won't start when cold

My 1992 Jeep Cherokee Laredo will not start when it is cold. (less than 40 degrees F)
It will crank but I do not get power to the fuel pump.
If I leave the key in the start position, eventually (15 min - 1/2 hour) the fuel pump relay starts clicking louder and louder, then the fuel pump comes on. About a minute after that I can start the engine without it stalling. If it is really cold (0F), it will stall while driving.

Only when it is cold out.

Please help

My 1992 Jeep Cherokee Laredo will not start when it is cold. (less than 40 degrees F)
It will crank but I do not get power to the fuel pump.
If I leave the key in the start position, eventually (15 min - 1/2 hour) the fuel pump relay starts clicking louder and louder, then the fuel pump comes on. About a minute after that I can start the engine without it stalling. If it is really cold (0F), it will stall while driving.

Only when it is cold out.

Please help


I cleaned the ballast resitor, didn't help. I pulled the 2 green wires off the ballast resistor and it still starts. Is this normal?

Yes, it will start without the ballast resistor but may not idle unless you jumper the 2 wires so there's still a circuit.

How did you determine the pump has no power? Have you changed out the relay?

Most likely the pump wont be getting constant power and will only get any power while the engine is cranking over.

Have you looked at the IAC Motor? Idle Air Control this acts like a choke.

Its just shooting in the dark unless you are 100% it is fuel related.

<quote>How did you determine the pump has no power? Have you changed out the relay?</quote>

I tested for voltage at the connector near the fuel filter with the key on and while cranking. No voltage present. After the clicking routine ends and the fuel pump comes on, I get 12 volts at the same connector.
Yes, I did replace the Fuel Pump Relay. And also the Fuel Pump.

I'm thinking it may be the Neutral Safety Switch. I also do not have Backup Lights prior to the clicking in the relay box.

How do you take the relay box off?

<I'm thinking it may be the Neutral Safety Switch. I also do not have Backup Lights prior to the clicking in the relay box.

How do you take the relay box off?

I cleaned and tested the NSS - it's fine, vey cleaned and lubed wit di-lectric grease.
Still have the same problem, it won't start when it is cold out. It's geting worse because it doesn't have to be that cold anymore.

It's got to be a wire or ground. I never traced a wire in a car harness before. looks scary, don't even kn where to start.

Please help!

<quote>How did you determine the pump has no power? Have you changed out the relay?</quote>

I tested for voltage at the connector near the fuel filter with the key on and while cranking. No voltage present. After the clicking routine ends and the fuel pump comes on, I get 12 volts at the same connector.
Yes, I did replace the Fuel Pump Relay. And also the Fuel Pump.

I'm thinking it may be the Neutral Safety Switch. I also do not have Backup Lights prior to the clicking in the relay box.

How do you take the relay box off?

I think I found the problem... A friend said it could be the ignition or key. If I jiggle the key while turning the ignition back and forth from ON to ACC, I have found a spot just before ON where the fuel pump kicks right in. Then after a few seconds it starts.

But now,
I have a blown radiator and a hole in the exhaust manifold.
I'm putting her away for the winter. Outside. South West New Hampshire
Any suggestions on storage techniques?

Yep, sounds like the ign switch.

I think I found the problem... A friend said it could be the ignition or key. If I jiggle the key while turning the ignition back and forth from ON to ACC, I have found a spot just before ON where the fuel pump kicks right in. Then after a few seconds it starts.

But now,
I have a blown radiator and a hole in the exhaust manifold.
I'm putting her away for the winter. Outside. South West New Hampshire
Any suggestions on storage techniques?


Sorry to hear about your continued problems with the jeep. I know its been a while since anyone has replyed to this thread but I figured I'd give it a shot. I have a 1992 cherokee that is doing the exact same thing.
It runs fine but will not start in the cold ( below 20 ) until I can get the fuel pump to kick on. The same symptom that you described with the relay slowly getting louder and then the pump humming. At that point I hear the pressure build at the fuel rail and then it will fire up. I have also replaced the pump, as well as the relay. I was leaning towards the ballast resistor and then found this thread. Did you ever determine if or not it was the switch? Any advise is appreciated.

Hey,


Where is the Ballast Resistor and what does it do?

There's a "thing" on the driver's side fender with two wires attached to it; right next to the EGR Solenoid and a relay. Is that it?

Thx, Phil:)

Hey,


Where is the Ballast Resistor and what does it do?

There's a "thing" on the driver's side fender with two wires attached to it; right next to the EGR Solenoid and a relay. Is that it?

Thx, Phil:)

If memory serves correctly the ballast resistor was on the firewall. It was either near the center, or to the passenger side. It should have orange wires on both sides. It was used on Renix Jeep vehicles to drop the running voltage to the fuel pump. They were trying to reduce complaints of noisy electric fuel pumps. The starter bypassed the relay to keep full voltage available to the pump during start up.

The truck would start and die if it's unhooked or defective.

Older Chryslers used it to reduce voltage to the coil. They changed to a coil with internal resistors.

I am not sure if they still used it after the switch to Chrysler electronics in '91-'92. Brain's getting foggy..