Starting Issue?

[bpossel]

I am helping a good friend of mine, Dennis Zanone, trouble-shoot a problem with his really nice looking 1969 280SL..

Dennis just had a new long block put in from Metric Motors, a rebuilt injection pump from Hans, new gas tank, recored radiator, and lots & lots of other new parts…

Today I installed new and correct Beru wires from Buds and W7DC spark plugs.  I also ensured the timing was set to 30 degrees BTDC at 3,000 RPMS and 8 degrees ATDC at 800 RPMs.

Overall, car seems to run very strong.  It has the nice chirp when shifting during acceleration….

[:0]Here’s the problem….

When hot or cold, doesn’t matter….  When you start the car, it seems like it is choking for fuel for approx 10-15 seconds, then it jumps nicely to approx 900-1000 RPMs .

Any comments on what the initial starting issue could be???  Air in the injection lines?  Fuel pump pressure?

As always, thanks for your help!!!

  Bob


bpossel
Memphis, TN.
1971 280SL
1997 E320

[hands_aus]

Hey Bob,
It helps to know the distributor number.

8 ATDC, with or without vacuum?

Could be too rich just at starting.

800 rpm HOT idle is correct, 900-1000rpm warming up seems right.

Was the CSV rebuilt too? If not, could it be leaking?
 
Have you checked the colour of the plugs?

Does his '69 have emission relays etc?

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[bpossel]

Hi Bob,

Thanks for your reply!
Yes, 800rpm is set to approx 8 degrees, and 30 at 3000 rpm.  The cold start was also sent to Hans, cleaned, checked and is not leaking.  I changed the plugs to W7DCs.  The mechanic had installed W8DCs.  When I pulled them out, they did look pretty nice!  They had a light greyish color.  I dont think Dennis's 113 had any emission relays.

It is odd that at start up (cold or hot) it seems to choke a bit for approx 10 seconds, then it perks right up!  

Does anyone think that air in the injection lines could cause this?  Maybe they didnt bleed each injection line at each injector, while craking the engine...

Another thought...  what if the mechanic didnt install the IP pump at exactly 20 degrees ATDC?  What would the symptoms be of this error?

Thanks!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

[Benz Dr.]

Change back to W9DC or the W8DC.
 W7DC is best for a full compression perfectly dialed in car. Smooth running at start up can be a challenge on these engines but what it does after runnibg for a while is more important as start up is usually the shortest amount of actual running time. In other words, how does it run at hot idle after a longer run?

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[Ben]

Does this car have the 1 second relay ?  And if so is it working right ?

Regards,
Ben in Ireland.
'64 230SL 4sp.

[hands_aus]

Bob,
I think the air would have been pushed out of the lines by now.

Ben,
I added the 1 second relay to my car and because it fires even when the engine is hot, there is sometimes more fuel than is actually needed to start the car.
The engine stumbles a bit but quickly recovers to run great.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[bpossel]

Thanks Bob, Dan and Ben!

Dennis's car runs really well after warm up...  actually also runs well after initial start-up also.  Just struggles a bit for a few seconds when initally starting it up (cold or hot).  Maybe I am too picky and this is normal for these older designs?  I thought that with a brand new engine, it would start up like a modern car?

Dan, for this being a new engine, do you still recommend the W 8's or 9's?  I thought that these were for older engines and also ones in somewhat colder climates?

Thanks again!
Bob

bpossel
Memphis, TN.
1971 280SL
1997 E320

[Ben]

quote:Ben,
I added the 1 second relay to my car and because it fires even when the engine is hot, there is sometimes more fuel than is actually needed to start the car.
The engine stumbles a bit but quickly recovers to run great

...........I just wondered since something is switching in that first few seconds which improves the situation. I recall when my car had issues it did something similar (stumbled) and I could hear an audible click befaore it recovered and idled smoothly !

Regards,
Ben in Ireland.
'64 230SL 4sp.

[bpossel]

Hi Ben,

It is something for us to look into..

 :?: What does the 1 second relay look like?  Which one is it?
These 113's seem to all look different...
B.

bpossel
Memphis, TN.
1971 280SL
1997 E320

[Ben]

Bob see the follwing link for details on some issues I had and the relevant details from the experts !

http://index.php?topic=2519+sec+relay[/url]

Regards,
Ben in Ireland.
'64 230SL 4sp.

[hands_aus]

Hey Ben,

What a great topic to link to!  

So much information, ball valve part number, relay types, TTS, CSV, CSS, how the system works!

Just like a workshop lesson.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL, auto

[Ben]

Yeah I know....it really helped me out at the time !!

Good luck !

Regards,
Ben in Ireland.
'64 230SL 4sp.