1985 Mercedes 380SE - wont start

[SummerSouvenir]

RE: 1985 Mercedes 380se


I hope someone here can help me out.
A few years back my car wouldnt start, and I knew it was the fuel pump relay,
so I jumpered terminals 7 and 8, the car started right up.
Now, a different but similiar problem, car wont start,
fuel pump not engaging (no sounds). I jumpered terminals 7 and 8,
fuel pump running BUT THIS TIME CAR WILL NOT START.
I bought a new fuel pump relay, no sounds of fuel pump running with this new relay installed.
I only hear the fuel pump when I remove the relay and jumper 7 and 8.
Last time the car started, now it wont start when it is jumpered.
Any suggestions please ???

Thanks,
James

[eric242340]

The pump is bad, when you put a jump wire in you send the full power to the pump and force it to rotate, but with a relay in and a high resistance from the pump the relay contacts will be forced to open.

[SummerSouvenir]

Originally Posted by eric242340

The pump is bad, when you put a jump wire in you send the full power to the pump and force it to rotate, but with a relay in and a high resistance from the pump the relay contacts will be forced to open.

Thanks Eric for your reply,
but what I dont understand is that when the jump the 2 terminals I HEAR the usual buzzing sound of the fuel pump, so I assume it is working.
A few years back as I said, my relay failed, I used a jumper wire, and the car started right up.
This time, I hear the buzzing sound using the jumper wire but no start.
Should I try and pour a little gas thru the throttle body, or use starting fluid to see if it attempts to start ??? Perhaps even the slightest indication that it wants to start would indicate a bad fuel pump ???
Once again, I always thought that the pump is working if I hear that usual buzzing sound ?


Thank You,
James

[eric242340]

Sure try a starting spray into the valve body to see if it starts, if it does then check the fuel filter to see if it is blocked.

[SummerSouvenir]

No good with the starter fluid, not even the slightest indication that it wants to start.
Seems to be a no spark situation. Never no recent driveability issues, always started with the first turn of the key.
Other day went from store to store no problems until I left the last store.
Now, just cranking and no firing.
Cap, rotor, wires, coil wire, plugs all good.
Coil tested around 9400 ohms secondary and primary at 0.80 ohms.
I dont have a spare coil to try, I did have a universal coil somewhere but cant find it now.
Guess this leaves ignition control module or distributor pick up (green wire) ?
I think thats all it could be.
Neither of these have ever been replaced.
I do not think that either of these can be tested or bypassed to test but I may be wrong.
Any suggestions please ?
Thanks,

JAMES

[eric242340]

Unplug the coil lead from the distributor cap and get some one to crank the engine whilst holding the lead close to ground and see if you get a spark.

[SummerSouvenir]

NO spark, but there is 12V going to coil.
I did as mentioned, check coil with ohmeter, was in specs.
I hope its not the dist. pickup, that looks hard to get to.
Any suggestions please ?

Thank You,
James

[eric242340]

Originally Posted by SummerSouvenir

NO spark, but there is 12V going to coil.
I did as mentioned, check coil with ohmeter, was in specs.
I hope its not the dist. pickup, that looks hard to get to.
Any suggestions please ?

Thank You,
James

12v to coil - no spark - bad coil.

[SummerSouvenir]

Hi Eric,
I put a different coil in and still not firing.
James

[eric242340]

Originally Posted by SummerSouvenir

Hi Eric,
I put a different coil in and still not firing.
James

Have you checked to see if this coil is giving spark? What is the vehicle identity #?