SL/R230: SL55 Fuel Pressure
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Joined: Jul 2022
Posts: 10
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From: Madison, Wisconsin
2007 Mercedes SL 55 AMG, 1955 Thunderbird, Durango HellCat, Crossfire SRT6, CLKAMG winter car
SL55 Fuel Pressure
Hi Guys...Found the cause of failed warm start...converted from returnless to a return fuel configuration...now start every time...fuel boiling in fuel rail causing pressure to exceed 150psi...stalling injectors from functioning...vapor lock...installed Holley regulator at fuel rail service port...returned fuel back to tank.
I purchased this 2007 SL55 simply because no one knew to connect an electronic remote fuel pressure gauge to the service port and log the pressure rise (SC heat coupled with engine heat = boiling fuel for 45 minutes (150 PSI). Gas boils at 160 degrees.
All works GREAT however...does anyone know what the fuel rail pressure is at idle for a M113K? I've asked MB service centers and referred to MB WIS with no luck. The Holley has a 1:1 boost port so it's what was needed in the first place (SC). Just need a curb pressure and good to go. The PWM takes care of flow.
I purchased this 2007 SL55 simply because no one knew to connect an electronic remote fuel pressure gauge to the service port and log the pressure rise (SC heat coupled with engine heat = boiling fuel for 45 minutes (150 PSI). Gas boils at 160 degrees.
All works GREAT however...does anyone know what the fuel rail pressure is at idle for a M113K? I've asked MB service centers and referred to MB WIS with no luck. The Holley has a 1:1 boost port so it's what was needed in the first place (SC). Just need a curb pressure and good to go. The PWM takes care of flow.
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Joined: Aug 2020
Posts: 1,328
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From: Gretna, NE
'03 SL55 Black, '03 SL500's Aegean, Mars Red, Tazanite, Alabaster, '11 S550 Flint Gray
I believe that is caused by a failed pressure regulator. Any excess pressure should bleed back into the tank.
I know that common practice on a boosted engine is to add boost pressure to fuel pressure. However, I see nothing to indicate that was done on the SL55 or any mechanism for it to happen. As far as I can tell, 5 bar at idle and 5 bar at full boost.
I know that common practice on a boosted engine is to add boost pressure to fuel pressure. However, I see nothing to indicate that was done on the SL55 or any mechanism for it to happen. As far as I can tell, 5 bar at idle and 5 bar at full boost.
