Security: I think so. I locked/unlocked a few times with with the fob. I also did the disconnect neg battery/press hood switch trick. Everything was normal.

This was on another forum:

The circuit is dead simple. Fuse F6 in the engine compartment box supplies power to the MFR and the ECU triggers the relay. Power leaves the MFR via the white purple wire and goes through the inertia switch and then out to the pump.

Check the F6 fuse in the engine compartment box. Turn the key on and check for power at the inertia switch. If no power at the switch go back to the MFR and check the connectors. The MFR itself is just a simple 3 relay affair shrouded in a plastic box. You can pull it apart and clean it if need be. Unless the ECU is not pulling the relay in you should be able to get this sorted out.

Does this mean that if I am getting no amps at the fuse, then the relay wont get power? If so does the mean the relay isnt the problem?

 

Ok, I was confused about this.

Does a 98 AEL truck have 2 relays for the fuel pump? One where you say, and one under the hood by the ECU and washerfluid bottle?

 

uhhh I'm not to sure about that I only know a select few of the relays under the passanger glove box.

I would say... It sounds like either the fuse isnt getting power becuse of a bad connection or something is killing the power. I know the CKPS kills spark and inertia switch kill fuel so many something wrong with interia switch wiring.. Start inspecting the harnesses..

You chane anything else or anything else strange happen lately?

Is your battery fully charged?

 

I changed the coolant and the radiator hoses yesterday. Took it for a little drive to make sure temps were ok and no leaks. Parked in garage over night. Start up this afternoon, back out of garage, turn off. Put canoe on top, try to start again, and nothing. Realize fuel pump is making no sound.

My neighbor is a technician for xcel enerygy and just stopped by to help me out with the multimeter. Pump fuse spot has no current with key "on". Injectors fuse has no current when cranking.

 

Get a test light and check for power(voltage not amps) at the pump harness. The plug that goes into the pump. I had two bad connectors on two separate harnesses. I finally cut off the plugs and and put tiny female spade connectors on each wire.

 

Doesnt no power at the fuse precede that?

 

Two fuses under hood - 6 & 7 . The multifunction relay pack controls all after this, on passenger side fenderwall between ECU and battery. See attached.

BTW, volts are the potential to do work, but amps are required to do work, such as engage a relay, a starter, or a motor driven pump or wiper. So if you have 12 volts presented to an item, but no current or very low current is flowing, that device may not work at all. The low current can be from a bad conection on the plus side or the frame ground side of the circuit. If you have no voltage, then there won't be any amps of current flow. Power (watts) = Amps X Volts or P=IE. 12volts X 5amps = 60 watts. My fuel pump draws about 5 amps. If I had a bad electrical connection, that connection would warm up from the power wasted in it, and melt the insulation on connectors, make them look bad, etc. You can have enough "volatge drop" on a connector to prevent operation.

Would be unusual to not have power at both sides of fuse (with a good fuse).

 

Something worth noting is that power is only supplied to the pump for a few seconds upon turning the key. If you're not quick with the meter you'll miss is and think there's no power there.

 

Yeah, I know. I have a key-turning assistant to help me

 

We tested continuity on these fuses, fine. We then checked current when key is switched to "on". Nothing on either of them.

Ok, so I should do a voltage check across #6 and #7 as well?

And this could all be a result of a bad ground? The one right under the fusebox looks ok. When changing my radiator hoses, I did notice the one attached to the frame is pretty rusty.

My neighbor also said I could jumper the Hazard light fuse into the fuel pump one and see if the circuit will run the pump. Is that ok to do?

Forgive me for my electrical engineering ignorance, but what does this mean?