lower down so it was below the fuel level, you will get the same flow as with the two pumps.

So in saying that two 910's in series is a waste of time.

[renxun]

What size are your fuel lines, surge tank fittings?
They could be limiting flow.

As others have said, running a 910 before the surge tank is bad.
Use a Holley Blue or a Carter Black pump (or similar), they are good for ~450HP.

no wonder u say its bad...bcuz i realised that my tank preassure is extremely huge.. everytime i tend to refill (after accelerating..) i had strong hissing sound when i partially open my fuel cap... it can hiss on for about 5-6 sec....im also scared that i might blow my fuel tank due to over preassure in it...

btw my fuel line size was 10mm inner diameter in and return for surge tank of 2 litres and 20mm from surge tank outwards b4 it was converted back to a 10mm fuel line of inner diameter.. wow tis thread had really enlightened me alot...i learn alot of new things .... all this while im just throwing money watever base on wat pl say and without proper explaination....alot of pl say my car could perform well more than just 400rwhp at 1.5bar on t70.. its just tat i need to get my tweaks correct and make it reliable for it....im aiming to go 500rwhp after i receive my 272cams and pulleys frm greenline..

but i guess thats another long way to go to reach there....as i know i might screw up a lot of things even b4 i reach there.. such as my tranny n my differantial....

[XR Pilot]

As others have said, running a 910 before the surge tank is bad.
Use a Holley Blue or a Carter Black pump (or similar), they are good for ~450HP.

Hopefully someone else with more experience can chime in on this, but what if you replaced your first 910 pump with one of the above suggested pumps, then run your existing 2 910 pumps in parrallel to provide more flow to the rail?

I can't see any problems with this, can anyone else?

[thechuckster]

none at all ... a bit over the top, but should do the trick.

given that a 2nd-hand walbro can be found for ~$120 on eBay, unless you buy a cheap facet pump for $40 or less, you're spending too much.

i realised that my tank preassure is extremely huge.. everytime i tend to refill (after accelerating..) i had strong hissing sound when i partially open my fuel cap... it can hiss on for about 5-6 sec....im also scared that i might blow my fuel tank due to over preassure in it...

this is a different issue - you must have disconnected the vent line that runs form the top of the tank to the charcoal cannister in the engine bay, or that cannister is not correctly venting to the engine.

search for 'charcoal cannister' as there's some threads on this very topic.

[MWP]

Hopefully someone else with more experience can chime in on this, but what if you replaced your first 910 pump with one of the above suggested pumps, then run your existing 2 910 pumps in parrallel to provide more flow to the rail?
I can't see any problems with this, can anyone else?

Nope, would work fine... except for one thing.
A 910 pump is also rated for ~400HP.... if your drawing enough fuel that you need two (in parallel), youll also need to double up on the lift pump.

[oldcorollas]

depends where the return lines go to (to the surge, with an overflow to the tank?)

some pumps have issues when they get to about 60psi, in that the flow drops off quickyl at higher pressure... normal rail is 40psi.. 1.5bar = 14.7x1.5 = 22psi..

gee, you're at 62psi

the HP rating of a pump is at a certain pressure. the fuel it can flow decreases with pressure.
fitting a rising rate reg, esp for 1.5bar.. is stupid instead of 62psi, the pump would need to do 73psi... just making it worse

you can use EFI pump to fill surge, as long as it doesn7t have issues sucking from tank.
since it runs at lower pressure, it will always outflow the pump going to fuel rail (if they are same).

you could run both 910's in parallel, giving you double the flow at high pressures, and then run return line to the surge.. and find a carby pump that can do your expected output to fill the surge back up...

(edit.. some sites say the 910 is rated at 73psi.. )

[renxun]

yupe im curently using setup which return frm fuel rail to the surge and overflow back to the fuel tank....so if i run 2 910 at parrelel with my upgrades the fuel matter should be solved....about the preset regulator... actually last time when i fit in 2jz injectors i fit in the whole thing including the regulator,injectors and the rail..and now when i upgrade to 650 and the parrelel fuel pump setup do i need to install the adjustable type...? currently without parrelel setup but having the injectors installed...with the correction of my fuel controller i dun have any idle problem and my air fuel indicator seems fine with it...issit necessary for the regulator upgrade beside for the good look..?

[thechuckster]

factory regulator should be more than adequate - and easier to setup

the adjustable reg (read: expensive bit of bling) would only be of benefit if you wanted to tinker with fuel rail pressures.