walbro install issue

[1990_fc3s_t2]

Right bit of an update, fuel pump installed, so i primed the system but thought it was a bit quiet def no louder than the stock pump? it started after a few seconds and ran pretty badly but it seemed to catch up and ran better. There isnt much fuel in the tank which may be my problem, im going to get some bp ultimate in the tank before i try again as the fuel is pretty old aswell! :o

Next problem, buddy club ecu worked and even idled better than stock but when revving from about 1200-3000rpm it stutters and sounds like its missing? so n380 back in and running good again...for now.

I have an apexi safc and can remove some fuel but cant seem to get it leaner than 11.4 at idle (same as stock pump) without it not running well. Is this too rich too pass mot? i can get it to 13 but it doesnt sound good and wants to die!
Nothing seems to have changed regarding afr\'s and the new pump?

[m1tch]

Did you cut the hard pipe and fit the hose or did you use the hard pipe? I found mine wasn\'t sealing properly and so the fuel pressure was dropping as it was leaking where the pump joined the pipework.

I am guessing you aren\'t running an air pump? I am, and im getting leaner than 20:1 as the O2 sensor is measuring the air coming in via the air pump, and then dumping more fuel into the engine lol

I would suggest that you get a tank of fuel in there and try and again

[1990_fc3s_t2]

Yup no air pump or acv, yeah i ended up cutting the hard line so got a good seal.
Im going to get some fuel tommorow and go from there. I cant drive anywhere yet as im not insured or taxed so limited in what i can do.

Ill try the other ecu again when iv got new fuel but i cant imagine it will be any better, so new ecu...maybe i should save a bit and get a power fc and do away with the piggyback stuff?

One other q, when letting off the accelerator the afr\'s shoot up to about 20 then when it gets to idle speed its back to 11.4 does this sound normal?

[Prof]

Yep - that\'s normal for the AFR\'s to go right up -  the ECU will cut fuel to both rotor\'s or one rotor depending on rev\'s gear selection and clutch (yep - sounds weird, but there is some clever jiggery pokery to give a better deceleration and reduce \'popping\' when you let off the accelerator - some of it\'s mechanical and some controlled by the ECU).

[1990_fc3s_t2]

Yep - that\'s normal for the AFR\'s to go right up -  the ECU will cut fuel to both rotor\'s or one rotor depending on rev\'s gear selection and clutch (yep - sounds weird, but there is some clever jiggery pokery to give a better deceleration and reduce \'popping\' when you let off the accelerator - some of it\'s mechanical and some controlled by the ECU).

Thanks for that, thought as much but wasnt sure, makes sense when you  think about it! :Thumbs-up

[TiddlesRX7]

Resurrection!

So I\'ve just bought a Walbo off M1tch (cheers fella) and I\'ve got a FPR coming from a mate. I\'ve done some searching but can\'t seem to find a guide to fitting the FPR on the FC. Does anyone have a "how to" link or any info of how to go about it? Do you have to modify the fuel rail to suit? Do you leave the stock one in place and run the new one inline with it?

Cheers

Ade

The stock pressure regulator can\'t handle full pump pressure, so the pump is \'throttled back\' be a series resistor which is in circuit on idle and low revs.  As soon as you give it beans, the relay shorts out the resistor so the pump sees the full 12V and full pressure.
 
Walbro pumps take half the current of the stock pump to produce the same fuel delivery, so the resistor is actually too small a value for them, hence quite a few people end up running rich after the pump swap.
 
If you have an aftermarket FPR this isn\'t an issue.

[Prof]

You can run the new FPR in series with the stock one - it will still work, and in fact will probably regulate pressure better than the stock one does at idle. The FPR needs to go between the fuel return line and the back of the secondary fuel rail
 
PS - what I posted just before editing this was a load of tosh - I was mesmerised by meerkats !!

[B.Martin]

Do you ever read a thread full of information and really try and take it all in? Then you get to the bottom thinking "what the hell did i just read?" When i change the fuel pump i\'m going to leave it to a proffesional i think.

[TiddlesRX7]

All the time. You get used to it after a while.

[1990_fc3s_t2]

Do you ever read a thread full of information and really try and take it all in? Then you get to the bottom thinking "what the hell did i just read?"

LOL i must of read how to set the tps about ten times and i still cant get my stupid head round it!

[B.Martin]

Well, having a piston powered european car would be dull wouldn\'t it.

[bumpstart]

do not whack it series,, you can never lower the set pressure - only raise it
the same restriction that was previously a bottleneck with this pump remains in place
and so you will always have too high a pressure during low load conditions

for s5 ( oz ) with the steel anodised fuel rails,,, you need to s4  ( alum ) secondary fuel rail and a few washers to space it up

and with this combo, s5 primary,, s4 secondary rail ,, amounts to having two dampners,, and no reg,, so the aftermarket FPR just attaches to the firewall and is hooked up with the return/s from the rails

if required the s4 dampner can be unscrewed and replace with a banjo fitting


with s4 t2 ( oz and jap ) the reg is on the primary rail,, and you can replace it with the banjo ends and dampner from another s4 secondary rail
( or fit an s5 t2 primary rail )

[Prof]

Putting it in series is less that ideal, but does get around the problem caused by dropping a Walbro pump in the tank.
 
The Walbro uses a lot less current for the same flow rate, so with the stock fuel pump resistor relay on idle, the pump is flowing a lot more fuel than the stock one would do - the standard FPR doesn\'t seem to be able to regulate the pressure (observed), so the AFR\'s go down and the car runs stupidly rich at idle.
 
The stock FPR is quite good at regulating fuel pressure at higher pressures, so using the 2 FPR\'s in series would run the rails at the pressure of the most restrictive FPR.  If you\'re external FPR is better at regulating the lower flow rate pressure - then it will determine the lower end - then whichever is set to the lowest pressure will regulate.  It effectively makes the stock FPR redundant if both are set to the same vac/boost source - but as you say, you can\'t flow more fuel than the stock FPR would allow.
 
I run just an external HKS regulator - I removed the stock FPR and the pulsation dampner - but still run a series setup.  I don\'t run banjo\'s for any of the connections - just gentle higher flowing bends on AN fittings - which means the fuel flow is more even and I don\'t see any dampening issues with 800 secondaries - you might if you went much larger.
 
With a parallel setup, the FPR sets the fuel pressure in both rails and acts as the dampener, so no pulsation dampner is necessary.

[bumpstart]

i beg the difference,, i am an ex control room process controller
( class 1 , zone 1,, explosive and asphixiating plant ,, hydrogen reduction )
and i know a thing or two about pumps,valves, bypasses, PLC\'s and also explosive limits

i have actually tried adding one in series before
and you will not get the fuel pressure lower than what is set already on the stock one
( which by your own admission will be often be too high with a walbro )
the reg cant stroke open enough to bypass it,, and so the pressure is at the high end of the factory 36-42 psi variances
in a stock setup,, all you have is the trim pot ( s4 ) or the AFM air bypass ( s5 ) to trim it , often not enough to avoid a flood start issue

when i did it,,( on a s5 NA )  i had 42 psi,, and there is no amount of adjusting the second aftermarket reg that will lower it

as i have said above,, the second reg will be useless unless you wish to run higher than stock pressures

when you go WOT,, and into boost,, and entirely different story,, as the volume bypassing through the stock reg drops ( the motor demands more )
and so it alone can sustain regulated pressure+ inlet pressure
( and so no need even for the aftermarket reg at high engine load )

BTW,, i have seen stock walbros installed on a relay ( no two speed ) and work AOK
some not,, and required the reg
,, but some others ran the stock reg indefinately,,
 some had creep issues months later
,, possibly due to a build up in the reg
it also seems the s4 reg can stroke a little more and handle the difference

my recommends is to use an external FPR
change the rail to a s4 secondary
 ,, and you can replace the dampners if you wish
 ( especially if the grub screw is already lost )

 if you wish to read back 10 000 posts i was the original proponent of the parallel fuel rail setup
and was doing so for myself back in the mid 90\'s
( this is due to my process experience )

NB
there is another solution,,one i did myself for a few years
 and that is to run parallel rails , WITH a reg on each rail
ie,, s4 t2 primary,, s5 t2 secondary rails
,,so two stock regs with the outlet returns teed together to the return fuel line
these will have enough combined stroke to control easily,, and not break the bank

[Prof]

I would have thought that running 2 FPR\'s in series would regulate to the pressure that\'s set lowest on whichever FPR - but I\'ve just realised why this won\'t work as I\'m typing it - lol.
 
The FPR will regulate the pressure behind it only, so the rails will be at whatever the stock FPR is, and the bit between the FPR\'s will be set by the external FPR before the return - so all that you\'d end up doing is getting the correct pressure on a bit of hose with no injectors on it - is that right ?
 
I must stop thinking electrically. :rollin
 
BTW - this is how my primary rail looks - with no pulsation damper:
 
http://www.mazdarotaryclub.com/forums/attachment.php?attachmentid=46610&d=1269107323
 
and this is the secondary rail and FPR:
 
http://www.mazdarotaryclub.com/forums/attachment.php?attachmentid=46485&d=1267998502
 
Not the neatest of jobs - but it works well.  When I move the engine into my new shell, I\'ll be changing the fuel filter for one with AN fittings as well, and I\'ll also just use a straight down bit of hose onto an AN fitting on the return pipe rather than that weird loop - need to by a bigger / stronger swaging tool first