While changing my fuel filter, and
the 2 copper "o" rings replaced with it, I noticed the lower fuel pump,
outer "o"ring was also leaking (92 190e 2.6) takes 3 copper "o"rings.
Removed outer bolt tightened inner sleeve bolt to compress center o
ring, then new copper o ring and install outer bolt, tighten slowly,
release C clamps on fuel lines......look for leaks no leaks.
Reconnect battery, start engine...let idle....look for leaks. Small
drops slowly forming, fuel pump outer o ring bolt....using socket
wrench...tighten bolt a little more, almost there, use open wrench
to hold fuel pump for last little bit. The moment the open wrench
touched fuel pump, the engine stopped. I know, forgot gas cap
(pressure). Turn over strongly, try to start, and die. 20 times. It
was like someone shut off the key. checked fuses, over voltage
relay, fuses look good ........please help..Rick
Karl - 26 Jun 2005 05:04 GMT
If it was running and you shorted the + connecter to the wrench..... you fried your fuel pump relay.
It is NOT fused!
> While changing my fuel filter, and
> the 2 copper "o" rings replaced with it, I noticed the lower fuel pump,
[quoted text clipped - 10 lines]
> was like someone shut off the key. checked fuses, over voltage
> relay, fuses look good ........please help..Rick
CaptainW116 - 26 Jun 2005 05:06 GMT
Fuel filter reversed?
Fuel pump is a roller vane type,did you squeeze it too tightly?
r parris - 26 Jun 2005 14:16 GMT
No, fuel filter properly installed. I didn't squeeze fuel pump, I was
holding 2 pump/ accumulator frame as I was tightening fuel pump cap nut,
a o ring.
Fuel pump connectors have rubber L shaped boots on them, now found to be
badly cracked. I Don't see fuel pump relay on list of parts for
1992 190E 2.6 . Goes from 190E 2.3 '87 to '93 190E
2.3-16 all....190E2.6 to '89 MAS control unit 190E 2.6
from '90 425.00 I'm screwed!
Lee - 26 Jun 2005 14:06 GMT
Sounds like you have. I've done it and seen it done a few times over the
years.
For some reason the fuel pump doesn't like to be touched when it's working
(like most of the office girls, ha ha).
ALWAYS turn the engine off when tightening the fuel pump.
> While changing my fuel filter, and
> the 2 copper "o" rings replaced with it, I noticed the lower fuel pump,
[quoted text clipped - 10 lines]
> was like someone shut off the key. checked fuses, over voltage
> relay, fuses look good ........please help..Rick
Tiger - 26 Jun 2005 14:55 GMT
Augh! I told you about the aviation form-a-gasket... the only way to solve
that leaky problem... Seems like you may have zapped the fuel pump relay.
Replace the fuel pump fuse... don't just look at it.
If you have service manual... it will tell you what pins you have to jump to
test the fuel pump... once jumped... start engine... if keeps running, then
it is fuel pump relay.
r parris - 26 Jun 2005 16:23 GMT
I only have a chassis manual and a Haynes Benz 2.3 '85 to '88 most
parts apply. I Now find major changes were made in the 201 series 1989
to '93 end of series. (tragedy really focuses your attention)
Stupid, to put a wrench on fuel pump without Redisconnecting battery.
Is there a way to check out fuel pump operation before commiting to
replace MAS relay. No fuel pump relay here. (just bought aviation
form-a-gasket) whimper, sigh......Public library has 103 engine manual,
and at least 40 Mercedes, and Bosch manuals
Tiger - 26 Jun 2005 16:53 GMT
You can buy rebuilt MAS relay... instead of the full price at dealer... go
to mbcoupes.com and look under part supplier list for electronic rebuild...
I'll check for pins tonite...
Tiger - 26 Jun 2005 16:58 GMT
Check http://www.mr-auto-parts.com
It shows you do have fuel pump relay... MAS is for like air conditioner
stuff...
Karl - 27 Jun 2005 02:53 GMT
MAS means Motor Aggregate System. MB combined the klima relay and fuel pump relay into one unit.
> Check http://www.mr-auto-parts.com
>
> It shows you do have fuel pump relay... MAS is for like air conditioner stuff...
Roland Franzius - 26 Jun 2005 18:47 GMT
Tiger schrieb:
> Augh! I told you about the aviation form-a-gasket... the only way to solve
> that leaky problem... Seems like you may have zapped the fuel pump relay.
[quoted text clipped - 3 lines]
> test the fuel pump... once jumped... start engine... if keeps running, then
> it is fuel pump relay.
Normally it should be battery 30 to 87. Of course you can test the pump
dirctly using a 3 m cable to battery dirctly.

Signature
Roland Franzius
r parris - 26 Jun 2005 21:05 GMT
I remember having to remove this MAS to shut off fuel flow
when I did a compression check. Black, 3x6 inch rectangular relay
behind battery, with a knob on top you turn to make it pull itself down
and seat. I forget now but it combines several functions into one
relay.
r parris - 26 Jun 2005 22:18 GMT
Went to Archives: Electrical troubleshooting manual N16 Engine
control systems,.....After 1990 these relays went solid state, combined
into MAS ..... fuel pump relay, air injection pump relay,
transmission control points relay, A/C compressor relay, heater for
O2 sensor, and some engine controls, But only in 2.6 201 series, 2.3
no change!