I just replaced my old factory pump with a Walbro 255 pump. Now when I give it a little throttle while in neutral or while in gear, it would flucuate from 1200 rpm to 2500 rpm over and over until I let go. Fuel pressure is set to 42 psi and it still does it. Any ideas? All I did was remove the old pump, and put the new one in, that's it. Is there something else I need to do? It came with a fuel strainer but it didn't fit so I used the old one, maybe I didn't seat the strainer in right? Is it suppose to be submerged in fuel?

Info: b20b, sri, exhaust, skunk2 manifold.

 

It didn't do this before, the reason why I replaced it was the old fuel pump kept losing pressure and gaining back pressure every 5 seconds. The Walbro keeps it constant at 42 psi even when the rpm flucuates.

 

What your fuel system consist? And your setup?
i.e. reg, fuel rail, turbo, injectors.

Every time I swap a walbro 255lph on a client car, I have to adjust the pressure down (most of the times you see a bump of 10psi).

If you was running stock pump why do you need a 255lph? Useless if you don't have mayor mod's.

If your car only have bolt-ons stock pump or walbro 190lph is the way to go.

Check your gauge weird it read the same as stock pump pressure with the walbro.

 

Stock fuel system minus the pump, when I put it on, the pressure went to 60 psi so I turned it down to 42. I got the pump cause I'm planning on going boost in a few months but the old pump was going out. The pressure would go up and down at idle with the old one and when I floor it in any gear but mainly 3rd, it would take a second or 2 to feel the pull. I thought it was the old pump not supplying fuel quick enough.

 

Do you have any CEL code?

how old is your fuel filter?

how look your strainer?

 

Yes on the CEL, code 41 but that has always been there.

Fuel filter about 6-7 months old

And the strainer look light brown, is it suppose to be submerged in the fuel or something cause I just put everything back into the tank quick.

 

If your pressure is bouncing around you probably have a bad fuel pressure regulator. Or a vaccum leak. With a cel and being in limp mode like it is mid 40s psi is normal.

 

first of all, fix the code 41= Primary O2

This code cause different symptoms from poor idle to hesitation and bad accel.

Yes the strainer going submerged in the gas tank, inside the baffle.

 

Ok, I just pulled out the pump again and made sure it was submerged. Then my buddy suggested it could be the main relay so I used the one he had that was working. Now the fuel pump is priming on both relays that had been working.

 

The pressure stop bouncing when I had the walbro pump in, the only thing with the walbro is that if I give it slight throttle, the rpm would bounce between 1200-2500 till I let go. If I give it like 50% throttle, the rpm wouldn't do the bouncing

 

Ok, got the pump to start priming. Now the only thing is is that it still does the bouncing of rpm with slight throttle. Could the tps cause this cause I looked at it and it's .23v idle and 4.12v WOT. There's no irregularity in the readings when I increase the throttle slowly. I know it's suppose to be .45v idle and 4.5v WOT but could that be why it's bouncing?

 

Here's a video of what it's doing, CEL is p1337, p0135, and p0141. I thought it was code 41 cause that was my other car, forgot this was obd2 so I scanned it and thats what came up.

 

until you fix the codes, you not know if something else happens!!!

P1337 = CKP
p0135 = o2
p0141 = o2 heater malfunction.

But jumping rev's and hesitate to accel. ill start with the crank position sensor.

 

I thought it was the old pump not supplying fuel quick enough.

 

Put the stock one back, you have no need for a 255lph .

 

fuel pumps are not linear increase in fuel.
each pump has its own specific curve.
your fuel system is tuned to OEM fuel pump.

just like it says on most dyno tuning shop webpages. YO HAVE TO retune it after fuel pump upgrade.

i used stock fuel pump when my gsr made 187whp with no problems.
then upgraded to walbro 190 and had to retune it because the fuel curve is completely different

 

take it to a shop, put your old pump back on ASAP! , your creating more problems for your self smh

 

I got the pump because according to some of the threads on here, they said it would be ok to use the walbro 255 on stock fuel system.

https://honda-tech.com/forums/honda-crx-ef-civic-1988-1991-3/walbro-255-pump-ok-stock-b20b-2888119/
http://www.b20vtec.com/forums/b-seri...ock-motor.html

 

i didnt see any of them using a wideband to make sure it isgood.
when i changed my fuel pump it changed fueling completely...

 

Ok thanks. I'm going to sell this pump and get an oem replacement and see how it runs.

 

Alright guys, I put the stock pump back in and it still does this. So could it be an ecu problem or a blown fuse I should check? What fuse should I look for? With the stock pump, it sounds like it is bogging out everytime it fluctuates, it stumbles even harder compared to the walbro.

 

maybe your tps sensor is bad

 

How do i if its bad. I got the reading .23v at idle and 4.12v WOT. There's no abnormal jump in volts when i increase throttle slowly.

 

I have been running a 255 on my gsr swapped hatch for almost a year with no problems with a stock p72. Boost has taken longer than expected.

You need to calibrate the tps if it's reading .2x. It needs to be between .45-.5 at close throttle. Computer is reading one thing while motor is doing another. It doesn't help the fact o2 sensor is bad so you need to fix that as well.

 

My car is straight piped when i got it and there's no o2 bung. I will try to get the volts within spec and update