|
|
|
|
|
#1
05-21-2010, 11:04 AM
|
|||
|
|||
|
1979 300td -- Can anybody walk me through a lift pump test?
Hi, thanks for reading. I have reason to think my lift pump may be underperforming and occasionally starving the fuel system a little bit. I'd be very grateful if someone out there could describe a good method for testing it in place. And what is the spec performance, if anyone knows?
Also, do these tend to fail all at once, or gradually? Many thanks! 
|
|
#2
05-21-2010, 11:46 AM
|
||||
|
||||
|
Perhaps you should start with why you believe your lift pump is failing. The lift pumps rarely go bad on these engines.
__________________
2009 ML320 Bluetec 1985 300CD 1981 300TD  Past Mercedes 1979 300TD 1982 300TD 2000 E320 4Matic Wagon 1998 E430 1984 300SD 1980 300SD
|
|
#3
05-21-2010, 10:54 PM
|
||||
|
||||
|
The first thing I would do is disconnect the return fuel line with the motor running. Let it run into a bottle. If you dont have a reasonable stream, you may have a lift pump problem. It does occur some times. The 2 non return valves in the pump can fail. do the return flow test first.
__________________
Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort....  1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles  1987 250td 160k miles English import  2001 jeep turbo diesel 130k miles  1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving
|
|
#4
05-21-2010, 11:30 PM
|
|||
|
|||
|
Could be a clogged fuel line too. I had one that acted like that before i finally figured out the line coming from tank was clogging occasionally. Would randomly die at times. I tried everything -- tank screen, lift pump, filters. Finally replaced that line with a 3/8 id rubber one from tank screen up to lift pump. Easy to do, cheap. Never had anymore problems.
__________________
What Would Rudolph Do? 1975 300D, 1975 240D, 1985 300SD, 1997 300D, 2005 E320 , 2006 Toyota Prius
|
|
#5
05-22-2010, 06:20 AM
|
||||
|
||||
|
Pete,
You may be on to something there. I have had a blocked fuel line. A total PITA ! I blew it out with compressed air. 120psi moves most things !! After, when the tank was full, if you disconnected the fuel line from the primary filter, the fuel just pored out the hose from just gravity.
__________________
Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort.... 1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles 1987 250td 160k miles English import 2001 jeep turbo diesel 130k miles 1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving
|
|
#6
05-22-2010, 10:33 AM
|
|||
|
|||
|
Quote:
The spec is 12 psi (minimum) at 3000 rpm.
|
|
#7
05-28-2010, 05:17 PM
|
|||
|
|||
|
Thanks for all the responses. The return flow wasn't bad, but maybe wasn't good, either.
My reasons for concern are spotty performance, a mechanic six months ago saying his test revealed fairly low flow (I've forgotten the number, and he didn't have the spec for some reason), and the fact that it was unfortunately exposed to cold vegetable oil several times. Thanks again.
|
|
#8
05-28-2010, 09:24 PM
|
||||
|
||||
|
You probably have a fuel line clogged with c##P from the WVO or maybe some croutons jammed in the pump.
__________________
Grumpy Old Diesel Owners Club group I no longer question authority, I annoy authority. More effect, less effort.... 1967 230-6 auto parts car. rust bucket. 1980 300D now parts car 800k miles 1984 300D 500k miles 1987 250td 160k miles English import 2001 jeep turbo diesel 130k miles 1998 jeep tdi ~ followed me home. Needs a turbo. 1968 Ford F750 truck. 6-354 diesel conversion. Other toys ~J.D.,Cat & GM ~ mainly earth moving
|
 |
| Bookmarks |
|
|
Linear Mode
