Running out of fuel at WOT

[84 BuickGNYorkPA]

Hi Guys,


Out of the blue I find myself seeing knock at WOT, in the past this has always told me it's time to replace the fuel pump. So 1st I replaced the filter with "Driveworks" fuel filter, as it was the only one in stock, still going lean in the gas. Checked the fuel pressure at the winshield while driving and had the 1 pound of fuel pressure for each pound of boost, now scratching my head and figure, well only one more thing to do... So next drop the tank and put a new Walbro pump in that I had new since the big Walbro incident a few yrs ago, where you sent in your defective s/n pump and they sent you a new one, guess what still have issue. Running the SD chip and it's showing the chip is trying to add the max fuel, so strange. Any ideas what might be going on? Going to replace the fuel filter again with a Puralator, but don't think that's it... Was thinking maybe the fuel regulator? Not sure....


Chuck

[SuperSix]

If the FP is rising 1:1 with the boost - what makes you think it's a fuel problem? What's your O2 at WOT?

[Steve Wood]

are you using a wb to drive the chip?

Are you spraying alky?

[84 BuickGNYorkPA]

SuperSix, it rises good staying in the 11.0 A/F ratio range, then as the rpm's build into the 4500 or so the A/F drops to 14 and I get out of it, glance at the scanmaster recall and it shows 22.1 

Steve,
Using wb to do chip correction, not sure if it's driving the chip, spraying alky, when it's at idle and I hit the test button the a/f dives into the single digits. I do have a gage I could put on the alky and check the pressure...

I have to run to a football game and watch my son in the marching band, I'll check the board later tonight and replace that fuel filter tomorrow with a puralator, keep the questions/comments coming...
Chuck

[Steve Wood]

okay...so we don't know if it is a wb problem or an alky problem...or something else.

If it were me, I would  turn off the wb in the chip and try it open loop first.  I think we can probably eliminate the fuel pump if the pressure is doing the 1 for 1 bit.

and, unfortunately, the test button on the controller only sprays a minute amount compared to full blast so we cannot say the alky is working right without some kinda pressure reading out of the pump...makes it hard to troubleshoot

[PacecarTA]

if fuel pressure  held  and wideband is correct and it truely went lean then its not burning on all 6  or your injectors are being underdriven
check the plugs  and wires ,
i know you are on TR6 but check the coilpack anyway   
verify the inj duty is correct  +25 we know but what was the commanded vs end result
check for a loose inj connector

 could be as simple defective o2 and its low reading is driving the fueling off (rich ) and causing kR from the excessive fueling
wouldnt be the first time with wideband control

are you logging alky pressure ??  might be time for a pump checkup

[84 BuickGNYorkPA]

Steve,


Have not checked the 1 to 1 with the new pump (need to do that), I have a alky pressure test kit, used it to test the pump when it was new last March, don't remember the value, may have it written down in the test kit box. Will check that tomorrow, may have to reach out to Julio to see what pressure I should be looking for. Will look at the chip next and see if I can turn off the wide band and run on speed density only.

Paul,

Never put the TR6 back on the car after the Ohio trip, have a new coil mounted to it and it's ready to go on, was keeping it as the spare, so I could try that.
When you say to verify the injector duty cycle is correct, I assume you want me to hook the laptop up to the power logger and check the duty cycle in the lean condition.
I will check the fuel injector connections, take them off and add some die electric to each connection.
Wouldn't surprise me though if it's the alky pump going south.... I'll update this post tomorrow, thanks again guys !!!

Chuck

[Steve Wood]

would think that if it was misfiring to that extent, a miss would be evident.

The wb uses the a/f of the alky plus the gasoline when measuring, but, it only controls the gasoline via the pulse width.  So if the alky is not there in quantity, it will peg the injectors trying to achieve the designated a/f programmed into the chip.

As you believed you had the proper pressure increase, I figured it was probably the alky...but, if you have not checked since changing the pump...be a good idea to verify that is still the case

[Steve Wood]

according to FB, his alky pump tested weak

[84 BuickGNYorkPA]

Alky pump pushing 85 psi, Paul replaced a pump that was 135 psi and the new one tested at 165 psi.


Chuck

[Steve Wood]

Not sure if the test is at full pressure, or not, but I thought they were claimed to be over 150 in the ads

[84 BuickGNYorkPA]

It would be hard to get used to but, I may tune the car for 15/16 lbs and just run it with out alky.... see how long I can stand the lower h/p. At alky control dot com, pictures show over 250 psi.

[Steve Wood]

That will last until the first time you drive the car! 

I find it hard to believe that the pump would maintain that pressure very long..but I have no experience with one so I really cannot say I know

[84 BuickGNYorkPA]

Just talked to Julio and he told me to check at the control box (the one under the dash) for 12 volts and check the ground and make sure the ground is not loose. He said the pump should be leaking if it's only putting out 85 psi. But I promised my better half to do stuff at her house this evening... I should get to it tomorrow.


Chuck

[Steve Wood]

Be nice if it was something simple like that.....