1982 300TD Trouble Starting after fueling up at gas station

[bassmun]

Been a while since I posted on here. So I have an interesting intermittent problem. About half the time, after I fill up at the gas station, my car won't start. It's almost like the car has lost its prime. So I end up popping the hood and using the priming pump (the old style one). After using the priming pump the car starts just fine.

I should mention that while driving to the gas station, the car is running fine.

Has anyone else had this problem? Thanks!

[Phillytwotank]

First thing You need to get rid of the old style priming pump

[bassmun]

I'll give that a try. I've got one of the new ones sitting in my garage.

[vstech]

Odd symptom.

How low do you let the tank get before you fill up?

Does the cap have a long whoosh of vacuum when you pull the cap?

[Diesel911]

Originally Posted by bassmun

Been a while since I posted on here. So I have an interesting intermittent problem. About half the time, after I fill up at the gas station, my car won't start. It's almost like the car has lost its prime. So I end up popping the hood and using the priming pump (the old style one). After using the priming pump the car starts just fine.

I should mention that while driving to the gas station, the car is running fine.

Has anyone else had this problem? Thanks!

I have never read of this issue before. And I started off on this forum in 2007 and for several years was on some of the other Mercedes forums.

[hercules]

This is what I have found in past:
1 Leak air into primer pump
2 Low fuel pressure,( Pressure regulator).
3 Weak lift pump, damaged or leaking ck valves.
4 Vacuum on fuel tank.
Number 4 easy to ck ,remove fuel cap, listen for the whoosh. Fuel cap or tank vent.
Number 1 get newer style pump.
Number 2 If two piece regulator, stretch spring to 19mm or renew spring., (member Greazzer) might still have some, Or renew. complete regulator.
Number 3 After doing others If still not fixed, renew pump ck valves and seal.
Yes there could be other sources of air leaking in But after this many years old, IT"S TIME to renew these parts.

[Diesel911]

Originally Posted by hercules

This is what I have found in past:
1 Leak air into primer pump
2 Low fuel pressure,( Pressure regulator).
3 Weak lift pump, damaged or leaking ck valves.
4 Vacuum on fuel tank.
Number 4 easy to ck ,remove fuel cap, listen for the whoosh. Fuel cap or tank vent.
Number 1 get newer style pump.
Number 2 If two piece regulator, stretch spring to 19mm or renew spring., (member Greazzer) might still have some, Or renew. complete regulator.
Number 3 After doing others If still not fixed, renew pump ck valves and seal.
Yes there could be other sources of air leaking in But after this many years old, IT"S TIME to renew these parts.

In this case he said right after a fuel fill. There would be no vacuum in the tank as he removed the cap to put fuel in.

Also the picture on post #3 has stretching the spring in the fuel pressure/overflow valve to free uncompressed length of 26-27mm.

http://www.peachparts.com/shopforum/diesel-discussion/247039-fuel-injection-pump-starvation-good-lift-pump.html

[hercules]

Yes spring length of 29mm is correct.

Vacuum on tank: If vacuum on tank is less than pump strength engine will run, now stop
engine, vacuum on tank is now greater pulling fuel back to tank ,loosing fuel prime.
Opening fuel cap releases vacuum on tank, now pump would be stronger. Just need to
prime again.