Question on loosing fuel pressure going down track.

[Jeff Stout]

No foam in cell. I'm going to bypass filter and retest filling time in bucket. I did notice once after shutting off car the cell acted like it was under a vacuum when I tried taking cap off. I will look at vented line to see if it collapsing or kinked. All lines,fittings,filter,pump,cell were all brand new.

[Tom Broome]

Originally Posted by Jeff Stout

No foam in cell. I'm going to bypass filter and retest filling time in bucket. I did notice once after shutting off car the cell acted like it was under a vacuum when I tried taking cap off. I will look at vented line to see if it collapsing or kinked. All lines,fittings,filter,pump,cell were all brand new.

Here in the Southeast. it's not unexpected to find mud-dauber plugs in things like a fuel cell vent.

[Kirk Morgan]

A lean miss-fire will show a rich condition due the un-burned fuel leaving the combustion chamber.

[cmracing]

Originally Posted by Kirk Morgan

A lean miss-fire will show a rich condition due the un-burned fuel leaving the combustion chamber.

A wideband sensor will show a lean miss-fire as a lot of excess oxygen in the system, fooling you into thinking the engine is running lean.

A severely rich mixture will also show as a lean condition on a wideband sensor.

Spark plugs and header tubes don't lie.................. But the widebands can.

[Ed Wright]

Originally Posted by cmracing

A wideband sensor will show a lean miss-fire as a lot of excess oxygen in the system, fooling you into thinking the engine is running lean.

A severely rich mixture will also show as a lean condition on a wide band sensor.

Been doing this many years, (not just my race car) I have never encountered that.
Misfires do look lean.

[Dave Noll]

YES, a mis-fire will show lean on a wideband sensor. All that sensor reads is oxygen, when there's a mis-fire, oxygen isn't getting used on that cycle so it passes through the engine un-used. A wideband sensor in a collector is seeing the average of 4 cylinders. If say theres a distribution problem in an intake manifold, the average of the 4 could show close to perfect, but with the bad intake it may have a severely lean hole. The better way to check would be to weld 8 bungs into the primary tubes of the headers and either install 8 sensors or rotate 1 sensor over 8 passes down the track.

[cmracing]

Originally Posted by Ed Wright

Been doing this many years, (not just my race car) I have never encountered that.
Misfires do look lean.

Pull a plug wire off sometime and watch the wideband sensor. You will see the same thing happen as if you unplugged a fuel injector instead of pulling the plug wire.

The too rich showing lean though, that can be tricky to diagnose. A N/A engine will typically be falling on it's face though, but on a forced induction it can be misleading, therefore plugs and collectors are the best thing to determine the root cause.

[Jeff Stout]

On my other car I use a 2 step and car goes rich staging with trans brake and 2 step. Takes about 1.5 seconds to clear up when released.

Maybe 2 types of misfires. One with plug not firing and car goes rich , the other if injected and injector does open then car goes lean? IDK

[Ralph A Powell]

Have had very little spider plug fuel cap vents over winter.

Originally Posted by Tom Broome

Here in the Southeast. it's not unexpected to find mud-dauber plugs in things like a fuel cell vent.