Nasty Wendy
Regular Contributor
OK guys one of my twins has decided to be a problem child. It runs fine in neutral up to 6000 + RPMs. In gear it'll only go up to 3000 before it starts coughing and bucking. It has to be under load to do this. If I bring the other engine up to 4000 rpms first I can get the "problem child" to run up to 4000 rpms. If I try to give it any more throttle it'll cough and buck in protest but it will ease up to 4200 but then cough and fall back to 4000. No alarms no lights. New fuel pump, new fuel filters, new fuel pressure regulator, cleaned fuel injectors (replaced one), cleaned the screen at the regulator, cleaned the screen under the fuel pump, new spark plugs (NGK IZFR6F11), primer bulbs function as they should, compression is great in both engines. The other engine "The good son" runs off of the same tank through the same fuel filter and water separator and runs perfectly whether it is running alone or with the "problem child". I'm STUMPED.
I ran the compression test when I had the plugs out which was early in this process of figuring out this problem. I do not remember the numbers exactly but I was surprised they were as high as they were. The cylinders were really close on the pressures. My memory is saying 110 to 125psi but that is my memory and not recorded numbers. It passed the compression test though with flying colors. The engine only has 500ish hours on it. I swapped ECMs with the "Good Son" and the problem persisted. ?????
I ran the compression test when I had the plugs out which was early in this process of figuring out this problem. I do not remember the numbers exactly but I was surprised they were as high as they were. The cylinders were really close on the pressures. My memory is saying 110 to 125psi but that is my memory and not recorded numbers. It passed the compression test though with flying colors. The engine only has 500ish hours on it. I swapped ECMs with the "Good Son" and the problem persisted. ?????