1990 300E Thermo Time Switch - Benzworld.org

frobi · 02-14-2008, 06:09 PM

Does the 1990 300E have a thermo time switch? If so, where would it be on the engine? I want to replace it as I have cold start problems. If not, what would be activating the cold start valve in cold and damp mornings? Thanks

RBYCC · 02-14-2008, 07:43 PM

Quote:

Originally Posted by frobi

Does the 1990 300E have a thermo time switch? If so, where would it be on the engine? I want to replace it as I have cold start problems. If not, what would be activating the cold start valve in cold and damp mornings? Thanks

What engine do you have?
Typically the cold start valve is activated by the fuel pump relay on the M103-12V or from the MAS on the M104-24V.

frobi · 02-15-2008, 05:17 AM

Quote:

Originally Posted by RBYCC

What engine do you have?
Typically the cold start valve is activated by the fuel pump relay on the M103-12V or from the MAS on the M104-24V.

I have 124030 chasis and 103983 engine. I checked the MAS (opened it) and all solder joints were intact. I resoldered them stronger). My problem is that in the mornings or after 4-5 hours, I have to crank it 5-6 tomes before it starts to stumble, hasitate and slowly pick up the rev. Once it warms up, it runs very smooth and nice. All electricals ( plugs, ignition wires, rotor, dist. cap, battery, air filter, fuel filter) are new.
The 10 amp fuse in OVP is ok.
Thanks for responding.

RBYCC · 02-15-2008, 06:50 AM

Quote:

Originally Posted by frobi

I have 124030 chasis and 103983 engine. I checked the MAS (opened it) and all solder joints were intact. I resoldered them stronger). My problem is that in the mornings or after 4-5 hours, I have to crank it 5-6 tomes before it starts to stumble, hasitate and slowly pick up the rev. Once it warms up, it runs very smooth and nice. All electricals ( plugs, ignition wires, rotor, dist. cap, battery, air filter, fuel filter) are new.
The 10 amp fuse in OVP is ok.
Thanks for responding.

If your engine has a combined MAS/Fuel pump relay then checking solder joints will not indicate a thing.
The loop starts with the engine temp sensor which will send a signal to the MAS / Fuel pump relay when it sees temp below a point.
The relay only pulses the cold start valve for a max of about ten seconds.

frobi · 02-15-2008, 01:01 PM

Thanks RBYCC.
I will try to put new engine temp sensor and let you know. Is the sensor with 3 terminals near the cold start valve? My MAS/fuel pump relay are combined.

ducatipaso · 04-12-2008, 07:50 AM

hey did you get your issues resolved? I have the same symptoms on my 190E 2.6 which also has a MAS. I've done a tuneup too.

jsbigone · 05-01-2008, 02:50 PM

Quote:

Originally Posted by RBYCC

If your engine has a combined MAS/Fuel pump relay then checking solder joints will not indicate a thing.
The loop starts with the engine temp sensor which will send a signal to the MAS / Fuel pump relay when it sees temp below a point.
The relay only pulses the cold start valve for a max of about ten seconds.

Does some of the Engine Temp sensors have 2 prongs instead of 3??? I think i have a Cal edition here cause it has the Cal Diagnostig thingy bye the battery!

frobi · 05-01-2008, 04:51 PM

I rewired the cold start with a push button switch and installed it near the foot cover on the left. When I want to start in the mornings or having it sat for hours, I press the switch for 3-5 seconds to open the cold valve to spray gas in the manifold. Is starts good. I had replaced the cold valve, temp sensor, MAS, but did not work.