Sudden fuel issue

[dwdsm]

This issue started half way down the strip the other week and I have yet to figure it out.
The car went way lean at 5,500 rpm all of the sudden and has done it ever since.
I have 6an line tank up, dsmlink, wbo2, aeromotive afpr, rewired walbro 255, fic 1000cc injectors.
It is knocking like hell from going way lean. The weird part is I can't throw enough fuel at it. So it has to be a delivery problem. I'm trying to avoid doing the replace parts untill it's fixed so hopefully someone has some insight. Here is what I've done so far.

1. Checked the alternator. perfect 14.2 volts at full boost.
2. check the filter. squeaky clean.
3. got some new gas.. although I haven't ran much of it through the car yet.
4. Checked the o-ring on the fuel pump. Could the pump be working at 60%? I was always told they just die when they go.
5. checked base fuel pressure and it was down a bit for some odd reason which makes me think afpr. I may replace that or at least try to rebuild it first but what could go wrong with such a simple thing? how could I test it with a gauge under hood?
I'll stop for now.

 

[bluegs03]

check to make sure your injector seals arent leaking? that would cause fuel to spew out and not get into the intake thus going lean? Also test to make sure you are getting the correct voltage at EACH of your injector plugs plus make sure the injectors arent clogged in any way.

 

[No_Skillz]

Are you assuming it's lean because it's knocking or are you seeing it on a wideband?

 

[steve]

Turn the pump on by connecting the check terminal to the positive terminal on the battery and then start applying pressure to the AFPR reference post and make sure the AFPR isn't leaking air and tracks the pressure applied 1:1

 

[dwdsm]

check to make sure your injector seals arent leaking? that would cause fuel to spew out and not get into the intake thus going lean? Also test to make sure you are getting the correct voltage at EACH of your injector plugs plus make sure the injectors arent clogged in any way.

I would smell that and see it on my manifold (sheetmetal) so there is only a slim possibility it's injectors. To boot the injectors are only 3 months old. how would I suddenly lose voltage at the injecotrs if in car I'm getting correct voltage?

 

[dwdsm]

Turn the pump on by connecting the check terminal to the positive terminal on the battery and then start applying pressure to the AFPR reference post and make sure the AFPR isn't leaking air and tracks the pressure applied 1:1

Hmm ok so I can just turn on my pump via DSMLINK and apply pressure with my brake bleeder that has a guage on it. I'll add 25lbs (because that's what psi I run) and see if the pressure regulator adds 25lbs. That is what I was looking for thanks.

 

[steve]

Hmm ok so I can just turn on my pump via DSMLINK and apply pressure with my brake bleeder that has a guage on it. I'll add 25lbs (because that's what psi I run) and see if the pressure regulator adds 25lbs. That is what I was looking for thanks.

Yep.

 

[dwdsm]

I had to add 25psi via air compressor and no dice. the fuel regulator added psi perfectly. At 25 psi it went to roughly 68psi of fuel pressure.

 

[dwdsm]

Ok now it's getting wierd.. I swapped out the MAS just to see and the car slammed 31psi for no reason??? I have no boost controller only an external tial with the two springs that create 23psi. It should blow open no matter what..So must have something going on with boost/vacume in the lines. I'll do a boost leak test next. After that the car wouldn't boost over 8lbs without bucking. If you saw my car you would understand why I'm so dumbfounded. Everything is new and clean. I have nothing I don't need.. wtf. It changed right after I got some gas.. could really bad gas be the problem? I wouldn't think.
The car has been run on it's current setup home built by my friend and I and now all the sudden. the only other thing that recently changed was I swapped out the clutch a few weeks ago when the old clutch started to slip.

 

[No_Skillz]

Of course bad gas could cause a problem, but to find out if it IS the problem you still need to answer my wideband question.

Do your BLT first, then you can try siphoning out the gas or driving it easy and not boosting until you use up the tank.

 

[crimsondragon]

How old is the Walbro?

 

[dwdsm]

Of course bad gas could cause a problem, but to find out if it IS the problem you still need to answer my wideband question.

Do your BLT first, then you can try siphoning out the gas or driving it easy and not boosting until you use up the tank.

Sorry but I didn't understand the relavence to the question and I thought I already stated that the fuel went lean. It's knocking because it's going lean. It shows on the log with the plx as well as on the gauge. It tests normal. I just couldn't imagine the gas could of been that bad. I could see if it just knocked a little. It was Sunoco 93.

 

[dwdsm]

How old is the Walbro?

2 years... 8-10 thousand miles.

 

[steve]

I had to add 25psi via air compressor and no dice. the fuel regulator added psi perfectly. At 25 psi it went to roughly 68psi of fuel pressure.

Sounds like the regulator is working so either your air metering went wacky or the fuel pump can't keep up under the demand where it can under no load during testing.

 

[dwdsm]

Wowow I just did a boost leak test and found a giant boost leak! I should of done that first but I jumped to conclusions when I was loosing fuel. It makes sense that the regulator couldn't keep up because it wasn't recieving the proper boost level. That also is why it over boosted. I hope this is all that it was. the only wierd thing is the idle was fine.