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Timebender
03-08-2016, 06:19 PM
I have a question in regards to this schematic, specifically pin 87b. It says it connects to the main fuel relay - I'm guessing it gets voltage from that, and is that relay #11 - the one 3 spots over from the red one? Also called the Lambda probe relay on DMC's site?

If that pin doesn't get a signal, i.e. the lambda relay is bad, then I would assume the RPM relay won't work and then run the pump, correct?

http://www.dmcnews.com/Techsection/images/RPM%20Relay%20Schematic%200.5sd.jpg
Bitsyncmaster
03-08-2016, 06:54 PM
The RPM relay drives voltage to two output pins. One is the the fuel pump, the other drives the lambda relay coil and the WUR heater. So if the lambda (main fuel relay) is not working it will not affect operation of the fuel pump.
Timebender
03-09-2016, 12:34 AM
intersting. So then why is it called the main fuel relay?
Bitsyncmaster
03-09-2016, 06:43 AM
intersting. So then why is it called the main fuel relay?

Good question.
Josh
03-09-2016, 04:20 PM
if you are troubleshooting issues with your car... It should not have a RPM relay. If it does, it is not required!
Timebender
03-09-2016, 11:28 PM
I figured that out finally. The original owner still had it in, with a power line coming off the #2 aux relay ignition pin, connected to pin 87b. It had worked for years like that until a couple weeks ago, and the rpm relay wasn't allowing the fuel pump to run anymore. So I took it out, and ran that 12 volts from there directly to pin 87 on the relay's socket. Now when I turn the key to on, the pump comes on.
Problem solved.
Elvis
03-10-2016, 01:01 AM
If you want to fix it - open it, resolder the relay and test it. in 90% of the cases that solves the problem
as just the relay pins are loose.
Timebender
03-11-2016, 02:48 PM
It was never really doing what it was supposed to, as in running the pump when the engine was running. The first owner took out the in-tank pump and put in an inline pump that just runs on ignition and is grounded to the frame. So not even the little switch in the footwell acts as a safety feature. I might though eventually do what Dave did and hook up a motion impact sensitive battery cutoff in the battery compartment. For now I have a manual battery switch in there.