'93 Jeep Cherokee, 4.0, Auto


When driving the Jeep, I can only press the gas as little as possible or it bogs and starts breaking up. If I floor it, it completely dies unless I let off the gas. It starts and idles perfect, the issue only occurs when pressing the pedal to send more fuel


Already replaced are:


Plugs, gapped to spec
Wires
Coil
Temp sensor that sends to ECU
Fuel Filter
Fuel pump


Fuel Pressure reading at the rail is 31-32 @ idle, when the gas pedal is pressed the fuel pressure drops, it doesn't drop to any specific number, it just drops. I'm thinking the filter on the pump, other wise known as the "sock" is getting clogged up due to a dirty gas tank.


I'm pulling the pump out and dropping the tank tomorrow, any other ideas for me? After cleaning everything is seafoaming it worth anything?

 

I'd take a look at the pressure regulator first.

 

Schrader valve on the rail is before the fpr. I'm losing pressure at the Schrader valve. I don't see how it could go through the regulator and back to the Schrader but I've been wrong before! Can anyone verify this?

 

Pressing the pedal "sends more air"...that should be followed by the ECU arranging for more fuel to be added....and it sounds like you're not getting that.

 

Exactly.

 

Anyone else have any input?

 

You said it idles perfectly? No backfires or misfire or rough starts? Listen for anything rough. I've been working on my wife's 89 and I will be replacing the powertrain control module. Also check and clean all of your throttle body and components. Check your iac and make sure that butterfly valve looks good and isn't loose

 

Check the fuel filter, on a '93, it should be under the drivers side, along the rail in front of the tank. It could also be your TPS. You can check that with a meter.

 

Check codes eliminate all ecu controlled sensors .

 

to me it kinda sounds like what people are saying. Some type of sensor. You have a TPS,CPS,MAP, and I think some type of idle position sensor. I always check all my fuses when I'm having trouble with stuff just to make sure.

 

Thanks for all the reply's. We pulled the tank and warranted the pump out for new one. It is an airtex pump, I've read that some guys have had nothing but trouble with them. They do have a lifetime warranty on them so that's good.

We cleaned the tank and put new pump in along with some seafoam and sure enough, it runs like a top.

 

You didn't just replace it with another Airtex pump did you?

 

I had a similar issue about a year ago and replacing the TPS completely cured it. Pretty scary when your jeep dies in the middle of a busy intersection.

 

Yep, TPS could be doing all this too.

 

Yes we did just replace it with an airtex for a number of reasons, the main reason being it was 8:00 and Autozone had one ready for us to pick up. I also believe that the main cause of the issue was the corroded tank. The tank was full of rust and other sediment. It also had the sock and pieces of rubber in it from the factory pump. The first airtex had gotten noticeably louder over the 2-3 weeks it was in there from what I believe was it being plugged up. With the tank now clean, some seafoam and fresh gas, this pump is almost silent. Also the fact that for me to pull a fuel pump or tank on one of these jeeps is literally a 10 minute job, if it fails again, its not that big of a deal and a Bosch will be going in.