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Fitted A Bosch 044 Fuel Pump, Running Extremely Rich Now!....

nsta

By nsta,
in Engines & Forced Induction

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nsta Mentor

nsta

Posted
Posted

Hey guys, just got as Bosch 044 fuel pump fitted to my rb26, and now the car is running rich, and chewing gas like nothing else, it was doing this beforehand as well, but now its doing it that much more.....ive setup the pump as the only one, and mounted it internally.

Now my plan in the next month is to get it tuned, and im making sure ive got everything i need before doing so, i think ive got everything now, and im aiming for 300-320rwkw, ...will i need a Fuel pressure regulator or not (i want to save money if i can).....

heres the mod list so far:

rb26dett r33gtr - stock internals

nismo n1 turbos (r34 ball baring)

arc cold air box, induction kit

3" exhaust, + xforce dumps

Bosch 044 fuel pump

nismo 555cc injectors

i also have some adj in and ex cam gears (greddy), that i was thinking of fitting, would this be worthwhile considering labour would be quite major to install these gears....

Duncan Grand Master

Duncan

Posted
Posted

strange - changing the fuel pump should not change how rich it is running because it does not increase the fuel pressure. fuel pressure is controlled by the fuel pressure regulator so maybe it is faulty and allowing the pressure to rise too high. I'm not sure if you need an aftermarket one but might as well if that is your problem

GeeTR Grand Master

GeeTR

Posted
Posted

That would make sense if you tuned it with an unhealthy pump, or a really dirty f.filter.

When you changed to the new pump, that actually holds pressure... the old tune proves too rich.

You mention getting it tuned, but lack a ECU on your parts list... so i assume you have something on there now?

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Nothing wrong with the stock reg. There are a lot more cars making a lot more power using the factory item.

I'd say get it tuned... doesn't sound like you have so it could be many things, starting with getting it on the dyno and see whats going on

r33cruiser Grand Master

r33cruiser

Posted
Posted (edited)

i just read your question man. it says u have 555cc injectors......and that u are getting it tuned soon. so are u putting around with these larger injectors, untuned?

Edited by r33cruiser
RodMonsta Collaborator

RodMonsta

Posted
Posted
i just read your question man. it says u have 555cc injectors......and that u are getting it tuned soon. so are u putting around with these larger injectors, untuned?

r33cruiser is on the money there. bigger injectors + untuned = rich

Shockster0429 Enthusiast

Shockster0429

Posted
Posted

Alot of us in the states have FPR issues in our s-chassis after installing a 255 pump, we use the nismo FPR and this straightens out the issue, gets better mileage and less flames.

I did however find that my NISMO FPR unit was running out of fuel around 400rwhp, I installed an Aeromotive 1000 FPR and issue has seemed to have gone away.

I'm running an 044 and a walbro 255 pump.

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Are you talking SR20's though? Thats a different kettle of fish far as i see it.

Heaps of cars here are making well over 400rwhp, using bigger pumps than a walbro (and much better, walbros are prone to issues) and all of these cars run factory fuel regs :banana:

Eg. Mine was around 500rwhp, factory reg with a massive bosch pump feeding the line and never had a problem and most of the cars that come out of the same shop are similar in that they work the same no problem

R31Nismoid Grand Master

R31Nismoid

Posted
Posted

Well my ~500rwhp was on my RB25 at the time.

I plan to have ~450rwhp with the RB26.

Both will use the factory reg for the motor, although i dont think they are any different.

Someone might be able to confirm that.

Shockster0429 Enthusiast

Shockster0429

Posted
Posted
Are you talking SR20's though? Thats a different kettle of fish far as i see it.

Heaps of cars here are making well over 400rwhp, using bigger pumps than a walbro (and much better, walbros are prone to issues) and all of these cars run factory fuel regs :)

Eg. Mine was around 500rwhp, factory reg with a massive bosch pump feeding the line and never had a problem and most of the cars that come out of the same shop are similar in that they work the same no problem

Just because we own s-13's doesnt mean we all swap SR's :P ... This was on an rb25/26 of mine, also one of the first mods I did to my BPU setup when I first got her running a few years back.

I was seeing 55 or so psi with the factory reg and walbro pump, swapped the nismo unit on and set to 43psi vac off. Fuel mileage increased about 20-25%, power felt a lot better.

Duncan Grand Master

Duncan

Posted
Posted

But....just like the guy above, a working standard fpr wont give you 55psi it gives you about 40 (with vacuum hose off). So yes if it is stuffed replacing it might make a difference, but otherwise?

We actually have the nismo fpr on the race car because we have to run standard size injectors, but in pretty much any other application I don't understand why you wouldn't just go larger injectors and leave the base pressure alone?

_x_FiReStOrM_x_ Community Regular

_x_FiReStOrM_x_

Posted
Posted
strange - changing the fuel pump should not change how rich it is running because it does not increase the fuel pressure. fuel pressure is controlled by the fuel pressure regulator so maybe it is faulty and allowing the pressure to rise too high. I'm not sure if you need an aftermarket one but might as well if that is your problem

Changing to an 044 will most likely increase the rail pressure, because its a higher pressure pump than stock. The FPR is mechanically controlled by manifold vacuum, and because of this it has no way of increasing the return flow to the tank to even out the increased pressure from the pump. As such, you get an increase of pressure at the rail (by however much pump pressure is higher than the stock pump).

So it will run richer for that reason.

Most people fail to realise this when buying a pump. You do need to look at the pump pressure aswell as LPH, unless you plan on running an adjustable FPR.

mambastu Collaborator

mambastu

Posted
Posted
Changing to an 044 will most likely increase the rail pressure, because its a higher pressure pump than stock. The FPR is mechanically controlled by manifold vacuum, and because of this it has no way of increasing the return flow to the tank to even out the increased pressure from the pump. As such, you get an increase of pressure at the rail (by however much pump pressure is higher than the stock pump).

So it will run richer for that reason.

Most people fail to realise this when buying a pump. You do need to look at the pump pressure aswell as LPH, unless you plan on running an adjustable FPR.

As has already been said the FPR controls pressure so if you stick an 044 in there and pressure goes up then change the FPR. Nissan FPR's seem to get weak with age. Seen it on CA's/SR's/RB25's and RB26's.

Incidentally someone mentioned that they thought RB25 and RB26 FPR's were probably the same but RB26's run 3 bar base pressure whereas 25's run 2.5 bar like CA's and SR's.

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