97 c230 Will Not Stay Running

[Mikito]

This is my mother's car. Went to start it after it had sat for maybe three weeks. It will start and run smoothly for three seconds then dies. It can be immediately restarted and will do the same thing. What I have done so far.

Fuel pressure 55psi
I can run it indefinitely on carb cleaner and runs smoothly
Show all 4 injectors receiving signal while running on carb cleaner
Pulled fuel rail and cranked and injectors squirted fuel only tried it for a second. Don't know if it was enough fuel.
Disconnected MAF with no change

Its getting fuel air and spark but still won't keep running

I have looked for vacuum leaks by blocking off various vacuum lines with no change

Another issue probably unrelated is that I flushed some of the fuel thinking it might be bad and ended up with the fuel tank dry. I had added 5 gallons because the gauge was reading almost in the red. I flushed out maybe a gallons worth and then reconnected and had no fuel pressure. Eventually figured out the tank was empty when I removed the line between the tank and fuel pump. The gauge was reading 1/2 tank at this point. I put in another 5 gallons and now the gauge reads 3/4 full. Any ideas on this? How does the fuel get from the drivers side tank half to the passenger side?

Other things I will try tomorrow.
check for codes
disconnect battery
disconnect camshaft position sensor
look closely at wiring and idle air motor. The idle air motor seems to make a loud whine when the key is in run is this normal?

Does anyone have any ideas? I am about to give up and have it towed to the mechanic.

Just had another thought. I never checked for spark, just assumed. Could I have a bad coil where the car will only run if extra fuel is getting to the working cylinders? Probably a long shot.

I just found this site yesterday. I have read back 36 pages so far looking for ideas. Lots of good stuff. Thanks.

[JRE320]

Does anyone have any ideas? I am about to give up and have it towed to the mechanic.[/QUOTE]

Very good idea.

[John Jones Jr.]

A wild guess but have a look at the OVP (over voltage protection) relay. It's in the engine bay. A silver unit with one or two fuses inserted in the top. When these relays start to go (dry solder joints usually) they can give all sorts of problems, don't know exact problems they'll cause on a 202 but on a W201 & 124 they can cause problems like you've mentioned.

What the cause I'd say it not a major repair but would be advisable to get a Merc specialist to look at it and get a Star diagnostic check done too.

[imautoparts]

Could it be the fuel pump relay? On most Mercedes, the relay triggers briefly to allow starting using one type of circuit, then when the key is released the other side of the relay clicks on for permanent running. I've diagnosed this problem once before (on a w116) by using a jumper cable to power the fuel pump direct from the battery to the pump side of the relay plug.

Good luck!

[taz069]

Have you tried a scan tool? How many mile's on this 97? If the car has got 145k+ it could be several lil issues. Now if the car has around 45-65k it could be a less. Now the ovp that John mentions is located under the hood on the passenger side under the black cover next to the fire wall. Check out the stickie here in repairs for fupabox. He does a retin(solder) on the ovp and he has several other related vid's that might be of service. Now on the gas going from one side of the tank to the other, this is one I have been needing to figure out on mine also. I have read that their are 2 gauges in the tanks one on the pass and one on the driver side. Just haven't bought the tool to pull them yet. I can deal with a full tank. hehe. Hope some of this helps.