1994 850 Fuel system relay turns off then back on

Fire at Will · Post by **Fire at Will** » 19 Aug 2013, 12:13

I've been chasing this for a while. Turn the car off, fuel relay (the grey one on the shroud) stays on for about 30 seconds, shuts off, as it should, then clicks back on. It will stay on indefinitely to the point of killing the battery. I've searched many times many forums, and haven't found a solution. The relay has been changed, as well as the ignition switch, fuel pump relay, and ECU. Same thing. What I have to do is turn the ignition back on then off again to get the relay off. Also if I unplug the relay and plug it back in, it won't turn back on.(until I turn the car on) ????? Bad ground?? Any Ideas?

Post by **abscate** » 19 Aug 2013, 12:47

I dont know the 1994 model that well, but I dont think fuel relays are on the shroud? Can someone verify this ?

On edit, corrected below - fuel relay is indeed on shroud on 1994

Post by **Ozark Lee** » 19 Aug 2013, 17:21

The master fuel system relay is indeed on the fan shroud on all of them, it provides power to the fuel injectors.

The ECU turns the relay on and off and this isn't a problem I have seen before. On a base 2.4 N/A engine the power to the relay is battery voltage between the violet wire and the red wire. The red wire is always hot but the violet wire should read + battery voltage when the key is off. The ECU takes the violet wire to ground to turn the relay on.

Is there anything aftermarket like a remote starter or an oddball alarm system on the car? If not then there is either a problem with the ECU (not likely) or the wiring to the relay (more likely). There have been a number of posts related to the relay not working and it is almost always a wiring problem right at the connector. The location of the relay and the way that the wiring is exposed going into the connector leads to problems.

...Lee

nedro018 · Post by **nedro018** » 19 Aug 2013, 17:48

lee he said that the relay stays on for 30 seconds after shutting the car off and he claims that this is normal operation. is this true?

Fire at Will · Post by **Fire at Will** » 19 Aug 2013, 19:58

There is an old non functioning alarm, I know it interrupts the starter circuit, but not sure about anything else. I will remove it completely but I'm not optimistic it will fix the issue. I've unwrapped the loom 18 or so inches back from the connecter and it looked great. This car had been garaged it's whole life and only has 95k on it.(we bought it at a retirement home, literally an old lady car) All the issues thus far seem to age related.

nedro018 · Post by **nedro018** » 19 Aug 2013, 21:54

well i just checked my gray fuel injection relay (1995 850 NA), the one you are talking about, under the shroud, and it doesnt stay on for 30 sec after i cut off the key circuit, more like 3 sec.

to check, i turned ignition ON thru an open driver's window, then turned OFF, then sprinted from window to relay. by time i could get up there, it was cutting off. about 2 or 3 sec....not 30.

based on parts you have replaced thus far (ECU and relay) it could be wiring....that is shorting out based on temp's inside engine cabin.

Post by **Ozark Lee** » 19 Aug 2013, 23:54

Fire at Will wrote:There is an old non functioning alarm, I know it interrupts the starter circuit, but not sure about anything else. I will remove it completely but I'm not optimistic it will fix the issue. I've unwrapped the loom 18 or so inches back from the connecter and it looked great. This car had been garaged it's whole life and only has 95k on it.(we bought it at a retirement home, literally an old lady car) All the issues thus far seem to age related.

If it is the OEM alarm then I wouldn't even bother to disconnect it, that wouldn't be the problem. As you are indicated in your post, it only interrupts the starter circuit to immobilize the car. Some of the aftermarket stuff tries to get fancy

Do you know which engine management system that you have? The LH 3.2 has two ECU modules plus the transmission control module (if it is an automatic) in the ECU box. The Motronic has one engine ECU and one transmission TCU. The reason I ask is for the next suggestion which will be to pull the appropriate control module and see if the problem clears. If the fuel system relay continues to engage then the problem is wiring. If the relay never turns on and stays off with the ECU(s) removed then that starts to point to the ECU itself as the culprit.

The ECUs are not a high failure rate item but, like anything else, they can go bad.

...Lee

Post by **BEJinFbk** » 20 Aug 2013, 00:22

There are two things that I would start with.
The aftermarket alarm module and the ignition switch.
Even if the alarm has a starter cut relay, you can still
unplug it to see if the problem follows the alarm brain.

The same check can be carried out to see if the ignition
switch has gone around the bend. It's relatively easy to access
and can be unplugged to see if the relay drops out when you
take the ignition switch out of the equation.

From there, you could have an overload relay in the mix, but
I'd have to get into the diagrams for your car to say for sure.
And it's getting late... Try the first two thing for a start.

Fire at Will · Post by **Fire at Will** » 11 Sep 2013, 20:08

Been a while but I finally got around to removing an old alarm, and poof, so far the main problem of the fuel system relay staying on is gone. The last problem is the fuel system relay not turning on when hot, but I can smack it and it turns on. There is one in the mail. It was a new one from rock auto installed and obviously it's junk, as was the temp sensor from them. Lesson learned, don't buy electrical items from the lowest bidder.