No Fuel in Return Line

[Lextreme II]

Mitch and I been working on this 5.2L with M112. We are trying to the engine fire up but still after changing the fuel pump still no fuel in the return line. What of the some of the cause of this? There is fuel in the inlet line but no return.

Possible Cause:
1. Physical Obstruction of fuel rails
2. Fuel Regulator
3. Fuel Pressure not enough
4. Fuel filter
5. Fuel pump control?

 

[XR8tt]

Is there some type of engine security happening ??
I would start from pump and work forward if there's pressurised fuel at pump..

 

[cribbj]

David, as XR8TT said, just work your way forward from the pump 'till you find the obstruction, assuming the pump is actually running and pressurising the supply line?

If the return line is actually "dry", with no fuel at all, I'd have a close look at the regulator and ensure it's not jammed or plumbed in backwards.

 

[Lextreme II]

Ok,

I took out the fuel regulator (FR) today and test it out. I adjust my air compressor to about 40 psi it was not opening but at 45 psi it does. So the FR is functioning properly. I think stock is about 42 psi. So it has to be a dirty fuel filter. I called few places and no one has it in stock except Napa. i will update with FF change.

 

[Zuffen]

You could have the fuel pump polarity reveresed so it isn't pumping but you can still hear it run.

 

[Lextreme II]

I double check the polarity is correct. They are color coded. Just got a FF and will install in few hours if i have time since today is Superbowl Sunday.

Update: Changed FF but still no luck. Here are my elimination possibilities:

1. Fuel Rail Obstructed
2. None functional Damper.

FR was tested and working within normal limits.

 

[cribbj]

David, here's what I'd do:

1) Make sure the pump is pressurising the system up to the rails. There should be a spare port on your FPR where you can fit a gauge.

2) If the pressure is OK at the rails, then simply take the FPR off and put a flex line in its place, put the other end of the flex in a 5gal gasoline can, turn the pump on and see if you get flow.

3) If you get flow without the FPR, the problem is either in the FPR, or the return line is obstructed downstream of the FPR.

4) If you don't get flow, then perhaps the pump suction is partially blocked, or the supply line is partially blocked. Sometimes with partially blocked lines you can get pressure, but no flow.

 

[stevieg]

i know its probably not it because its so simple but i've accidentaly plugged the feed from tank into the return port of the FPR.

steve

 

[Lextreme II]

Found the problem.. fixed and engine running

 

[spf_lexus]

So the stroker m112 is finally singing? Cant wait for a sound clip! Congrats david

 

[Lextreme II]

check it out... it is alive.. http://www.youtube.com/watch?v=qNfNyYsWxMI

 

[cribbj]

Found the problem.. fixed and engine running

What was it?

 

[spf_lexus]

For a stroker its very quiet and smooth. Great job Lex, you have a 1 off beast LS400 in your driveway!

 

[Lextreme II]

What was it?

A year ago I put in a new washer for the damper and it was wrong which i should have caught that. The washer plug up the inlet fuel.

 

[Lextreme II]

For a stroker its very quiet and smooth. Great job Lex, you have a 1 off beast LS400 in your driveway!

Well,

I expect to be alot smoother when Mitch come this Thursday.

 

[rma]

David , whos intake manifold are you using and how much taller is the m112 setup than the m90 .. i read somewhere another guy made his manifold for a m90 it was 55cm (i think)from the oil filler cap to the top of the supercharger.

Thanks!

 

[Lextreme II]

David , whos intake manifold are you using and how much taller is the m112 setup than the m90 .. i read somewhere another guy made his manifold for a m90 it was 55cm (i think)from the oil filler cap to the top of the supercharger.

Thanks!

Top of the charger (front flat portion) to the top of the oil cap is about 3.75 inches.

 

[rma]

Top of the charger (front flat portion) to the top of the oil cap is about 3.75 inches.

Thanks .. whos manifold is that ?

 

[rma]

sorry about that david i found it in your 5.2 stroker thread .. Bullet .. are they really the only ones making these types of manifolds ...