1979 300sd

[leanjoe]

Hello all,
Brand new here but,glad I found it! Friend has 79 300sd for sale.Problems include not accelerating to more than 25-30 mph,also sunroof wont open.
Was told fuel distributor needs replaced.$200-$300. True?Car is in good shape and for $1200.00 I figured I'd check with you guys.I'm here in Henderson NV,just next to Vegas.Being from Illinois,it's strange to see vehicles with no rust!
Anyway,would just be used for around town ,maybe long road trip once a year. I'm a truck driver,so I know the importance of changing filters religiously.Think it'll be ok?
Thanks for any help,advice....lean

 

[dieselman]

Is there smoke or complete lack of? Does it start from cold ok? Is the accelerator pedal fully pulling the injector pump lever?

It is unusual for an injector pump to work partially. It sounds like the fuelling may have been turned down or the diesel filter is blocked.

 

[slkbenzman]

Sometimes a fuel hose can crack with age and let air into the fuel system without leaking fuel. Take a short piece of fuel pipe connect it to the fuel pump inlet and run the engine from a small can of fuel this rules out filters fuel tank problems and fuel lines.If no improvement check timing fuel pump and engine cylinder leakage.

 

[leanjoe]

Yes,

Is there smoke or complete lack of? Does it start from cold ok? Is the accelerator pedal fully pulling the injector pump lever?

It is unusual for an injector pump to work partially. It sounds like the fuelling may have been turned down or the diesel filter is blocked.

There's smoke,not a lot though.Starts right up.I presume by "cold" you mean oil temp,cause it sure is'nt cold here in southern Nevada!Looks like lever is fully extended.Thanks for your help.

 

[leanjoe]

Sometimes a fuel hose can crack with age and let air into the fuel system without leaking fuel. Take a short piece of fuel pipe connect it to the fuel pump inlet and run the engine from a small can of fuel this rules out filters fuel tank problems and fuel lines.If no improvement check timing fuel pump and engine cylinder leakage.

How about fuel pressure?This is my first M/B and not familiar with test procedures though. Thanks for responding! Joe

 

[slkbenzman]

Sometimes a fuel hose can crack with age and let air into the fuel system without leaking fuel. Take a short piece of fuel pipe connect it to the fuel pump inlet and run the engine from a small can of fuel this rules out filters fuel tank problems and fuel lines.If no improvement check timing fuel pump and engine cylinder leakage.

How about fuel pressure?This is my first M/B and not familiar with test procedures though. Thanks for responding! Joe

Joe
Fuel pressure is not much help because it wont show air in the system

 

[dieselman]

Fuel pressure doesn't apply, it's a diesel and the supply side piping is under vacuum.
Anyway the pump is pressurising ok because the car starts and injectors need the same pressure to start as they do to run flat out.

As suggested by another poster run it from a can as this will eliminate the fuel filter and piping. Dono't forget to return the leak off pipe to the can also otherwise it will soon run out.

It's possible the maximum fuel screw has been wound in to reduce smoke emissions and is now cutting the fuel.