1998 Jeep Wrangler (TJ) misses when the engine is cold.?

Feb 12th at 12:29 am By: jj

I have a 97 wrangler and have had both of these things happen.

First the hard start. This is caused by the check valve within the combined fuel filter/pressure regulator failing, and allowing the fuel line to empty back into the tank when it’s left to sit. Before starting it might help to prime the fuel line two or three times by simply turning the ignition on for a few seconds then off and on again. If that works you could either put up with it or swap the fuel filter/regulator.

You can get the filter here… http://cgi.ebay.com/ebaymotors/NEW-FUEL-PRESSURE-REGULATOR-1997-2001-JEEP-CHEROKEE_W0QQcmdZViewItemQQ_trkparmsZ65Q3a12Q7c66Q3a1Q7c39Q3a1Q7c72Q3a1683Q7c293Q3a1Q7c294Q3a25QQ_trksidZp3911Q2ec0Q2em14QQhashZitem27a54fbfa4QQitemZ170277191588QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

It requires dropping the tank to replace it. It sits on top of the fuel pump module, which you do not have to change, but you might want to get new strainers for the bottom of the tank and replace them. Fuel pump replacement showing how to drop the tank… http://www.dailydriventj.com/fuel_pump.shtml

The stumbling from cold starts is caused by the upstream oxygen sensor, and I can prove it’s at fault too. It’s in the exhaust pipe just below where it mounts to the manifold. Follow the wires up to the connector and unplug it. Try driving for a day or two and your problem will have vanished. Plug it back in and the problem will return. Replace the sensor to rectify the problem fully.