How do i tell if my lift pump is dead? I replaced the glow plugs and she still has a hard start. I have to pump the accellerator to get her started but she runs great when at operating temp. Anyway she squeals like a banshee when i put the key in and the yellow (0) light stays on till she starts up. I cannot hear the lift pump priming over the sound. How do I tell if it is the lift pump or not?

Thanks

If it leaks fuel when you prime the pump manually, it needs to be replaced.

which one is not supposed to leak the manual priming pump or the lift pump?

when i pump the primer it leaks but i thought that was to show that the fuel has reached the lift pump. also the fuel gauge does not work. it sits real low but like a cm above empty.

The primer pump is the one that commonly leaks. It is not supposed to.

If fuel can get out, air can get in. An updated model can be bought for under $20 (It can be found on eBay for ~$20 shipped) that does not need to be unscrewed to pump.

http://cgi.ebay.com/ebaymotors/MERCEDES-DIESEL-BOSCH-PRIMER-PUMP-ALL-MODELS-TO-1985_W0QQitemZ140109358334QQihZ004QQcategoryZ33555QQcmdZViewItem

It only leaks when i unscrew it and begin pumping the primer. I thought it was supposed to eventually spew fuel out once all the air was pumped out.

Air leaking into the system would explain a lot as far as the hard starting. Does the lift pump assembly need to be replaced along with the primer pump? Is she screaming at me because the lift pump has gone out?

A bad lift pump or hand primer will not make the engine squeal. The old style hand pumps do leak some when you pump them, and as said they could also let air in even when screwed down. They can be replaced separately from the lift pump by turning them out via the hex facings at the base of the hand pump. If you can see fuel squirting into the fuel filter when it's running, and there is no fuel leaking from the lift pump itself when running, chances are the lift pump is fine. Pumping the throttle like a carby gasoline engine makes no difference on a diesel. If you need to give it throttle to get it started and then it squalls when started, try checking your belts, particularly your A/C compressor, they're known to lock up and make the engines have difficulty. If it only squalls when first started then goes away, you probably need to tighten a belt. As far as hearing the lift pump, you wont, not with a running diesel clattering right beside it.

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Chris
64 190D R.I.P.
80 240D W/617 engine -for sale
82 240D -for sale

Is the screaming inside the cab and only with the yellow glowplug light on?

If it is, that's how it works. It's not for the glowplugs, its for the seatbelt. It will buzz for a few seconds or until you buckle your seatbelt as a safety reminder to buckle up before you drive.

yeah it is the seat belt alarm. so if i do this bosch upgrade the hard start problem should go away? Maybe I just need to replace my fuel filters.

p.s. how about that fuel level gauge? is there a quick fix for that?

Thanks for your patience and advice.

It's possible to disable the buzzer and still let it function as a "headlight's on without the key" reminder. There is a plug under the drivers seat, unplug the connector and it won't buzz anymore.

Remove the first aid kit and that will give you access to the level sender. You will need a 46mm socket to remove it. Be very careful when cleaning it and it would be a good idea to lay down some plastic or towels to keep any fuel drips off your seats.

Awesome. Thanks very much.