need info on fuel pump wiring for '92

[John_D.]

I posted this in 3rd gen, and in general tech, but nobody has the answer to the wiring question yet.

The in-tank fuel pump in a '92 tbi car is not operating. I want to find out if it is getting electricity, or if the pump has just died.

Without dropping the tank and taking the pump out first.

The fuel pump and sending unit are all-in-one. There are 3 wires going to it. One is probably a ground. Another must be for the fuel gauge, and the third one must be the hot wire for the fuel pump. Before I go shooting 12V into the wires at random, or checking for 12V coming off the wires, I'd like to have an idea of what each wire is supposed to do.

The haynes manual does not show the wiring diagram for tbi cars (not for the fuel circuit anyway). It only shows the tpi and carb cars.

So I haven't been able to figure out:
1. Which wire is the fuel pump hot wire.
2. Where the relay is located, to test/replace it.
3. What (if any) oil pressure feed is involved.

Any suggestions?

[DominusEtDeusNatus]

If you turn the key in the ON position and it's not making any noise then it's not getting any voltage or it is completely dead. Did the car just die out of nowhere or where there signs? Mine died gradually. Once I put a fuel pump in my tank and the connector by the fuel pump came loose somehow. I made sure to jam that thing in there between hoses so it won't come off.

[John_D.]

It's my son's car. It's up in Ky. He thought the rear main seal was out, and also thought it was out of oil. The oil filter was seeping a little around the gasket under pressure (we found while trying to start it), and it was a quart and a half low. So anyway, it sat for 6 months without being started, because he thought it needed a rebuild, was locked up, etc, etc...

When we started on it a couple of weekends ago, the battery was shot. So we replaced the battery, and it still wouldn't hit, even though it turned over fine and built oil pressure. Finally figured out no gas to the tbi. Thought (hoped?!) it was the filter, so we swapped it out, and fuel siphoned out of the tank continously while I tried to get the new filter on... But wasn't that simple of a fix.

So now I need to figure out if we are up against a wiring problem, and start tracking that down, or if we have to drop the exhaust and the tank and all, to replace the pump.

Neither one sounds likely, from just sitting. I figured gummed up injectors or filter. But the line (and apparently the screen) are clear.

[John_D.]

This is what I got from the guys at thirdgen.org

"You should have power on the tan/white wire at the tank flange/fitting. There should also be a pink wire (gauge) and black wire (ground). You may measure voltage at the pink wire, but it should be lower than 12V."

So I'm going to try it this weekend.

Also the relay is on the firewall next to the brake booster, and the oil pressure switch is above the oil filter.