Author Topic: Fuel injection line bleeding  (Read 1555 times)

Tom in seattle

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Fuel injection line bleeding
« on: August 03, 2022, 03:35:51 »
I removed my fuel filter and the car sat for 3 days before installing a new filter.  Upon assembly I let the fuel pump run for several minutes before starting.  It ran very roughly but finally ran with one or two cylinders failing.  Prior to the this work it ran very smoothly.  I have removed all plugs and all but # 4 and#6 were perfect but the 4and 6 were dark brown. I also put a strobe light on each plug wire.  All were firing. I’m of the opinion that there may be air in the injection system.  So I plan to remove all plugs and sequentially crack each injector flange  at the head until I see plenty of gasoline escape.  This after disabling the ignition power .  Am I on the right track?  Is this a proper procedure?   I’ve not had this problem before..
Tom Averill
1967 250 SL Auto Euro Spec

kampala

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Re: Fuel injection line bleeding
« Reply #1 on: August 03, 2022, 14:54:38 »
There is normally a bleed screw on top of the filter housing.  You crack that and run the electric pump to bleed air. 

Since you’ve run the car, and if you did not bleed, you may still have to crack the injectors as you mentioned.
250sl - later - manual
280sl - 1971 - Auto - LSD

Benz Dr.

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Re: Fuel injection line bleeding
« Reply #2 on: August 03, 2022, 19:39:07 »
Generally not need. The lines self bleed as fuel is pushed through. It's a different problem.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

Tom in seattle

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Re: Fuel injection line bleeding
« Reply #3 on: August 03, 2022, 20:31:38 »
I wish to report back that I have solved the problem. I noted that plug 6 looked suspect so I bled injector line 6.  This did not solve the problem.  I then took it for a drive and it sounded like a 4 cyl but low on power but was at running temp.  I then thought to remove and inspect plug 6 again.  I found that plug wire 5 was plugged into 6 and plug wire 6 into plug 5. So I’m offering a caution that I suspect my wife did this to get me to do house and yard maintenance if I became frustrated enough to
Tom Averill
1967 250 SL Auto Euro Spec

Mike Hughes

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Re: Fuel injection line bleeding
« Reply #4 on: August 03, 2022, 21:18:06 »
Ha! She has a wicked sense of humor!  My best man (a Rolls-Royce technician) did the same thing to our '51 M.G. TD at our wedding reception 46 years ago, switching #2 and#3.  What he didn't know was that the starter was on the fritz.  I had to hand crank the car while Lucy steamed up the windows and all our wedding guests were standing around under umbrellas.  It ran fine when I parked it there earlier.  When I finally got it started, I wasn't about to shut it down again to see what the problem was, so we putt-putted away on two cylinders until we got to the covered entrance of the elementary school round the corner where I quickly discovered my friend's devious prank . . .
- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havana Brown (408)
  Light Beige (181)
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