So first off, I'm about 80% sure my fuel pump is trying to crap out on me, so I've come to the conclusion that I should try and replace it before I get left stranded on my way out and about. The car is a 1995 Civic DX, with a B16 swapped into it. I bought it stock almost 2 years ago and it never crossed my mind to change or even look at the fuel pump. Anyhow, I browsed the chain automotive stores for prices and I'll be damned if they arent all 140+ for a kit, with a 1 year warranty, provided you drop the tank, clean it, blah blah blah. So I'm thinking walbro. Thing is, the 190lph pump seems like it would be more than sufficient for my needs, but for ~$20 more I can get the 255. Here in lies by question. Should I get the 255 for the extra fuel it can pump, even though there is nothing done to the car besides the swap that would require massive (relative) amounts of fuel?

What leads me to suspect my fuel pump you ask? The car sputters randomly under partial or no throttle, but seems just fine under WOT(under 6-7k RPM) conditions. This lead me to think my problem was ignition related. I have changed the ignition coil, rotor button, cleaned the cap, and replaced plugs and wires. Conditions still remain. The likely hood that it is my distributor is slim, but possible.

HALP!

e: The pumps recommended for my car are rated at 40-50gph or roughly 189lph

 

So the engine sputters under low load, but works fine under high load, so you think it's the fuel pump? If it was possibly a fuel pump problem the symptoms would be the opposite. It would be fine under low load and have problems under high load because the pump wouldn't be able to keep up.

Anyway, your problem is most likely a sensor problem. I'd suspect something like the O2 sensor, because the ECU goes into open-loop mode at high throttle and doesn't use the O2 sensor. The TPS is a likely suspect also, because a TPS can get worn out at the lower throttle positions where the engine spends most of its time.

I don't see anything that points to a fuel pump problem at the moment though.

 

Having the same problem in a K20 Integra... no MIL... 2 diff TP sensors, cleaned IACV, played w the throttle stop, plugs...

I might throw an O2 sensor at it, thats a good idea... if not, I'll have to try the coils... I just hope it isnt the KPro/tune itself =\

Let me know when you figure it out, Im kinda out of my element with modified shit : P

EDIT: Might as well get the 255 l/h... it'll do what you need it to do for now, and it'll also keep the doors open for upgrades down the road

 

Checked the MAP sensor or intake air temp sensor yet?

 

IAT is functioning... reading proper temps w no drop outs/open circuit. (TPS also reads properly/no open circuit/re-calibrated via KPro)
Not sure what to look for on the MAP... I unplugged it and it wouldnt start/ran like shit... figured that was adequate

Wanted to find IACV duty specs to make sure the throttle stop was adjusted properly...but Honda doesn't release that shit because they dont want you messing w the throttle stop. Well, I already did... =\

 

If it runs like shit when you unplug it, that just means the MAP sensor hasn't catastrophically failed. It can still give incorrect readings or have problems over a certain part of the pressure sensing range.

That's because there isn't any concept of a single set of duty cycle specs (high and low) for the IACV. It's either a vector or a table, I can't remember which. Those values are then offset with temperature, pressure, etc. and the IACV is used closed-loop to reach a target RPM (which is also a vector or table based on temperature, etc).. So it's not as simple as you're thinking.

 

Yeh, I'll do some datalogging and check the MAP and O2 readings... the lean miss seems to happen only under load, which was strange to me. I suppose I fucked myself when I messed with the throttle stop, so I'll have to play with it and get it close, let KPro do the rest.

 

The throttle stop has nothing to do with anything except idle operation. If your problem happens at some operating point other than idle, it's not the throttle stop.

 

Yeh, I suppose. I was thinking it would throw the whole throttle sweep off, but maybe not.

Also, it doesnt seem to be an issue of closed vs. open loop. The sputter/miss happens at 5-10% under load... so its still closed at that point. From 11%-WOT it runs like a champ...

 

There's honestly no need for a 255 pump for a stock B16. And even if you get it, the motor will still use what needs with the stock injectors/regulator.
So IMO, unless you're planing on boosting the car and push 10,000hp, go with the OEM and cheaper 190 pump.