380 se wont start - PeachParts Mercedes-Benz Forum

earl orchard · #1 03-09-2015, 10:41 AM

Hi all
could someone tell me were to find a diagnostic for a 380 that wont start? my 126 was running awesome and when i went to start it this morning it just cranked over with out starting. this engine would only need the slightest bump from the starter to get running, then all the sudden no start. i couldn't find anything in the service manual and didn't want to just start stabbing in the dark

thanks

kenny

earl orchard · #2 03-10-2015, 10:06 AM

ok so last night i got out the multi meter and had 12 volts at the battery, 11.5 at the coil, spark at the spark plugs, it would run for a second with starting fluid, and when i pulled a plug it was dry, i also cracked an injector line on the top of the manifold and no fuel came out. am i supposed to hear the fuel pump when the ignition is on? i could hear a buzzing under the hood with the ignition turned on. i saw something in the FSM about jumping the 7/8 pin on the fuel pump relay, is this to see if you are getting fuel to the fuel distributor? i am thinking i have a fuel problem early research seems to indicate that the fuel distributor fails in these cars

any thoughts or comments most welcome

thanks

kenny

pawoSD · #3 03-10-2015, 11:01 AM

Sounds like a stuck/failed fuel pump or bad fuel pump relay. I have never heard of the fuel distributor just up and failing...

When you turn on the ignition to position 2 before cranking you should hear the fuel pump(s) run for a moment then switch off.

Sugar Bear · #4 03-10-2015, 11:07 AM

X2 on what pawoSD stated. Sounds like no fuel delivery to the injection system.

earl orchard · #5 03-10-2015, 11:22 AM

thanks for the reply's so when i turn on the ignition to pos 2 i should here the fuel pump whine ? back by the gas tank correct? i hear a buzzing in the engine compartment. yeah the car was running like a champ and then as soon as i went to drive it again which was about 2 hours later nothing, so fuel distributors kind give a few symptoms before dieing?

Elektri · #6 03-10-2015, 12:06 PM

Relays will "buzz" if they don't have enough power... AKA: A poor electrical connection to the relay.

I would track down the buzzing noise - if a relay, unplug it from its socket and clean its electrical connections with electrical parts cleaner and a tooth brush.

Electrical parts cleaner at auto parts store.

P.S. I assume everyone knows all about these things, but suddenly realized that may not be so... But for further knowledge, a relay is like an electrically operated switch. It would "click" on or "click" off in normal operation. If it was buzzing (not working properly), it would be rapidly be turning on/off or moving the "switch lever" to almost on, then back to off again. Bottom line: It would never switch on, to in turn switch on, whatever it was supposed to switch on! (That could be the fuel pump if it is associated with those - OVP relay, fuel pump relay, or possibly something else.)

earl orchard · #7 03-10-2015, 12:27 PM

what test do i do to determine if i need a relay or if i need a fuel pump ?

thanks

Kenny

earl orchard · #8 03-11-2015, 10:39 AM

update when i had my son turn the key, no sound from the fuel pump, when i had my hand on the relay i thought i could feel it click, so relay works fuel pump does not?

Frank Reiner · #9 03-11-2015, 04:32 PM

eo:

In your second post you noted that you had seen a reference to jumping contacts 7/8 in the fuel pump relay socket. That in fact, is your next step. Remove the relay from the socket, and fashion a jumper wire that can be inserted in the sleeves of the relay socket. When 7&8 are jumped power will be supplied to the fuel pump. CAUTION: #8 is hot at all times; insert the jumper into #7 first, then #8. If the pump is good, it will be heard running. If so, let it run, and attempt to start the engine. If the pump runs and the engine starts, look to the relay, and/or the contacts in the socket and pins as the problem.

earl orchard · #10 03-11-2015, 04:49 PM

thanks frank i had a feeling that was next but unfortunately my ignition is all messed up, it wont turn the car off,is stuck in the #2 position , wont go to the start position it still locks .

earl orchard · #11 03-13-2015, 10:49 AM

further research seems to indicate that the spring in the ignition is broke, looks like i will order the parts and install them, as i said my ignition is stuck in the #2 position, as the radio is on as is the ignition(battery cable discontented) so since its stuck in #2 do you guys think the tumbler will come out without a problem?

earl orchard · #12 03-25-2015, 10:02 AM

update
got the new ignition in and it works, jumped the 7/8 in the fuse box got the car to start so i replaced the fuel pump relay and now the car runs, thanks to all that helped, and Frank thanks for your help and i apologize for high jacking that other thread, it was immature of me

kenny