I have an 89 Ford Aerostar. I don't have any power to the inertia switch for the fuel pump. I have tried to jump hot wire from battery to inertia switch and still nothing. I found what I think is the relay under the dash for the pump. I have power there when I turn key on. Is there a fuse, or relay between there and the inertia switch? Could it be that I have a blown fuse between there and that the fuel pump is also bad that when I jump hot wire to inertia switch the pump don't kick on?

Thanks

Jaime

 

Jaime,

Jumping a hot feed directly to the inertia switch should tell you whether the inertia switch is good or bad and whether the fuel pump is good or bad provided you jump power to the appropriate wiring at the right relay.

According to my Chilton's engine control wiring diagram for 86-91 3.0L engine, the fuel pump receives power directly from the inertia switch through a pnk/blk wire.

The inertia switch receives power directly from the fuel pump relay through a pnk/blk wire. Power from this wire is also feed to pin 8 of the EEC module though either a pnk/blk wire or a org/blk wire.

The fuel pump relay receives power from fuse link E through a yellow wire that also feeds power to the PCM power relay. Fuse link E has power at all times.

The PCM power relay feeds to pin 57 of the EEC module through a red wire. The PCM power relay also has a blk/lt grn wire to ground and a red/lt grn power wire from fuse link G through the PCM power relay diode.

To be sure that you're checking the fuel pump relay it should have the following wires.

Yellow power feed from Fuse link E,
pink/black feed to inertia switch and EEC module pin 8 (pin 8 feed could be orange and black - so fuel pump relay may have pink/black and org/blk at same connection)
tan/light green to pin 22 EEC module, and
red to evap. can purge solenoid

To check the fuel pump relay, you should have power to the yellow wire at all times. With the ignition switch "on" engine "off", the relay should energize and provide power to the pink/black feed to the inertia switch. Note: the fuel pump relay is energized by power from the EEC module through the evap. can. purge solenoid and back to the EEC module. Therefore, if the fuel pump relay is not energizing, the problem could be an open evap. can. purge solenoid.

To check the inertia switch, the wiring from the inertia switch to the fuel pump, and the fuel pump.

First disconnect the connector to the inertia switch. With an ohm meter check for continuity through the switch. The inertia switch is normally closed so you should get a infinite reading. A zero reading and the inertia switch is either tripped or bad.

To check the wiring to the fuel pump, with a jumper apply power to one and then the other pink/black wires of the inertia switch connector. If you hear the fuel pump activate at one pin, then that's the feed to the pump and the pump and wiring to it are ok. The other pin is the feed from the fuel pump relay. If you don't hear the fuel pump energize, then you need to check the wiring from the inertia witch to the pump and the pump itself.

Hope this helps. LOL

Ron

 

Hi,

Thanks for your post, it helped. We found a short in one of the relays, got that fixed. The van now isn't spinning over fast enough to create a good spark. We're going to replace the plugs and put a good battery in it and see if that helps. It seems it's the battery so we tried a few different ones, it just drains them. Any other suggestions?

Thanks!

Jaime

 

Jamie,

If it's draining the batteries, you may have another short somewhere that may take some time to locate. Did the relay you fixed repair the problem with the fuel pump?

Have you been able to start the van at all, or is it just turning over really slowly? If the later, you might check the starter relay, the starter solenoid and/or the starter itself for power and/or shorts to ground. I used to own an Explorer that had bad contacts in the starter solenoid which caused the starter to bog down and not have enough torque to properly turn over the engine. Repeated tries at starting would also drain battery power. Replaced the copper contacts, about $2 at alt/starter repair shop, and it worked great for years afterward. LOL

Ron