Update: it was something simple as I suspected. When I put the motor back in I never finished tightening the power wire from the alternator. The nut that holds it on was just about to fall off LOL

so, my car has never really idled right and is even worse on a warm startup. but.. today i'm at a stop light and i can hear my fuel pump doing something new.
as i'm at the light i can see AFRs going from normal idle readings to a bit on the leaner side (16:1 or so). as it's going up and down i can hear the fuel pump going up and down with it.
what i'm trying to figure out is if the fuel pump is the problem or if its just responding to something else.

will voltage and flow to/from the pump vary so much or should it be constant no matter what?

the pump is supposedly a legit Walbro but the guy that sold it to me turned out to be very shady. the gears are all metal, so i assumed it was real. so there's that.

i have an HPDE coming up on Sunday, so if my pump is bad, i need to put one in no later than Fri.

opinions?

is there a way to log fuel pump activity?

 

walbro---apparently start to make noise when they start to go...invest in something a little better, it will be quieter and last longer--

 

i'll get another Walbro. i've used then for years and this is the first one i've ever had give me problems. i can't complain, really.

 

Yea, its the pump.

 

Are you on the factory wiring also, or is the pump rewired?

 

Factory wiring. No need for me to rewire a 255.

New pump is on the way, dang it.

 

I think the reason that question was asked is because the factory system is two speed.

 

It is, but mine was oscillating at idle.

 

Let us know if the new pump helps. I get the warm startup issue and random leaning idle. I've never correlated it to pump noise though. I see people commenting that a noisy walbro means its failing. Honestly the one I installed over 8 years ago (but only about 25k miles) has been noisy since day one. I remember calling buschur and asking them if it should be so loud. They said that's how you know its working lol. But this was long before afr gauges and logging were common to the average evo owner...which are a much better means of identifying problems.

Anyway, there was a member who started a thread a few months ago on the topic of crappy warm start up and leaning idle. Kaj, I think I remember seeing you comment in that thread. He went through and ruled out a lot of components. I'm on the same train of thought as you and am refreshing fuel system components since most of it is dated. My old *** fuel pump will be first. I'm interested to see if you perceive a difference since we seem to be experiencing some of the same symptoms...

 

I haven't had a problem in the 13yrs I've been using Walbros. This would be the first.
Like I said, I don't trust the guy that sold it to me. It could be an eBay pump, for all I know.
New pump should be in today. I had to get it from Amazon to be here in time. It was pretty cheap...I'm skeptical LOL
It better be legit.
Also, I can hear my pump really well, because I have no rear interior. I hear the rear diff, the pump, all kinds of stuff.

 

Update: the fuel pump is now very quiet, but my lean idle continues. Weird.
When it goes lean, I can see the gauge cluster flickering and the alternator voltage drops. I think that's to be expected, though the RPM doesn't drop much at all.
I'm thinking Alternator....which would suck.

 

If you're loosing voltage, the injectors take longer to open. Try increasing the latency values a bit in the lower voltages. (leave 14v alone)

 

i can try that, but:

the alternator tested fine. issue continues but is intermittent. i got home and the battery light was on. turned the car off.. turned it on.. fine. i think i may have an issue in the harness, maybe. i'm going to check my connections on the Alternator tonight.

 

Sounds like you have an issue. lol

 

Ground!