MFI pump, running out of ideas
 

Hope you guys can help me.

This winter I pulled my engine, cleaned, adjusted, replaced a few seals, new injectors, cleaned lines and reassembled everything. I didn't touch the MFI pump, just removed and refitted it. The pump was calibrated by Mark Jung, about 3 years ago. Before my winter project, the car ran fine (besides a few very annoying oil leaks)

Spark, fuel flow, lines, all is fine. Still the motor won't run because of fuel starvation. If I crank the engine and check fuel at the end of the hard fuel hose (in a jar without injector), it just drips a bit at every crank with hardly any pressure. I think I hear a hissing sound at the top of the MFI pump while cranking.

Any idea what I do wrong and how to check?

Thanks,
Ed

Is the belt OK?

Thanks,

Yes replaced the belt. Nicely rotates while cranking.
Timing set at FE (360 + 40 degrees after TDC #1).

Ed

If you have correct fuel pressure coming into the MFI pump then it must be something going on with the pump. I would give Mark a call.

Thanks.
Already sent him a mail. Agree, I'm afraid it is the MFI pump :-( I stored it for 6 months in my garage. Maybe the seals are dried or something like that....
Ed

I just saw Mark a couple hours ago. He's down here in CA at a local Porsche show and he hasn't been checking email over the weekend. I'm sure he'll get back to you. It may be that the rack in the pump is stuck from sitting. You can try pulling the black plastic cap off the back of the pump and sticking a small screw driver in the hole to push the rack. It should push in easily and then return after you remove the screw driver.

Make sure the pump is primed. Wrap a rag around an air hose until it fits the gas fill. Pressurize until gas comes out the pump discharge. You should be good to go.

Sounds like there is air/vacuum in there somewhere.

Regards
Mike

Thanks guys.

With ignition on and the fuel pump zooming, I get a nice and steady flow from the MFI pump return. So fuel is IN the pump I guess.

I'll try the rack. Somehow I lost the plastic cap...

Ed

The rack moves freely...
Ed

Remember...there is a screen type filter in the feed line of the tank...to keep big rocks out of the pump probably.
But...it can get clogged...you might try back pressuring the feed line to the pump just to make sure you have a clear line.
Bob

Double check the routing of the fuel lines from the fuel filter console to the MFI pump and to the fuel pump. There are diagrams out there that are wrong. Disconnect the fuel cutoff solenoid wire to be sure its not being activated by some mischief somewhere. Good luck.

Any luck figuring this out?