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1984 Mercedes Benz 300SD
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18 Posts
Discussion Starter #1
I have a 1974 Mercedes Benz 280C - in almost perfect condition with 56k miles. However... Its sat for over 16 years. It *will* run, but will not stay going unless your holding the throttle and will stall when put in gear unless your prepared to feather its first step. And even at that its running rough. After a while it gets to be not so bad - but as soon as I get new gas in it - it runs like hell unless I let the car sit for 10 minutes. I've been advised this is probably due to the fuel tank as it probably has deteriorated and when new gas is put in, it mixes up the sentiment and causes issues.

I don't know where to start on this. I've contacted several mechanics. One of which said that he would completely redo the whole fuel system from start to finish, which was quoted at 6-7K. This car does mean a lot to me, but I'm totally unaware what is necessary. Which can be dangerous.

Thanks in advanced
 

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'72 250C, '74 280C, '85 500SEL, '81 300CD.
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1,041 Posts
I'd check with some different mechanics. 6 or 7 HUNDRED would be reasonable but no way thousand.

Have the fuel tank removed and cleaned.

Clean the lines using a "rust buster" (WD-40, PB Blaster, whatever) sprayed into the lines, let sit for an hour and blow the lines clear using compressed air. Capture the residue in a receptacle to see the progress. You can use a thick weed whacker string to "snake" out the feed line.

Replace ALL rubber fuel lines. They deteriorate and will crumble internally. They also will not take the newer oxygenated fuels.

The carburetor is going to be the sticky part. The Solex 4A1 can be quite problematic with age. They are good carbs (European licensed versions of the Rochestor Quadrajet) but by this time they have usually been abused by well meaning individuals, over tightened, plates warped, etc.
 

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Dallas, Texas
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7,751 Posts
What happened to hole in gas tank? http://www.benzworld.org/forums/new-member-introductions/1538025-new-vehicle-ownership.html#post4293690

You have asked same question back in August. http://www.benzworld.org/forums/vintage-mercedes-benz/1538026-need-advice-my-1974-280c.html#post4293696

What have you done so far? Why was this car parked for 16 years? Death in family? Hole in gas tank? Blown head gasket?

Has anybody qualified looked at this vehicle to assess its condition? Projects cars are great if you can do work yourself or write check for ten grand and ask to be called when ready.
 

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2017 Police Interceptor Utility, 2017 Police Interceptor Sedan
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If there is one thing I hate it's a sentimental fuel tank. All you wanna do is fill it up while waxes on and on about relationships. Annoying.
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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The most expensive part on your fuel system is the injection pump. Sounds like that could be your problem, or the fuel tank, or timing tune up issues.

I would start with drop , clean ,line tank, change filters, tune up, (plugs/wires/rotor etc.). If none of that works fuel pump/ injection pump/ injectors. This is exactly what I had to do to get my 67 to run right, it sat with a tank full of gas for almost 10 years.
 

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2021 SL770
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46,428 Posts
The most expensive part on your fuel system is the injection pump. Sounds like that could be your problem, or the fuel tank, or timing tune up issues.
Erm. it would be if the car were not equipped with a carburetor.
 

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1970 250c, 300e amg
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446 Posts
quick question. never payed attention actually, but are the lines that run underneath the car rubber? If so, to change them, can I buy them at any parts store? Thanks boys
 

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73 280SE 4.5, 71 300SEL, 03 BMW Z4, 72 Fiat 850, 80 Triumph TR7, 85 Porsche 911
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2,280 Posts
Erm. it would be if the car were not equipped with a carburetor.
Someone ELSE is doing their homework! :) :)

Under-car piping isn't rubber, it's metal (don't ask me the kind though). You can replace it all with rubber hose, but be sure to do so with fuel injection rated hosing. It's strong, will take gasoline, and will last a long time...
 
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