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Discussion Starter #1 (Edited)
as far as a problems goes i think im running out of options here, i have an 83 300dt that will only run if i keep my foot pressed on the gas pedal(even when trying to start up), meaning the car can actually run, but if the rpms drop below about 1000 the car will stall out, if i try to change the gear out of park, it will stall out, and in one of my tests i got a separate fuel source hooked up to the big oil filter and it seemed to suck 1/4 gallon of fuel down in a matter of seconds so basically its undriveable because it will stall if i try to do anything

things i have tried: Changed both fuel filters, changed tank fuel strainer, changed all the injector lines, changed air filter,drained the fuel out of the tank(and its not a dirty tank), made sure the injectors were all getting fuel(which they are), taken the injectors out and checked them for blockage, checked for IP leakage or fuel pump leakage, but dont really see anything...

Ideas i have but havnt followed up on: bad fuel pump? or bad injection pump? IP timing? Valve adjustment possibly? fuel being redirected back to tank(because of amount of fuel consumption)or bad ALDA Boost Switchover Valve?

any ideas would be awesome since im pretty much out of them...
 

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as far as a problems goes i think im running out of options here, i have an 83 300dt that will only run if i keep my foot pressed on the gas pedal(even when trying to start up), meaning the car can actually run, but if the rpms drop below about 1000 the car will stall out, if i try to change the gear out of park, it will stall out, and in one of my tests i got a separate fuel source hooked up to the big oil filter and it seemed to suck 1/4 gallon of fuel down in a matter of seconds so basically its undriveable because it will stall if i try to do anything

things i have tried: Changed both fuel filters, changed tank fuel strainer, changed all the injector lines, changed air filter,drained the fuel out of the tank(and its not a dirty tank), made sure the injectors were all getting fuel(which they are), taken the injectors out and checked them for blockage, checked for IP leakage or fuel pump leakage, but dont really see anything...

Ideas i have but havnt followed up on: bad fuel pump? or bad injection pump? IP timing? Valve adjustment possibly? fuel being redirected back to tank(because of amount of fuel consumption)or bad ALDA Boost Switchover Valve?

any ideas would be awesome since im pretty much out of them...
IF anything like the 126 series: In engine compartment, driver-side firewall corner by hood hinge, rests a small black plastic dial, size of drinking water bottle cap, that trims the idle. Turn it carefully to avoid breakage. Brittle over time. If that does not perk up idle enough, a more drastic adjustment can be made in linkage to IP. Related area for this adjustment is located near center of engine block, way inside by glow plug #4 (counting from front grill, backwards to cabin.). Merely alters length of linkage using lock-nuts. Caveat: above applies to model 126 series. Yours s/b not much different.
 

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I have not read the other posts so this could be a repeat. Unfortunately there is more then one area that can cause the issue.

The fuel supply pressure is controlled by the Fuel Pressure Relief/Overflow Valve, It is located in sort of the rear middle of the Fuel Injection Pump Housing and looks like a typical Banjo Bolt. The Fuel Line coming out of the housing is bolted on by it.
In side of it is a ball bearing that used as the valve and a spring.
If you have the type that can be taken apart you are allowed to take the spring and stretch it to a free length of 27mm (that is in the service manual).
Unfortunately I don't have a good clear picture. They one you can take apart will have a smaller and larger hex on the end of it.
10184


If you are pumping on the Hand Primer and it is leaking it should be replaced because it allows air to enter the system.
The Hand Primer screws into the Fuel Supply/Lift Pump. There could be an issue with it but there is no easy way to test it. About the best you can do is get a container of diesel fuel like one of those 1 or 2 liter fuel containers and a length of hose and draw your fuel from that fuel can.
If it will idle with the fuel being drawn from the fuel container it is likely your Fuel Supply/Lift Pump is not working well.

Disconnect the Vacuum Line from the Vacuum Shutoff on the Fuel injection pump and see if that allows it to run at lower rpm. If that happens the vacuum switch on the Steering Colum lock needs replacing.

On the bottom of the idle adjustment screw is a spring loaded plunger. The spring loaded plunger is supposed to hold the throttle in the Idle position but they can rust inside and the plunger can get pushed up and stay up and your throttle will go past idle in the shutoff direction.

10185



The aluminum bracket on the Idle Adjustment Screw has been known to crack off and you may not have an Idle Adjustment Screw any more. There is a fix for that.

Next there is a part called the Governor Idle Pin/Rack Damper Bolt. People erroneously use that to adjust their idle speed and when they do that the Fuel Injection Pump doe not act normal. Back that out and see if you can return to normal idle.
 

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Next there is a part called the Governor Idle Pin/Rack Damper Bolt. People erroneously use that to adjust their idle speed and when they do that the Fuel Injection Pump doe not act normal. Back that out and see if you can return to normal idle.
10186
 

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Next there is a part called the Governor Idle Pin/Rack Damper Bolt. People erroneously use that to adjust their idle speed and when they do that the Fuel Injection Pump doe not act normal. Back that out and see if you can return to normal idle. View attachment 10186
 
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