This last weekend my motor took a dive on the dyno I'm trying to formulate what could be the cause so that I can put it back together successfully this time around

First off, the pertinent parts of my setup:
b18c /w benson sleeves, full-race rods, CP pistons
255hp awlbro pump, aem FPR, stock lines and rail, 1000ccc precision injectors.

I had a problem with the fuel pressure tapering off under boost. With a fuel pressure gauge on during a pull, the pressure would sit aroung 70pi until the turbo spooled, and then instantly drop down to ~58, which would cause a lean condition.

I tried changing the fuel filter and regulator to a B&M regulator with no progress. So, I put in a new walbro255ph pump. After this, I couldn't get the fuel pressure below 95psi. I switched back to the AEM regulator and adjusted it all the way down with no change in fuel pressure.

I'm trying to figure out what happened... it slowly started to smoke more and more on the dyno, and then after a pull, it was idling for a few mintues, and then just died. A compression test yielded low compression in all 4 cylinders. 2 spark plugs were black, and 2 were not (indicating 2 cylinders were running pig rich and the other 2 weren't). I pulled off the charge piping at the throttle body and fuel poured out onto the ground.

I think it may have been due to the fact that the fuel pressure was rediculously high, and perhaps that high pressure held 2 of the injectors closed. What would cause that high fuel pressure with the walbro 255hp pump, evern with an AEM adjustable regulator backed all the way out?

 

are u running stock fuel lines?

 

Yes... completely stock fuel lines. AEM FPR (also tried a B&M stock modified FPR), walbro 255 high pressure pump, stock rail, stock lines, 1000cc precision injectors.

 

I've tried aems and b&ms both with walbros and neither would adjust the fuel pressure below around 35 without modification, but i've never seen 95. the low compression may be due to the excessive fuel in your cylinders washing the rings out. put the injectors in the rail, but dont install them in the manifold, turn the key on to prime the pump and see if any of them are leaking. sounds like you have injector and pressure issues.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by servion &raquo;</TD></TR><TR><TD CLASS="quote"> What would cause that high fuel pressure with the walbro 255hp pump, evern with an AEM adjustable regulator backed all the way out?</TD></TR></TABLE>

Are you sure you were adjusting the fpr's the right way? Did you try a stock fpr?

 

Yeah... I tried both ways on both regulators just tomake sure.... originally I though the gauge was toasted, but my motor is the only thing that is toasted

 

I had a problem like that a long time ago, I was getting like 75psi with a walboro on a stock motor almost. I took the fuel filter and changed it, it dropped to 65psi with no other changes. Then I got aeromotive regulator and it worked fine after that.