Hey guys,

As some of you know I have been trying to get my Green setup fine tuned...

It seems just when we get her dialed in to 400whp, something changes..... today I think I see it more clearly.

Here is a screen shot of two runs performed 10 minutes apart. The ONLY change is that I added 3 gallons of fuel to the tank.

Tank was 1 bar below half tank, WB02 started reading lean....I added 3 gallons and that put me 1 bar over half.

Here are the results:



Is this a fuel pickup issue or the walbro getting hot, then cooled down my the additional fuel? Anyone else see a "0.8" difference when they fill up?

 

interesting, keep us posted. same octance? same gas station? same time when you got the fuel or the 3 gals u added was in the can sitting down for a long period of time ? afaik, 1/4 tank of gas the fuel pump is still fully submerged with fuel.

 

You are sure it was the same road, same spot, same throttle? Did you hit the same load cells? Same gas station within a days time?

Might be more scientific / repeatable to do something like driving till almost empty, filling up 5 gallons short and filling a 5 gallon jug, doing a pull with it in the car (to make sure the weight doesn't change), fill up, drive long enough for it to circulate, and pull again.

Seems like alot of work, but I think a change in wind, weight, fuel quality, or one of any number of reasons is cause for change (of load cells or physical inputs). I think there are probably too many factors here to rule it fuel quantity.

It would also be helpful if you could reduce the scale on that chart so we can see the difference easier.

 

What are you using to mount your single walbro?

- Bryan

 

I participated in this thread on the other forum. He's using the foam/zip tie/clamp approach. I think I've talked him into getting a kit.

 

Still waiting on Kris to email me with the specifics on converting the stock housing to accept a walbro.

Have you seen this behavior before Bryan?

 

I've run some Evo's pretty low before on the dyno while tuning for 91 before tuning for E85. That said the dyno doesn't have G-forces like the real world so the fluids don't really slosh around.

Do you have a photo of how your single pump is mounted?

This is quite interesting

- Bryan

 

I'll scrounge around for a photo but don't think I have one.....I might be able to pull it for you tomorrow, but I basically followed the how to on the evo x forums using the foam/ziptie and hoseclamp method.

 

Here you go guys....some pics of the setup.

I noticed that the hose clamp that holds the pump itself loosened enough to allow the pump to sit on it's filter sock. I don't believe that to be a problem, but will readjust so that the filter sock sits just above the bottom. DO you guys think that could have caused fuel delivery variations?

Also please notice all the black debris in the filter sock and the bottom of the fuel pump housing cup...

Is it normal for the filter sock to look this dirty in 11 months? Is this just charcoal elements I'm seeing or dirt from the gas stations?

pics below




This hose clamp was loose, allowing the pump to sit on it's filter sock...


Should the sock be this dirty in 11 months?



Notice the black debris in the housing...normal?



Tank looks clean, maybe the black debris from the filter itself (charcoal)?




Ideas guys?

 

You run pump gas right? Is ethanol in it? Those hoses look like what E-85 does to plastic. Your hose clamps look the same. The black crap could be that foam thing falling apart from Ethanol.

 

Nope, 93 octane only!

But keep in mind, most gas stations use 10% ethanol in gasoline, so the color change didn't really alarm me.

The foam spacer looks new...

 

i remember AMS (i'm pretty sure it was AMS) reporting leaner afr when the tank is at half or below half. this was right after the X came out in 2008.

 

I thought that was TTP....I think they were laughed at as well.

 

maybe it was TTP. i think the fuel pump relay thing kind of took the focus off that.

 

Yeah, I never really heard much after TTP stated this....We hear alot about the hard left fuel starvation, but rarely do we hear how the fuel level in the tank affects normal straight line acceleration.

My best guess is that the pump shifted to low in the housing preventing fuel from coming in on the underside of the filter sock....I'll probably raise it an inch and see what happens.