wojtekj1977

Hello,
This season was supposed to be a good one with me planning to return to the track with the newly installed SOS 1200 charger and 3.8 pulley on my 2006 S, although things have not turned out the way I wanted to... As part of the install I bought SOS fuel pump wiring kit and their AEM 320 fuel pump, having returnless system I knew I needed more flow (also using ID1050x injectors).
Fast forward to few months ago, I got Jeff Evans to start E-tuning with me (flashpro), strange things started occurring:

1. First with the original AEM 320 pump - Jeff noticed that the injectors were running at 94% duty at 7K rpm, something was definitely wrong, we have tried few things and he suggested to swap for another fuel pump.
2. Returned the AEM 320 for a new unit - Got the car running again although the AFRs were fluctuating - first WOT run was nice and rich, went below 12s although stock wideband O2 doesn't show lower values. Every WOT pull after that started getting leaner, after two pulls car was into mid 13s. Removed the pump, checked all hoses, put it back in. Same behavior. Was the pump overheating, maybe.
3. Got another fuel pump, this time went for DW200, lower capacity pump with 255lph - popped it in, suddenly the car on the same calibration was so rich that Jeff had to lean it out. Once we got it to low 12s and car was running good, similar thing happened, the cars AFR was varying across different runs, at the beginning showing nice and rich, few pulls after mid 13s...
4. Jeff suggested getting an AFR gauge and dedicated wideband, once installed, it confirmed that the OEM wideband is very close to the aftermarket (AEM X-series), so AFRs is good.
5. Suspected FPR, although they rarely fail, what else could it be right... ordered SOS modified FPR (flows 3-4psi more), while I was there I also ordered a new fuel filter (aka fuel pump cradle) and installed fuel tank baffle while I was in there.
6. Got it installed last night, at the same time I wanted to ensure that the fuel pump hose is as rigid as possible, so I installed a brass rigid fitting inbetween the pump and the inlet to the fuel filer (pump cradle) - after getting on a road (highway ramp) - same thing. First pull 10.8 AFR across high rpm, second 12.2, third 12.6, fourth 13.X - what the hell....
7. Today, I threw in the second AEM 320 pump that I had lying around, just to check behavior between two pumps - same thing - first pull 9.4:1 AFR, second 10.8, by third or fourth I was in 12.5 - 13.0 - cant explain what is causing it... I have to say that Jeff is a great tuner and has been super patient and helpful throughout these issues.

Any ideas guys, I am so disappointed in the car - any help will be appreciated as I run out of ideas, parts to change and time left this season (as winter is getting very close). I know some of you will say invest into return fuel system and call it a day, although I am trying to get it running without going through the hassle + additional expense.
Thank you.

Kyle

Personally I'd try running a Walbro 255 on stock wiring. You're going to hit the limits of the returnless system before you run out of pump, even with just a 255 on the factory wiring. The hardwire kit wasn't necessary for you at all, and realistically unless everything is crimped perfectly, it will cause more headaches than anything.

Bottom line though, you're really pushing it. If you want to stay where you are, just drop in a 255 on stock wiring and be done with it, but anything more, and you'll need to go returnless for sure. There's reports of people hitting the limits of the returnless system at roughly 400whp. 11.5 psi from a 3.8" pulley on a 2.2L is definitely there.

wojtekj1977

Thank you Kyle, what turned me off from Walbro is the noise, and since I don't have aftermarket exhaust and the car is weekend driven I wanted a quieter pump. Also my 3.8" pulley is pushing about 10.5 psi right now.
Should I go back to DW200 (walbro equivalent) and switch to stock wiring?

Kyle

Yea, try that. It'll be a good start to rule out the wiring being an issue. Realistically that's all I can think of at this point, considering you've changed so little.

The thing that made me suspect the hardwire was the fact that the lower electrical demand (& output) pump was actually giving you more fuel right out of the gate vs a 340, but they all seem to suffer after given enough time to "warm up". Seems like there's some resistance in the wiring somewhere that's getting pretty hot and starving the pump after it heats up.

Car Analogy

This was exactly my thoughts when reading through the original post. All that talk of pump after pump, any one of which should have been sufficient, but no mention of wiring except that mention of installing the sos wiring kit. Certainly all those pumps couldn't be faulty.

Resistance in the wiring. Wires overheat, resistance increases further. As resistance goes up, voltage at pump goes down. Pump gets worse and worse.

I'd love to see what a voltmeter reads, tapped into wires where they go into tank, at the start of a session, and after things go South. I would guess voltage starts out low, and just gets lower and lower.

dustin02rsx

The walbro really isnt that loud, and this is coming from someone who had the same concerns you have. I have a stock exhaust and the only time I have noticed the pump is either when I first turn the ignition on before the car starts, or when the fuel level gets to less than 1/4 tank. I would say it is kind of loud when the tank gets low (still dont notice it while driving), but just keep fuel in it and this isn't a problem. I've only driven top down with it, it may be more noticeable with the top up.

Ivanaguilar

After having had the Walbro 255, I will say once you figure out the wiring, switch to the SOS Walbro 450 setup. As quiet as OEM, and will flow plenty for your needs considering you already have the SOS wiring kit. The 255 is unnecessarily loud, and it surprised me when I did my 450 how quiet it was compared to the 255.

Mijae007

How much boost are you running? Also condition of your battery? Check everything with the SOS rewire kit. i've had the relay go bad twice now. First one was the provided relay from SOS, second one was one sourced from Autozone. Also the 25a fuse has burnt out twice as well. You have to make sure all the crimps were done properly and soldered where appropriate (hopefully you had the proper crimping tool to complete the install --very important). Although the SOS rewire kit is a great upgrade when compared to the OEM setup for aftermarket fuel pump use I wish they used one step thicker gauge wires as the wires still tend to get hot enough to burn out the provided fuse.
Having said all that, I dont think your problem lies with the relay or the fuse since those issues will usually disable the fuel pump all together. I've ran an AEM320 and now on walbro450 (not loud at all btw) with no issues. I'm also on the SOS return kit which could be your problem but unlikely. Check all your terminals, crimps, connections, etc.

giorgosgrts

I am having the same problem but with a 2002 s2k tts supercharged....
I am running id1050x injectors and they are at 94% duty, i changed 2 fuel pumps and also i am using sos wiring and i have the same problem...

flanders

Did you check the wires included in your SOS kit?
I bought my kit back in may and now when I started installing it I noticed the wires are much thinner than what they should be.
Only 14AWG when it should have been 12AWG.


I think 12AWG seems a bit thin as well so I bought and installed 10AWG from battery to relay.
Used 12AWG from relay to pump carrier.