1987 Mercedes 560 SEC - starting (or refusal to) after period of standing!

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GAllen1976

New Member
Joined
Jan 26, 2021
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6
Location
Essex, UK
Car
1987 Mercedes 560 SEC
Hi all.

I hope someone may be able to help me.

I've just bought a beautiful 1987 Mercedes 560 SEC. Although it has been left standing for a number of years, it's still in excellent condition.

Prior to me buying it, the car has been started by the long-term owner (on old fuel) and driven around.

However I'm told it stopped revving and he limped the car in to the parking spot where I viewed it - on idle.

On the key, you can hear the fuel pump prime.
It does try to start (and splutters a bit, occasionally up to 1k rpm) but it won't fire and run.
It seems slightly better if you prime the fuel pump a couple of times with a few flicks of the key ahead of engaging the starter.

It will fire on brake cleaner sprayed directly into the air inlet - but stalls once it's burned through it.

When starting on brake cleaner, the throttle pedal makes zero difference - which suggests to me it is either a fuel pump / filter or fuel delivery issue.
- Since I can hear an audible buzz of the pump priming I am assuming that the relay is OK??

I do have a new fuel filter on order from Euro Car Parts coming in tomorrow.

Is there anything you would check?
Any tips or advice for changing the fuel filter / anything I should be aware of?

Ay advice greatly appreciated. I can't wait to get this back up and running!
 
Last edited:
I'm going through the same issue. (I actually made a crappy video on it yesterday)
First thing is to remove the fuel feed line to fuel distributor and direct it to a bottle to see if you're getting fuel to the engine.
 
I'm going through the same issue. (I actually made a crappy video on it yesterday)
First thing is to remove the fuel feed line to fuel distributor and direct it to a bottle to see if you're getting fuel to the engine.

Thanks Al. Do you have a link to the video? G.
 
Thanks Al.

I'll certainly do the bottle test - ahead of checking the piston in the fuel distributor. That's something I can do before changing the filter...

Just bought 1 x Fuel pump as a second hand (unfitted so basically brand new) one was cheap on eBay locally to me (£35 inc delivery).
I'm not [yet] familiar with these Mercs but believe they have 2 so worth it as a spare regardless.

I also think you can remove the fuel pump relay and bridge 2 of the terminals to power up the pumps???
I'm thinking it may be worth checking that also......... Are you familiar with this?

I'd rather test the original setup and find the actual issue without messing around with it and potentially introducing unknown problems.

G.
 
Thanks Al.

I'll certainly do the bottle test - ahead of checking the piston in the fuel distributor. That's something I can do before changing the filter...

Just bought 1 x Fuel pump as a second hand (unfitted so basically brand new) one was cheap on eBay locally to me (£35 inc delivery).
I'm not [yet] familiar with these Mercs but believe they have 2 so worth it as a spare regardless.

I also think you can remove the fuel pump relay and bridge 2 of the terminals to power up the pumps???
I'm thinking it may be worth checking that also......... Are you familiar with this?

I'd rather test the original setup and find the actual issue without messing around with it and potentially introducing unknown problems.

G.

Yep, 30 and 87. The relay is right there up on the firewall. There are two pumps on this car. I'm not discounting that the issue could be with the filter or the strainer in the tank as the tanks can get rusty.
 
Hi all.

I hope someone may be able to help me.

I've just bought a beautiful 1987 Mercedes 560 SEC. Although it has been left standing for a number of years, it's still in excellent condition.

Prior to me buying it, the car has been started by the long-term owner (on old fuel) and driven around.

However I'm told it stopped revving and he limped the car in to the parking spot where I viewed it - on idle.

On the key, you can hear the fuel pump prime.
It does try to start (and splutters a bit, occasionally up to 1k rpm) but it won't fire and run.
It seems slightly better if you prime the fuel pump a couple of times with a few flicks of the key ahead of engaging the starter.

It will fire on brake cleaner sprayed directly into the air inlet - but stalls once it's burned through it.

When starting on brake cleaner, the throttle pedal makes zero difference - which suggests to me it is either a fuel pump / filter or fuel delivery issue.
- Since I can hear an audible buzz of the pump priming I am assuming that the relay is OK??

I do have a new fuel filter on order from Euro Car Parts coming in tomorrow.

Is there anything you would check?
Any tips or advice for changing the fuel filter / anything I should be aware of?

Ay advice greatly appreciated. I can't wait to get this back up and running!
You have a fine, fine car there, assuming no ghastly rust. My view is that it probably needs a complete revision of the service parts - all fluids and filters and the entire HT system.

This will not be a low cost operation as only genuine MB or top quality aftermarket parts befit a car of this quality. I say this as I am always cagey about parts recommendations from Eurocarparts, AutoDoc etc. I'm not saying that they shift dodgy parts, only that they do not always link you to the best quality parts.

By all means, buy from these people - I use AutoDoc a lot - but find the MB part numbers from the MB EPC at this place and then cross-reference those numbers to the recognised brands like, for filters, Mann, Hengst etc., and for suspension parts Lemfoerder and for HT Bosch or Beru but, in my experience, for HT I favour genuine MB, albeit at a cost.

For MB bits I use Originalteile - Willkommen bei den KFZ Teile Profis who are in Munich so this may cause you grief with all the Brexit bollocks. Others on here might recommend a good MB dealer for the genuine parts.

Sorry to spend your dosh so freely and the very best of luck with a stunning, potentially, car.

RayH
 
2010-11-13_222126_fuel_pump_relay_test.gif

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MEANT TO POST LAST NIGHT SORRY
 
Thanks - Tried this today but no difference. At least it suggests the relay is OK!!!! :)
 
Ok, so I spent a bit of time today on the car...
I've just got in, degreased myself and am beginning to warm up as I'm freezing (so please excuse any typos!)!!! :)

Fuel Pump Relay:
Tried bypassing the fuel pump relay - no difference (Thanks for the diagram Graeme).

Fuel Filter:
I replaced the fuel filter with a new one.
The old fuel inside was very watery and sludgy and way passed its best.
Changed the copper washers both sides of the banjo and refitted.

Old Fuel:
Dropped the main pipe off the pump.
Drained a bucket full of fuel to the point the fuel actually looked clean and smelled OK.
(at which point was thinking that basically having a bomb in a bucket wasn't the best idea - so transferred it in to a jerry can and refitted the pipe to the pump!!!)

Fuel Distributor (Thanks Al !)
I removed the fuel distributor as per Al's video.
The pin was indeed sludged up, sticky and a bit rusty.
I cleaned it up with brake / clutch cleaner and a brass brush, added a drop of 3-in-1 and freed it off, then repeated the brake cleaner and blew it all out with an air line.
* I noticed the main O-Ring at the bottom of the main unit is very loose / stretched *
I have refitted it to see if freeing the pin has made a difference - it hasn't.

Current status:
The car turns over and tries to fire.
I think that the fuel filter has made it very slightly better, but could be placebo!
I have also noticed the fuel pumps are making a gurgling/bubbling squelchy sound every now and again.

Next steps:
Fuel distributor O-Ring
- Would anyone have a part number, or is this a stock sized O-Ring?
1 x Fuel pump on order - Just need to order another one)
Fuel valve near the pump/filter assembly - unsure of the name of this part) - is it worth changing?

I have noticed the pumps buzz (constantly when the FPR pins are bridged, but didn't check when relay in place).
* There is also a constant loud hum from what seems like the rear left of the car when sitting inside. Any idea what this is?? *

Anyway, I've ticked a few things off but not made as much progress as I'd have liked.

Thanks for your ongoing help and advice!

G.
 

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