lbhsbz

swapping a '99 motor into an '86 truck.

I'm having some problems keeping the fuel pump running. The ciruit opening relay originally had a green wire that appears to have been grounded by the MAF when the engine was running, which along with the black key-on hot, kept the fuel pump running.

On the new harness, the key-on hot is white/red, so I've got that spliced into the original black.

The switched ground on the new setup doesn't come straight from the MAF, but looks like it comes out of the ECM as a green/yellow wire. What inputs does the ECM need to see and where in order to ground this wire under running conditions?

Here's another thing that's got me confused. In an effort to figure out what I was missing, I went in and started doing the pinout tests. The FSM says that I should see 12V between this green/yellow wire and ground with the key on....which seems to make no sense.

What am I missing here?

lbhsbz

WOOHOO I figured it out

Since the '86 diagram doesn't show pin locations or anything, I mistakenly assumed that the green wire at the body connector was from the MAF....but I was wrong.

The green wire from the MAF that originally grounds the Circuit opening relay does not go through any connectors, its a straight shot from the old MAF plug to the COR. It ties into the original fuel pump check connector, but that's it.

Solution: Cut the green wire coming from the COR and connect it to the Green-yellow coming off of the ECM...problem solved.

I read a few posts on here regarding this problem...even one who had used the ORS harness. The reason is because this appears to be the ONLY wire involved in this swap that doesn't go through any of the plugs by the ECM.

Hope this helps.

Now, can someone tell me how to make a '86 4 cylinder tach work with the signal from a 5VZ ECM?