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Discussion Starter · #1 ·
So I believe my fuel pump has finally seized on me. I headed over to Autozone to check their prices along with RockAuto. Autozone doesn't even have a fuel pump in their computer for a '98, but they do have one listed for a '99. RockAuto has one for a '98 but it's listed at $480(!).

I recall reading a while ago that in '99 they switched the gas tank to a plastic one and reduced the capacity by 1 gallon. In that same thread I believe someone mentioned having a different retainer mechanism on the top of the tank.

My question is - is a '99 fuel pump compatible w/a '98, despite parts listings? If it isn't, then would a '99+ plastic fuel tank bolt up to a '98?

EDIT: The issue was not the fuel pump, but for some reason no power getting to it. I'm currently investigating why this is happening. Read through the thread to see what I'm doing.
 

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Discussion Starter · #3 ·
Might as well try it out. Thanks.

I wonder what the deal is for every place with a parts listing just skipping out on the '98...
 

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Discussion Starter · #4 ·
Well, I tried it out. Pump looks great. Still doesn't work.

I was lazy and only tested the fuse and relay for the fuel pump. Looks like I spent $90 and a few hours for no reason. Oops.

Any idea why the pump won't turn on if it's not the relay or fuse?
 

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Discussion Starter · #5 ·
Update:
I have done a lot of searching for my issue and what I've turned up was initially very promising but turned out (I think) to not be the issue.

The pump cut out on me on a somewhat hard turn into my driveway (exacerbated by the fact that I have no sway bars). I found someone with a similar issue that had their ECM fuse blow when this happened, causing the signal to turn on the relay to be lost. The other day my instrument cluster/taillight fuse blew on me for no reason, so I thought there might be something shorting on me. Unfortunately, there are no blown fuses in the engine bay. Tonight I'm going to check that I'm getting power on the fuses I would expect to have power in the on position, and I'm going to verify that the wiring to the pump from the relay is OK by jumping it.
 

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Problem Solved. If Isuzu had fixed it they would have replaced the wiring harness and charged a fortune. Theres no telling how many wiring harnesses have been replaced to fix this problem. After testing almost every circuit with a repair manuel to no avail, I was working with a technician friend who undone the computer from its cradle and moved it up and toward the front of the engine. A squeel started and low and behold it started. Trying to get the problem to repeat itself, their are 4 multi pin connectors on the left front fender (drivers side). Two of these connectors can shut the engine down. Unplug each connector and reconnect one at a time. Try to start. This fixed my problem

i picked this up from another site , also i think your rodeo has a fuel pump cutoff switch that cuts the fuel pump off in case of a accident or roll over. bad switch/connector ??
 

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Discussion Starter · #7 ·
I'll try playing with the engine harnesses when I get home. I believe I only have 3 because it's not an automatic (black, green, and blue?).

I tried googling around but couldn't come up with where this fuel cutoff is, but I did find the sensor for sale in many places. Does anyone have an idea where it might be located?
 

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Discussion Starter · #9 ·
If it's part of the pump assembly (which the float arm is part of), then that has just been completely replaced with new stuff, so that is unlikely to be it.
 

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There is a rollover valve mounted in the gas tank vent which is connected to the charcoal canister. If the tank is inverted it seals the tank. The electrical schematic does not depict any kind of a switch that would disable the fuel pump. On 98 Rodeo the pump will run only as long as the ECM receives a 58x signal from the Crankshaft Position (CKP) sensor which is generated as long as the crank is turning, the ignition is in the run position and there is voltage available to generate the sensor reference voltage. The ECM will also start the pump for two seconds after the ignition switch is placed in Run/Crank position to prime the injectors for startup.

The ground for the fuel pump relay goes though fender connector H-5 Pin 14. The +12 VDC signal to energize the fuel pump relay comes directly from the ECM. The fuel pump relay provides +12 VDC to the O2 sensor heaters and fuel pump when energized.
 

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Discussion Starter · #11 ·
Sigh. As it turns out, I'm stupid. :banghead:

After I checked the ECM and fuel pump fuses visually, I did a quick check of every other fuse in the car with a multimeter set to continuity across the top check pins. Unfortunately I didn't really consider that as long as they're plugged in, the two sides of the fuse would be connected in another way through the car.

Instead of the ECM fuse blowing, it was the Electric Ignition fuse. Discovered this after noting that the ECM relay wasn't switching, and once I jumped it, all was well.

Thanks for all the help, everyone. This place has been good to my Rodeo :)
 
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