Fuel pump relay
 

So, a few weeks ago my '99 sl2 just would not start. Cranked fine and was making sparks. In checking out the fuel system I narrowed it down to the fuel pump relay, which I swapped out. It's been running very well except that on three occasions the engine just died while I was sitting in traffic. I pulled the fuel pump relay out, plugged it back in, and the vehicle started up and ran fine again. I have another relay to swap in, but I'm wondering if something in the electrics is causing the relay to behave like this. Unplug it and plug it back in and it's fine. An easy fix, but inconvenient. Any thoughts will be appreciated. Thanks.

Get some electrical contact cleaner and remove the relay and spray the plug. Insert and remove the relay several times and then try it. Sounds like you've got some corrosion in the connection.

Fouled contacts can cause all sorts of problems ....

That's what I'm hoping it is. When I installed the replacement I applied some connector protector thinking that would help, but you're right a good cleaning first would have been more helpful. With the weather the way it is I'll tackle it tomorrow. One thing I do recall is that when looking at the socket the relay plugs into, the top right contact looked almost like it had been overheated, like it had melted a bit. If that's the case I guess I'll have to replace the entire board. Can that be done without removing the console or am I looking at a good couple of hours work? Thanks for your help!!

I'm not sure, but I would THINK you could just remove the fuse box by locating a couple of mounting screws. MAKE SURE TO DISCONNECT THE BATTERY FIRST! Back when I was a young man, I replaced a few contacts in fuse boxes this way. They must come out from the back side of the fuse box. Used to be a small flat "keeper" that could be depressed with a small flat blade screwdriver and then simply pulled out of the fuse box. I don't know about that anymore. I haven't done it since the late 70's.

So I thought this was fixed, wrong again. A couple of days before I got around to cleaning the contacts the vehicle was starting fine but as soon as I had driven 1-2 miles the engine just shut down. Not blubbering like it was running low on fuel but just an instant shutdown like someone hit a kill switch. Tried to restart but it wouldn't. I pulled the fuel pump relay out, gave it a second, reinstalled it, and the car started right up and I had no problems after that.
I picked up some Deoxit and cleaned up the contacts. You were right, they do pull out the back with a bit of help, but what I thought was possible a melting socket had actually been drilled out in front (lazy I guess) by someone and the contact was replaced. But I cleaned up the contacts and for 4 days had no problems at all until today. Same thing, drove about 2 miles and the engine shut down... took out the relay, reinstalled, drove away without any further problems.
It doesn't seem like it's a fuel problem rather than electrical one. If I had any hair I would be losing it...

Obviously, a loose connection (fit) in the fuel pump relay block.

Yep, sounds like it may be time to hit the salvage yard and grab another fuse block. I'd also recommend taking a few of the connectors unless you want to pull the entire harness. You clip a few of the connectors for spares and just splice in new one where you need it and have a few extra for backup. Be sure to solder your splice and use some heat shrink on the soldered connection.

Yes, by all means, solder your splices, and cover them with heat shrink (I just LUV the guy that invented that stuff-LOL)

Having spent the better part of my life in working with electronics, relay contacts and sockets you plug them into are the high mileage, many years failure items in todays cars. The mechanics with reasonable maintenance will last almost for ever as will the engines unless you are using 5W20 motor oil. Todays (pick your brand name) are a long way from my first car, a 1930 Model A Ford in which the electronics consisted of a horn and it's button, a brake light (not two just one) and it's switch operated on by the brake rods, an ignition switch, the starter was some mechanics on the floor you pushed with your foot that operated directly on the starter and the assorted head lights, no parking, no turn signals and only one tail light and "A" dash board light. Todays whatever has more electrical stuff on it than that to turn on a dome light, which my old Ford did not have. I did though install a radio. I put it under the rear seat as the dash board was full of gasoline tank and a radio would not fit.

And speaking of that, my 94 S series coupe has had some problems with the electric windows going up and down, and the drivers side is down. I have to go out and figure out how to get the door skin off so I can see if I can find out what is binding it. I'm not looking forward to that right this min. The car has been basically problem free for years and years. That record is going to break today!