Fuel Injection Pump Problems

[jackhughes81]

I am a new member and not totally familiar with this site.   I have a 65 230sl and dont know much about it.  My dad bought in 70, stored till I bought in 2007.  Drove it for a couple years then it simply died.  I am quite mechanically inclined, electrical as well (engineer).  I have taken to 2 'euro' repair shops who claimed to know, but after 2 weeks just wanted diagnostic $$$ with no fix suggested.    One important note- during its last summer days, I noticed a tapping type noise- in the engine at low speeds while driving.  The car will start sometimes, and runs terribly for a minute or so - sounding like timing is way off then stalls.  I have removed and cleaned the fuel pump, checked flow rate and flushed the lines.  The injector pump may have an issue.  6 months ago, I noticed the oil level (removed red cap on injector pump) was low.  I could not find any spec on the replacement oil so I used some lightweight I had. 

Mechanics tell me they know nothing about the injector pump and cant test it.. I am convinced it has an issue.

HOW DO I CHECK THE FUEL INJECTOR PUMP??? any suggestions would be greatly helpful

[Jordan]

Jack, welcome to the forum and the Pagoda family.  WRT your problems, perhaps you could be a bit more specific as to what the problem is besides sometimes starting and runs terribly. 

Before you start playing with the injection pump have you checked the usual suspects; timing, dwell, spark plugs (colour and if you have spark), coil etc?  There are a lot of brilliant members on this site and you should hopefully get it sorted out.  The tapping doesn't sound good but lets not start with an engine rebuild.  It might be something far simpler.  There is also a wealth of info already on the site, just use the search function.

[Bonnyboy]

Jack, welcome to the forum.   Just a shot in the dark...You noted that you flushed the lines, did that include the fuel return line - did you see fuel coming back into the fuel tank at a good clip when you remove the fuel sending unit from the trunk? 

[ja17]

Yes,

Welcome Jack.  You can check the basic adjustment of the injection pump by removing the small round cover on the front of the injecion pump. You can then check to see if the rack moves freely. Search up "injection pump tour" on this site. The injection pumps in the tour are a bit different from your 230SL pump but most of the information is relevant. As mentioned, also need to check the "warm running device"  (WRD" on the injection pump, to make sure it is not stuck. Get back with us with more questions after you take a look at the information here. 

[Peter van Es]

Jack,

with your issues, I'd recommend reading lots in the Technical Manual:

http://www.sl113.org/wiki/Fuel/Start

And then click through all the links. That's also where you'll find the links to WRD etc.

Some of the material (e.g. the Engine Starting Aid Tour) is for Full Members only. However the $30 you'll pay to read that info, and possibly provide to your mechanic, you'll save many times over. Check this for details on membership.

Peter

[glenn]

Hi Jack...   How many miles on it??    First thing- adjust valves and sync crank and cam shafts.  Engine's the most expensive item($2500?).  Next run engine for 5 minutes with Gunk Engine Flush(quart), drain and fill with (Castrol) 20-50 extended mileage oil.
     Is the tapping coming from the top or bottom?

[jackhughes81]

Since my post, I have read a lot in the tech manual.  Thank you so much!  The section on fuel system is invaluable.  Some additional info-

The car has 75K original km on it.  Verified by title, maintenance information and my father who bought in 70 and stored in barn till I bought in 07. 
Body rust has taken its toll in Seattle, and the new paint to cover for sale in 70 went right over everything.
Original tool kit
Original UNOPENED first aid kit...  well untill I opened it...
Dad replaced flex brake lines, new plugs, rotar, cap

power washed then started.  Drove to LesSchwab for new tires the I drove off to Spokane (about 300 miles)
the car ran great, and at times cruised at 100km/h while I forgot about the world

Ran summers with minor issues involving fuel pump clogging.

Last August back in Bellingham, Wa it stalled going around a corner and I thought out of gas since fuel indicator only works on upper half..

Could not start so stored for winter.
2 shops claimed the could fix and after $600 'diagnosing the issues' I was no closer to a fix.

Then comes my discovery of the forum and the manual.

Spring time and the car is up on stands with me removing the fuel pump.  All OK.
I disconnected fuel line from tank and return line and placed them in a large gas can with long tube extensions to ease the process.
Meantime I remember putting oil in the injector pump a couple years ago thru the red cap in top
recent running past the pump has been loudly ticking but paid no attention

Car starts and runs for 1 minute then stalls.
It really sounds like fuel starvation.
Sit a bit then start again with same result.
Timing OK
Dwell OK
Pump working OK..  I hear it pressurize then hold. 

HOW DO I INSERT PICTURE?  THANKS SO MUCH.. JACK

[Peter van Es]

Posting pictures: see: http://www.sl113.org/FAQ/items/FAQ-Images.html

[ctaylor738]

The fuel pump should not "pressurize and hold." It should just run.  It supplies more fuel than the engine needs.  What isn't used by the injection pump is returned to the fuel tank.  This line may be plugged or the return passage in the tank may be plugged. Suggest unhooking the line at the pressure regulator and blowing it out with compressed air.

When you serviced the fuel pump, did you remove the inlet fitting and clean the filter in it?

Cheers,

CT

[Bonnyboy]

It sounds to me like the pressure valve on the outlet end of the fuel pump is either not working or the pump isn't pumping with enough pressure.   When I was playing with my pump I had volume but not enough pressure which I tested using a garden sprinkler guage to get an idea of pressure.  My pressure valve was too strong for the old pump I had and wouldn't let fuel back into the return line.  I put in a new pump and voila - the fuel now flows.

[garymand]

Now we are getting some where, I would check fuel pressure and volume at the engine.  The cold start valve is a good place to do the measurements.  It is in the manual.  Ensure you are getting the required fuel pressure and volume to the FI pump.  Let us know.  

[ja17]

Yes, hook  up a gauge.   Most likely you will see the fuel pressure drop off right before the engine stalls.

[jackhughes81]

PRESSURE VALVE ON THE OUTLET OF FUEL PUMP..  I have removed and cleaned this older version of the pump and am not familiar with this valve.  I have the Chiltons manual but do not see this item... BTW.. moderator, I tried to sign up for full membership and the system did not like the fact my mailing address is different than PO billing..  how to get around this?
I have spent the night reading about the FI pump and the 'warm running device' on the injection pump.  Excited for dawn to pull the filter and see performance..  in addition, I have read much about linkage adjustment procedures, but do not see them.. is this part of the full membership? 
I will try again to post pics.. spring is here in the NW and I want to take this little beauty for a spin.  When it ran, it was a pleasure to drive... like it was on rails.. cheers- jack

[Jonny B]

As a full member you have access to the technical manual. Go the "Technical Manual" tab, then scroll down to the bottom of the page, and you will find a link for the linkage tour, and other content available to full members.

[ja17]

Most likely you have sediment in the fuel tank and fuel cannot get into the flower pot.  Top off the tank with fuel  and see if the problem goes away for a while.  Your problem will return when the fuel level gets to about 1/2 tank. Another check you can make is to remove the fuel sender in the trunk and look into the tank with a flashlight.  Any crud in the bottom of the tank will clog the intake for the "flower pot".

[jackhughes81]

Yes I did, and there is a good flow on the return line.  Currently I have both the pump inlet line and the return line in a 5 gal gas can.  Car runs for 1-2 minutes then appears to stall out..

[jackhughes81]

Took the assembly off, inspected and returned ..  simply to become familiar with the mechanics.  I hear the sucking but cant determine if it changes in any way.  The filter on the assembly has no cartridge but is simply a round canister?  After re-assembly the same stalling after fairly good running for a minute or so..  I will time the running today and report back. 

[jackhughes81]

Thanks for the help-  I can not find the pressure valve.  I have an early style tall pump, and have been pouring over the documentation looking for the pressure valve.  Can you point me to the location of documentation showing the valve?  thanks- jack

[jackhughes81]

what would make the pressure drop off?  I am looking for the fuel pump pressure regulator valve...  diagram?  thanks- jack

[ja17]

Are you saying that  your main fuel filter  canister had no cartridge in it?  On  the early 230SL pumps the fuel pressure regulator is built into the fittings toward the front of the IP.  On the later W113 engines the fuel pressure regulator is built into the fitting at the rear end of the IP.  The fuel line coming from the fuel filter canister is the supply line. The return line is the fuel line going back to the tank. Where the return line leaves the IP you will find the regulator.

Attach a pressure gauge to the system and run the engine.  This should help pin point the problem.

[jackhughes81]

I did find the pressure regulator valve between the fuel filter and the FI pump.  Tomorrow I will get a pressure gauge and test it.  Supposed to be 70F tomorrow and the 230 needs to be driven.  I also took the fuel pump apart again and found NO screen on the input, so putting a inline fuel filter between tank and pump.. 
I also have an issue with the ignition.  I lost the original keys, sent to MB for code, made another and they dont work.  Needs to wiggle intensely and maybe start.  I want to remove ignition and bypass the key.  Anyone know easy way?  I have a wiring diagram..
I will post pressure results tomorrow.
jack

[ja17]

Some of the earliest version electric fuel pumps did not have the screen on the intake fitting. Removal of the ignition is a lot of work. You will have to remove all the gauges to get to the mounting bolts one or two are below the dash, and one under the center gauge. There is a hidden pin under the clamp around the steering lock which holds the assembly in the column.   You have to move the clamp out of the way and turn the key to position #1 before you can depress the pin. Once the pin is depressed, the whole steering lock and ignition can be removed.  You may want to check with some good lock smiths first. They may be able to make a key or adjust the one that doesn't work with the ignition still in the car.
 Also if you can get to the three small slotted screws on the electrical switch at the rear  of the lock assembly, you can remove it and activate the ignition/ starter etc. Be careful some of these wires are live. You may want to disconnect the battery so you do not get a short.

Sometimes the early style check valve/regulators on the IP get stuck. Take it apart and clean it. Later versions do not come apart.

[jackhughes81]

Thanks Joe..  I have not been able to find a pressure gauge but have access to the valve and am taking it off this afternoon.  The fuel tank is questionable-  could not remove the plug and have resorted to return line and fuel pump inlet line extended into 5 gal gas can.  The Key is frustrating and will try taking the switch from the rear of the lock assembly.  I have a remote start button and will install that if possible short term..  thanks for the alternate advice.  The valve looks fairly easy to take apart.  I am electrically and mechanically quite inclined.  I am a retired chemical engineer with lots of time and not so much cash.. again thanks!  jack

[ja17]

Hello Jack,

The electric fuel pumps on these cars are gravity feed fuel. So as  you can see the bottom of the electric fuel pump is mounted level with or below the bottom of the fuel tank. Be careful running fuel in to separate containers. A spark from the wiring or static electric could be cause a dangerous fire. 

A simple universal pressure gauge will work for checking fuel pressure.  A  0 to 60 psi. range is good.

[jackhughes81]

Got a gauge but am a bit confused how to hook into system.  I have pump with inlet, outlet and the return line to tank.  All these lines are exposed and I have access, but the connections to them are sometimes hard coupled.  I dont think dead end to the pressure gauge is the way to measure it, or is it?  I read somewhere about using a 'T' arrangement, but are we talking at the outlet from the fuel pump?  Seems like maybe I want to have a tee on the return line and full flow rate?  Not sure how the pump likes being static pressure.. seems like the return line 't' would be the way..  any advice?  I am collecting lots of connectors, tubes and other small fittings and items in an attempt .. raining hard now so need some sunshine to work. 
thanks again- jack