Fuel Injection

[Bobo]

 
 Hi everybody I am new to this site and hope someone can help me. I have a 1967 230SL which has been laid up for a few years while I have carried out restoration work to the body. Now I come to start it I am getting no fuel into the injector pipes from the pump. The fuel flows into and out of the pump but not into the pipes. The fuel delivery and return quantities are correct and there are no strange noises when I spin the engine over. 

[glenn]

Does the rack move (and rotate the pistons as they go up and down)?  Probably not(FIP laid up for years).   Got to free up the FIP.

[Bobo]

Thanks Glenn How can I check the rack and free it up if nec. Can I do this  without removing the pump?

[hands_aus]

there is a fuel injection pump tour here
http://www.sl113.org/forums/index.php?topic=790
have a read, absorb as much as you can,
then 'search' on your exact topic as I vaguely remember this has been discussed

[waqas]

I freed up my injection pump rack a couple years ago. This thread might help: http://www.sl113.org/forums/index.php?topic=7100.0

Also read through Bob's suggested links.

[Bobo]

Thank you all for your response, it does appear that my injection pump is siezed.
I am now checking out all the links on the forum and will follow the advice given.

[stickandrudderman]

You'll do well to take it off and have it properly overhauled/calibrated.
I can recommend an outfit in London who've done several for me and the results are always good.
It might seem expensive initially but the hours you'll save yourself trying to sort out why the engine doesn't perform properly will make it all worthwhile in the end.
Ask me how I know!

[ja17]

However, if you want to give it a try freeing it up yourself, let us know.  You may not succeed but you will learn a lot!

[Ron]

Using Joe's instructions I freed up mine, 3 out of the 6 pistons were stuck.  It's worth a try!  Ron

[Bobo]

Yes please Joe I would like to give it a try.
Maybe I will have to get back to you stick.

[ja17]

Hello Bobo,

Yes make sure fuel is getting to the IP first via the electric fuel pump.

First make sue the WRD (warm running device) on the rear of the injection pump is not stuck. The slide valve in the bore must be free.
The WRD has three tubes going to it. Two are engine coolant one is auxillery air for the engine when it is cold. The unit can be removed by disconnecting the hoses and unvastening the two slotted screws.  You can clean it up and get it operating smoothly while off the car. Re-install on IP.   
Next remove all six of the metal fuel lines at the IP. Start from the back one and work your way forward slidding each fitting up out of the way as you move forward.

With the ignition on hold the accelerator pedal all the way to the floor and crank the engine. You should see fuel emerge soon  in some of the IP fittings.  Let us know how what you find. ( you will not see large volumes of fuel, the IP pumps a precise but small quantitiy of fuel at each stroke).

[Bobo]

Hi Joe
I have managed to get the car running for two to three seconds at a time just on the cold start solonoid.
Next I checked the WRD and made sure it is nice and free. I have disconnected the fuel lines from the pump and cranked the engine with full throttle but the IP fittings stay completely dry. I have allso checked the rack by putting a bolt in the end and it is has no movement at all. I have allso taken out of the pump one of the fittings that the fuel lines connect too so as to see which type of no return valve this pump has. From what I have read it is the type that needs a puller to remove.

[ja17]

Hello Bobo,

Is yours is the early injection pump with the spring and cone valve under the 19mm fitting?   If so, just remove the spring  and lift out the cone vavle, and you will be able to see the top of the plunger.  Soak them with penetrant Turn the engine a view them moving up and down. You will most likely find one or more not moving.

If yours is the later IP , your pump will have the "ball check valves. These valves are threaded on the outside.  You can find a metric brake hose or clutch hose fitting to thread onto the ball check valve.  The fitting can now bbe pulled out.

Let us know what you find.

Joe

[Bobo]

Okay Joe I have removed the check valves on the IP, they are the later ones with the thread on the outside.
I have removed the spark plugs and turned the engine over by hand. There does not seem to be any movement at all in the IP.
Bob.

[ja17]

Hello,

If you look into the IP you will see the plugers (pistons) sitting down in the  cylinders. They should move up and down as the engine is cranked.  First of all soak all the plungers with penetrant  (WD40 or similar).  

After soaking, you can tap down lightly on top of each plunger with a blunt drift (soft metal like brass or aluminum) or hard wood dowl. You should be able to get some plungers to move down. Some will not because the cam below is pushing them up. Some will not because they may be stuck. Be gentle and take it slow. Rotate the engine and repeat as needed until all plungers move up and down on their own.  When this happens the rack should be free. During re-assembly the 19mm fitting on the pump should be torqued in at 18-20 ft. pounds. Do not over torque or under torque.

You may wish to leave the spark plugs out of the engine and the fittings at the injectors loose while you are priming up the system with fuel. When the fuel emerges at the injectors tighten the fittings, crank some more, install the spark plugs and fire it up!

Good Luck

[Bobo]

SUCCESS !

After removing the the one way valves I started to gently tap down the plungers, this did not seem to be working so I began to tap a bit firmer. This resulted in a small amount of movement and the more I tapped, sprayed, and turned the engine by hand the more confident I became. By this time I was able tell which plunger was on the cam. It was just a matter of patiently tapping and turning until they all moved by themselves. The rack does not seem to be totally free yet, although it does move quite easily it will not return by itself.
I connected everything back up but as I cranked the engine fuel began to bubble out of the top of the cold start solenoid, the sealing ring has broken up, so I have  ordered a new one but this has to come from Germany and is going to take about a week. Hopefully when this is all back together the car should run.
Thank you Joe, your help and information has been fantastic. I will let you know what happens next.thank you again.

[ja17]

Hello Bob,

Sounds good, you are making headway.  I assume you got all the plungers to move up and down on their own? 

Joe

[Bobo]

Today the the seal for the cold start solenoid arrived, so I assembled  everything back up, removed the spark plugs and cranked the engine for a good while but when I cracked the pipes at the injectors there was only fuel at no. 6 injector. After quite a bit more cranking there was still no fuel at the other 5 injectors but plenty at the pump end on all 6.
So I thought I may as well give it a go and hope that if it starts it will pull the fuel through, back went the plugs turn the key and Hey Presto it started instantly!
It ran very fast for a time then settled down a bit but began to 'hunt' (running fast and slow) hopefully this is just down to the dreaded linkage adjustment and fine tuning.
Still it's great to hear it running after at least eight years.
Without your help Joe and this forum it would probably have taken me a couple  more! Thanks again.

Bob.

[ja17]

Hello Bob,

You welcome and good job!  Right, the "linkage tour" and the "split linkage CO test" will become your next valuable lessons.  The "hunting" is a mixture problem at idlle.

[Bobo]

Okay, I have worked through the linkage tour and found it very user friendly and easy to follow, I am happy with all my settings. I cannot find any information on the split linkage Co test. The hunting problem appears to have been an air leak which is now cured. My next problem is the static timing, I have one book that says it should be 2* BTDC and one that says 6*BTDC  (the marks on the pulley only go up to 5*) The distributor no. is JFUR6 0231 116 051 the car is a 1967 230SL
Can anybody let me know the correct setting?

Bob

[Bobo]

Can anybody let me know the correct static timing for my 230SL please?

[DaveB]

my MB manual lists, for an 051 distributor, assembly setting 6° BTDC and for 'stroboscope check at starter speed with spark plugs installed': 8° without vacuum.

[Naj ✝︎]

In my view, setting static timing is there to help you start the engine.
More important is to set it at 30*BTDC at 3000 rpm without vacuum. Then see what readings you get at idle without and then with vacuum reconnected. (all this of course after having the dwell angle within spec.)
That should tell you how your centrifugal advance and vacuum are performing.

naj

[IXLR8]

Hi--

I have the early fuel injection pump with the spring and valve under the 19MM fitting.

I have pulled the six springs and valves from the pump. Should the valve body also be removed to gain access to the pistons below?

If so, how do they come out?

If not, how does one get to the pistons to loosen them up?

Looks like the valve body hole is just about the same diameter as a golf tee. Is this where one uses the golf tee per Joe Alexander's suggestion to push the stuck piston back down to the cam?

Thanks in advance for your help.


Joe

[ja17]

Hello Joe,

Soak the plungers down with penetrant then turn the engine to see which ones are stuck.

Do not remove any more parts from the pump for now. If you determine which plungers are stuck, try penetrant then tap them down. If they do not move down, turn the engine since it the cam may be holding the piston up.