67 GMC
NAXJA Forum User
- Location
- Fort Erie, ON
1987 XJ, 4.0L, Renix, 4X4, AW4
Spent a lot of time on this already. Refreshed grounds, new TPS, new distributor cap, rotor, plugs, cleaned connectors etc. Jeep runs fine when cool. Starts fine. Fuel pump is noisy but when cold, every seems ok-can accelerate normally. When Jeep gets hot, I go to a no power condition. Can barely get engine to rev past idle. If I increase throttle, it backfires out intake and eventually dies.
We've had some good weather and it was running great every day. Yesterday was pretty hot and it was running fine and then suddenly it had no power and it would backfire through the intake if I stepped on it. Limped home and took a look at throttle body. Very clean etc. When I moved the throttle manually it revs up and then starts bogging down. If I move it quickly, it will backfire. I'm thinking it's a hot-wire issue. I've re-done the grounds, re-did negative battery cable to block, cleaned up dipstick grounds, cleaned up block to firewall ground etc. I had routed all of the wiring away from heat spots etc. It has a new TPS sensor. I just re-did rear shoes, drums and wheel cylinders, front ball joints and u-joint, new e-brake, so I've got money in it now.
Thinking it might be coolant temp sensor, knock sensor or O2 sensor but not sure. Did the fuel pressure at the rail and it goes to zero when I move the throttle plate open but could it be the ECU telling it to back off on pumping if the sensors are saying the engine is cold? Kind of stumped at this point.
Willing to change fuel pump but don't want to rule out sensor issue first.
Thanks!
Spent a lot of time on this already. Refreshed grounds, new TPS, new distributor cap, rotor, plugs, cleaned connectors etc. Jeep runs fine when cool. Starts fine. Fuel pump is noisy but when cold, every seems ok-can accelerate normally. When Jeep gets hot, I go to a no power condition. Can barely get engine to rev past idle. If I increase throttle, it backfires out intake and eventually dies.
We've had some good weather and it was running great every day. Yesterday was pretty hot and it was running fine and then suddenly it had no power and it would backfire through the intake if I stepped on it. Limped home and took a look at throttle body. Very clean etc. When I moved the throttle manually it revs up and then starts bogging down. If I move it quickly, it will backfire. I'm thinking it's a hot-wire issue. I've re-done the grounds, re-did negative battery cable to block, cleaned up dipstick grounds, cleaned up block to firewall ground etc. I had routed all of the wiring away from heat spots etc. It has a new TPS sensor. I just re-did rear shoes, drums and wheel cylinders, front ball joints and u-joint, new e-brake, so I've got money in it now.
Thinking it might be coolant temp sensor, knock sensor or O2 sensor but not sure. Did the fuel pressure at the rail and it goes to zero when I move the throttle plate open but could it be the ECU telling it to back off on pumping if the sensors are saying the engine is cold? Kind of stumped at this point.
Willing to change fuel pump but don't want to rule out sensor issue first.
Thanks!