Chick-N-Picker

1989 Jeep XJ Pioneer 4x4 auto 81,000 miles


Well it's out again. I ran a new ground wire just as Cruiser said in my last thread 3 weeks ago and it's still going out. It started humming really loud again today.

It's like clock work. Every 200-300 miles it started humming then goes out. This leads me to believe that it is a constant issue causing it to burning out at exactly the same intervals. Maybe it's voltage related.

Correct me if I'm wrong but the only 5 things that effect the fuel pump is.
1. The pump
2. The tank(trash)
3. The ballast resistor
4. The harness/ground wire

Should I put another in and get a new ballast resistor or just bypass it? Could the BR even cause it to keep burning it self out every 200-300 miles? I really need help because I know eventually the auto parts store will quit letting me exchange these. I'm sure you guys can talk me through how to figure this out.

Rambler65

I would definitely check what voltage you're getting at the pump's electrical connector.

From what I've read a lot of guys just bypass the ballast resistor but I'm not authority on that so you'd want to do some checking on it.

Jeep Driver

I suggested you replace your resister in your last thread...........did you?

DFlintstone

I hear sometimes an assembly line can keep cranking out the same fubar part. They may check one in 100, but still defects get through. Wonder if your store has a box of crap pumps. Cruiser says the resistor was only added to quiet the pump after customer complaints.

Fuel in the tank helps cool it. You are not driving around always under 1/4 thank we assume....

cruiser54

Are you using Airtex or Carter pumps?

Ballast resistor being bypassed ain't causing an issue, unless the jumper is crappy and not letting full voltage to the pump.. Check the voltage as suggested.

Got the internal hose clamped properly so it can't suck air?

Chick-N-Picker

The pumps are from NAPA so they are supposed to be Carter but on the pump it's a sticker that says Airtex.

I do not or have not had the ballast resistor bypassed. I was asking if it was bad and hooked up if it could cause this issue? Sorry for confusion.

I'm fairly certain I have the pump installed and all hoses hooked tight.
The fuel pump is what was bad in the jeep when I got it and it had stock pump. So I know it was installed correctly. The issue ruined the stock pump so I'm fairly certain it's a constant such as voltage burning the pump.

How do I check the voltage? Just simply back probe the connector near the back tire? What voltage should I have?

Chick-N-Picker

Well on the first ones I was but on the last one, no. I kept more fuel in it to try and rule that out. Even though I didn't think that was it.

Also the first 5 pumps came from 1 Napa. The last from another and the next will be from another. I'm store hopping just in case what you say is true. Also the first store was getting nervous about changing the pumps. At the moment I don't have an extra $100 laying around so my receipts are a life saver.

Chick-N-Picker

No. I did the ground wire fix first. I was hoping that was it. I should have just done it anyway just to rule that out as well. I will certainly replace or bypass it this time.

jordan96xj

During any of the swaps have you taken the time to thoroughly clean the inside of the tank?

If the tank is not clean it can cause premature pump failure because it works extra hard to provide the same level of pressure as particles build up on the sock or in-tank filter. I would think a clogged up external fuel filter would also contribute to this problem. This will probably be indicated by a higher than normal amperage draw from the pump (I'm sure the pump can be researched to determine the normal amperage it should be drawing under routine conditions and pressures).

Here is an article covering this type of testing:
http://www.underhoodservice.com/fuel...-current-draw/

Airtex is routinely cited as a brand of fuel pump to avoid at all cost on the forums. I would do whatever you can to make sure you are not using this brand (no matter what brand is stamped on the box). If you are saving some money, great, I get that. But its not worth the trouble its putting you through if its just a bad provider.

Chick-N-Picker

I agree with everything you said about airtex but they don't make Bosch assemblies for the year 89 and I didn't have $400 for a dealer pump so it's one those things and now I'm stuck with it.

As far as trash going into pump. I thought that may be it but if it was trash in the tank wouldn't that cause it to go out at varying stages as it sucked trash. One at 100 miles and then one at maybe 400 miles depending on how fast it sucked trash? Instead it constantly goes out at exactly the same intervals. Just brain storming . Not saying it ain't trash

jordan96xj

I'm not talking about trashing getting INTO the pump, just that the pump is working harder than it was designed to in order to provide a specific fuel pressure. This would lead to failures at various intervals as you have described.

I'm almost certain given all you have described that an amp-draw test on your pump would show that it is pulling more amperage than would be expected. Like any electric motor, it can operate at higher amps for short periods of time, but it will die quickly if subjected to that constantly.

Did you check out the article?

Chick-N-Picker

Ok. Just read the article. It doesn t fail at various intervals but at exactly the same one everytime.

I need to try to do these test. But is it saying I need leads on my multimeter long enough to go from the battery all the way to the connector at the back tire to perform this?

Also I went out and checked the voltage on my connector.

From wire C (red lead) to wire A (black) I had 8.9 volts at idle and from wire B (red lead) to wire A (black lead) I had 1.18 volts. I reckon I did this correctly.

cruiser54

red lead to red wire at fuel pump harness. Black lead to ground.

TempBlueRidgeMark

Those numbers are ugly. I'm not sure if you measured correctly or not, but I can't think of any way you should be seeing those numbers.

I suspect you have some corrosion somewhere in your wiring harness going to your fuel pump. This would create a high resistance, which will fry an electric motor.

Same idea as having the sock plugged, but for a different cause. You are working the motor way too hard, and it dies an early death.

Chick-N-Picker

Hey I just want to thank all you guys for helping me.

Do you have any idea what voltage I should see at idle?
How the heck do I check the full harness because it goes up into body/frame?

EDIT:
I just went to check voltage again and when the key turned to the accessory position the voltage spiked (normal) to 6 volts then went to 0.
Then I started the jeep and it went to 8.9 volts again and held steady at idle.

I then bypassed the ballast resistor and rechecked. In accessory it spiked to 12 volts the back to zero. Then I started the jeep and it went to 13.2 volts and held steady at idle.
What does this mean?