ER34 Walbro GSS342 Pump Install - Bogging Down During Acceleration

[GoHashiriya]

Hi all,

Over the weekend I installed the Walbro GSS342 (G3) 255 fuel pump in my ER34 RB25DET and replaced the fuel filter. I used the original strainer with the pump. The pump did not fit directly in the cradle, I had to bend the seat outwards to get it to fit. As you may have guessed from the title, the car has been bogging down under acceleration, under any kind of load it will initially bog down before picking-up again. 

The car is bone stock besides a cone filter.

I have read the threads regarding the rewiring to a direct feed from the battery but didn't think this was a mandatory requirement for running the pump with a stock car. Could it be that the Walbro pump is faulty?

I have since bent the cradle back and thrown the stock pump back in, it now seems to be working as it was before.

I switched the pump due to the original one having a faint whining sound and also delivering occasional bouts of bogging down during acceleration. Say, two or three times over the last 1,000 kms. 

Any input would be much appreciated, before I spend forever filing a return in Japanese.

 

  

[BK]

Before you go jumping to any conclusions about faulty fuel pumps you need to know what your actual fuel pressure is at idle and onto full load. Without knowing this you are just clutching at straws. Know, not guess.

Get a fuel pressure gauge on it and report back.

[GoHashiriya]

Appreciate the feedback, I’ll get on the case.

[JustJay]

Not sure if you got this sorted but I had same problem. Took the pump 3 times before finding the problem. With me, the pick up hose was getting kinked when I was putting the pump in. It would start and idle fine but would bog right down on acceleration.

[GoHashiriya]

On 5/15/2021 at 10:01 AM, JustJay said:

Not sure if you got this sorted but I had same problem. Took the pump 3 times before finding the problem. With me, the pick up hose was getting kinked when I was putting the pump in. It would start and idle fine but would bog right down on acceleration.

Thanks for the response. I did wonder if this was a physical install problem, particularly sicne the pump didnt fit in the cradle properly. I haven't had time to reinstall the pump since chucking the factory one back in but this is good to know.

Did you have any issues with fitting the pump in the bracket?

I have since hooked the pump up to an external power source and that was fine from 11.5v up to 14v. Although, that's not really gonna show me what I need to know. 

[JustJay]

Sorry for the late reply, but yes, I had some difficulty with the cradle. It was a few years ago so I don’t exactly remember. But it was a bastard to get it re-installed and I you couldn’t tell the hose was kinked. But I do seem to remember it seemed to go together better and easier once I got it in there right. So maybe an alignment issue while wrestling with it.

[GoHashiriya]

So here we are, two years later and I'm just clearing this as my OCD won't allow threads to go unfinished. Today, I finally got around to wiring the fuel pump from the battery. However, first, I tested the Walbro with the OEM loom, took it around the block and it worked fine, so went ahead with the battery direct feed anyway as I was there.

The most relatable thing that's changed since I last attemped this was that there is no longer an immobiliser (relay) along the OEM fuel pump power line. Could that have caused this? beats me. 

Also changed since I attempted this two years ago:

- Battery

- CAS

- Boost leak fixed (this had a slight impact on drivability - leaking from the factory boost sensor hose)