Supercharger troubleshooting: FMU/FP

[wpurple]

I am no longer getting any additional fuel pressure while under boost.

The booster pump is turning on, and the FMU is getting a boost signal.

What is the best way to troubleshoot the FMU and/or fuel pump.

Can the FMU be dissassembled to inspect without needing a rebuild kit?
I would imagine if the pump runs, it should pump, but maybe not.



*this is a returnless system such that the FMU is in series with the pump. The FMU acts like a shunt to the booster pump.

 

[performancenut]

You should be able to open the FMU and inspect the internal disc and gaskets. Obviously, no boost is recommended until you resolve your fuel issues. Generally, the forced induction folks recommend a good tune and discontinuation of the FMU as it is generally unreliable and unpredictable. Doug of Bamachips will likely remove mine next month at Dynotune time.

 

[wpurple]

On my way this morning I cliped a couple wires to the hobb switch and brought it inside to a switch such that I can manually turn on the pump.

During boost I manually turned on the pump and it seemed to work, I say seem as at 6psi I started to drop pressure slightly until the FMU decided it was going to up the psi to 72 (12X)

As soon as I get some extra cash, I want to remove the FMU, go with a new in tank pump, and a tune.

Your right the FMU is a wee bit unpredictable, but I must say up until recently, it performed flawlessly. Might have been my accident that upset something as I was hit right where the FMU/fuel pump was located.
(The other night on Myth busters they stated that an auto accident can product G's in excess of 200!) no wonder my back hurt

 

[CDW6212R]

Do get rid of the FMU, as soon as possible. Besides that, how much power are you looking at? If you go much beyond 350-400, you should consider upgrading the fuel line, all of it. Good luck,