Fuel Pump Issue (Renix - no start)

Another Renix no start thread! Arrgh!! Okay here's it goes: I went to start my 90 XJ the other night after getting out of work, I turn the key to the "on" position and I hear no fuel pump hum - strange. Turn the key to start, 4.0 cranks over clean but doesn't start.

Long story short, I end up disconnecting the battery for about 15 minutes and unplugged and re-plugged in the wiring pigtail underneath that connects to the fuel pump. Lo and behold it starts and runs fine....for about a week - weird, but okay....so I come out the gym on Monday to head home and same thing happens - no fuel pump prime and no start. I disconnect the battery again/wiring pigtail and after a few minutes - voila! It starts and runs fine until..today.

A little history, I replace the fuel pump with the NAPA replacement in the spring of '07 after trying a number of other "no start" suspects, the CPS and the CPK to no avail. The Jeep has run like a champ other than that. I kinda find it hard to believe that the pump crapped out again already...not sure exactly why the battery disconnect method has been working so far.

Any ideas or suggestions what I should be looking at? Thanks in advance!

I'm confused.

You unplug and plug a wiring harness connection in a high-corrosion area and the fuel pump works--right?

Sounds like your problem is a corroded wiring harness connection too me. If that is the case you can 1) eliminate the connection by soldering the wires together, 2) extend the harness so that the connector is further from the battery, then clean it and coat it dielectric grease, 3) keep unplugging and plugging that connector.

Could some body tell me where that connector is? I have a 96 xj,and the fuel pump doesn't come on.The fuel pump was recently replaced.

Dirty Bill said:

Could some body tell me where that connector is? I have a 96 xj,and the fuel pump doesn't come on.The fuel pump was recently replaced.

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Renix = 87 to 90.

Not sure if you have a connector that is similar, but on the Renix it is under the battery.

Old cars have old wiring. The connection is most likely the culprit - each time you disconnect, you scrape corrosion off the terminals and get good voltage again.

After 19 years every loom connection starts looking like last years battery terminals. It's the major cause of voltage drop, bad door locks, weird fuel injection symptoms, and no starts. It's also the No. 1 killer of cars when submerged Katrina style. Bad ground connections are a big part of all that, too.

Premium wiring harness construction is not a goal of our throw away society, and Cherokee owners won't get any reprieve the longer we hold on to them.

A can of Coke will do wonder for the corrosion. Just make sure to pull theground off the battery

I appreciate the responses! I'm sorry I couldn't reply earlier as I don't have regular access to the internet. As for the wiring pigtail I'm referring to...it's located actually underneath the vehicle right in the same vicinity as the fuel filter.

But now I've eliminated that wiring connection as the culprit as well, now when I get the "no start" issue I can just disconnect the battery for about 10 minutes and then reconnect it - starts on the first try. Battery terminals and connections are very, very clean. I'm going to keep reading up and see what I can find. I appreciate all the help fellas!

Still might be wiring or ground at the mains.
Every time you move the wiring rights the problem.
Try to clean up your mains, grounds, and relays.

joe_peters said:

Renix = 87 to 90.

Not sure if you have a connector that is similar, but on the Renix it is under the battery.

Click to expand...

What "under the battery connection" are you talking about? The only one close to that location is headlights that I know of?

Wildcat, there is a relay near the battery. It is one of 4 on the passenger side. The starter switch is also a possible problem area.

I would bet on corrosion & dirt at the relay, or relay contacts, and I would tighten up the pigtail contacts at the fuel pump again. Ammonia is great for cleaning brass contacts after a spray wash with aerosol solvent. Try tightening the female pin contacts with needle nose pliers.

I have had the same problem twice, each time a year apart. So far cleaning and tightening the female contacts on the fuel pump pigtail fixed mine.