Hey guys well gave me the run around even broke down took it to shop. It gave them the run around. Tested the replacement parts. So I know that they are good and some of the old parts are good. Great compression and had them scratching there heads. The fuel psi gauge drop to zero and didn't hold psi. Replaced the fuel pressure reg it got better. But still acted up I have the advanced evap. Gem motor. I picked up new fuel pump senser unit replaced it today. Done fix no issues, no high idle, doesn't drop psi, doesn't start rough or mis fire. This thing runs like a champ now.

 

I'm not a mechanic, but own a 98 and had some issues. I found that the ecu in front of the glove compartment had been getting wet due to a hole in the fender below it. I took it out opened it up- not too hard and found a lot of corrosion. I carefully cleaned it out,
checked for anything loose- solder jts. then reassembled, with sealant around the joint reinstalled, after checking the plug too and cleaning it up, and it solved quite a few issues.
Now I'm thinking of doing that to some of the other modules with many wires leading to them under the front seat and steering wheel.

 

I find I have to replace O2 sensors much more often than I should.
I do lend the truck out so worry that they don't want to pay for 93 octane, but
I think it's more- maybe something in the fuel- E85?
Now I have an issue I can't figure out- tail lights and running lights not working, so cannot drive at night. Many mechanics in my area refuse to work on these. They say as soon as something is fixed something else goes. I've found that too - always needing something. I suspected maybe they are not disconnecting battery ground and might be part of it.

 

Aftermarket bumpers? If so, wires for running lights that were eliminated may be shorting. Obviously check fuses too. If thats not it get out the voltmeter. These aren’t complicated vehicles.

 

Robert Thanks for the reply.
I looked at all fuses and seemed ok. They are original bumpers. I had replaced both of the rear tail light housings, checked bulbs, no corrosion, but it is possible that some of the lights in the bumper are not working. I'll have to look at those wires.
-Geoff

 

To knbaudio what exactly is a fuel pump sensor unit. I have the same exact issues with the high idle and hard starting and have now ended up extending the idle air control valve to it's longest position and reinstalled it but left it unplugged. This fixes the high idle but the truck wont always start quickly. Advice would be appreciated thanks.

 

Auto correct changed fuel pump sender unit it the tank. The whole unit has check valves in it. I was told by dealer it's a none serviceable unit for the advance evap gem motor. After taking the old one out my fuel gauge acting up was a wire going bad on the sender. I took the bottom off the sender and the filter sock was real dirty 175k miles on my disco1. The pump looked like I could have replaced even though I was told it couldn't. But the check valves molded in and were shot. So I finally won one off eBay and saved $600- $800 from factory unit.

 

oh ok cool so I just replaced my fuel pump motor with the airtex e3270 style pump. (one from ebay) and now the truck always starts on the first crank now, which is great. But I haven't yet plugged my iac valve/ stepper motor back in to see if the idle issue has been corrected. Should I ? lol

 

ok so replaced the fuel pump and now the truck starts up the first time, but I always need to step on the gas pedal to keep it running until it warms up. And with the IAC connected it will still idle high, checked to mass airflow sensor with a voltmeter/multimeter today and it seemed to be working fine. Any suggestions on what else to check for a high idle? Thanks

 

search for high idle on this forum - some have found it to be the vehicle speed sensor - others just a reset of the adaptive settings