fuel pump queery

buddah · Post by **buddah** » Mon Oct 20, 2008 7:12 pm

I was wondering if anyone could tell me what the best fuel pump would be to go from the main tank to the surge tank?

My car- 84 EJ20t wagon

I just recently upgraded the surge tank to engine pump to a bosh 044, after hearing a noisy whining sound coming from the pump. As the fuel went down in the tank it would get louder.

But after installation I noticed that only half the noise went away, and the other noise was coming from the pre surge tank pump. Which I didn't replace

So I figure I should definately replace that one as well, especially as I don't want to starve the suction end of the 044.

It is a much smaller pump, around half the size.

What fuel pump would people recommend?

Should the pre surge tank pump be around the same size as the post surge tank pump?

Also there is no regulator and I'm using standard 91 lib injectors (which I hope to upgrade soon), would this be likely to cause a problem?

Cheers,

GOD · Post by **GOD** » Mon Oct 20, 2008 7:34 pm

You only need a small pump to keep the surge tank full. There's absolutely no point pumping ~200kPa into a reservoir. If your car had an electric fuel pump with the original engine, that will do it. Otherwise go to any parts shop and ask for a fuel pump to suit a carbied engine. Should only be around $100.

Dane.

Matatak · Post by **Matatak** » Mon Oct 20, 2008 7:47 pm

only need a carby pump to do that.

once its full its a very low volume getting used up for the injectors so aslong as you keep the return off the engine going in there itll stay full fairly well

discopotato03 · Post by **discopotato03** » Mon Oct 20, 2008 8:43 pm

I hope I don't live to regret asking but why would you be running a Bosch 044 pump in an application like that ?

One thing you can't get away with on a fuel injection system , particularly one with a swirl pot , is major overkill on the main pressure pump .

What these pumps are designed to do is move a LOT of fuel and not suffer pressure drop while doing it .
When people use these pumps in cars that don't require anything like what they can pump the dramas usually go like this .

1) The volume of fuel passing through the injectors is miniscule compared to the available supply so the fuel pressure regulator stays wide open in an effort to keep fuel pressure referenced off manifold pressure .

2) Engines/bays get hot and heat is transfered to the fuel now doing fast circuits between the swirl pot and the rail . The swirl pot has a relatively small volume compared to the main tank and can heat up fairly quickly particularly in hot weather . Fuel can get hot hot enough to boil (boils at a fair bit lower temp than water) and the pump cavitates making the chuffing and whining noises .

Transfer pump or what some people call lift pump .

All this pump has to do is initially fill the pot and then supply it with more than is passing through the injectors . This ensures that the fuel level in the pot does not fall .
When you think about it the circuit from the main pump to the fuel rail - FPR and back is acting like a closed system and a small fuel tank . Most of the fuel is going around in circles and only the volume passing through the injectors does not return . So really all the transfer pump has to do is supply a bit more than that not returning from the fuel rail . Right ? Well yes doing it this way works but the temperature of the fuel in the pot and high pressure circuit is dependant on the volume of "cool" fuel the transfer pump moves to the pot from the main fuel tank .

There is a cheeky way to avoid the heat issues and still have the swirl pot to avoid the surge . What you do is have the fuel rails return line go back to the main tank and not the pot .
Yes I can hear you asking why the level in the pot doesn't drop rapidly . Well to do it this way means the transfer pump has to be able to supply a greater volume than the total out of the high pressure pump and its not as difficult to do this as you may think . You don't have to go looking for megga high capacity low pressure pumps because another EFI style pump can do it easily . Can hear the voices - no way this felas full of it - but hear me out .

Pumps work on volume and pressure right ? If a high pressure pump was pumping into an area of low pressure (say a swirl pot) it would move a hell of a lot more than say the same pump pushing against an EFI type fuel pressure regulator right ?

Doing it this way means that a lot MORE fuel is circulating from the main tank to the high pressure circuit and returning back to the main tanks reservoir of cooler fuel .

The pot itself - I always get into arguments here .

Comercially made ones usually have a largish (say 10mm/3/8") barb at the bottom to sypply fuel to the pressure pump . Up towards the top they often have 3 more (8mm/5/16") barbs for the rails return plus the transfer pumps supply and the pots main tank return .
I would prefer the transfer pumps supply to enter the pot lower down (not quite as low as the lowest barb) so that the coolest fuel enters the pot slightly above where the main pump draws from .

On a parting note you can use an EFI type pump as a transfer pump and still have the fuel rails return line returning to the pot .

Ok one more , those 044's have been known to cause fuel temp problems in high powered factory EFI cars so it truly is overkill for just about anything engine wise in an MY or L that didnt blow the transmission to smithereens first time out . Sledge hammer and walnut I'm afraid .

A .

buddah · Post by **buddah** » Mon Oct 20, 2008 10:55 pm

discopotato03 wrote:I hope I don't live to regret asking but why would you be running a Bosch 044 pump in an application like that ?.........

..........Ok one more , those 044's have been known to cause fuel temp problems in high powered factory EFI cars so it truly is overkill for just about anything engine wise in an MY or L that didnt blow the transmission to smithereens first time out . Sledge hammer and walnut I'm afraid .

A .

Well I after reading a thread in here and other places that mentioned upgrading EJ20T's to an 040 or 044.
I decided to go for the 044 because I'm going to do other things with the engine to increase it's power, so if I have to replace the fuel pump now I may as well replace with one that will be good enough.

It's not just an EJ20t adapted to fit the old running gear either, it has the five speed, diff, and 5 stud conversion from an rs as well. So it should be strong enough to handle a fairly substantial power increase. Shouldn't it?

So do you still think the 044 would be excessive, and I should downgrade?
Or should I upgrade the injectors

I'm not sure about switching the return line to keep the fuel cool, I will have to read what you've suggested again to fully understand it I think

But I understand that if it's pumping to much fuel it might overheat the petrol. How would I tell if this is happening?

Thanks for the advice

discopotato03 · Post by **discopotato03** » Tue Oct 21, 2008 7:20 am

After a bit of traffic driving put your hand on your swirl pot , you may be surprised at its temperature .

Years ago we converted a carby Bluebird to EFI for an FJ20ET motor , the pumps used were a Bosch 975 for the injection and a Carter for the transfer pump . I gave up using Facet pumps for transfer because they failed too often .
That reminds me , when the transfer pump dies the main pump has to draw fuel from the main tank (usually from the pots return line) and that makes EFI pumps howl a bit .

The overall point I'm making is that the swirl pot is usually about 1-2 liters capacity and it doesn't take long to heat up esp when its cycling fast between the pot and the engine bay .
The transfer pump doesn't have to move much fuel to keep the pot topped up and by not moving a great deal of fuel volume wise it doesn't exchange hot fuel for cooler stuff in the main tank unless its a high volume pump .
EFI pumps move LOTS of fuel when being used in low pressure apps so they can work well .

The reason the 044 is overkill is because it'll just make the fuel do faster circuits between the pot and the fuel rail which achieves nothing - unless you intend to run 750cc injectors (or more) and run big turbos (GT3582R big)to the limit (600 + Hp) . The RS box is not going to cope well with that sort of power and torque if you can make it and use it .
The 975 I used was more than enough for the 300 I was after and its basically a 984 (Which is a Porsche K Jet pump) with a larger inlet barb ie ~ 15mm .

Examples of probs with 044 come from Skylines , GTST's and GTR's , with high horsepower engines driven on the street . If the pump runs flat out (Skylines low voltage/full voltage pump supply relay disabled) the fuel gets hot and pressurises the fuel tank and you get all kinds of pressure balance problems .
The fix is to use an adequate pump or find a way to reduce the current supply to the pump so that the fuel flow is adequate and not overdone .

Anyhow your call , cheers A .

buddah · Post by **buddah** » Tue Oct 21, 2008 1:34 pm

Hmm ok, well I was thinking maybe 600cc injectors and a VF34(or there abouts) could be nice, I'd like to have 200kw atw. But that's not going to happen tommorrow.
So I'll check the surge tank's temp after sitting in traffic and see how hot it is. And then consider whether to downgrade the pump or move the return line in an effort to keep the fuel cool.
Do you know what specific issues having excessively hot fuel would cause? Will it damage the pump or lines? Not pass through the injectors or not vapourise properly?

Thanks again,

GOD · Post by **GOD** » Tue Oct 21, 2008 2:42 pm

Hot fuel will cause cavitation in the pump, which will be noisy and ultimately damage the pump. I imagine it would also reduce pressure at the injectors which would prevent their proper operation (->lean mixtures?)

Anyone know the average flow rate of a Bosch 044? Just curious for a quantitative idea of what "too much" is.

Dane.

twilightprotege · Post by **twilightprotege** » Tue Oct 21, 2008 3:38 pm

http://www.bosch.com.au/content/languag ... lpumps.pdf

044 = 200lph (good for 700 engine hp apparently)

discopotato03 · Post by **discopotato03** » Tue Oct 21, 2008 4:46 pm

Yes that table gives a good indication of what they sell .

I would question the Motorsport Pump title because most of those pumps were OEM on old mechanical fuel injected cars like Volvos Porsches Mercedes BMW etc . They also ran at significantly higher pressures that later L jetronic(flap afm) / LH jetronic (H for hotwire maf) and Motronic EFI systems .

The one at the bottom of the list is the real Bosch motorsport pump and it's rated at higher pressures as you can see . The 044 is the more affordable fix for big power or huge capacity engines

At this stage I would not have the fuel rails return going back to the main fuel tank because it'll be difficult finding something affordable that can keep up with that 044 even in a low pressure situation . The bottom line is that you have way too much flow capacity in that 044 pressure pump and it's questionable whether you can use it productively .

When I replaced the std fuel pump in my R33 skyline (std 185 Kw turbo 2.5 six) I fitted an R33 GTR pump because they are a direct change over in these cars . I could have used a Bosch K jet pump like an 044 but I didn't want the heated fuel problems which you usually get even with a factory EFI car if you over do the fuel pump .

I hope you went the CrossBred kit and at least MY99-2000 Rex brakes (all round) if your aiming for anything like 200 Kw in an early MY , the std configuration suspension would be suicidal as well . L's are a bit better with rear coilovers std but even stock RX's are distinctly diabolical in std trim . Really bad body roll (at std height) and front positive camber that goes from horrible to death is iminent bad .

Again your call but you have to be able to make it steer and stop if you give it grunt .

Cheers A .

H-top · Post by **H-top** » Tue Oct 21, 2008 7:59 pm

Is a Bosch 910 too much for an EA82 non turbo?

discopotato03 · Post by **discopotato03** » Wed Oct 22, 2008 8:14 am

I'd say so yes , more expense that is justifiable and you get packaging probs because those K jet style pumps are larger in diameter than most Bosch external type EFI pumps .
Put it this way a Commode Door VL turbo was rated at 153 Kw and used an external pump that fits into the standard L/Vortex pump mounting bracket .
The pump is a little longer than the std one and uses different electrical connections to the std JEC's pump - the hose barb sizes are identical .

We fitted one to my L RX-T a couple of weeks back and it works fine . My rally people used a pair of them some years back in an expensive to build Laser TX3 Turbo AWD rally car , it was really torquey and in no way lacking grunt . They had two pumps with the second being a backup only in case the first one failed .

It's what I'd use in any EA82 powered L or Vortex simply because they don't cost the earth and are common .

PS we cut the wiring from the original pump and used soldered and shrink wrapped insulated eyes so that the new pump plugs into the std loom with the std pump side plug . Not that it would ever get a new std pump but it would fit and plug in as per std .

A .

twilightprotege · Post by **twilightprotege** » Wed Oct 22, 2008 8:25 am

i'm putting a walbro 255lph pump in my rx-t. way overkill for now, but i'm future proofing myself for when i go ej25t

buddah · Post by **buddah** » Wed Oct 22, 2008 9:31 am

discopotato03 wrote:

I hope you went the CrossBred kit and at least MY99-2000 Rex brakes (all round) if your aiming for anything like 200 Kw in an early MY , the std configuration suspension would be suicidal as well . L's are a bit better with rear coilovers std but even stock RX's are distinctly diabolical in std trim . Really bad body roll (at std height) and front positive camber that goes from horrible to death is iminent bad .

Again your call but you have to be able to make it steer and stop if you give it grunt .

Cheers A .

Well the brakes are from 96 wrx (should be good enough?), and front suspension is lowered with monroe shocks. Rear end is still a little high though and it does suffer from a little body roll at the rear going round a tight corner. But the splines need to be redrilled to get the back end down. Another thing on the cards.
Front strut is also on the list of things to get, but I'm just trying to find out where I can find or mod one to fit

I know I'm a bit of a noob but I'm not completely brainless (I think), I realize that with that sort of power I need to be able to stop and turn as well as I can take off.

I think I'll just replace the transfer pump with something small but sufficient, and keep monitoring the fuel temp. If find that it's getting excessively hot and causing issues then I will have to downgrade. I guess I'd prefer not too, but I probably should have done some more research before getting this massive pump.

Thanks again,

Jeff · Post by **Jeff** » Wed Oct 22, 2008 5:29 pm

What mods do you want to do to your struts?

discopotato03 · Post by **discopotato03** » Wed Oct 22, 2008 6:06 pm

What I'm on about is using capable brakes in a car with enough power to get itself into hot water . People put serious power (200 ATW Kw's) in a car for a reason and it's not to go slow , should someone else get behind the wheel and give it a hiding they won't be going slow either .

I'm probably going a little overboard using 99-2000 Rex brakes on my RX but the thing will stop .
If I get 160 + crank horse power out of my EA82 I'll be pretty happy , with close short ratios it should be a lot of fun . Fuel system wise all it will need is that VLT pump and a set of slightly larger injectors ie 280ZXT or FJ20ET ones - either go straight in .

EJ25T , I'd be putting that into a modified early NA Impreza because the chassis would have some chance of handling the power .
Don't know how your going to keep gearboxes together .

As for the Walbro (I realise you probably think I'm just being negative) , they are a common upgrade and can move a reasonable volume of fuel but they are famous for quickly losing volume supply when the pressure goes up - which it will on a turbo engine .

Your money your calls , cheers A .

buddah · Post by **buddah** » Wed Oct 22, 2008 6:15 pm

Jeff wrote:What mods do you want to do to your struts?

Well the front is pretty good, perhaps a little stiff especially with low profile 40's, I just wanted to put a strut brace on it. So I wanted to know if it was possible to modify an existing strut brace from a different model to fit. Because I didn't think that there were any after market strut braces to fit an 84

I saw in a different thread on "brownster's" brumby that he had one so I thought I might ask him, unless anyone who reads this could help?

However the rear is still at standard height, so I need to get it down. I asked in "brownsters" thread about getting the back end down and he said the rear splines have to be re-drilled. I'm not sure how much more is involved. It might be sitting on the rubber stoppers if it's much lower though, could take them out but I'm not sure about that....

Any ideas?

Also checked the fuel temp in the surge tank after driving in traffic for about 20 mins and it was luke warm to touch. Probably around the same temp as my hand, so I'm guessing around 35 deg.
Might be slightly hotter in the middle of the day though.

Cheers,

twilightprotege · Post by **twilightprotege** » Thu Oct 23, 2008 8:37 am

discopotato03 wrote:EJ25T , I'd be putting that into a modified early NA Impreza because the chassis would have some chance of handling the power .
Don't know how your going to keep gearboxes together .

will be doing chassis strengthening for sure - and gearboxes holding together are all about how you treat them. most gearboxes blow because of sudden force (ie change of gear). it's just a matter of making the weakest link in the system the clutch. i'd much rather fry clutches than gearboxes

As for the Walbro (I realise you probably think I'm just being negative) , they are a common upgrade and can move a reasonable volume of fuel but they are famous for quickly losing volume supply when the pressure goes up - which it will on a turbo engine .

true - and i have heard the same, but that's not going to be a problem for anything i do even with an ej25t. 255lph is good for a bucket load of power. the vl turbo pumps only flow 130lph and can still handle plenty of power. i got the walbro simply because of price compared to a similar bosch because of my contacts through b3motorsports

SUBIIE · Post by **SUBIIE** » Sun Aug 21, 2011 9:20 pm

Starting this thread up again.

I take D03's advice, but find it really confusing for a pretty standard brain.

I have a ej20t in the brumby.

Scrapped the old carby pump and just plumbed in a bosch 044 (at least thats what I can remember).

Now the engine is going the pump runs but makes this, dare I say it, cavitating noise almost constantly, at least for the first couple of minutes.

What should I do, or is there something I have done very wrong?

Cheers

stenno · Post by **stenno** » Mon Aug 22, 2011 12:32 pm

Got a one way check valve before the pump (from tank) to prevent a "dry" prime of the pump? I seem to remember someone saying that these also like a positive inlet pressure too.