Hello All, I purchased a DeatschWerks DW300 fuel pump a few months back. I used stock wiring and didn't modify anything other then the housing to get the pump in there. Everything seemed fine since I installed it. However, now that I am actually checking the AFR and Fuel Pressure on it (data logging and etc). I am noticing that it's dropping pressure from idle (58 PSI) to under 40 PSI WOT. This is not a problem under normal situations with my NA engine. Now that I am running nitrous on it, it's has become a huge problem. I purchased DW pump because I am running e85 and they have a 3 year warranty. They even checked in house on a 370z to make sure it worked for me. But I don't think they tested under WOT with a pressure gauge.... I checked my battery voltage, soldering, hoses, clamps, npt, an fitings, tried a few things, looked for leaks and etc. Haven't found anything that would cause such a drop in pressure. I also spent a ton of time on myg37 and 370z forums. No solution as of now. If anyone has any suggestions or a solution. I am all ears.

Video of the issue:

 

Have you called them and told them your setup?

 

Haven't heard of "DeatschWerks" brand (DeutschWerks?). Walbro didn't have a suitable pump?

 

Yeah I called and emailed them. Got an RMA to send it back to them for testing. Meanwhile I have ordered a OEM pump with 19K miles on it from Ebay to substitute it with while I figured this out.

 

I wanted something reliable, compatible with e85 and backed by a 3 year warranty. I thought going with more expense pump was way to go... I should have just got a Walbro 255 at this point. Walbro 255 has 1 year warranty and is not officially e85 compatible. But a lot of people, including my tuner recommend them....

 

I have same pump... is changing wiring recommended? Is there a wire kit upgrade?

 

DeatschWerks does have a wiring/relay kit. But it wasn't part of the g37/370 kit or a requirement. I am doing more testing right (swapping parts) now, could have been caused by small leak in the tank and or a faulty gauge.

 

Im also losing fuel pressure WOT. Mine goes as low as 10 sometimes. AFR is off the carts. My setup seems mild. I changed my injectors at first and im on my 3rd fuel pump.

Stillen Gen 3 CAI
BERK HFC
Tomei y + Tanabe Axleback

 

I fixed my issue eventually... My pump was find the whole time... If you changed the pump 3 times it's probably something else. Are you running DW300, stock pump or other performance pump?

Here's list of things to check and look for:
1. If you fuel pressure drops to 0 right after you turn off the car. You probably have leak in your fuel pump assembly since you already replaced your injectors. You can find a used fuel pump assembly + pump on ebay for cheap. Drop it in and see if have same results.
2. Weak battery voltage or damage wiring to the pump. Things that draw a lot of power, or redistribute grounding like a grounding kit. Limit the cars ability to charge or have peak voltage at WOT.
3. Kink in the fuel lines or narrowing (from build up or gunk).
4. Placement or a bad fuel pressure gauge could result inaccurate numbers (make things look worse then they seem).
5. Using stock wiring for a performance pump that requires more voltage at WOT. I didn't have to upgrade my wiring, but did have to make sure I had solid connections (soldering when it doubt).
6. Leaking (from build up or gunk) injector(s), You would also have rough start, running rich, possible backfire at startup. Check your plugs wouldn't be a bad idea to see if any cylinders are running rich.

Good luck!
J

 

Not 1, after shutting the car off the psi will start top diminish but not drop rapidly.
Im thinking its 2, has to be electrical at this point. I do have a Stillen grounding kit installed. May remove after swapping battery since the warranty is almost up anyway.
Im running the DW200 currently.

 

Pressure normally should hold for a few mins, drop to 20 psi in about 20-40 mins, and 0 in about an hour. I removed my Stillen grounding kit as well, you'll notice voltage jump at start up now (charging a full capacity). Check those terminal connectors on the pump assembly, I soldered the pump leads directly to them. Those leads are really small.

 

I wonder if this has anything to do with the return less system after all the line feeding the rail is 5/16 -8mm.
The pressure is adjusted by the regulator in the pump assembly. If this regulator is damaged/ leaking you'll have these problems.
The internal filter of the assembly might be clogged. pressurized fuel gets filtered first then regulated. if your car is over 100k your filter is dirty. Mileage will add to this saturation.

If you add a stock pump and run into this you might want to start looking into a return style system.

 

I just installed a new Fuel Sending unit along with the DW200 and im still having fuel pressure issues. At this point im going to look into the harness. I dont know how to measure the current/voltage under load. Neither do i know what pins to check. Alas, research as always. My AFR is also running lean but im attributing it to the fuel pressure. Im attaching a copy of my latest pull to see if anyone with the knowledge can help.

 

Reviewed the logs, looks like the full pump is not able keep up with demand. Your LTFT show that it's been running rich during normal driving and ECU has been making a correction over time. What's does your STFT look like? What injectors size are running? Are you running e85? Has your car been tuned with the current mods?

 

I am not running E85. I have been trying to get the car tuned, during revisions, my tuner saw that my Injector duty cycle is really high. He told me that there may be a vacuum leak or some issue causing this. I am running stock injectors and i did swap them with injectors off a 370z to make sure mine were not bad. I am planning on getting GTR injectors in the near future. I am hesitant because i want to get this issue fixed first. I am unsure on the STFT, i have not had it selected while logging but i will be sure to add it to the list.