Author Topic: Starting Engine after opening injector lines?  (Read 3991 times)

bpossel

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Starting Engine after opening injector lines?
« on: February 15, 2009, 12:26:37 »
Hi All,

What is this groups opinion on the proper procedure to start the engine after the fuel lines have been opened?  This could be due to IP Pump reinstallation, injector lines replaced, etc...

The BBB and Haynes says to ground the "W" on the Thermal Time Switch until the engine starts.  At some point I recall another procedure that says to open all injector lines at the injectors, have another person crank the engine and as fuel comes out of each injector line, tighten accordingly. Of course with the later procedure you would also want to ensure that the engine does not start up by removal of the rotor.

So my question is, with the BBB procedure it doesnt allow for air to be removed from the lines.  Or is this not needed and once the engine starts up, the air is pushed into the cylinders?

Bob  ???

jameshoward

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Re: Starting Engine after opening injector lines?
« Reply #1 on: February 15, 2009, 12:54:33 »
Hi Bob,

When I replaced my FI pump I went for the second of your options as it seemed simple enough. We just reinstalled the lines and then with someone cranking the engine with the HT lead removed cracked each one at a time at the injectors until the fuel came out then tightened up on the lines. Didn't take too long at all and worked fine. As ever you'd want to put some spill sorb on the floor in a pan to catch drips and have a decent extinguisher nearby.

I wasn't aware of the procedure in the BBB.

James

(In sunny Lashker Gar)
James Howard
1966 LHD 230SL

ja17

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Re: Starting Engine after opening injector lines?
« Reply #2 on: February 15, 2009, 14:18:34 »
Hello 

Bob,


 Getting the max. volume of fuel down the lines and to the injectors is the idea here.  The BBB procedure simply activates the intake cold start valve while the starter is engaged. Another thing to do is hold the accelerator pedal to the floor to increase fuel delivery.

The lines will actually bleed themselves, however sometimes cracking the lines at the injectors to watch the fuel arrive is reassuring.

Removal of the spark plugs will also allow the engine to crank faster delivering fuel sooner. When the fuel arrives at the injectors reinstall the plugs and tighten the lines.

The IP injects very small quantities of fuel on each stroke, so it will take some cranking to fill those long injector lines.
]
Good luck,

Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

graphic66

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Re: Starting Engine after opening injector lines?
« Reply #3 on: February 15, 2009, 20:11:19 »
Just be careful not to overheat your starter. 15 seconds on and 15 seconds off can help keep the starter cool. You can burn up your starter from continuous cranking. Starters are not made to run continuously. Also watch out for sparks that may ignite fuel that may come from bleeding your lines. Watch the coil wire if you unhook it, it can arc and ignite fuel. As for a fire extinguisher, the dry powder can cause as much damage as a fire. I like Co2 or Halon the best. Sometimes just a thick blanket can starve the fire by just throwing it over the fire.

bpossel

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Re: Starting Engine after opening injector lines?
« Reply #4 on: February 15, 2009, 20:48:24 »
Thanks Joe, James, Graphic66,

I have done this before with cracking open the injection lines, and that procedure works good.

Today I tried it with grounding the themo time switch and it only took a couple of cranks before it started.  It did run very rough at first, then it kicked in and ran good.

I had to do this procedure because I removed my IP yesterday.  I wanted to ensure that it was installed at 20 ATDC  :-[.  It was....