wack the fuel tank with a 2x4 or shovel.not hard enough to crack it but a good wack.then try and start her.

 

Yup, that's another method to try.

 

fact #1 - you have 0 fuel pressure at the rail, checked via a gauge.
fact #2 - when turning the ignition to on, you do not hear the fuel pump come on (no whine sound).

remove and test fuse #9 in the dash. make sure its good.

lets go back up to post #4 for determining if power is getting to the fuel pump.
ideally you'd just unplug the electrical connector at the pump and check for power. but, since its impossible to get to, its easier to test it from the engine compartment end to begin with.

lets see if this makes sense.....
you will need a voltage tester of some kind - digital, analog, or light, and an assistant. turn ignition off. remove fuel pump relay. determine which pins should have power in the on and off positions - you can practice on the horn or wiper.... turn ignition to on. verify 12 volt on the hot side. if none, then the fuse between here and battery is bad. (as CM said, after about 3-4-5 seconds of being ON, the PCM will command the ASD to shut down, so you'll have to keep cycling the key off and back on). turn ignition ON and see if you get 12 volt on the switched side (with relay installed, you'd hear a click). if you do, it should go off after those few seconds.

i suppose an easier way is to have an assistant turn ignition to on. with relay installed and your finger on top, you should feel/hear it go click..

what this is doing is determining if the fuel pump wires are getting power or not - since the pump itself is in such a hard place to get to... on top of the tank and directly under the bed of the truck.

 

It's programmed to run for a MAX of 3 seconds at which, point, if a no crank, no engine running condition is present, the PCM will kill the ASD relay in 3 seconds. Post No 8 covers how to measure the voltage at the pump. If and when you measure IN the engine bay, that's only going to tell you if it's present at that particular point.

If and when there's a voltage drop / loss along the way, there's no way of knowing from that point of measurement. It's best to crawl under there, and backprobe the connector. NEVER - EVER take the connector off and measure it from the PIN SIDE. ON some CKTs, it needs to be LOADED DOWN and, if and when the connector is removed, you've just removed the LOAD off of that CKT which is really a bad thing to do. RULE OF THUMB: always leave the connectors plugged in and backprobe them.

Since this line is rated 20A and, a DEAD SHORT across the pins may inadvertently occur, this could induce damage due to a huge voltage spike all the way back to the PDC. I NEVER measure from the pin side as it's unsafe.

CM

 

Is this the FUEL PUMP fuse? I am trying to locate my 99 manual and, at current, I'm at a loss as to where the fuel pump fuse is on a 98 and, it's driving me mad as I can't find the information I need on this.

IF the 20A fuse is not located in the PDC on a 98, then where did they re- locate it is my question?

CM

 

dang. its tough trying to outpost chris.

 

Ok where exactly are the wires I need to test the fuel pump at in the engine bay

 

I would test it AT the FUEL PUMP connector. This way, if there's voltage loss along the way, it will be measured / witnessed at the pump.

PROCESS:


1. Set the meter to DCV and to the highest AMP rating on the meter that it will go to e.g. 10A, 20A etc

2. Insert the RED (+) probe into the RED wire at the rear of the connector

3. Place the BLK (COMMON -) lead to chassis GROUND. May have to use sandpaper to clean a good spot for ground.

If you can't obtain a good ground there's an option*

4. Turn KEY <ON>

5. Note voltage reading

6. KEY <OFF>

<END>

*OPTIONAL: Using a paper clip, wrap electrical tape around it minus just 1/8 at the tip. Attach this to the black probe and insert this BLK probe into the BLK wire at the pump connector.

CM

 

It is indeed the "Engine" fuse. Fuse number 9 in the junction block. (fuse block on the side of the dash.)

Keep in mind, this fuse only controls power to control the relay. NOT a fuse for the pump itself. Fuse number 3 in the PDC IS for the fuel pump feed. (at least, according to the 01 FSM.....)

 

Yeah, and, the 2004, 1996 as well so, the question is, why is there no FUEL PUMP fuse at the PDC on a 98. Is the 99 also like this as well - no FUEL PUMP FUSE? It's a 20A CKT so, I know by design, it's got to have fuse.

Normally, it's always located in the PDC and, it's located two above the FUEL PUMP RELAY in that same row / column (depending on perspective).

EDIT: After referencing some schematics of this CKT, here's what I found:

FUSE 3: is a 40A fuse and, is SOURCE TO the ignition switch thus, <IF> that were to blow, the vehicle would not even turn over. It would be totally dead.

FUSE 8: is a 20A fuse that supplies The PCM, the FUEL PUMP RELAY (coil) AND the TRANS solenoid. IF the TRANS solenoid is shorted, this would also blow the fuse thus, not energizing / switching the FUEL PUMP RELAY thus, NO POWER TO THE PUMP. This has to be good for, he had spark. If this FUSE were blown, THE PCM would have NO POWER thus, no power to the EFI system thus no power to the coil.

FUSE 9: is a 10A POST ignition switch that feeds a few CKTs such as the ASD relay, EGR and EVAP solenoids.

CM