Rufus Sanders

For those who are really sharp, it may be appearent that I had an EFI relay issue on Sat. We were in Houston Mn. the day after the Mn. & Wi. Fun Run. We'd stayed in the most wonderful B&B, and had an awesome breakfast with the other guests of the B&B.

They were all quite interested in the Shark, and I was looking forward to seeing their faces when that RMB sound hit 'em in the face. But when it was time for us to pull out, the thing would NOT start. (serves me right, I know...)

After about 30 min. of jumping 30 to 87 and 30 to 87-87, she fired up, but I noticed the EFI relay looked a little "beat up". It seems the PO had opened up the relay and put it back together and re-used it. That's OK, since it's worked for 2 yrs. and got me thinking about trying it with a dead relay myself. But it got me wondering exactly where the pin 85, 86 lead to, and what the little diode on the diagram is supposed to do Any insights? - Ruf

ViribusUnits

The relay has a bit of microcircut wizdery in it. Thats the whole point of the extra lines on the schematic.

That extra little pin of to the side gets a feed from the ignition box for the tachometer. When the engines running, the tach is pulseing, and this keep the relay closed. If you wreck, and the engine stops, the fuel pump stops, so it doen't pump a bunch of fuel through a busted line.

It also works your rev. limiter. At 6100 rpm, the thng cuts the fuel pump out. When you hit the rev. limiter, there is a rather abrupt wall... And yes, you can get it to over 6,100 rpm before the rev limiter engages. Don't ask how I know.

Anyways, pins 85 and 86 are the pins that power the coil, closeing the relay. IIRC, 85 comes off of the key, and 86 is the ground, or visa versa, I never can rember.

Rufus Sanders

ViribusUnits, Sounds like you're talking about the Fuel Pump Relay (XVII on my '82). I of course suspected it as well, but it's the relay that powers up the EFI brain (L-Jet on my car) that I'm wondering about. Actually, now I'm wondering if the PO swapped this relay with another one from the panel, and that's why the pin numbers seem odd to me.

BTW, the only reason I know how the fuel pump relay works is from a post by you and one from Wally P. so keep tin good info coming! - Ruf

WallyP

On the '82, the circuits for Relay XVI are:

30 - Straight from the battery thru V4
87 - feeds to the injectors thru W2 & W3, to the control unit thru W4 & W5
85 - straight to ground thru the 31 bus in the panel
86 - activation power from the 15 bus, fed by the ignition switch thru A4 & A5

Not a clue as to why there is a diode in series with the operating coil...

Rufus Sanders

Thanks Wally. Maybe that diode symbol was something else, I'll look closer at the one I ordered from (who else?) 928 Spec. (You guys got any new MAF's for 80 bucks?? ha ha). - Ruf

scott863

Wally,


After making a switched-on fused jumper for the fuel pump relay, still no start. Luckily someone gave me a new noid a while back, tested the injectors, and nothing.

I checked the EFI relay, and once I got it out it was clear that it had been "adjusted" by some screwdriver blows to the case, and taken apart several times. I need to make a jumper for this relay as well to get down to 928 Intl.

jpitman2

That efi relay just powering the brain should be a std type unit - anything that will plug in should work....

jp 83 Euro S AT 50k....brainless