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#1
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Fuel pressure question
Heya folks
I am having trouble accessing a workshop manual and hence my question. I have a 65 220 w111.021 se coupe and would love to know what the fuel pressures are. Can someone LMK what the line pressure should be after what would be called the lift pump at the rear and finally what that pressure should be after the injector pump. I have inherited this LHD coupe (imported from the USA 22 years ago) and am endeavouring to get it running right. I appear to have approximately 5-6 lbs at the rear pump but have no idea of the spec for front. HELP...!!! Peter |
#2
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How's the injector spray pattern? Poorman's injector test is pulling an injector then hooking it up and shooting a piece of cardboard, caution on shooting yourself in the hand or arm, pattern should be wide not narrow.
Also separate oil reservoir for the IP on them, not sure what's the best recommended oil. Common hazards include rusty fuel tank, varnished injectors and IP innards and porous fuel lines too. With LHD at Australia it must be fun to freak out front seat passengers, makin em sit there on RHD driver's side with no steering wheel or pedals. |
#3
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Here's what my Mercedes factory manual gives for the 220Seb.
Electric fuel pump is tested with the engine off, a minimum of 11 volts at the pump and tank at last half full. Fuel pump delivery pressure measured behind the fine fuel filter - 0.6-0.8 atm (8.8-11.8 psi) Minimum delivery volume measured after return flow damper bowl - 1.0 litre in 15 seconds. Spray pressure of used injection nozzles or valves. Minimum - 13.0 atm (191 psi) Happy Motoring, Mark
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DrDKW Last edited by Mark DiSilvestro; 12-05-2005 at 06:40 PM. |
#4
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In other words, delivery from the fuel pump is measured by its huge volume and not pressure. It's the distributor at the front that generates the high pressure needed for fuel injector operation.
If I remember rightly, the pump should be generating "something like" 14psi. In comparision, the mechanical pumps for cars with carbs do about 5-7psi. The D-jet EFI system is calibrated to 32psi and the CIS systems work at or about 75-82psi. DANGER: At all times working with fuel under pressure, there is a very real chance that you can inject it into your skin. This is a VERY bad thing to do. Also fuel coming out of an injector is that much more flammible thanks to atomization. Try hard not to burn down your garage, immolate the car or roast you and yours. -CTH |
#5
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reply to info left
Gentlemen thank you for your time and effort in responding.
You have left me the vital key which I need b4 getting my hands dirty and hence will allow me to complete my dianostics fully. I have an injector dianostic machine which will allow me to clean nozzles and check pattern followed by flow rate. Alas I havent had a passenger yet as I am still getting it right for registering and a ways to go yet...but in having said that I have had and still have other MB' but this would have to be my favorite by a long shot. Cant wait to get it up and running smoothly...enjoy it for a while then slowly move through the vehicle bringing it back to a state of excellence. Thank you once again to those responded. On a closing note being a LHD parts are reasonably hard to get here in Oz, is it possible for any of you guys to throw a name or two at me. Parts of interest for me immediately would be the steering box and pitman arm if its different from conventional to power steering. I can replace the pump off a like type model as they are all the same..??? Can any one tell me where the flasher cam hides on this thing. Cheers Peter |
#6
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Would 12 - 14 psi be about right for a 68 280se as well? My Haynes manual is silent on this.
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#7
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That's right Justin. The electric fuel pump only supplies fuel to the injection pump which then supplies fuel to the injectors at much higher pressure. The 220SEa and220SEb has a two plunger pump and the others have 6 plunger pumps, the 6.3 uses an 8 plunger pump.
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Regards Warren Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL ENTER > = (HP RPN) Not part of the in-crowd since 1952. |
#8
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Thanks Warren. I'm sure people won't like this but I'm thinking of putting in something like this:
http://www.holley.com/12-802-1.asp It claims 88 GPH at 9 PSI. Sounds like a pretty close match. I've already torn my old pump apart apart once, cleaning up the stator and replacing the brushes. But it is still unreliable. Let me know if anyone has any suggestions. |
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