Those with YJ Electric fuel pump experience

[fgcox1]

I have a 93 base YJ, manual trans 4.0 that is getting no fuel pressure at the rail. I have 12vdc at the fuel pump relay and it is switching just fine. I used clip leads to hook it up separate from the PDC and got 12vdc out of it.

The FSM electrical manual shows an indication of a black connector at the right rear of the engine that carries the voltage to the pump but I haven't been able to locate it. It doesn't indicate either high or low behind the engine but I didn't see any connector either place.

I want to check voltage at the pump first without dropping the tank but cannot figure out how to get to the connector, short of either dropping the tank or cutting an access hole in the rear tub floor.

I have read a few mentions of folks who apparently have gotten to the tank connector but it is not clear if they dropped, or partially dropped the tank or were able somehow to reach it with the tank in place..

If there isn't any other way I will drop the tank but just am curious if I have missed anything that would make it easier?

Tnx Fred in Mesquite, TX

[chuckp]

I don't think there is much chance of getting at it without dropping the tank. If you had a big body lift you might be able to get your hand up in there. Pretty simple to drop the tank, easier if you can siphon most of the fuel out.

[yj'er]

Went through that whit my 88 yj. Couldn't really find any easy way to check without dropping the tank. Turned out the pump was bad so the drop wasn't that bad. Easier to drop the tank than to keep fishing, Just my opinion though.

[pschneider]

On my 95 I was able to get at the connector in the back through the drivers wheel opening without dropping the tank. look real good between the frame and the tub I'm not sure if your 93's the same?

[Pokeman]

on my '91 its impossible to get to that connection with out dropping the tank, in fact I did just that last night

[AR_Guy]

It will be quicker to drop the tank.

[partsphil]

My 92 and 93 both have that connector accessible in the left rear wheel well. It runs along with the fuel lines on top of the frame rail. It is not the connector on top of the tank, but another connector in the harness.

[kloppk]

If the pump is getting power and working you should be able to hear it cycle on for a sec or two when you turn the key from OFF to RUN.
Have someone get under the rear of the Jeep and listen for it.

As others have said the connector is usually accessible in the wheel well near the frame.

[Jeeper_Dan12345]

Does your fuel gauge peg out at full? If it does you have a bad ground to the fuel pump. The gauge and pump use the same ground. It ground point is at the parking brake pedal mounting bolt. If the bolt is lose it will lose it connection.

[Jeeper_Dan12345]

Also when you turn the key on the fuel pump only runs about 3 seconds then shuts off. I was trying to drain my fuel tank one time and thought I would just turn the key on and put the hose in a gas can. It does not work. It will make you think you have other problems. If it does not detect the engine running the pump stops. There is a relay just like the fuel pump relay (next to it I think) that controlls this. I cannot remember what it is called without looking at a shop manual. I will try to look this up later. Check the ground first as I stated last posting.

[partsphil]

Here is a link to a previous thread that might help.

http://jeepsunlimited.com/forums/showthread.php?t=882101&highlight=FUEL+GAGE

[fgcox1]

You guys Rock!
:bowdown:

I'll check all tomorrow morning before it gets too hot.

I'll post what I find

Tnx Fred

[fgcox1]

It hit 102 so it really kept me from doing much. The jeep is in a metal commercial storage place that doesn't have any power hookups so I can't even use a fan!

Before I got too sweated up (I'm an old man) I discovered (by following above info) the connector just barely peeking out at the drivers side front of the gas tank. When I intially unplugged and checked I didn't have any voltage. I could get to it without dropping the tank! I plugged it back up and pulled the relays (fuel and asd) and jumpered the connections. The fuel pump came on but the fuel pressure was way slow coming up on the rail gauge. I figure that may be the filter or the pump so I will change the filter and hope for the best.

The jeep reluctantly started when the pressure got high enough. I let it run for a while to warm up and noticed the fuel gauge stays pegged at full (ground probably) and the temp gauge pegs max except when I rev the engine and it drops to zero ands then back up. That may be a separate issue.

I looked all around the emergency brake mounting bolts for the black/yellow ground connection and I'll be darned if I can locate it. I found the emergency brake switch wire fine and also traced the black/yellow wire up the harness from the floorboard as far as I could but got too hot to stand on my head in the floorboard to trace it all of the way. It almost looks like the wire was going into a pretty good sized connector just above and to the left of the emergency brake.

Anybody know if the later (93, 94, 95) Wranglers changed the ground location?

Anyway, by this time I was too drained to do anything else and went home.

I came back this morning (still hot) to continue. I did everything the same as yesterday (jumpers, etc) but no fuel pressure again. I also noticed the ignition switch feels real funky (sticky, hard to turn, uncertain feeling) and am thinking it may also be contributing to all of this.

Anyway, my plans are to swap the ignition switch, see of I can locate the fuel pump ground and verify it is good or bad, and check the cooland temp sender and gauge for problems.

Anything else I sould keep my eyes open for?

Again, thanks for all of the help!!

:bowdown:

[wcjp]

You've now spent more time worrying about the dropping the tank than it actually takes to drop the tank. Buy a new pump, drop tank, clean accumulated sediment. Now is a great time to add a Kilby or Warn skid plate. This is very easy to complete.

[fgcox1]

Well, well.

Learn something new everyday. The 93 and later Wranglers doesn't get their fuel pump ground at the emergency brake, it is on the engine ground on the right hand side of the 4.0 block, same place as negative battery cable. Found that little gem in the FSM. Cleaned and tightened, fuel gauge now stable.

Also, no or low fuel pressure coming up slowly problem was plugged fuel filter, pressure now at 30 +/-. Used a fiber optic camera to check tank for sediment, very little to be seen even with stirring and sloshing.

Imagine, all of that without dropping the tank!

As for "Now is a great time to add a Kilby or Warn skid plate." from wcjp, this is a daily driver just acquired. Don't think I will ever be going off-road so no need to waste money!

Like I said before, you guys rock