Car dies and may or may not restart - Page 2 - PeachParts Mercedes-Benz Forum

lorainfurniture · #16 03-04-2014, 10:04 PM

Quote:

Originally Posted by JamesDean

Coincidentally I am running into a similar problem on my 420SEL. Just happened all of a sudden. arg. I was on my way to work today. I pulled off the turnpike and noticed the engine rmps drop below 500. I pulled it down a gear, and kept them up for a bit. Then I hit the EZ pass line and had to stop. She stalled and didnt restart. I pulled all the relays, put them back. No difference. I tried to jumper the fuel pumps ON but it was hard to hear if they were on. I wasn't sure which 87 pin was the pumps. I tried all of them I think. One of them gave me a click somewhere in the engine. Maybe something to CIS. Anyway, towed it back home and sure enough it started up at the garage. Oy.

Best I can tell the pumps and accumulator are original at 225K.

The symptoms for the no- restart of the warm engine is a classic cap and rotor failure.

It could be fuel pump or relay, or crank sensor, but those are easy to diagnose.

A simple fuel pressure gauge would figure the fuel system, and a voltage tester will sort the crank sensor in short order.

The cap and rotor can seem fine, but fail when warmed up.

Ivanerrol · #17 03-04-2014, 10:26 PM

Check CPS plug at EZL with an ohm meter. You measure the resistance between the centre contact and the outside covering.

Another problem with the distributor is the yellow plate at the rear of the cap. These break down and crack.

If you are driving down the road and the engine just suddenly shuts off this is symptomatic of a Fuel Pump relay fault. The circuit board in the FPR is known to fail due to soldering dry joints.

Your O2 sensor does nothing except minor alterations to the mixture via the EHA. It will not cause your engine to stall and not be able to start up again.
If you disconnect the O2 sensor and the engine runs roughly then this is indicative of the whole K system not have been adjusted correctly.

lorainfurniture · #18 03-04-2014, 10:45 PM

Quote:

Originally Posted by Ivanerrol

Check CPS plug at EZL with an ohm meter. You measure the resistance between the centre contact and the outside covering.

Another problem with the distributor is the yellow plate at the rear of the cap. These break down and crack.

If you are driving down the road and the engine just suddenly shuts off this is symptomatic of a Fuel Pump relay fault. The circuit board in the FPR is known to fail due to soldering dry joints.

Your O2 sensor does nothing except minor alterations to the mixture via the EHA. It will not cause your engine to stall and not be able to start up again.
If you disconnect the O2 sensor and the engine runs roughly then this is indicative of the whole K system not have been adjusted correctly.

Just for the sake of giving good information the acceptable range of the crank position sensor is 680-1200 ohms, hot or cold. I said in an earlier post it was 1200 ohms, and it turns out that is the maximum allowed.

JamesDean · #19 03-04-2014, 11:28 PM

Quote:

Originally Posted by lorainfurniture

The symptoms for the no- restart of the warm engine is a classic cap and rotor failure.

It could be fuel pump or relay, or crank sensor, but those are easy to diagnose.

A simple fuel pressure gauge would figure the fuel system, and a voltage tester will sort the crank sensor in short order.

The cap and rotor can seem fine, but fail when warmed up.

After reviewing the FSM, it turns out I was not on the correct 87 pin for the fuel pump relay. I never sent power direct down to the pumps.

About 9 months ago we ran into a similar problem where the car would randomly stall out and be un-startable for some random period of time.

I traced it down and found a cold solder joint on the fuel pump relay. I reflow the joint and recapped the relay.

Problem free ever since.

I think this issue resurfaced today. I think the joint failed again or my repair included too much solder--at least too much to properly withstand these temperatures we've been having.

Had I only jumped the correct pins...I would be able to tell you. Arg. Hindsight.

I've since ordered a new relay. Actually looks like MB replaced the one that I have 2-3 times.

dennish · #20 03-06-2014, 02:48 PM

I received a new fuel pump relay for my 1992 190E 2.6 and go to install it. CAN'T LOCATE IT. It's not near the OVP and MAS. Did a search and read that it(FPR) is integrated into the MAS. Is this correct?. No FPR on the '92's

JamesDean · #21 03-06-2014, 03:29 PM

Quote:

Originally Posted by dennish

I received a new fuel pump relay for my 1992 190E 2.6 and go to install it. CAN'T LOCATE IT. It's not near the OVP and MAS. Did a search and read it must be integrated into the MAS. Is this correct?. No FPR on the '92's

Correct. Fuel pump operations were integrated into the MAS unit..Around 1990 I believe.

RickBryan · #22 03-10-2014, 11:21 AM

Quote:

Originally Posted by Ivanerrol

Symptomatic of a faulty Fuel Pump Relay.

When your car stalls, remove the F.P.R., give it a bit of a tap and see how you go.

F.P.R.'s and O.V.P.'s are trouble spots for these cars.

Can you say where is the most likely location for the fuel pump relay, please, and what does it look like? I am having a similar problem as the original poster and believe the problem is either with the alarm immobilizer system or the fuel pump relay.

JamesDean · #23 03-10-2014, 12:02 PM

It depends on your car. The 126 chassis fuel pump relay is located in the firewall area between the engine and cabin.

It is the relay between the long box (ABS) and the KLIMA relay. I think it might says KICKD on the top of it.

PICS:
http://imgur.com/a/fPL4F

dennish · #24 03-12-2014, 07:28 PM

UPDATE: My problem was due to worn distributor cap and rotor. I bought a used MAS and tried that first but car didn't start. New cap and rotor and it started up. Problem solved.

Ferdman · #25 03-13-2014, 07:15 AM

dennish, glad to hear you resolved the problem.