1989 300E

I recently acquired a 300E and encountered difficulty starting the vehicle. It had been sitting for approx 6-8 weeks. The car would crank over but the engine would not engage. Only after numerous attempts and moderate use of the accelerator pedal it would actually start. After the engine started, the idle seemed rather low - 550-600 RPM, and the engine would keep running only with encouragement from the accelerator pedal. Once the car was driven, it would run well.

I have confirmed that each cylinder is receiving a spark and also confirmed that the wires are fine. May I assume that this issue is fuel related? If so, what would the diagnostic steps be?

Secondly, I have noticed that the seatbelt warning light remains on all the time. What would this be caused by and how would I resolved this issue?

Lastly, the powered passenger seatback adjusts for recline position but will not incline back to a vertical position. All other functions of the seat are fully operation. How would one diagnose this problem?

Many thanks in advance for any assistance that may be offered.

Kind regards,

Keen

check your overvoltage relay fuse.
for the seat switch spray some contact cleaner in the switches
and then operate them. do it several times and this should take care of it.

george

I had the same cold start issue with my eng. and it went like this.

Wouldn't fire when cranked until I depressed the pedal just a little bit.
Then I had to hold it that little bit until it warmed up a little or it would idle so slow it would die. Once the eng. was warm it ran fine.

The cold start injector only assist in geting it running so I bypassed that and went to the coolant sensor (notorous for failing) and that was the reson I had no cold running enrichment.

That is the easyest to Diagnose and cheepest Idem in the fuel system too.

Do a search for coolant temp sensor testing.

I also had the same prob. with seat switch only I wasn't able to get it cured with the contact cleaner so I had to disasemble it and clean the contacts
it worked great.

Good luck.............

Being a novice DIYer, where would I find the location of the OVP and how do I test if it is working or not?

Secondly, how would one access the contacts for the car seats?

Thank you in advance for any help you are able to offer.

I have searched the site and found a number of suggestions regarding the potential cause of the hard starting issues I am encountering with my 1989 300E.

The plugs and distributor cap and rotor have been changed.
The wires have been tested and are not arcing
The cold start injector valve has been inspected and confirmed operational
The OVP fuse has been inspected and is fine

After taking it to a second mechanic, he has indicated that it is a fuel related problem and has suggested that we test the fuel pressure in the system. He indicated that he suspects that there may be a leak in either the fuel injectors or fuel regulator valves near the fuel pump.

Would anyone be able to confirm whether this is a viable conclusion.

Another well respected mechanic I spoke to indicated that he would hook it up to a diagnostic machine (ALLEN) and attempt to diagnose the situation that way.

Which would be a better alternative? Any insight would be appreciated.

Thank you

Fuel pressure testing is a basic diagnostic tool and gives the tech a good starting point in any fuel related running/starting condition.
Easy to do and is a must for fuel checks. Sure doe save for a lot of guessing.........

I wouldn’t pay for anything else until you check coolant temp sensor. If it is functioning you're rpm's should be closer to 1000 till the engine is warmed up.

If cleaning the seat switch does not fix. (Does it feel like there is a broken spring in seat?) This happened to me: 300 E seat motor problem
You have to just about disassemble the seat from the back to get in there and unbolt it from the floor to get under there. You can then see your wires pretty well.

Sounds like you might have a few problems to deal with but none to serious. Knock on wood.
Good luck

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

I have driven the car for several days after the engine was pumped with a cleaner. My mechanic had indicated that since the car was not driven very much, the injectors seemed to be clogged up which accounts for the difficulty starting ( he determined this by doing a fuel system pressure test which indicated that there was a leak ).

Much to my dismay, this cleaning has not improved the starting issues I was having. The mechnic suggested replacing the injectors next. Before going this route, should I test the OVP relay (even though the ABS light is not on ) or the coolant temperature sensor?

Any insight would be appreciated. Thank you.

water Temp sensor=$30.00 http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1FX0MB1RS1G11BKPGU&year=1989&make=MB&model=300-E-002&category=C&part=Water+Temp.+Sensor&appEngines=_any
OVP=$78.00 http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1FX0MB1RS1G11A0FSC&year=1989&make=MB&model=300-E-002&category=P&part=Overload+Relay

An extra OVP never killed anyone though.
Help!! Need OVP plug schematic!

__________________
-Marty

1986 300E 220,000 miles+ transmission impossible
(Now waiting under a bridge in order to become one)

Reading your M103 duty cycle:
http://www.peachparts.com/shopforum/831799-post13.html
http://www.peachparts.com/shopforum/831807-post14.html

the best info i can give you at this time is to get another tech. if you have a leak down of pressure then this should be zeroed in on. next cleaning the injectors takes time. full tank and then some cleaner. another tank and then some cleaner. bg being what i use. also the basic setting of the flap of the air flow sensor must be checked. does your engine have some vac leaks? how is the pressure/flow of the fuel pump? if a slight application of the gas pedal while starting works then thats as far as you need to go. as you can see there is a lot than can cause this problem. lastly, whats the mileage? maybe as you drive it more it will get better. i only recommend chevron super gasoline. seems to cure a lot
of issues after a few tanks. but mostly its time to get a second opinion.

george