92manche Posted October 4, 2021 Share Posted October 4, 2021 1992 comanche 4.0 5 speed sat for 4 years with a bad fuel pump. Pulled it out of the weeds recently to get it running. Dropped the tank did a full cleaning, new pump new filter and she fired up. On the second drive she started sputtering and missing at about 40mph and it has drastically gotten worse. Takes a second to start but idles fine, will rev up fine in neutral as long as I'm easy on the throttle but once in gear it falls on its face throughout the whole rpm range. Spits sputters back fires through the intake, and won't gain speed. Sometimes if you keep it floored it will get through the sputtering and bucking and just take off with all the power in the world. Like I said new fuel pump, new filter, since the problem occurred ive replaced tps, cap, rotor, wires and plugs Link to comment Share on other sites More sharing options...
jdog Posted October 4, 2021 Share Posted October 4, 2021 Have you checked the map sensor? Vacuum at idle? Fuel pressure? You said new pump, what about the hose between the pump and the sending unit? Link to comment Share on other sites More sharing options...
92manche Posted October 4, 2021 Author Share Posted October 4, 2021 2 hours ago, jdog said: Have you checked the map sensor? Vacuum at idle? Fuel pressure? You said new pump, what about the hose between the pump and the sending unit? Replaced the pump and the in tank hose, waiting on a fuel pressure gauge. Read about the map but unsure on how to check it, explain the vacuum at idle as well? Link to comment Share on other sites More sharing options...
jdog Posted October 4, 2021 Share Posted October 4, 2021 Need a vacuum gauge to see what it's reading 2 hours ago, jdog said: Have you checked the map sensor vacuum line? Link to comment Share on other sites More sharing options...
gogmorgo Posted October 4, 2021 Share Posted October 4, 2021 Have you checked for fault codes? Link to comment Share on other sites More sharing options...
92manche Posted October 4, 2021 Author Share Posted October 4, 2021 1 hour ago, gogmorgo said: Have you checked for fault codes? Only showing fault 12 and 55 Link to comment Share on other sites More sharing options...
gogmorgo Posted October 4, 2021 Share Posted October 4, 2021 Check your fuel pressure. I've had a few things cause similar behaviour. One was the cam sensor in the distributor. It was a little while driving with it doing that before it triggered code 54. When you had the cap and rotor off, did you wiggle the distributor shaft to see if there was any play in it? The other thing that immediately comes to mind is when the fuel pump was dying. I know you've just changed all the fuel parts, but there are things that could cause all new parts to fail, and it needs eliminated. Link to comment Share on other sites More sharing options...
92manche Posted October 4, 2021 Author Share Posted October 4, 2021 1 hour ago, gogmorgo said: Check your fuel pressure. I've had a few things cause similar behaviour. One was the cam sensor in the distributor. It was a little while driving with it doing that before it triggered code 54. When you had the cap and rotor off, did you wiggle the distributor shaft to see if there was any play in it? The other thing that immediately comes to mind is when the fuel pump was dying. I know you've just changed all the fuel parts, but there are things that could cause all new parts to fail, and it needs eliminated. Working to get a fuel pressure gauge asap! I did not wiggle the shaft much when changing the cap Link to comment Share on other sites More sharing options...
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