ProblemPioneer Posted June 5, 2020 Share Posted June 5, 2020 Hey all, first time on here. Have an 88 4.0 automatic Comanche, as stated in the title the thing is hesitating under load and spits and pops. Over the last few years I have replaced a ton of stuff on this thing. New intake/exhaust gasket, knock sensor, throttle position sensor, map and mat sensors, ecu, timing chain and gears, fuel pump, injectors, fuel pump relay, O2 sensor, complete exhaust system, crank position sensor(on bell housing), and the idle speed sensor. There’s more but I think that’s all that would pertain to this issue. Recently replaced the timing chain and gears and it ran good for about 15-20 minutes. It overheated and shortly after ran like crap. As far as I can tell no blown head gasket. Has good compression in all cylinders 135-150. Any ideas? Do distributors go bad in these things often? Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 5, 2020 Author Share Posted June 5, 2020 I forgot to mention the obvious, I also replaced wires and plugs, cap and rotor. I did put the I believe they are called E3 plugs in. Same heat range as original plugs. Link to comment Share on other sites More sharing options...
jdog Posted June 5, 2020 Share Posted June 5, 2020 Get some copper core plugs in it, what test have you done, have you done cruisers tips 1-5 and index the distributor. How are the vacuum lines, have you checked the line from the throttle body to the map? Link to comment Share on other sites More sharing options...
JMO413 Posted June 5, 2020 Share Posted June 5, 2020 Have you checked fuel pressure? Mine was similar when the hose fell off the fuel pump in the tank. Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 5, 2020 Author Share Posted June 5, 2020 Did a smoke test and any lines leaking I replaced. The MAP vac line has been replaced. I unplugged all sensors and put them back on one by one to see any change and nothing. I did try testing fuel pressure and came up with about 22 psi straight off the rail. My Haynes manual wants me to plug or unplug something on the throttle body when I test pressure but I have zero adjusting that I can see on the throttle body. Nothing to plug or unplug. Manual says it should be 14-15 psi, it’s kinda unclear to me how the manual guides you to test it for my throttle body. It looks stock to me. What is a proper way and what should fuel pressure be on this? Link to comment Share on other sites More sharing options...
JMO413 Posted June 5, 2020 Share Posted June 5, 2020 Fuel pressure should be 31 PSI with the vacuum line attached to the first pressure regulator. Fuel pressure should be 39 PSI with the vacuum line disconnected from the fuel pressure regulator. Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 5, 2020 Author Share Posted June 5, 2020 When I was testing the fuel pressure I removed the vac hose from the fpr And had no change. Replaced the fpr and still the same thing. The fuel pump I purchased through summit so I would think it’s a quality pump. The fuel filter has also been replaced. Also blew out the fuel lines and see no leaks. Would there be anything else keeping it from building pressure? Link to comment Share on other sites More sharing options...
JMO413 Posted June 5, 2020 Share Posted June 5, 2020 I would check the hose in the tank from the pump to the sender. Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 6, 2020 Author Share Posted June 6, 2020 Problem Pioneer is back on the road!! Was a bad wire on on the hot side on the fuel sending unit. I attached a pic below. Made a new wire and it runs great. Thanks for all the input... Link to comment Share on other sites More sharing options...
OptimusPreem Posted June 6, 2020 Share Posted June 6, 2020 11 minutes ago, ProblemPioneer said: Problem Pioneer is back on the road!! Was a bad wire on on the hot side on the fuel sending unit. I attached a pic below. Made a new wire and it runs great. Thanks for all the input... Nice work! It's alllive, it's alllllive. Link to comment Share on other sites More sharing options...
cruiser54 Posted June 7, 2020 Share Posted June 7, 2020 The ground wire was bad on mine. So, have you done the Tips? Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 7, 2020 Author Share Posted June 7, 2020 I have not done the tips yet. Link to comment Share on other sites More sharing options...
cruiser54 Posted June 7, 2020 Share Posted June 7, 2020 Need to. Link to comment Share on other sites More sharing options...
ProblemPioneer Posted June 8, 2020 Author Share Posted June 8, 2020 Is it worth it to get a SnapOn MT2500 scanner for my Comanche? Link to comment Share on other sites More sharing options...
cruiser54 Posted June 8, 2020 Share Posted June 8, 2020 No. There are other options. And, a scanner will not detect the things that my Tips cover. nickintime makes engine monitors. His info is on the first page: http://cruiser54.com/ Link to comment Share on other sites More sharing options...
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