Help! Bad Cold Start w/ heavy smell of Gas!!

[lil_dz33]

***LOT of info here. Tried to go into detail the best I could. Cliffs:

-Car is EXTREMELY difficult to start when cold.
-Strong smell of gasoline after the car has been sitting.
-"Chuggs" when cold, as if missing when sitting idle in gear. Idles fine when in Park while cold.

See more details below:

Hey guys, I did a quick search, but it wasn't extremely helpful.

About 6 months ago, my 500E developed a difficult cold start; taking solid 25-30 seconds of cranking before turning over. This is when the car has been sitting over a period of about 8+ hours. After starting, it would "chug" a little as if it were experiencing a slight miss.. The "chugging" was only experienced while in gear. If placed in Park, the chugging goes away and the car idles normally.

(side note, while the car "chugs" there would be a loud "knocking" noise coming from what appears to be the rear of the car, under the passenger rear seat. Once warm, the "knocking" would disappear.)

After completely warming up (say the end of my commute), it would run perfectly fine.

Now, it takes a couple of attempts of 30 second cranking with a bit of pumping the gas to start. It will backfire quickly before struggling and will weakly start.

There is also a VERY strong smell of gasoline when the car sits. There is a faint smell of gasoline when driving, but I think this may just be the smell lingering since it was so strong while sitting still. I've never experienced the smell until recently, when it became extremely difficult to start when cold.

There is no smoke on start up, even when cold.
The plugs do not look foul. Excessively burnt or carboned up. (Although they do appear to be a bit more "Tan" than usual with a hint of corroded "green?")

There appears to be no leaks, at the FPR, Fuel Rail, or injectors.

Please give me a hand. I love her, and at the moment, shes my daily! Quite embarrassing to sit in the parking lot at work and struggle with such a pretty car!

 

[ccc]

I don't know the answer in total, but,
I wonder what has been done in the six months you have been observing?
Have you had it into the shop?

There is likely something wrong with the fuel management, probably at the sending end. The fuel pump is under the rear seat where you are hearing a noise,
so i would think the pump or its control is faulty in some way. Change the fuel pressure regulator and filter while at it. When was your fuel filter last changed?
The leak? Have the shop look in the same area, the leak might identify the dysfunctional part.

Smells of gasoline. mmmh. Imolation is not something i want to hear about.
Stop driving it and take it to the shop! You really don't want to be messing with the fuel yourself anyway. Have you done that before? Changed my fuel filter before. Twice. Don't even want to do that again. Do you have the facilities to deal with ea fuel leak, spray or fire? Be careful.



Chris

***LOT of info here. Tried to go into detail the best I could. Cliffs:

-Car is EXTREMELY difficult to start when cold.
-Strong smell of gasoline after the car has been sitting.
-"Chuggs" when cold, as if missing when sitting idle in gear. Idles fine when in Park while cold.

See more details below:

Hey guys, I did a quick search, but it wasn't extremely helpful.

About 6 months ago, my 500E developed a difficult cold start; taking solid 25-30 seconds of cranking before turning over. This is when the car has been sitting over a period of about 8+ hours. After starting, it would "chug" a little as if it were experiencing a slight miss.. The "chugging" was only experienced while in gear. If placed in Park, the chugging goes away and the car idles normally.

(side note, while the car "chugs" there would be a loud "knocking" noise coming from what appears to be the rear of the car, under the passenger rear seat. Once warm, the "knocking" would disappear.)

After completely warming up (say the end of my commute), it would run perfectly fine.

Now, it takes a couple of attempts of 30 second cranking with a bit of pumping the gas to start. It will backfire quickly before struggling and will weakly start.

There is also a VERY strong smell of gasoline when the car sits. There is a faint smell of gasoline when driving, but I think this may just be the smell lingering since it was so strong while sitting still. I've never experienced the smell until recently, when it became extremely difficult to start when cold.

There is no smoke on start up, even when cold.
The plugs do not look foul. Excessively burnt or carboned up. (Although they do appear to be a bit more "Tan" than usual with a hint of corroded "green?")

There appears to be no leaks, at the FPR, Fuel Rail, or injectors.

Please give me a hand. I love her, and at the moment, shes my daily! Quite embarrassing to sit in the parking lot at work and struggle with such a pretty car!

 

[bing]

Sounds like the rare "fuel knocking/missfire" issue. Do you hear the fuel pump relay clicking underneath rear seat? Hopefully not as this could mean a faulty LH module.. How old are your fuel pumps ?

 

[gsxr]

Fuel pump relay is located below the rear seat cushion on the passenger side. The fuel pump package is located under the car in that same area. Very likely you have a fuel leak at the fuel pump area. DO NOT drive the car with a fuel leak... get it fixed immediately. Don't end up like this poor guy with your 500E burned to the ground.

 

[lil_dz33]

Walking out to my car for lunch today, I found a small puddle of gasoline! I think I found my problem. '

I also found out that the knocking is DEFINITELY coming from the fuel pump relay! I've got a new one shipping to me. Hopefully that fixes THAT problem...

 

[gsxr]

Um. If your fuel pump relay is "clicking" rapidly... a new relay most likely will not cure it. This is caused by a faulty LH module. It's relatively rare, but I've heard of about 3 or 4 occurrences in the past several years. If you have trouble locating a replacement LH, drop me a line. If you have a 93-up model with the stock module, this would be a handy time to upgrade to the '92 module...

 

[gerryvz]

I had a persistent gasoline smell on my E500 for a couple of years. Not horrible and no fuel on the ground, but a persistent smell nonetheless.

I ended up tracing it to a VERY slightly loose connection at the fuel rail underhood. Just a few mm turning the connection with a wrench solved the problem and I've never had a fuel smell problem since. This was a disturbed fuel connection as part of the installation of the NOS system back in 2004.

Probably would be a good idea to check the integrity of all of your underhood and fuel line connections running along the underside of the car, as well as at/around the fuel pumps and filter area underneath the car.

Cheers,
Gerry

 

[lil_dz33]

Um. If your fuel pump relay is "clicking" rapidly... a new relay most likely will not cure it. This is caused by a faulty LH module. It's relatively rare, but I've heard of about 3 or 4 occurrences in the past several years. If you have trouble locating a replacement LH, drop me a line. If you have a 93-up model with the stock module, this would be a handy time to upgrade to the '92 module...

Thats troubling news. What in the LH module goes bust, do you know? Im going to be installing the new pump, filter, lines, updated washers and the relay tonight. Hopefully this cures the issues. I shall report back.

 

[gsxr]

Thats troubling news. What in the LH module goes bust, do you know? Im going to be installing the new pump, filter, lines, updated washers and the relay tonight. Hopefully this cures the issues. I shall report back.

The only symptom is the relay clicking. Sometimes it varies depending if the module is cold (early morning, right after startup) or hot. It shouldn't affect engine operation in the short term, but the clicking is not good for either the relay or the pumps. First order of business is to fix the fuel leak(s), once that's done, then focus on fixin' the clickin'.

 

[ccc]

luv this mushroom picture,

Nice help here Sounds like you are all organized for work on the car tonight. Let us know how it goes. I'm interested to know where you found that puddle of fuel? under the filter/pump area?....livin' dangerously!

 

[lil_dz33]

Hey Guys!

The source of the leaking was a cracked fuel filter! :O

Swapped it out, took less than an hour. No fuel smell, no more leaking. The filter was pretty clogged, It looked like it had hadn't been changed in ages! The car now runs AMAZING. MUCH smoother and a lot more punch. No more hard starting. (Not during the day, any way.)

ON to the clicking relay. I know it may be futile replacing the actual relay based on what I hear from gsxr, but I sourced one new from Mercedes for 15 dollars, so why not try and replace it?

Are the LH modules the same on all 92 500 series like the 500SL and 500SEL? If so, I may peruse a few wrecking yards to see if that solves the clicking relay if still plagued by it.

 

[bing]

Are the LH modules the same on all 92 500 series like the 500SL and 500SEL? If so, I may peruse a few wrecking yards to see if that solves the clicking relay if still plagued by it.

Part # 012 545 6232 , Dave/GSXR has one as he mentioned.

 

[ivanned]

I had to replace the fuel line from the tank to the pump/filter assembly - it was shot to hell and leaking a ton after I had just got the car.

Recently, I found a cracked valve for the fuel evap system where all the return line and evap. hoses enter the tank - accessible from under the car. The valve number is 1244760432. It cracks where it is clamped to the lower hose. I changed all hoses there too since they were all original. The clamps too because they just fell apart. It seems they get brittle even if not rusty.

 

[bgreene30]

Hi Gerry,

Any schematic of all the fuel lines from tank to injection around? I would like to give them all a good looking over.

Thanks.,!

I had a persistent gasoline smell on my E500 for a couple of years. Not horrible and no fuel on the ground, but a persistent smell nonetheless.

I ended up tracing it to a VERY slightly loose connection at the fuel rail underhood. Just a few mm turning the connection with a wrench solved the problem and I've never had a fuel smell problem since. This was a disturbed fuel connection as part of the installation of the NOS system back in 2004.

Probably would be a good idea to check the integrity of all of your underhood and fuel line connections running along the underside of the car, as well as at/around the fuel pumps and filter area underneath the car.

Cheers,
Gerry

 

[gerryvz]

I've attached a few diagrams from the EPC that may help with general fuel line routing. That's the only thing I can think of per what you ask.

Cheers,
Gerry

 

[doolar]

Old thread, but I did a search for fuel hoses today after seeing the burned 500E posted here today as a salvage auction. Do we have any updated info on which hoses to look for in particular? I'm gonna redo all the flex/rubber ones this winter. Do I get it right in that some of them (all) are NLA?

Edit: Found this per Gerry: http://www.500eboard.com/forums/showthread.php?t=9492

 

[gsxr]

Photos & part numbers are in this thread:
http://www.500eboard.com/forums/showthread.php?t=8977

Only get the OE / Genuine hoses... no aftermarket stuff, unless you want to risk an 036 flambé.