Jeepjunker Posted June 15, 2022 Share Posted June 15, 2022 I got my 1990 4.0 with a no start condition. Well sort of . It would start then die immediately . I went to replace the 02 sensor broke it off . So once i fixed all that up pulling the intake and header . It runs . But it runs extremely rich . Backfires and smells of gas . The previous owner bypassed the EGR system . If someone could point me in the right direction I’d be much appreciative. It’s been one thing after another with this one . Link to comment Share on other sites More sharing options...
CrustyBoy Posted June 15, 2022 Share Posted June 15, 2022 I could be wrong but usually a consistent start followed by a stop is caused by a bad fuel pump ballast resistor. There's a part in this video where he starts the engine prior to fixing the problem to show you the symptoms. Watch and see if yours is behaving the same way. Edit: Sorry I missed the part where you said it's running after the O2 sensor was fixed. Still probably worth it to confirm that resistor is good but maybe it isn't your problem. Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 15, 2022 Author Share Posted June 15, 2022 I appreciate the input . Initially the resistor was bypassed when i got the truck . But after getting it running . I’ve rehooked it with no change to running condition before or after Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 15, 2022 Author Share Posted June 15, 2022 It Also has a new fuel pump and 4 hole injectors . Did a tune up new plugs and wires . Check distributor index it was dead on. Map line was previously replace with a hard steel line so no cracks there . Link to comment Share on other sites More sharing options...
JustEmptyEveryPocket Posted June 15, 2022 Share Posted June 15, 2022 11 minutes ago, Jeepjunker said: 4 hole injectors What part number on those injectors? Also, where did you purchase them from? Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 15, 2022 Author Share Posted June 15, 2022 Part number : 0280155746 i bought them off kSuspension 87-90 range Link to comment Share on other sites More sharing options...
cruiser54 Posted June 16, 2022 Share Posted June 16, 2022 those are the correct injectors. Pig rich is generally caused by a faulty MAP sensor reading. Any change if you unplug the MAP sensor vacuum line or electrical plug? Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 18, 2022 Author Share Posted June 18, 2022 Cruiser . I would say you’re spot on to something . Went out played with the map connector it killed the truck . Then went right back to the original no start issue i was having . The previous owner was a bit of a get er done mechanic from what i can see . Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 18, 2022 Author Share Posted June 18, 2022 Started stripping back wiring and found this . After just pulling back the amount of electric tape it started right back up and is running smoother but any idea what they’ve done here ? Link to comment Share on other sites More sharing options...
cruiser54 Posted June 18, 2022 Share Posted June 18, 2022 It all needs to be redone with soldering and shrink tubing. Link to comment Share on other sites More sharing options...
Jeepjunker Posted June 18, 2022 Author Share Posted June 18, 2022 Looks like learning to solder is this weekends project . Should i go ahead and put a new map on it since I’m doing all this? thank you for the quick diagnosis and pointing me in the right direction Link to comment Share on other sites More sharing options...
cruiser54 Posted June 18, 2022 Share Posted June 18, 2022 No need to replace the MAP sensor. Buy shrink tubing and a lighter. Link to comment Share on other sites More sharing options...
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