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New XJ in the family need some help |
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THE MENACE
AMC Addicted Joined: Nov/04/2008 Location: So. California Status: Offline Points: 4438 |
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Seems like a lot of people overlook the fuel filter on XJ's for some reason. It's above the rear diff.
Injectors get clogged. A great upgrade for 91 up 4.0L XJ's are Dodge Neon injectors. They are a simple direct replacement (no mods) for the OE injectors and are pretty common to find at the bone yards, at least around here. Get them ultra sonic cleaned and they work like new. My 91 XJ ended with better acceleration and slightly improved fuel mileage with the Dodge Neon injectors. |
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Former Owner of:
The Craig Breedlove "AERO AMX" Still Owner: SS/AMX #9 replica (THE BIG MENACE) 70 AMX 416, EFI, Nash 5 speed 70 Javelin 401, 727 (Wife's car) 72 Gremlin Autocross Project. |
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Pdok
Supporter of TheAMCForum Joined: Apr/03/2011 Location: Alabama Status: Offline Points: 1025 |
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This link is useful for MPFI troubleshooting:
Symptoms could conceivably be caused by: erratic fuel pressure or regulator Erratic fuel delivery (as mentioned, injector clogged), or more rarely, injector wiring faulty ground injector problems will usually throw an OBD code, however, even if intermittent. I've found that to be true anyway. Ignition coil issue O2 sensor (engine never gets past open loop warmup) We're sure no valves are sticking? No vac leaks, intake/exhaust tight and gaskets good? Best of luck, wish I could fly down and drink a beer while you fix it...
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76 Grem X 258/904,4.0 head/MPFI, Comp X250H cam, Hughes springs, Clifford header, serpentine swap.
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5807 |
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I think I will start with this stuff and a compression test, then move onto the electronic stuff. |
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70 Donohue 390
Supporter of TheAMCForum Joined: Jul/11/2007 Location: S. Oregon Status: Offline Points: 4338 |
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It's currently for sale on The Medford Craiglist I bought my 172k mile 96 from the original owner after she totaled it. I rebuilt it and have put 12k miles on it the last 18 months. It was running rough, when I first bought it. so I ran a can of Marvel Mystery Oil down the carb and 90% of the miss was gone. Then I wanted a smoother idle and better gas mileage so I changed my cap, rotor & wires. Get the better heavier cap (I think that may have been my main problem) My E3 type plugs are very clean but the wires were showing their age. Keep an eye out for a leaking oil pressure sending unit. They blow the back off and oil on hot pipes is ugly. |
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67 Rogue 290 Convert
70 BBO 390 5 Speed Javelin-under construction |
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WesternRed
AMC Addicted Joined: Aug/03/2010 Location: Australia Status: Offline Points: 5807 |
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I should update this, replaced the rear main seal and oil filter adapter O-rings, fixed a small vacuum leak in the PCV system and the thing has been running fine ever since.
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I've finally given up drinking for good...........now I only drink for evil.
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73Gremlin401
Supporter of TheAMCForum Joined: Mar/02/2013 Location: Stmbt Sprgs CO Status: Offline Points: 955 |
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Sometimes it is the simplest of things that makes them run right! AMC 6s in general are super sensitive to vacuum leaks, so this repair makes sense. Glad it's doing well.
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73 Gremlin 401/5-spd.
77 Matador Wagon 360/727. 81 Jeep J10 LWB 360/4-spd 83 Concord DL 4-dr 258/auto |
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