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1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #1 (Edited)
I have a 1985 380SL, in a no start condition. I have checked fuses, OVP. I have replaced the fuel pump and jumped the relay. New wires, rotor and cap . I'm getting power at the pump. I'm also getting power at the cylinders. I get spark at cylinder. Thoughts? Solution?
Thanks in advance.
 

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1984 380SL
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2,343 Posts
Questions and apologies if it's me being dense, are you able to get the starter to turn over?

If so, have you confirmed spark at the plugs?

No power to the ECU wouldn't lead to a no start, just a rich running machine.

Check if you're getting spark. If so, then the last thing to check at air intake issues.
 

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'80 450SLC Afro RHD Ikonengold
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2,864 Posts
If there was no or insufficient ground on the block, crank would not be possible and spark would find the easiest route to bridge the block-chassis gap (could be your radio but really anything).

I cannot think of a reason that a K-Jet needs negarive on the block apart from CSV for temp under 15°C.
Ignition does require negative block as spark quality relies on on it.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Where did you check ground in the engine bay? Your picture shows the 12V positive block. Both of those connections are always hot even with ignition off.

Do you hear the pump for a second or two when turning the ignition on?
 

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1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #5
I can get it to crank. On this car the pumps only run when cranking, not with the key in the on position. But when I jump the FPR I hear it run. both hot leads? One side is a ground. You will see one leads to the engine as a ground. Its basically a battery terminal in the engine compartment as the battery is not accessible for things like a timing light attachment. I have spark at the cylinders.
 

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1984 380SL
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Check the green wire going to the ignition control module as well as the ICM itself. Is the wire stout and not falling apart? Is the ICM the Huco module or the giant resistor one?
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,899 Posts
Yes both are hot unless they changed for the 560SL which I doubt but anything is possible. The one on the right goes to the starter. I read 12+V on each and continuity between the two.
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #8
Check the green wire going to the ignition control module as well as the ICM itself. Is the wire stout and not falling apart? Is the ICM the Huco module or the giant resistor one?
The wire is stout, firm....I checked the end that goes into the distributor and it had some brown wire wrapping i mbelieve but i knocked it away. The ICM is the silver box Bosch
0-227-100-042
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #9
Yes both are hot unless they changed for the 560SL which I doubt but anything is possible. The one on the right goes to the starter. I read 12+V on each and continuity between the two.
You are correct sir! I just tested them both, but only get voltage when the ignition is in the on position. So, I just jumpered the relay and it almost caight 2 times....but now nothing. Something tells me this is electrical, as it was "missing" under load as I drove it and then it just wouldn't restart , luckily in the garage not out and about. Perplexing....
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #10
Check the green wire going to the ignition control module as well as the ICM itself. Is the wire stout and not falling apart? Is the ICM the Huco module or the giant resistor one?
Is this the giant resistor one??
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
Joined
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150 Posts
Discussion Starter #11 (Edited)
Check the green wire going to the ignition control module as well as the ICM itself. Is the wire stout and not falling apart? Is the ICM the Huco module or the giant resistor one?
How can I test this module?
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #12 (Edited)
Check the green wire going to the ignition control module as well as the ICM itself. Is the wire stout and not falling apart? Is the ICM the Huco module or the giant resistor one?
I have found a new ezl/icm made by Bosch for $31.95 with the same part number as the big box. I'll grab it if you think it might be the problem.(EDIT) But, now that I look further its the right number but not for this model 002452830 both numbers have to match.
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #13
I just checked to be sure. I have spark at the number 5 cylinder. Have a light that connects to the plug and the wire. It lights up! New fuel pump. I did recently replace the fuel filter and the filter basket on the fitting before the fuel distributor. Should I check the fuel pressure at the distributor and warm up regulator? Or perhaps the fuel pressure regulator?
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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31,899 Posts

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
Joined
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150 Posts
Discussion Starter #17
Thus the "for the future reference". In case you ever need one.

Have you tried pouring a little gas down it's throat or starting fluid? If it starts then it's a fuel issue. There was a thread where someone changed the filter in the distributor inlet resulting in a no start but it was a 560SL.

Found it https://www.benzworld.org/threads/no-start-after-filter-replacement-fuel-distributor.2992371/
Brilliant. I had seen that thread previously some months ago. My recall isn't what it used to be lol. The thing is, that I replaced the fitting and the car started and I drove it and then parked it and it would start after that drive. Thoughts? Wjile you consider that, In the mean time I will crack the lines at the injectors and jumper the FPR and then press the deflector plate to make sure I have fuel in the lines.
 

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1985 380 SL
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62 Posts
Question: how was it running before the no start? Did it give any indications of a pending problem such as misfire or low power? When you crank it, does it seem to spin faster or slower than normal?
 

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Registered
1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #19
When you gave it gas under load it was missing a bit, nothing different when it cranks.
 

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1990 560SEC 334K miles as of 5/19, 1990 500SL (Euro Build) 67K miles as of 5/19 1985 380SL 130K
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150 Posts
Discussion Starter #20
Ok, update. I put my fuel pressure gauge on. I get 5.0 bar system pressure when i jump the FPR and the valve closed with the valve closest to the WUR. When I open the valvem I get 0. zip, zero, nada. Then I unjumper the pump and it goes to 2.0 bar.. But thats not the reading, as we want it under pressure from the pump, correct? All of this has started from a replacement of the accumulator and the filter. I believe the increased fuel pressure has gone on to blow out one or both of the fuel pressure dampers as they have affect control pressure. Can I test them individually?
 
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