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Mmmmh - on another note; have you swapped the Overvoltagee Protection Relay (the one with the red head & fuse(es) on top, don't knowthe correct name in englsh)? This thing can cause all sorts of funny problems... Or the fuel pump relay (which also acts as the rev limiter & cuts off the fuel pump). Funny little curse word relais these... But they can be re-soldered, in most cases it's just a 'cold' solder joint  Just another idea... Mmmmh - if it's under 5°C, the starting valve (a secondary injector) comes into action. It should see 10V for a few seconds. It's controlled by the temp. sensor ontop of the head, the one with the single connection IIRC. Do you have the Workshop Manual? There are reference values in there for either sensor & valve. Start-up can indeed be frustrating if it's below 0° and the valve doesn't work... Yeah, just some other ideas... Cheers, Jan |
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you heard a pop while running on gas? was it a intake backfire? if it was they can break all kind of stuff, i had one that bent and seized the airflow meter flap, they have a lot of force. if this is the case it could have damaged the metering head.
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Onne
Part of things
Posts: 822
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Thanks chaps, regarding the OVP relay, not changed that, wouldn't the ABS light normally come on if not working properly? Might just take all the relays out and clean them.
One important thing is that I'm running a cheap (probably nasty) fuel pump from eBay. If it doesn't pressure up properly it won't start properly either. How can I test fuel pressure?
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Onne
Part of things
Posts: 822
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Feb 13, 2012 14:12:20 GMT
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Broke down again at the Limes Cafe meet (good place for it though!)
Issue was quickly resolved (pipe had come off)
Can any of you wise people guide me to what pressure tester is compatible with Bosch systems? Does anyone know the book figures for what the output should be?
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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scruff
Part of things
Posts: 621
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Feb 13, 2012 16:16:19 GMT
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Where are you based, I've got one I bought from the USA a while back.
You can also make your own you just need to get a fuel gauge into the control pressure line on the top of the fuel dizzy.
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1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
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Onne
Part of things
Posts: 822
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Feb 13, 2012 17:35:05 GMT
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I'm near Derby, working just north of Nottingham. Have you got an idea of what pressure it should be running at?
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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scruff
Part of things
Posts: 621
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Feb 13, 2012 19:34:05 GMT
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Delivery pressure is up to about 5 bar so less than that....
The control pressure depends on what the warm up regulator is doing at the time, and there are variations by model too.
You need to find the factory settings from someone.
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1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
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Onne
Part of things
Posts: 822
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Feb 14, 2012 20:18:29 GMT
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Looked up the value, should be between 5.3 and 5.5 Bar.
All I need now is a suitable tester to rule things out. Any suggestions? EBay links welcome!
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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scruff
Part of things
Posts: 621
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Feb 14, 2012 20:43:12 GMT
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Make one up from bits?
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1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
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Yeah, that's about 80psi so you should be able to get a cheap-ish gauge and some decent fittings to make your own.
Airgas may be able to help.
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Onne
Part of things
Posts: 822
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Feb 16, 2012 13:18:56 GMT
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Cheers, I'll give that a try, Found my handbook, with full instructions on where to measure it
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Onne
Part of things
Posts: 822
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Feb 21, 2012 15:52:47 GMT
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Fuel pump seems ok, next step is to swap the OVP relay for a known good one. We'll get there!
(I should listen better to mr DieselWeasel!)
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Last Edit: Feb 21, 2012 15:53:54 GMT by Onne
1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Onne
Part of things
Posts: 822
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Feb 24, 2012 13:17:01 GMT
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So, just to bore you all a bit more, went to the garage to check with a known good OVP relais. No difference... I have now done the following: The symptoms: Mainly happens with a cold start -Car seems top catch first thing but then neds to be churned for about 10 secs to finally start. -Definetely have fuel, she smells like she is almost flooding -OVP relay has been changed to a known good one -Put a new OE rotor and dizzy cap on yesterday (old ones were the originals,car has done 175K miles, they were really pitted and horrible, arcing all over the place) -Changed the pipe from the ICV to the inlet as it was too loose, and generally old and tired. -Changed fuel pump and filter (way before any of this started, as the pump was leaking) (Not sure if I changed the one way valve though) -Obviously fully serviced her, new fluids, filters, plugs and leads Bit scared to dig in deeper though:  |
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Last Edit: Feb 24, 2012 13:17:53 GMT by Onne
1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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scruff
Part of things
Posts: 621
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Feb 24, 2012 19:22:52 GMT
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Have you tuned it?
The CO needs to be set at idle, on the porker it's 1.5-2% at 900 rpm.
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1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
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Onne
Part of things
Posts: 822
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Feb 24, 2012 19:53:59 GMT
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It has been in the recent months. The thing runs beautifully once running though...
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Feb 24, 2012 20:26:27 GMT
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Does it have the extra "cold start injector" - the electrically operated one?
If so, disconnect it. Just unplug the electrical connection. Your problem will probably go. Has worked for me on all three K-jet vehicles I have owned - 1 early Mk2 GTI and 2 x Audi 90s with 2.2KV engine.
No idea why the damn things are fitted. All three of the above continued to start and drive perfectly from UK winter cold without any fault. Presumably some places get cold enough for them to be useful....
Nick
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1967 Triumph Vitesse convertible (old friend)
1996 Audi A6 2.5 TDI Avant (still durability testing)
1972 GT6 Mk3 (Restored after loong rest & getting the hang of being a car again)
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scruff
Part of things
Posts: 621
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Feb 24, 2012 20:32:44 GMT
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OTOH the Porker won't start without the CSV.
CSV fires when the car is cranking and the thermo time switch is still made, it breaks after 8 secs.
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1994 Lotus Esprit - Fragile red turbo with pop up lights.
1980 Porsche 924 - Fragile red turbo with pop up lights.
I spy a trend...
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Onne
Part of things
Posts: 822
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Feb 24, 2012 20:40:57 GMT
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Does it have the extra "cold start injector" - the electrically operated one? If so, disconnect it. Just unplug the electrical connection. Your problem will probably go. Has worked for me on all three K-jet vehicles I have owned - 1 early Mk2 GTI and 2 x Audi 90s with 2.2KV engine. No idea why the damn things are fitted. All three of the above continued to start and drive perfectly from UK winter cold without any fault. Presumably some places get cold enough for them to be useful.... Nick I'll give that a go first tomorrow, seems an easy start! Weird for it to start playing up though gradually though? |
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Onne
Part of things
Posts: 822
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Feb 25, 2012 16:00:21 GMT
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Tried the unplugging trick, weirdly it fired up straight away (no airfilter housing or anything on) first time, but wouldn't do it again.
Tested the values for the sensors, they are all within limits (3.2K Ohm at 13c)
She runs lovely once started, no excess smoke, no blue/black, opened the oil filler cap, bit of smoke, but hardly noticable (car was still cold, so I'd expect it to evaporate a bit)
The CSV gets its 11V for a couple of seconds as per manual, but can't hear it click, sadly I haven't got a long enough allen key to get it out (must invest in a set to go on the wrench) and test if it:
A, opens
B, has a 45 degree spray as per manual.
Grrr
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1990 Mercedes W126 300SE
1997 Mercedes W140 S320L
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Kai
Part of things
Posts: 276
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Mar 14, 2012 13:00:30 GMT
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...have you checked the Warm Up Regulator?
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