Yellow Relay from Hell...to finally solving the problem

[flashgordon64]

In the never-ending circle of the yellow overboost relay from Dante's 9th circle of the Inferno, I've decided to set the 930 on fire...well maybe not, but I thought about it.

I have an '86 930 with basic bolt-on mods in which the previous owner decided to do some creative wiring to in order to solve these problems. Problem is the car is driving me batty. From pumps shutting down to replacing relays, I've decided to bypass it all.

After sourcing Primemvr(MSD), A930Rocket(pumps), and Mark Houghton(relays): thanks for all the help guys. I grounded the pumps, installed an inertia switch, and also installed an MSD 6AL-2 ignition box. Here's the problem: I discovered that if if you use the 6pin CDI box harness, everything still runs through the relay from hell....the car cranked up on the 1st try but after moving the hell relay it shut down. AARGGH

Question: Isn't there a point further up in the harness that I can splice into that will bypass all the mess? And if so, where is it? Next Question: does anyone have a diagram, schematic of said point? Thanks in advance

Mitch...holding a gun to the head of the yellow relay from hell

[s5uewf]

I am facing the same issue with my EFI conversion. I recently have been told to jump into the blue wires that are connected to both relays in the trunk. This is the low amp 12 v circuit that energizes the relay so they can close the high amp circuit that runs the pumps.

I have not tried this yet but willl as soon as I have a weekend afternoon to get to it. In the meantime I also route my fuel pump energizing circuit via the yellow relay.

If you get to try the blue wire before me, please let me know if this is the trick.

I will update when I try in case I get there before you.

It reminds me of some stereotypic bomb defusing movie "cut the blue wire!!"...

[flashgordon64]

I see that you're in MD. I am as well....I'll keep you posted on the progress

[CaptainCalf]

Count me in guys. I'm planning on using the fuel pump relay from a DTA S80 Pro ECU and bypassing all those oem relays from hell, so pls let me know how you're doing it and I'll post up anything I find in the meantime too!

Thanks

[flashgordon64]

Hey guys, to answer the question, yes there is. It's been a while let's see if I can remeber. We located the constant 12v wire and wired the MSD unit directly from that. Everything else is wired directlly from the MSD unit. I've since removed all of the relay crap that usually sits in the rear tray. No more start/shutdown issues ever

[CaptainCalf]

That looks like a great solution Flash & congrats on working it out!
RC

[flashgordon64]

Originally Posted by CaptainCalf

That looks like a great solution Flash & congrats on working it out!
RC

Yeah no more of what I call hope and pray start-ups, especially when you're far from home.

Mitch

[s5uewf]

Hi guys. I am still creeping forward with my effort to eliminate the relays in the rear engine bay from my fuel/start loop. I recently introduced a pretty sever short when trying to jump one of the relays and in the process I am trying to clarify which wires I damaged and now need to repair.

Here are my questions:
One rear engine compartment relay just has a single green/white stripe wire coming from it. Anyone know which relay this is?

One rear engine compartment relay has: black/red stripe, red/white stripe, red, brown wires coming from it. Anyone know which relay this is?

I have a single white wire coming from the rear 14 pin connector block. I think this is the overboost switch wire. It is now just hanging free. Anyone know where this should connect?

I also have a brown/black stripe wire coming from the 14 pin connector block. I believe this is the air flow meter switch. It has a metal crimp where another wire was joined to it a few inches up from the connector block. Should a ground wire connect to this, or should the white wire connect to this? Or other?

Last, I have a single black wire and a single brown/red stripe wire coming out of the harness from the firewall. Does anyone know what these wires are for?

I have looked at various reference material, but am not able to find the answers to the above.

[JFairman]

You could run a 12v switched 12 gauge wire from the front fusebox to the engine compartment to turn things like the CDI on and off. For the high amperage 12 volt supply wire from the MSD go to the starter motor for the best 12 volt source.

That way you bypass the factory alarm system, the speed relay under the driver seat, the yellow relay, and the ignition delay relay.
All of that old CIS crap will cause problems if you leave it. Bypass it all or delete it and the BS goes away.

[billjam]

Emery,
I distilled this wiring diagram from the spaghetti of the WD in the manual so I could figure out my own fuel system wiring problems.
I am currently running with the speed relay by-passed and the oxygen sensor and fuel enrichment control units disconnected. The bulkhead connector at the front left of engine is unplugged and terminals 3 and 12 are jumped.
I hope this helps fill in a few blanks.
I also have a clear pdf file of the engine WD which shows which wires and devices can be removed to get it back to basics. Email me if you'd like a copy.

[mark houghton]

Originally Posted by billjam

Emery,
I distilled this wiring diagram from the spaghetti of the WD in the manual so I could figure out my own fuel system wiring problems.
I am currently running with the speed relay by-passed and the oxygen sensor and fuel enrichment control units disconnected. The bulkhead connector at the front left of engine is unplugged and terminals 3 and 12 are jumped.
I hope this helps fill in a few blanks.
I also have a clear pdf file of the engine WD which shows which wires and devices can be removed to get it back to basics. Email me if you'd like a copy.

That's some excellent work Bill. Finally a schematic I can understand and follow. I had considered bypassing the speed relay under the seat until I managed to re-solder some of the internal points and resolved a gremlin that plagued me, but was never sure of how to go about bypassing it.

Thanks for sharing....this will be printed out and added to my plethora of info.

[billjam]

Originally Posted by mark houghton

That's some excellent work Bill. Finally a schematic I can understand and follow. I had considered bypassing the speed relay under the seat until I managed to re-solder some of the internal points and resolved a gremlin that plagued me, but was never sure of how to go about bypassing it.

Thanks for sharing....this will be printed out and added to my plethora of info.

Mark, and others,
If you are interested, email me and I'll reply with a nice clear pdf or Visio file of this diagram.
In case you don't have it already, I also have the WD sheet 6 for '86 930 available as well. One version is complete and another version (below) shows what can be deleted. I put this together so I had a clear picture of how my own car has been modified for future troubleshooting.
Pic below is the connector (T66) at front left of engine with jumper between terminals 3 and 12. This connector was cable-tied to shock tower as a temporary fix some time ago and effectively isolates all the red items on the wiring diagram.

[s5uewf]

Thank you for all the advice and schematics. Let me make another run at it this weekend and report back (if I actually get the time this weekend!).

[SusnaWit]

I recently have been told to jump into the blue wires that are connected to both relays in the trunk

[1-6-2-4-3-5]

Billjam,

I just realized today that the frequency valve pulse is energized by the black relay behind the yellow relay (item "G" shown in your post #10). Does the wiring diagram in post #12 show this? If so, could you send a high-res copy to me at kirkdunn01 (at) yahoo dot com? I want to trace the signal back to the lambda box under the driver's seat if possible.

Thanks for your help!

[JFairman]

The black relay next to the yellow relay supplies current to the heater element in the lambda system oxygen sensor after a cold start so it heats up faster and starts leaning out the mixture and meeting emissions faster than if it relied only on exhaust heat to get up to operating temperature which would take a longer. It is not connected to and has nothing to do with the lambda frequency valve/pulse valve/inline injector.

The lambda frequency valve is operated or controlled by the k jetronic lambda ECU under the driver seat.
The vertical rubber socket that looks kind of like a round relay socket is for checking what fequency the pulse valve is operating at with an oscilliscope or similar test equipment.

[1-6-2-4-3-5]

Hmmm... strange. I've been chasing a fuel issue in another thread:

Need help with a fuel issue

I replaced the black relay, and the frequency valve fired up. I pulled it back out, and the valve went off. Maybe the wiring in my car has been changed? Sounds like I need to trace the wire from the frequency valve and see where it goes...

Thanks

[mark houghton]

Originally Posted by 1-6-2-4-3-5

Hmmm... strange. I've been chasing a fuel issue in another thread:

Need help with a fuel issue

I replaced the black relay, and the frequency valve fired up. I pulled it back out, and the valve went off. Maybe the wiring in my car has been changed? Sounds like I need to trace the wire from the frequency valve and see where it goes...

Thanks

Hmmmm....weird. Unless that relay also sends power to the Lambda computer under the seat, otherwise Jim's comments are right-on.

So now that your freq valve is buzzing, how's the car running?

[1-6-2-4-3-5]

After an adjustment to the mixture, it is running great! Cleaning out the fuel system as I was troubleshooting probably helped as well.