Can not run my 280sl - Stuck on street! - Fuel issue???

[Intex]

Back on this site, after 7 years and 30 miles on my fully resored 1970 280SL...

I havent driven the car for 8 months, and I didnt notice the tank was almost empty. I started it, and it fired up OK. Drove it out of garage, and it was fine, about 2 blocks later, while I tried to idle, it stopped. It fires up if you give it over 2300 rpm, but dies with anything less. I went to get more gas, and filled it up with 5 gal more, same issue. I had to have it towed to my storage facility.

I am thinking (limited mechanics experience) it is one of the 3 possiblities:

1. There was crud in the bottom of the tank, and it go sucked into the fuel system, and the car starves for fuel.
2. Bad Fuel pump (Fuel pump was replaced 3 years and 20 miles ago, so I dont think that is the problem?)
3. Car needs a tuneup. I looked at Dist Cap, and the contacts were just a little bit corroded (we live sort of near ocean), the rotor also just a bit as well.

I could not find an inline gas filter, is there one?
Is the only gas filter under the allen head bolt on the bottom of the fuel tank?

What ideas does anyone have on how to proceed, I hate to tow it to a M/Dealer and spend big $$$$, my 2 independent shops nearby went bellyup. Shall i take out gas tank, and clean it out? Shall I fill the tank full of gas and hope it does suction up crud on bottom?

All assistance greatly apprecaited. Also, how do I determine what Dist Cap/Rotor /Condensor to buy and from who now?

Thanks!

[DaveB]

Sounds like you may have sucked some air into the fuel delivery system? If that's the case you could try cracking the injectors and cranking the bubbles out. Be aware of the fire hazard.

It may also help to put another 5 gallons in the tank.

[Intex]

Thanks
Where are the injectors located, and do I just unscrew them?
So you don't think the fuel line is clogged?

[kampala]

I don't know if you have fuel delivery problem since it runs at higher revs but not at idle.  Some of the more knowledgeable folks may help diagnose it when they respond.

 However, if you want to check that the fuel system is generally pumping enough fuel you would disconnect the fuel RETURN line at the tank, turn ignition enough so that the pump will run and measure how much fuel you get in 15 seconds.  It should be one liter. 

By the time the fuel gets to the tank from the return line, it has travelled through the screen in the tank and through the filter in the engine bay and back to the tank.

best of luck

[66andBlue]

.... I hate to tow it to a M/Dealer and spend big $$$$, my 2 independent shops nearby went bellyup. ...

None of the Mercedes dealers in SD county will be able to help you.
But if you do not want to tackle this problem there are at least two shops still around who know our cars, one in Escondido and the other in Chula Vista. Let me know if you want the address and I'll send you a PM.

[ja17]

Hello Intex,

Yes, it could be a fuel starvation problem.  It could also be a stuck WRD on the injection pump.  If it is stuck in the rich position the car will start and run cold but will die at idle after the car has warmed up, when the mixture should be leaner.  See if it idles ont he next cold engine start.

If you remove the fuel sending unit in the trunk, you will be able to view the condition of the fuel and the fuel tank inside.  The big 17mm hex drain plug under the tank has a fuel filter screen attached to it. This is the first line of defense against dirty fuel. If you remove the plug, the fuel in the tank will run out. Be prepared to safely deal with it. Be very cautious when dealing with fuel. Vapors can  ignite even from a static electric spark.

The intake fitting of th electric fuel pump has an even finer fuel screen built into it. If you remove the fitting you will be able to examine it.

The main fuel fitler is the last line of defense. The problem usually happens before the main fuel filter however.

[Benz Dr.]

Let's face it. Some things are just too complicated for those who have little or no idea how this stuff works. It's not like I'm opposed to telling somone how to fix things but I, as a mechanic, had to figure this stuff out on my own or at least spend time to learn it so I would know.

This is the information that your mechanic needs to know, not you. Telling you, is in effect, telling your mechanic, because whatever we say here will be most certainly relayed directly to him/her. Because of distance limitations, it stands to reason that the hand full of people on this site who know our cars are also unable to work on them. If your mechanic needs help I'm sure someone here could help him - I know I would.


This site undoubtably saves many owners thousands of dollars in do it yourself repairs. However, it should never be used as an alternative to getting a good mechanic to look at and service your car. The info relayed here is of general use and you better understand that there's a lot more things that I and others ( if they're smart ) simply won't tell you for any number of reasons.

I'm not trying to pick on you or single you out - this is for everyone. Joe, Collin, and others, help you out of the goodness of their hearts to save you money, right?  When's the last time you threw them a bone?


Go see Bob Gunthorp in Chula Vista. I met him once and found him to be a good guy.

[Flyair]

Back on this site, after 7 years and 30 miles on my fully resored 1970 280SL…

as a side remark, great that you are back among us on the site, despite of the fact that the circumstances that induced your move are linked with the unfortunate issues with your car.
Good luck

[Intex]

Thanks all for the replies
I am not trying to take biz away from mechanics, but if this is just a clean the filter job, there is no reason an owner ant handle this one of the main reasons I purchased the car was to. Be able to do the renovation on my own as much as I cold.

What is the name of the shop in Chula Vista?That is going to be an expensive trip via flatbed truck

[66andBlue]

What is the name of the shop in Chula Vista?That is going to be an expensive trip via flatbed truck

ONAGER Corp. - Bob Gunthorp

[andyburns]

I had a similar problem on my 280se.  Turned out to be an issue with the cold start valve being jammed open and over fueling.  When the car has an open throttle the additional fuel is negligible but when closed it drastically over fueled the car and it was stalling.  From memory the plugs quickly fouled as well.   Like your scenario mine occurred after recommissioning the car after a 15 year lay up.

I opened up the cold start valve on the side of the inlet manifold and discovered a build up of congealed gluey fuel which had blocked the valve into an open position as it had unlodged and then tried to pass through the valve.

Worth a try as well.  Hope you find your issue and get the car back on the road asap.

[ja17]

Good additional comment Andy.   I think it could be an over-fueling problem also.  As Andy suggests check the  CSV.  Also check the WRD.  Either device could cause an over-fueling situation.  Check the condition of the spark plugs while your at it.

[andyburns]

Checking for the cold start valve problem takes a few seconds.  Even pulling the entire thing apart, cleaning and reinstalling will only set you back an hour at most and is worth a go.

I did take some pics of the problem with the entire assembly apart but cant seem to locate them so I have taken this quick snap of the assembly from parts car for you to have a look at.

Hey Joe whats the best way to test the WRD (warm running device) on the injection pump.  I have always assumed that if you can no longer hear the inrush of air into the little attached air filter after the car has reached normal operating temp that this little sucker is operational and has done its job.  Dont think the internals of this assembly (all 3 parts) is rocket science either and is easily tested in a cup with boiling water and a ruler.  I am interested if this is correct.

Nothing worse than taking your car to the professionals when the solution is so simple and within your reach (with a little bit of help).  I really like these forums for this reason.  A little bit of friendly knowledge (even from another rank beginner), sometime saves you heaps of money, time and aggravation.  More importantly educates.  As the supply of garage mechanics who can actually work on these old girls drys up it more and more important that as a community we can freely share this knowledge with each other to keep the cars going.

[Intex]

Andy, JA17
Thank you for the assistance
As soon as I get a chance, I will check both of these and get back to you

[hands_aus]

i found a couple of CS Valve pics dis-assembled

[ja17]

Yes Andy, the WRD should close by the time the engine reaches running temperature.  I listen to the rushing of air, with a hose, like a stethescope. Some people remove the small air filter and feel for suction. Sometimes they are stuck rich (never close) and sometimes they are stuck open (always closed).