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Fuel Pressure Check Valve Location
Last weekend I successfully replaced my driver-side window regulator on my '78 280E. Two weeks ago I replace the Idler Arm bushings. I'm on a roll thanks to many helpful threads here.
I started to replace my fuel pressure check valve on Sunday and was dismayed to find no mention of such a part in my Haynes manual, in the fuel pump section. Help, where does the check valve live? Here's the background. My 280E now has only about 48,000 miles on it. On its maiden(under my new ownership) trip of more than 15 miles made last December, it died on me 40 miles from home. Fuel pump quit, but for less than $100 I had a new Bosch fuel pump installed and all seemed well. The car always starts well from cold, 3 to 5 turns and it fires first time. When off for 5 minutes after running for a while, it fires right up. But if I leave it off for much more than 5 minutes, it cranks and cranks, but does not fire for three extended cranking sessions, and then it fires up with a little help from the gas pedal. It spudders, like running on 1-5 cylinders, then gradually smooths to a normal idle. Happens in a time frame of 20 minutes at rest up to 4 to 5 hours at rest. This has been the case regarless of ambient temperature or moisture. Once fired-up, it always runs smoothly. Recently I've switched to "Plus" grade fuel, but this has not helped the starting problem. So where does that check valve go? Thanks for your direction, Alex
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'78 W123 280E, 58,000 mi! '97 Mazda Miata '94 Isuzu Trooper, 4WD '03 MB C240 4-matic Wgn - Wife's From the Archives: '73 2002 '68 TR-250 '67 Austin Cooper "S" '59 Austin Seven (Mini) various p'up trucks |
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Apodman,
Check out this link: http://www.auto-solve.com/mech_inj.htm and consider the possibility that the fuel accumulator is not holding system pressure up after the pump is switched off. I had almost the identical symptoms you're describing on my '86 300E in June of '02, (here's a link: http://www.peachparts.com/shopforum/showthread.php?threadid=40454 and I found that replacing the accumulator and the fuel filter (just because I was in there) cured the problem for me. Here's a short quote from the text: "Within the data books for this system, it is shown that the critical time for maintaining these pressures is between 5 and 20 minutes. After a journey, when the engine is switched off, the under bonnet temperature increases causing the fuel in the lines to heat and it attempts to evaporate. Maintaining the pressure eliminates this problem and ensures a clean start when the vehicle has been standing with a hot engine" Hope this helps, Gary PS - Here's another related post I just found that may be helpful: http://www.peachparts.com/shopforum/showthread.php?threadid=8527&highlight=Fuel+Check+Valve |
#3
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Warm Start Problems
Gary,
Thanks for the three links. Lots of information, some help, more questions, but now closer to a solution then before.
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'78 W123 280E, 58,000 mi! '97 Mazda Miata '94 Isuzu Trooper, 4WD '03 MB C240 4-matic Wgn - Wife's From the Archives: '73 2002 '68 TR-250 '67 Austin Cooper "S" '59 Austin Seven (Mini) various p'up trucks |
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Apodman,
BTW, if you're still looking for the location of the fuel pressure check valve (I think it's really the fuel pump check valve you're looking for - serves the same purpose), it's screwed right into the end of the fuel pump. Here's a picture from the FastLane catalog page for your model. Is that the piece you're talking about? Gary |
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Gary,
Great shot of the fuel pump and check valve. I'll be working on it this week. Thanks, Alex
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'78 W123 280E, 58,000 mi! '97 Mazda Miata '94 Isuzu Trooper, 4WD '03 MB C240 4-matic Wgn - Wife's From the Archives: '73 2002 '68 TR-250 '67 Austin Cooper "S" '59 Austin Seven (Mini) various p'up trucks |
#6
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As far as I know, a new fuel pump comes with a new check valve. If you changed your pump, then you have a new valve. Your problem is related to what is called " Rest Pressure" or the ability of the fuel system to hold fuel pressure after engine shut off. Two things to look at: 1. Fuel accumulator and fuel system pressure which is bolted to the fuel distributor in older CIS fuel system. Try this link to better understand the CIS fuel system .
http://www.auto-solve.com/mech_inj.htm
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Meza 1993 190E 2.6 Advanced Diesel Systems Test and Research Engineer |
#7
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[QUOTE]Originally posted by Meza
[B]As far as I know, a new fuel pump comes with a new check valve. If you changed your pump, then you have a new valve. Hi Meza, I have a 260E from 1988, changed fuel accumulator, and I am suspecting problem with erratic loss of fuel pressure ( engine stalls for a few seconds while running ) Do you know whether there is a check valve on the pump of the 260E model from 1988 , The engine and equipments should be very similar to those on a 190 2.6 Thanks |
#8
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mecedes 280e fuel problem
hi there my 280e wont start the fuel pump keeps running is this a regulater
problem cheers paul |
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