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  #1  
Old 10-29-2004, 08:11 PM
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Hard Start (E420) - Recent Tune Up, etc.

Ok,

this is getting on my nerves. Over summer, the car started acting up. Whenever I leave the car and the engine is warm, upon coming back, chances are I could crank forever and nothing would happen.

When that happens, sometimes it might seem like it's going to fire but it doesn't. Other times it just cranks to no end.

If I give up and crank it again, it fires up as if nothing ever happened.



Power is good, mileage is good, everything else is fine. Never a problem when the engine is cold though.

Mind you, it does not happen all the time.

The spark plugs, distributor rotors, caps are recent - say about a year ago or 10,000 miles.

Over summer when it started acting up, the dealer replaced the crankshaft position sensor and shimmed it as per MB's suggestion. They also claimed that they could not replicate the problem.

Upon taking the car back, I stopped for gas. When I tried to fire it up, it just kept cranking. But! The second time I tried (right after), it fired up like it would normally.

It did it again a while back, and in the past two days it failed to fire up three times.

The wiring harness is new too.

Any ideas?

Plug wires maybe? or should I try replacing the spark plugs anyhow? I do have 8 Bosch Supers doing nothing on the shelves somewhere.

Fuel Pump? Fuel Pump Relay of some sort maybe?

Any suggestions will be great. The car is obviously going back to the dealer that tried to fix it. What a waste of money it was!

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  #2  
Old 10-29-2004, 08:28 PM
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New fuel pump relay, and probably an accumulator (that can be checked, fuel pressure must stay up when switched off). Most likely a fuel pump relay, though, or OVP relay.

Peter
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  #3  
Old 10-30-2004, 03:51 PM
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The symptoms aren't quite right but I would replace the fuel pressure regulator anyway - it's on the top, back, right side of the engine I believe. They're cheap, maybe $30, and easy to put in. They are a common failure problem and they do cause start up problems when they fail.
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  #4  
Old 10-30-2004, 04:59 PM
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I'd put a fuel pressure gauge on it so you can see what the rail pressure is when it won't start. Sure would help in diagnosing the problem.
Did yo put in the approved plugs or some kind of "super-hype" plugs? These engine "like" the approved plugs better than anything else. Also are you using high octane, and if so you could try switching to mid-grade for a few fill-ups to see if there is a change. I've also heard of problems like this when the weather starts getting colder and the fuel being purchased is still a summer formula (usually the gas station will have no idea if the fuel is still summer formula or not, but the summer formula gas can be a problem in cool weather)

Gilly
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Old 10-31-2004, 03:17 AM
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I replaced the spark plugs today and it was still alive after :p - but I'm not sure if it fixed the problem as I did not do a hot start.

I don't like throwing parts in, but I guess I could put in a new fuel pressure regulator. Next weekend maybe...

Also thought of the accumulator, but once it didn't start after cycling the fuel pump before trying to crank the engine, so I guessed that it wasn't the problem.

The E420 doesn't have an OVP relay, it has these 3/4 fuses in place of it and I've replaced all four of them

not sure if it has a fuel pump relay either?

Gilly

I put the approved F8DC4 Bosch plugs in the car - I just replaced the ones in the car today. All looked ok.. (didn't look too good though) - but one was weird. It felt like it was held by some sort of sticky stuff and when it came out:



Seemed like oil around it...

I am currently using 93 Octane from Sunoco, I'll switch to 91 or something and see if the problem persists.

and it rarely fails to start, so it's kind of hard to get ready for it...

Also, here's a naked M119 - beautiful thing, why do they have to cover it up...



Is that the fuel pressure regulator that I circled in red?

Would gasoline start coming out if I take it out to put the new one in?
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Last edited by Holson Adi; 10-31-2004 at 10:26 AM.
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Old 10-31-2004, 07:35 AM
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You can relieve the pressure at the rail test connector, you won't lose much fuel in the process.
None of your pictures worked........
Gilly
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Old 10-31-2004, 10:31 AM
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Thanks for the tip Gilly, where is the rail test connector btw? (Is it the A/C-like valve on the large u-shaped thing on top of the injectors?)

by relieving the pressure you mean, opening the valve and letting the pressure out or something?


I fixed the broken picture links hopefully.

Also ordered the Fuel Pressure Regulator, i'll throw it in this week sometime.

we'll see how this goes.

Thanks again guys,
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Last edited by Holson Adi; 10-31-2004 at 10:46 AM.
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Old 10-31-2004, 01:51 PM
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Yes, you can see it on the picture with the regulator circled (which BTW yes that is the regulator). It's on the front of the U-shaped thing you mentioned (which BTW that's the fuel rail). It's under the copper hex shaped cap, there is like an AC style Schrader valve under there. Just protect your eyes and face and push in on the end of the valve, you'll release the pressure and a bit of fuel. It's like letting air out of a tire.
Gilly
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  #9  
Old 10-31-2004, 06:47 PM
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Is there a fuel pump relay on the E420? I remember trying to find out more about it and couldn't find anything on a fuel pump relay.

I'm going to do the fuel pressure regulator - but if it happens again (problem is that it happened 4 times since July ... so it's hard to show a mechanic what the problem is); I'll have the fuel pumps and the accumulator looked at.
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  #10  
Old 10-31-2004, 07:11 PM
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E420 will probably have a MAS relay (combined) rather than a separate fuel pump relay (electronic vs KE-Jet fuel injection).

No, I would not replace fuel pumps on a program, wait for them to die, as many go 300,000 miles or more, and condition can be easily tested by measuring current draw.

Peter
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  #11  
Old 11-01-2004, 02:42 PM
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i used to have the same problems u described but i have a E320 and for me a new fuel pump relay and ovp cured everything

it was just strange, u go for a drive.....stop by a store or whatever real quick (under 10mins)....return to the car....cranks forever....nothing.....then wait a bit....starts up up fine as if nothing is wrong

ur car might not have any problem during cold starts but eventually for me just driving the car was a crap shoot....i'd never knew if it was gonna start in the morning or worse leave me stranded if i dared turned off the car

good luck on ur problem and do keep us posted

the 420 is the back up plan if i can't find the e500 :-)
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  #12  
Old 11-01-2004, 06:52 PM
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On the 210, used a few different schemes. MAY be a small "cube" type fp relay under the seat by the battery, or there is a component in the underhood area called the "fuse and relay module"
Gilly
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  #13  
Old 11-02-2004, 12:06 AM
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Was browsing through Fastlane and found a green relay called Fuel Pump Relay under Body Electrical - Relay (this is for the 95 e420)

so I ordered that and a few other things along with it - we'll see how it goes. It doesn't bother me too much but it's embarassing :p

Again thanks for the suggestions guys, keep 'em coming if you have new ones. I just don't read as much about hard starts on the 420...
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  #14  
Old 11-02-2004, 02:01 AM
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E420 starting problems

I posted my own thread on E420 starting problems, then happened on yours regarding the same subject. I was wondering if you satisfactorily solved your 1995 E's starting problems with the R&R of the fuel pressure regulator, or if you are still dealing with it.
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  #15  
Old 11-02-2004, 04:36 AM
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I don't know how my brain got hijacked into thinking this was originally posted about a 210 E420, so forget about the Relay Module. I believe also that it's a MAS module for the fuel pump relay. Pretty rare car though, not sure, but may be able to research it off of the 124 disc.
Gilly

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