My '81 380 SE has started stalling at infrequent times. There is no warning, the engine just stops. Usually at stop lights, but sometimes just going down the road. I suspect it is the fuel pump relay. Is there a way to test the circuits to determine if the problem is with the relay or some other problem with current not getting to the relay? I have checked the wiring at the fuel pump and the ignition switch and I can't make the system malfunction in the driveway. Any ideas??

Send me an email and I'll send you the procedure off the CD

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

Since my last message, it appears that the fuel pump relay is not the problem. The car will run without the relay if I jump the contacts for the relay connections. The problem continues when the engine is warmed up and I release the accelerator at a stop. The engine dies and I suspect that the problem is related to the idle circuit somewhere. The idle control valve is receiving voltage and is functioning as intended. Perhaps the problem is with the throttle plate position sensor or the idle speed control brain box. Any ideas??

Your last post didn't make sense to me. If you jumper the socket with the relay out and it runs fine, it is the relay that is the problem. If you are saying that the car still stalls with the relay jumpered out, I would try cleaning the idle control valve as has been suggested on this forum several times.

Thanks for your input. Yep, I already removed the valve and cleaned it as best I can with Gumout and brake cleaner. As I said, the problem occurs when the throttle is closed and the engine dies. My understanding of the throttle plate sensor is that if it is not functioning, the engine idle would be too high, not too low. It seems like the engine is not getting enough air to keep running at low rpm under load and it stalls.

Oh, I've also heard people mention cleaning the air meter thing (forget the name) inside the air cleaner housing.

Have you checked your timing?

I had a similar problem with my 380SE. It was solved when I installed a new idle control valve.

Yep, I had to do that too. Mine stalled out a bunch until I drowned it in WD40. It has only done it twice in 5 months since. However, my fuel economy has declined.

Watch out, even wholesale that part is expensive. About $300 for a part the size of a roll of quarters.

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