Fuel pump “over spraying?”

[Toddavid]

Been battling a bad misfire issue on my 2014 V8-380-C-D. Rich codes on both banks, you can see the short term trim pull fuel on both banks as soon as the O2 sensors come online. Oil getting lots of fuel contamination. Raw fuel on spark plugs.

Threw in the towel and decided to let a local VP dealer do the diagnostics. They diagnosed it as an “over spraying fuel pump”.

Is that even a thing? All the VP fuel pump failures I know about are from paint contamination and resulting low pressure.

With proper duty cycle on injectors, can too high pressure from a pump really cause fuel flooding issues? It’s a returnless system with an integrated pressure regulator.

 

[Scott Danforth]

I would be looking at sticking injectors. Have them cleaned and flow tested

 

[Toddavid]

I would be looking at sticking injectors. Have them cleaned and flow tested

I agree, but this is the diagnosis from the authorized VP service center. Is this even possible?

For what’s it’s worth, since this is a returnless fuel injection, pressure modulation is done by an integral regulator at the fuel pump. So if the regulator failed, it means whole pump replacement, even if the pump componets themselves may still be good.

 

[Toddavid]

Ok, seems like I jumped to conclusions regarding the regulator being the failed part on the pump,

It’s most likely the float assembly in the fuel cooler cell.

The needle assembly tends to gunk up preventing the float from shutting off fuel to the vent, which connects directly to the intake manifold, which then floods the plugs, mainly on the vent port side.

Makes a ton more sense than what a stuck FPR would do.

Apparently this is a known common issue. FYI.

 

[QBhoy]

Hi. Not totally familiar with this engine. But I know my GM mpi overfuels plenty when it’s cold (and because of cam..but that’s a whole other story). If your temp sender is thinking it’s cold..it will over fuel constantly. Is your temperature showing too cold perhaps ? Is this one of the newer made in house engines or still the GM type ? If it’s the latter, there could be a few other things causing this too.