Posted: 1/6/2013 7:12:24 PM EDT
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In my jeep I've got a 4.2 with a TBI from chevy 4.3 (Howell Kit).
It'll drive about 5 miles and then start cutting out and eventually die. Even if I let it warm up. No mater if It takes an hour it seems to do it at about 5 miles. What would cause this? My only thought could it be fuel pressure related? Other than that I'm out of ideas. |
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I would first suspect fuel issues. I suspect that something is causing the fuel system to have just enough pressure to keep a decent idle but the pressure falls when fuel demand rises. I would try to get your hands on a fuel pressure gauge and see what the fuel pressure actually is and does while driving (if possible).
Any chance that you have contaminated fuel or a rust in the gas tank? |
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I would first suspect fuel issues. I suspect that something is causing the fuel system to have just enough pressure to keep a decent idle but the pressure falls when fuel demand rises. I would try to get your hands on a fuel pressure gauge and see what the fuel pressure actually is and does while driving (if possible). Any chance that you have contaminated fuel or a rust in the gas tank? I plan to buy one in the morning and test it out. It's new gas and it's done the same through a few tanks full. It could be rust in the tank. I definatly won't count that out. I may pull it tomorrow and check that out as far as I know it's the original tank from 78. |
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I would first suspect fuel issues. I suspect that something is causing the fuel system to have just enough pressure to keep a decent idle but the pressure falls when fuel demand rises. I would try to get your hands on a fuel pressure gauge and see what the fuel pressure actually is and does while driving (if possible). Any chance that you have contaminated fuel or a rust in the gas tank? I plan to buy one in the morning and test it out. It's new gas and it's done the same through a few tanks full. It could be rust in the tank. I definatly won't count that out. I may pull it tomorrow and check that out as far as I know it's the original tank from 78. You should at the very least replace the fuel intake sock or screen while you have the tank out. It will eliminate one potential problem spot at least. |
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In my jeep I've got a 4.2 with a TBI from chevy 4.3 (Howell Kit). It'll drive about 5 miles and then start cutting out and eventually die. Even if I let it warm up. No mater if It takes an hour it seems to do it at about 5 miles. What would cause this? My only thought could it be fuel pressure related? Other than that I'm out of ideas. Im assuming this fuel injection has at least one oxygen sensor. Unplug upstream oxygen sensor(s). And drive it. After the car warms up it goes from open loop to closed loop and begins to look at oxygen sensor data and if sensor(s) is bad it could cause problem you describe. |
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I would first suspect fuel issues. I suspect that something is causing the fuel system to have just enough pressure to keep a decent idle but the pressure falls when fuel demand rises. I would try to get your hands on a fuel pressure gauge and see what the fuel pressure actually is and does while driving (if possible). Any chance that you have contaminated fuel or a rust in the gas tank? I plan to buy one in the morning and test it out. It's new gas and it's done the same through a few tanks full. It could be rust in the tank. I definatly won't count that out. I may pull it tomorrow and check that out as far as I know it's the original tank from 78. You should at the very least replace the fuel intake sock or screen while you have the tank out. It will eliminate one potential problem spot at least. Will do. I planned on pulling it tomorrow anyway to replace the sender. Ill definately be doom this. Thanks. |
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In my jeep I've got a 4.2 with a TBI from chevy 4.3 (Howell Kit). It'll drive about 5 miles and then start cutting out and eventually die. Even if I let it warm up. No mater if It takes an hour it seems to do it at about 5 miles. What would cause this? My only thought could it be fuel pressure related? Other than that I'm out of ideas. Im assuming this fuel injection has at least one oxygen sensor. Unplug upstream oxygen sensor(s). And drive it. After the car warms up it goes from open loop to closed loop and begins to look at oxygen sensor data and if sensor(s) is bad it could cause problem you describe. I will do this as well. Will it stay in closed loop I'd assume then, with it unplugged. |
| It's gotten worse it'll no longer go more than a mile. I tried the o2 sensor, ruled it out. Hooked up my new fuel pressure gauge. Idles at 12(spec is 9-15), under load drops to 5-7. Pulled the tank and the sender looks good tank looks dirty but ok. Replacing the sender anyway while I have it out and the fuel filter(new but changing it anyway) and putting new gas in. Anything else I should be doing? |
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Had the same issue on two separate vehicles. Ignition coil was the culprit both times. While I won't rule that out and plan to change it too, that would explain the drop in fuel pressure. Unless under load it's normal for it to drop to about 5-7 pounds. At idle it's at 12 at all throttle levels. |
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Had the same issue on two separate vehicles. Ignition coil was the culprit both times. While I won't rule that out and plan to change it too, that would explain the drop in fuel pressure. Unless under load it's normal for it to drop to about 5-7 pounds. At idle it's at 12 at all throttle levels. No, Throttle body injection is usually closer to 22 13psi. I'm not sure on your specific system though. Fuel present, is enough to make it run rough. That was not your original problem listed though. run, then warm, then die for 30 min or so. <- that, I'm guessing is the coil. You may be fighting two or more separate issues. |
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How is your tank vented? Try driving is sans gas cap and see what happens Ran new breather hoses at the same time. So I don't think that's the problem. Are you relying on the 70's era evap can to handle your tank venting? How is your return line ran? Its a simple test try it |
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Had the same issue on two separate vehicles. Ignition coil was the culprit both times. While I won't rule that out and plan to change it too, that would explain the drop in fuel pressure. Unless under load it's normal for it to drop to about 5-7 pounds. At idle it's at 12 at all throttle levels. No, Throttle body injection is usually closer to 22psi. I'm not sure on your specific system though. Fuel present, is enough to make it run rough. That was not your original problem listed though. run, then warm, then die for 30 min or so. <- that, I'm guessing is the coil. You may be fighting two or more separate issues. No the absolute maximum for GM tbi is 15lbs above wich the fuel pump either stalls or the injectors start to leak |