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  #1  
Old 08-22-2007, 01:59 AM
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1987 420 sel fuel fouling

I just bought a 1987 420 sel and it is fuel fouling the plugs replaced plugs and started it it ran for a little but it now does not start the plugs are soaked in fuel not oil I need help took it to serveral shops and everyone of them keep giving me the run arounf I have done a lot of work to these veh some shops say replaced the primary fuel pressure regulator one said replace the fuel distutor one said replace the warm up regulator but no one came give me a sure anwser please some help!!!

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  #2  
Old 08-22-2007, 07:19 AM
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Do a SEARCH!

It could be any of those items, or others like the cold start valve. No one on this board can tell you exactly what's wrong. You need to work through the components one-by-one until you find the problem(s).

There are lots of posts on dealing with these problems on this engine, use the Search feature to find them.

Good luck.
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'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #3  
Old 08-22-2007, 08:26 AM
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87 420sel's don't have a warm up regulator , this problem is sometimes caused by a worn and sticking plunger in the fuel distributor , allowing fuel to drip into the intake manifold.
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  #4  
Old 08-22-2007, 09:38 AM
david s poole
 
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especially if the car has been sitting for some time.to check this identify fuel pump relay in front of windshield under hood and join pins 87&30.this will run pumps without engine.you can then listen to see if fuel going thru injectors.will usually make a screaming sound.now take rubber mallet and tap on top of fuel distributor to see if you can free the piston.
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  #5  
Old 08-22-2007, 09:41 AM
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The cold start valve might be stuck open.
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  #6  
Old 08-22-2007, 10:09 PM
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thanks for all your help I checked the fuel dist and cleaned it freed up the plunger valve and the little roller that conacted the plunger cleaned the iac vavle and checked the primary fuel pressure regulator it holds vaccum how far down should the plunger come down it seems the contact the air meter plate roller when i reassem and retested bleed the air off the fuel sytem according to what the guys at the dealer said and tried to push down the air meter plate it had pressure all the down removed all the line from the injectors and tested to see if fuel bleeds out of with the key on motor off jumped the fuel pump relay no fuel bleed by no fuel no nothing pushed down on the air meter plate a little and fuel comes pouring out.

wher is the cold start regulator
and what I am calling the warm up regulator I mean main control pressure regulator the little black box on the fuel disulator

PS sorry about my bad spelling
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  #7  
Old 08-23-2007, 11:26 AM
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spark and fuel is needed

the black box on the fuel distributor is the eha, electro hydrostatic acctuator, a faulty one won't keep your engine from starting , does your engine have spark ? , have you checked to see that your engine hasn't become a victim of the timing chain guide issue ?
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  #8  
Old 08-23-2007, 01:49 PM
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yeah it has spark and the chain had areally been replaced and is this motor not zero calreance if the timing jump would it not lock up or had at least a valve hit a pistion. I have been told and taught that if spark plug are drowning in fuel they will not spark.

compression is good in all the cylnders and she is trying to start but the plugs are fouled out. she is spitting and sputteing, what is the correct firing order. and if the eha dosen't go out what contrlos the main line pressure.
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  #9  
Old 09-30-2007, 12:35 PM
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I am trying to jump on this original post. I am having the exact issue with a 560 and cannot find a direction to go in. I have replaced plugs, fuel pump, ovp relay, eha valve, cold start valve and the air fuel mixture tower. All these things have been replaced recently for one reason or another so I am wanting to think I can rule these out. I know even new parts fail sometimes. On our 560 I pulled the plugs and cranked the engine and as the piston came to TDC every time it shot out massive amounts of fuel. I took off one injector line at the fuel distributor and fuel was coming out when I cranked the engine. I think I read somewhere on her that if you have fuel coming out of the fuel distributor at idle it is bad and needs to be replaced. I want to check my fuel psi but I am not sure how to connect the gauge. I have heard to hook it to the cold start valve and I've heard connect it to the lower chamber on the fuel distributor? I've checked timing and spark. The fuel pumps do come on for a few seconds when key is turned on and then stop but they run all the time as the engine cranks. I have read that the ovp relay controls the fuel pumps and to test this cross the 86 & 87 pin but my issue is that the pumps stay running so this test may not work for me. Any help would be appreciated.
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  #10  
Old 09-30-2007, 01:56 PM
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Arrow

This is the cold start valve on your engine.
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1987 420 sel fuel fouling-cold-start-valve.jpg  
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  #11  
Old 09-30-2007, 01:59 PM
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Vacuum leaks?
Vacuum leaks will cause a car to run rich and like ****
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  #12  
Old 09-30-2007, 04:03 PM
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Yikes. You need fuel from the FD all the time, but it's metered proportionately to air flow. I think the only way you can get that much fuel cranking is to have the plunger in the fuel distributor stuck in the wide open position. Suggest that you buy the o-ring for it, pull the FD off, check the plunger, free it up if necessary and put it back together.

You can check the CS valve buy removing it, reconnecting it, and letting it squirt into a jar, and observing it while cranking.

Your fuel pump relay is working right.
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'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #13  
Old 10-02-2007, 10:56 PM
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I think I found the problem

Sorry to jack this post but I thought maybe it would be ok since we are dealing with the same problem. I think I have traced my problem to a faulty fuel pressure regulator. The round canister one not the EHA Valve.I tested the fuel psi on the main line coming from the fuel pumps and got over 100 psi (as high as the gauge goes). I then connected my gauge up to the fuel line coming out of the Fuel Dis. and got the same reading. I then tested after the Pressure regulator and got nothing. I took the line from the Fuel Dis. and placed it in a clear jug to do a volume test and when I did this the car started off the fuel that was in the cylinders and ran for a few seconds. My fuel psi gauge had a valve on it that I could control the psi by turning and got the car to run. I have ordered a new Fuel regulator. Just for kicks I hooked my old regulator to my air compressor and even at 120 psi I could not get the regulator to releive pressure. I also took off my Fuel distributor and found the o-ring was half gone. This is probably the source of my rough idle. Thanks for all the help. Sorry again to eugene but hopefully this helps you.
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  #14  
Old 10-03-2007, 06:08 AM
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Nice wrench!

Be sure to post results.
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'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe
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  #15  
Old 10-03-2007, 08:29 PM
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ahhhhhh!!!!!!!!
nice call ctaylor...thanks for the information
it looks like I am on the right track
but I need to check the fuel distributor o-ring too and the plunger/ is this like a float value of old?

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