QuestionQUESTION: This is a 1993 N-14 Clect. It was diagnosed with a bad ECM, that was replaced with a rebuilt. It then logged a 121 fault code, for the engine position sensor, and it was replaced with a new one. Now there are no fault codes.
But the engine has a surge or bark to it, at an idle and also high idle. There are no air bubbles in the sight glass, and the fuel pressure is running 155 psi at an idle and around 175 psi at high idle. What could cause this surging.
ANSWER: Have you singled out the injectors to make sure they are all working? The other is has the overhead been run recently? Was this doing this prior to ecm replacement and the crank position sensor?
---------- FOLLOW-UP ----------
QUESTION: No sir, I had unplugged each injector atthe pass-thru connector,and they all seem to be hitting, but I was told this was not always an accurate way of cutting out the injectors. I'm in the process of locating an electronic tool, such as an E-chek, ect. Also I have not ran the overhead, or checked it myself. The owner says It wasn't surging like this before the ECM went bad. I was leaning toward setting the overhead, but it's going to be a tough one,as this engine has jakes, and is laid sideways and halfway under the cab of a Ford L-9000.
AnswerJust checking to see how everything has come out and if you figured your problem out.
I figured you had unplugged the injectors. Do not believe its a injector issue anyway but its best to try you never know. you get more of a missing with a injector not a surge. Would definitely try to get a scan tool. Did you check for air in the fuel between the tanks and the pump or out the return line. If you did between the tanks and the pump i would try doing out the return line and see what that gives you could be a possible bad injector o-ring or cup. Might also try wiggling your harness around your ecm possible you have a intermittent problem there since youve moved that harness replacing the ecm.
