1978 450 sl fuel issues, please help!! - Mercedes-Benz Forum

 
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post #1 of 7 (permalink) Old 04-13-2011, 04:36 PM Thread Starter
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1978 450 sl fuel issues, please help!!

Hello:

I have always been a muscle car/ mustang 5.0 guy and have built several cars like these over the years. Last year I bought my wife a 1978 450sl. The car ran very well. It always sputtered a little at start up, but a quick rev up to about 2000 rpm and the car ran great after that.

The car sat for about 3 months while being repainted. When I picked it up, the car ran rough. I could not get it over 20 mph. I put gas and fuel cleaner in it with no real notice. (Although it has only run (very roughly) for 20 minutes with new fuel). Now the Mercedes dealership (Crown in Bham, AL) says that they need $8500 to replace basically every part between the tank (including the strainer in the tank) to the motor.

A fuel pump (aftermarket) is $219.00. What is wrong with the idea that all I need to do is to get filtered fuel to the motor? There are apparently fuel 'actuators' and all manner of pieces. At the end of the day, you have to get fuel to the motor at a certain flowrate and pressure. What am I missing here? Please help!!! I just can't spend $8500 on an $11,000 car.
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post #2 of 7 (permalink) Old 04-13-2011, 06:09 PM
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Originally Posted by zwk2433 View Post
Now the Mercedes dealership .... What is wrong with the idea that all I need to do is to get filtered fuel to the motor?
Nothing... Why are you taking a 33 year old car to the dealer and how many cars do you think they see that are more then 5 years old?

Remove the strainer and drain the tank. If you have a blockage, you won't get the fuel pressure needed. The replace the fuel filter and take it from there.

With best regards

Al

Check out the W114, W115 /8 enthusiast forum http://www.stroke8.org

My 280SL restoration
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post #3 of 7 (permalink) Old 04-13-2011, 06:22 PM
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You must have a minimum of 70 p.s.i. at start up as long as you have a new fuel filter your flow rate should be right.

Can you get a list of the part's they wanted to replace, it would help in finding out what they think is wrong with it.
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post #4 of 7 (permalink) Old 04-13-2011, 06:28 PM Thread Starter
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Thanks. As to why it goes to the dealership, try getting anything other than a chevy repaired in Central AL. The speed shops won't touch it. The one that did charged me $5000 to fix an airconditioner and I ended up with a toggle switch in my glovebox b/c no one can figure out how to wire it up!!! No kidding, a new rheostat, compressor, condensor, but no one could figure out the wiring. The one Mercedes shop in downtown Bham can look at it in 2 weeks.

I will try and get a list of all the parts that they listed. I am not a Mercedes guy, but I swear it sounded like everything between the tank and injectors.

Also, it ran great for a very short period of time last Friday. This makes me think it is a blockage (some piece of gunk breaks through the filter or gets disloged, but then replaced by another piece of gunk???).

Any additional feedback from forum members is always appreciated.

Last edited by zwk2433; 04-13-2011 at 06:32 PM.
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post #5 of 7 (permalink) Old 04-13-2011, 06:58 PM
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You sound like you know your way around cars. Old MB's are not difficult to figure out. If you know how to wrench and don't mind doing it, then I would thinking about rolling my sleeves up and buying a set of metric sockets .

There is a R/C107 dedicated section on this forum. Stop by and post your questions there as there are lots of knowledgeable people and some may be in your area.

If you don't mind taking it up to Atlanta, I know of a couple of good guys there that can also help.

With best regards

Al

Check out the W114, W115 /8 enthusiast forum http://www.stroke8.org

My 280SL restoration
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post #6 of 7 (permalink) Old 04-16-2011, 03:33 PM Thread Starter
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Thanks for the help. It turns out that there is a box where all the fuel lines come out of and all we had to do was remove the hex screw and bleed/vent ?? the system. The car is very slow on the bottom end, but once it gets up to about 2500 or 3000 rpm it is quick.

Is there something wrong or is this just what 1978 felt like??
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post #7 of 7 (permalink) Old 04-17-2011, 01:01 AM
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The mechanic at the dealership has apparently ascertained that your fuel tank is contaminated. Whether or not that is the case, it does happen, usually from sitting for prolonged periods with an empty or half-empty fuel tank. If that is the case, you will need to replace pretty much the entire fuel system, after the fuel tank has been evaluated and either dipped or replaced. Were I you, I would get a second and more qualified opinion.

"If spending money you don't have is the height of stupidity, borrowing money to give it away is the height of insanity." -- anon
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