1986 Euro 500SL stalls during driving

[tommymic]

My 500 with 72,000 miles stalls after driving awhile, starts right away, but then stalls again after a bit. Only stalls while driving. Cold starts right up, idles well & revs up fine, in park. Warms to 80C in park and runs and revs up fine. But drive for a bit and I can here the fuel pump(s) wine a little and engine drops rpm and stalls. Read on forum thread that the pump relay could be the problem, so got a rebuilt from ProgRama Inc, because couldn't find a new one that would fit socket on a Euro, but does the same thing. New pumps, filter, accumulator and tank screen clean last year at local independent shop with 4 Yelp stars. The mechanic said he used Bosch parts, but they are not, and won't back his work, so he is done. Overload relay checks out, gas is good, vac lines look good, air filter good. Forum post says it might be the crankshaft position sensor, but it is hard to change out. Anyone have any thoughts before I try changing out that sensor or change out the pumps with Bosch or try another FPR. Or does anyone know of a good independent mechanic in the Madison, WI area. Hate to take it to the local dealer$$$$$$ when they know it's your toy. Much appreciated.

[Frank Reiner]

tm:

If you will expand a bit on "Only stalls while driving." it will help to get started.
Does driving include all vehicle speeds? OR, Only when coming to a stop in traffic? OR, Only at highway speeds?
If at highway speeds, how long must the speed be maintained before a stall?

[tommymic]

Haven't taken on highway because of problem. Just let it warm up in garage and take it around in the neighborhood, probably less than 30mph. Stalls sometimes on a decelerate and sometimes just at constant speed.

[Frank Reiner]

tm:

A 1986 non-US car could have KE-Jetronic (CIS-E) injection, or the preceding version, K-Lambda. Are you familiar with the systems? If the car has two fuel pumps it is probably KE.

[alabbasi]

fuel pump relay is probably bad , gets hot. Stalls restarts

[tommymic]

Frank, Yes KE-Jetronic FI and two fuel pumps.
Alabbasi, Had trouble finding a replacement FPR. If you think it bad I can return it to ProgRamma Inc. under warranty, but I am told they have a pretty good rep for not sending out bad rebuilts. I have not tried to jump the relay to keep it on because it always starts right after a stall. I could still try that, but the socket is behind the glovebox on the firewall and very hard to reach.
thanks all

[Frank Reiner]

Originally Posted by tommymic

Frank, Yes KE-Jetronic FI and two fuel pumps.
Alabbasi, Had trouble finding a replacement FPR. If you think it bad I can return it to ProgRamma Inc. under warranty, but I am told they have a pretty good rep for not sending out bad rebuilts. I have not tried to jump the relay to keep it on because it always starts right after a stall. I could still try that, but the socket is behind the glovebox on the firewall and very hard to reach.
thanks all

Given the indications described above, jumping the relay would be the next step. The location does make it a bit difficult; however the box itself is retained by plastic rivets that can be popped out. Access is much improved with the box removed.

Experience with ProgRamma is somewhat mixed. The restart can be attributed to the relay bypass feature when cranking, and the possibility that the relay re-latches during that sequence.

[tommymic]

that's disappointing to hear about ProgRamma. Do you know which poles to jump, 30 & 87 like most relays? it's a 10 pole relay.

[tommymic]

sorry , 9 pole relay 0035450105, 3 over 6.

[Frank Reiner]

Originally Posted by tommymic

that's disappointing to hear about ProgRamma. Do you know which poles to jump, 30 & 87 like most relays? it's a 10 pole relay.

Correct, fortunately.

[tommymic]

thanks Frank, will do next time I get a chance and post results.

[tommymic]

Jumped the relay, started fine, warmed up and drove around awhile, pumps started to whine (pretty loudly) and then engine sputtered and stalled. Thinking now the cheap aftermarket pumps?

[tommymic]

on another post someone said it might be the ignition module. Frank, what say you?

[Frank Reiner]

Originally Posted by tommymic

Jumped the relay, started fine, warmed up and drove around awhile, pumps started to whine (pretty loudly) and then engine sputtered and stalled. Thinking now the cheap aftermarket pumps?

Originally Posted by tommymic

on another post someone said it might be the ignition module. Frank, what say you?

If the pump noise increases with operating time that should be seen as a fault. 200K, 30yr. old pumps do become a little louder than new pumps, but the sound is constant during any given period of operation. (Until outright failure.)
Since the pumps are plumbed in series, with the objective of raising the operating pressure over the previous system, the "second" pump operates at a higher pressure than the "first" pump. The OEM pumps are quite OK in this situation; aftermarket maybe not. System pressure is ~91-92psi.

The ignition module and/or crank pickup could produce similar stalling, but would not change the sound of the pumps.

[okyoureabeast]

My money is on the pumps given what was said.

I would do both the fuel pump relay and the pumps.