550 whp on E85 is definitely not a strain for a double pumper, so overheating of the pumps seems unlikely unless perhaps you have them wired to both run at full power all the time.

 

You need to know iat after the cooler which the Maf doesn't read. I'm betting its not mechanical, it temp related. Run the car until it goes lean, then spray the ic with nitrous to cool it. Make another run and see what it does.

 

Well, you gotta think....on an OEM regulator, the fuel pressure spikes 70-75 psi when the second pump kicks on since it can't keep up. Is it possible the regulator has fatigued over the last couple years?

 

It takes a pretty substantial temp change (maybe 40f) to change afr by 1 pt if air temp is not being factored in sd calcs.

 

And Iat can range from 100-200f..... when doing back to back pulls.

 

Wow. I've never seen that in the ~500 WOT logs of my Evo. From pull to pull on the dyno when using big fans, the most I've seen is 10 degrees. On the street, I've seen maybe 20 degrees if I don't do a cool-down drive. Besides, if he's not compensating for IAT, AFR will go rich as IATs go up.

 

Stock regulator still?

 

Ahhh, I guess you got this under control then Fred. Good luck to the op! Hope you figure it out....

 

Thinking from the opposite end, what are you usin to measure your AFR? Can it be possile the wideband sensor is bad or going bad? Just food for thought.

 

Stock regulator yes,

browningderek... what IAT tables are you talking about? the IAT/Baro compensation tables? I am on MAF not SD...

 

So after reviewing logs looks as if IDC slightly changes after a few runs, hard to see as I have 2150s and I am only at like 43% IDC LOL... anyway ordered 2 new fuel pumps/socks and finally broke down and bought everything to do a -6AN feed line from the stock hardline in the engine bay... that alone was $90... I hate spending money but been wanting to do it for a while so I splurged... we shall see how this plays out as I should have everything in this week and should be able to install everything next weekend...

Also after thinking about it a bit more, I remember people having premature failures of pumps due to the worm clamp holding the pumps together being to tight and in the wrong spot... perhaps this is the case as well...

 

Have you logged or watched fuel pressure? Perhaps the regulator is dropping pressure after prolonged bursts of pressure without rest.

The issue does seem odd its not like your carb'd.

 

It is a stock regulator, and I have yet to see one of those fail... not saying it didn't, but I know that my primary walbro got super loud last summer when I was in FL after tuning in 100* + heat... may have overheated the pump enough to degrade the pumps motor enough to cause this issue and not completely die... the pumps are 2 years old now, so I figure it is cheap insurance anyway...

 

That is true. I forgot about the worm clamp distorting the body of the pumps. Been a while since that was brought up. As for the pump maybe being on the way out, Wally 255's are well known to fail....which could be the root as well.

 

Aight got the new Walbro GSS340 pumps installed today, also replaced the lines running from the pump to the in-line fuel filter with -6AN Russell Pro Classic hose. Much to my surprise the -6AN Russell Pro Classic hose fit the 5/16" barb fittings I had perfectly! I also made a -6AN line from the stock feed line in the engine bay to the fuel rail with this correctly made fitting http://www.3sx.com/store/comersus_vi...dProduct=30271 . Will be testing later this weekend to see if the same crap happens with the car...