JMO413 Posted September 23, 2018 Author Share Posted September 23, 2018 I got tied of tracing wires. So I put in the later 89 ECM I already had purchased. I was looking for the idle stability and better starting and power. Now my fuel pump shuts off. Not sure how or why! Link to comment Share on other sites More sharing options...
JMO413 Posted September 23, 2018 Author Share Posted September 23, 2018 Well that was short lived. If you turn the key to on it keeps running again even if you shut the key off. If you unhook the fuel pump at C157 and then hook it back up it no longer continues to run. It's also doesn't stop after primed in the first key position like it did the first couple times when it worked right today. Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 24, 2018 Share Posted September 24, 2018 Since the pump did shut off with the key after you swapped ECM's, I think you're at the problem AO. Check the ECM connector and pins. Look for any bent and/or recessed pins. Clean up both the module and especially it's cable with contact cleaner. Link to comment Share on other sites More sharing options...
JMO413 Posted September 24, 2018 Author Share Posted September 24, 2018 I cleaned the connectors going to the ECM and the ECM is a reman looks brand new. What really gets me is that it worked right the first three times I started it. Now it never stops running like it did those three times. It would prime and stop. Now it just runs. The fuel pump is also very loud when it continues to run. The times it worked right it was quiet when the truck was running. I found seven or eight wires that had bare spots showing repaired them but still not fixed. The fuel pump still continues to run with all the relays taken out of the engine compartment, the ballast resistor unhooked, & unhook the starter relay. It only stops if you disconnect the pump or battery cable. It does not come back on when you hook them back up unless you cycle the key after that. It is getting power somewhere just got to find where. Link to comment Share on other sites More sharing options...
JMO413 Posted September 25, 2018 Author Share Posted September 25, 2018 I pulled the connectors at the ECM they are all in great shape. Checked the ECM pins all are straight. Not sure what you meant by AO Link to comment Share on other sites More sharing options...
HOrnbrod Posted September 25, 2018 Share Posted September 25, 2018 13 minutes ago, JMO413 said: I pulled the connectors at the ECM they are all in great shape. Checked the ECM pins all are straight. Not sure what you meant by AO Sorry, AO is a military term for Area of Operations. Where you want to be when troubleshooting. Just for grins, have you tried to measure fuel pressure at the rail test port with a gauge while the pump is running with the ignition off? It may be running backwards because of the harness short. Link to comment Share on other sites More sharing options...
JMO413 Posted September 26, 2018 Author Share Posted September 26, 2018 So I found another spot where the fuel pump feed wire was rubbed through to a green wire with black tracer. Cleaned the ECM connectors again. Hooked it all back up and it works as intended. We're on start and shut down 10 and all is good. I believe it was the last short I found. Will update if it changes. Now I just have to put it all back together again. Thank you everyone for your help with this!!! Link to comment Share on other sites More sharing options...
Ωhm Posted September 26, 2018 Share Posted September 26, 2018 Good work. Good find. Hope this ends your electrical nightmare. Link to comment Share on other sites More sharing options...
JMO413 Posted September 26, 2018 Author Share Posted September 26, 2018 I hope but something tells me it won't be. This truck only has 109000 miles on it but I believe she had a hard life!! Thank you again for the help! Link to comment Share on other sites More sharing options...
bad_idea Posted September 26, 2018 Share Posted September 26, 2018 Glad you got it sorted. That's a lot of breaks in the wire insulation through out the harness. Sounds like it may not be a bad idea to swap out the harness. Link to comment Share on other sites More sharing options...
JMO413 Posted February 26, 2019 Author Share Posted February 26, 2019 In the end this was all a wire behind the fuse block died to the fuel pump wire. Just updating in case someone reads this later. The orange wire is the fuel pump. The red is a constant at the fuse block. Link to comment Share on other sites More sharing options...
Ωhm Posted February 26, 2019 Share Posted February 26, 2019 You found it. Link to comment Share on other sites More sharing options...
JMO413 Posted February 26, 2019 Author Share Posted February 26, 2019 Yeah I believe I did. But I have thought that before. It worked right three or four times before. I don't understand how it ever shut off. Hopefully this is fixed and stays fixed. Link to comment Share on other sites More sharing options...
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