newjeepguy33

Thanks for all the input!! I have narrowed it down to the fuel pump not getting power. Relays and fuse seem to be good. Chasing out the ground right now. Wires on the outside of the unit are in good shape. Cant find any broken grounds. Any ideas where the ground for the fuel pump ends up? And are there any grounds that are hard to spot and might be easily overlooked?

cruiser54

Yes. Behind the trim panel that's behind the spare tire. Why not check with a meter?

newjeepguy33

is this the ground hard to find or the one for fuel pump? and I have no meter
where this problem came directly after hitting a sunken culvert hole, I have been looking for loose/broken items.


Just for good measure I even took apart the NSS and cleaned it.


Could the jarring have killed the fuel pump?

67 GMC

There are many things that could cause this...but if you don't have a basic voltmeter at the very least, you can't even start figuring out what has power and what doesn't. Even if you hear the relay click, how do you know the contacts inside are energizing the circuit.
Walmart sells a basic voltmeter for under $20-so does Autozone. You absolutely have to have one if you are going to do anything with these Jeeps other than driving them. Your Jeep is almost 20 years old and lots of things can suddenly break, grounds come loose, wires cross, sensors go bad etc.

That will be the best $20 you ever spent.

cruiser54

I think you should get a meter and learn how to use it as 67GMC encourages you to do.

But, if you insist on using the Fred Flintstone method of diagnostics, here's the location of the ground.

newjeepguy33

Hey, what do you want , I've never needed a meter until now lol. I'll get that meter and get back to you folks.


Thanks for all the help thus far. Even though I have yet to fix my fuel pump, I have found a few new minor problems that have been easily fixable.

cruiser54

That, my friend, is called progress.

BillyBoy

You can always lick a wire to tell if it's hot...
I've even seen some guys that can tell you the roundabout voltage using this method...

Unfortunately, when they tell you what it is, they usuall slur.

"Itttfffsss abOUT foooooty ammmmppzzzsš."

Really, harbor freight has meters on sale for about 10$. Your dad or gramps might even have one in a box somewhre if you ask. Then, search ome youtube vids, and learn the biz.

Good luck, have fun.

Btw, my wires broke to my fuel pump at the connection going to the tank. Might be loose. Cleaning spray works wonders in that area for your connections also. Just sayin.

newjeepguy33

All right... so I bought myself a new multimeter. I checked the resistance (ohms) at the fuel pump wire harness. I get 1.1 - 1.3 ohms to that point. I'm going to assume that my fuel pump is shot. Is this a good assumption or should I be checking other possibilities?

cruiser54

What are you checking? I'm lost.

ajk0204

There are several suggestions out there ranging from ground to NSS to fuel pump connections...only thing you can do is try to step through one at a time. I would get out my trusty multimeter and see if the fuel pump is getting power for starters.

newjeepguy33

I hit a sunken culvert hole in the road. Jeep stopped running. Will turn over but not start. Fuses and relays good. Wiring and grounds good. Sensors seem ok. Every other electrical component is in working order, which is a good indication I have no bad grounds. One of the other members, 67 GMC, suggest I get a multi meter. I did. So I checked all pertinent wiring with it. I unplugged the fuel pump, checked the resistance, and they where in normal operating range. Still no power to the pump. So I'm guessing I need a fuel pump.?.?


Also my oil dummy light is on. Is there a low oil pressure shut off? The vehicle was low on oil at the time of incident. I have since filled it, but light stays on.


I feel like this Jeep is a can of worms. For that matter we wont talk about the needed body work under the carpet


Please forgive the ignorance on some things. I am not a mechanic. This is all a big learning experience for me. I truly appreciate all the help so far.

DFlintstone

OK, take it one step at a time. It takes a while to get familiar with a meter.

"resistance", just checks the "continuity" if a wire, (or anything). For instance you would hope to have around one ohm between any metal on your engine and the Battery negative post. (meaning it's connected/grounded well). (or the fuel pump ground wire, and ground)

You have two voltage ranges, DC (for your Jeep) and AC, (for your house). Often the deal has a wiggely line, ~ for AC, and a flat one for DC --. The DC 20 volt scale is the one you would use to check power/voltage. You ground the black lead, (harder than it sounds, I might file or scrape the frame to be sure I'm getten to metal), then you can check for voltage with the red lead. For starters, just check the voltage of your battery. Should be around 12.5 sitting and 14 running. (I "get it", yours doesn't run, yet!)

Once you handle that, see if the power wire to the fuel pump is getting power. Since it only powers up a second when the ign is turned on, you probably will need a helper.

(Btw, the other end of that power wire ends at the fuel pump relay socket)

The whole metal frame of the Jeep and the engine is connected/grounded to Battery Negative, (hopefully). If the Positive touches it, it will short and blow a fuse, or start a fire.

67 GMC

Get the wife to turn the key while you have the multimeter set for DC volts probing the harness to the fuel pump. You should get around 12V for a few seconds if the relay is clicking and sending power to the harness. You may very well need a new fuel pump but try the easy stuff before putting big bucks out and swapping out good parts with new parts. Have you got a Haynes manual? There's some good trouble shooting stuff, a section on electrical stuff, wiring diagrams etc.

DFlintstone

Like GMC says, if there is no power, changing pumps won't help! I'm not familiar with how many wires are there and which are for the gauge sender.