S2/RS2 Fuel Pump Testing

[S2central.net]

I was looking at this for someone and figured it as handy to share more widely. I will have to scan in some graphs for the complete picture but here's a summary.

With 12V across the fuel pump terminals for exactly 15 seconds...

The S2 (3B and ABY) fuel pump should deliver 650cc of fuel. Something in the area of 2.2 liters per minute is needed for ~400bhp remembering that we will something like 1.5-1.6bar boost in play for a rail pressure of up to 5.6bar. This might be a stretch for a tired old S2 fuel pump - especially if the fuel filter is old and congested.

What is the max power anyone has ran reliably on the S2 fuel pump I wonder ?

Sorry if this has been done to death before but I couldn't find it...


The RS2 pump is rated for 750cc which equates to 3 liters per minute which gives some more headroom.

The next level up is the Bosch 044 motorsport pumps which provide even higher flow capacity - there is a very high specification one capable of flowing well with a lairy 8bar fuel rail, but the normal choice is nominally rated at 5bar.

[GazzaG60]

s2 pump.

i managed 325. it was runnig out of juice on the squirters first.

then on the 650cc injectors it would be basically all out for about 350hp.

i had to trim lots of over compensation on the map to allow boost when i installed the 044.

id hazard a guess at the aby being about 20% down on say a kjet rs turbo or vw 16v pump. maybe only half the flow of the 044.

[S2central.net]

Ooh thats interesting Gazza... I have someone running slightly lean at ~380bhp on an aggressive RS2 setup who is still using the S2 fuel pump. You can see the power curve flattening off too in the high revs. I was going to richen the chips a tad but maybe it is wiser to upgrade that fuel pump first.

It looks like the 3B/ABY pump cannot sustain the necessary 2.2liters of flow per minute at a rail pressure of 5.6bar... Well maybe a fresh pump is OK, but a tired old teenage one could struggle.

Anyone else have a datapoint they can share for comparison on this one ?

[S2central.net]

What sort of money is in the 044 pumps nowadays ?

[GazzaG60]

i bought 2 from an escort WRC. paid 150 for the pair.

on the 65o's i could see from say 4000 (coming on good boost) it was running very high on the injector DC. basically they were going static at about 4500. then it was leaning all the way. i had 1.3bar upto 6200 or so and the party was over. i had boost set and the controller alarm set not for boost but for fuel supply limit.
i calculated about 430hp if i could hold on so yes id say 350-370 before the demand outstripped supply totally.

id look at the injector DC as an indicator to fuel pump issues. id say you would be 100% dc by about 5700. my turbo is a lot bigger than the rs2 though but i only run 1.3 or so. id expect you are at 2bar.

be ready to trim the map with the 044.

[S2central.net]

Cheers Gazza... The 044 should richen it up at WOT alright... Then I'll see how much the AFR needs tweaked.

[GazzaG60]

are you trying to target 400hp with this new chipset?

sounds maybe possible.

[S2central.net]

Dunno if the RS2 turbo will puff quite that high... I'd be happy with 380-390 which is probably the max on RS2 injectors with a 4bar FPR anyway.

[GazzaG60]

would be nice to break that barrier though.

get yerself a fire extinguisher for the intercooler for the run. add a few psi to the tyres.

if it saw 380 before then its close. little porting of the hotside maybe?

good to see you are still pushing the motronic for good results. a

[S2central.net]

RS2 or 7A EX cam might make the difference too

[GazzaG60]

or maybe a slight retard on the current set.
it will loose the punchy feel with the 7a

[dobbin]

fuel pump testing

what voltage should be at fuel pump? and from which cable is fuel pump relay, i thought it was thick brown cable but no voltage at all but have got 10.2 from small purple cable

[S2central.net]

See what you get with engine running... ~2V below battery isnt unusual... hence a local relay feed is a good idea !

[dobbin]

on thick brown cable when running it shows 2v as you described, is this correct then.
ive just changed fuel filter because noisey fuel pump and gurgling on start up . i have just bought a fuel pressure test kit off ebay will try to pressure test over this weekend.

[Kieron20V]

Isnt the brown a ground?

pretty sure from relaying mine that the feed to the fuel pump is a yellow and green wire.