losing my prime

[xxbxrxextxtxx]

i have been having problems starting my car. ots fine if i leave it reved but if i let it idle some how my fuel pump empties out even when i have a full tank. i have to get out prime it and do it all over again . what can i do?

 

[television]

What is the car sir

 

[xxbxrxextxtxx]

1983 300d turbo

 

[Number_Cruncher]

The priming pump itself can be the cause of horrendous leaks. There is a modern Bosch replacement with much better sealing which can be screwed in place of any of the older primer pumps.

When priming, you should hear the relief valve at the outlet side of the injector pump squeak - if not, it's possible that this valve is sticking open, thus preventing the lift pump developing any pressure.

In very rare circumstances, the seal on the lift pump operating rod fails - a symptom of this is that the engine oil level begins to rise (the camshaft of the injector pump is part of the engine's oil circuit)

All the low pressure pipe work, including the injector leak off pipes should be checked to make sure they're leak tight. If at any point, the vehicle has been misfuelled with veg oil of various types, it's also worth checking the tank strainer isn't clogged with disgusting slime.

 

[Bolide]

You have an air leak in the fuel system. Find & correct the air leak and the problem will go way

On the later cars you can replace the old, flattened O-rings with new ones. Don't know about the early cars

Nick Froome
www.w124.co.uk

 

[Number_Cruncher]

On the older cars, the low pressure fuel lines are terminated with good quality banjo fittings, much more like you might find on a commercial vehicle - they don't tend to suffer the same problems of the later cars.

The nasty plastic fittings and O rings of the later cars make them much quicker and cheaper to assemble, but they do form a serious weakness in the fuel system.

 

[Number_Cruncher]

Here's a link that shows a piccie of the updated hand primer pump;

http://www.boschautoparts.com/Products/DieselParts/Hand+Primer.htm

If the hand primer pump doesn't look like this, it's worth updating, as all of the older types usually leak badly after a year or two's service.

The modern pump also has the advantage of not needing to be unscrewed before use, and tightened again afterwards.

 

[xxbxrxextxtxx]

thx guys i realy appreciate the help

 

[roofless]

this might be some help http://www.mercedesshop.com/Wikka/PrimerPump

 

[xxbxrxextxtxx]

ok so now when i start its it starts better but it still dousnt want o shift for a long time say it takes a couple miles to get to 40. then i will go into the store or something and come back out and drive it and it will shift trough all the gears fine. then the rest of the day shifting wont be a problem. all the wile during idle its is running realy ruff

 

[Number_Cruncher]

>>then i will go into the store or something and come back out and drive it

This sounds like the fuel filter blocking, or even the fuel in it gelling - are you somewhere cold? I say gelling, because, perhaps the heat soak while you're parked up and in the shop is un-gelling the fuel.

One way to be sure is to tee in a pressure gauge in the line between the filter and the injector pump - you should see something like 10 psi of fuel pressure there - much less and you have a problem.

As you prime the system, does the primer handle become difficult to pump as the air is expelled, and does the relief valve in the injector pump squeak?

The poor change up suggests that you are having to push the throttle further than normal in order to make any progress, and the control pressure cable is being pulled further than normal, and preventing upshifts. The power issue is probably related to the fuelling problem.

Having said that, when did you last check and adjust the valve clearances? If your car has done a large mileage, you should also check for timing chain stretch while doing the valve clearances.