shardonnay Report post Posted April 21, 2017 We have a CAT C9 in our 2007 Fleetwood Revolution LE. We experienced a "Check Engine" light and some rough running while driving in Texas. The ECM told us we had an electrical connection issue on injector #2. The issue was intermittent, with the light coming on sometimes, and staying off at others. We took it to Mustang CAT in El Campo, Texas to get it fixed. After a day and a half of working on, they were not able to find the issue (it would not occur while they had it). They changed the fuel pressure regulator (pressure was a bit low, and the plunger looked a bit worn--after only 43k miles!). They also changed the fuel filter and water separator. $1200+ later, we were on our way....my confidence was not very high that it was actually fixed. Sure enough, a couple hours down the road, the "Check Engine" came back again. We backtracked to another Mustang CAT dealer (in Beaumont, TX)....by the time we got there, the light was out, and it was running fine.....so no repair work was done. The ECM confirmed that it was once again injector #2 that was malfunctioning. Finally, while driving a couple days later in Louisiana, the light and rough running returned. We went to Louisiana CAT in Bossier City. Fortunately, it was running on 5 cylinders when we got there, and the technician was able to capture the event on his laptop. The next day, he found the issue.......the terminal for the #2 injector wire was not securely seated in the electrical connector for the injector wiring harness. The harness was replaced -- the technician (Gary) came in on Saturday to get us back on the road -- and we drove several more days without incident. Kudos to Gary at Louisiana CAT in Bossier City. His experience with CAT engines helped him find and fix the problem. I would take my CAT-powered equipment to these folks any time. I do not have similar praise for the crew at Mustang CAT in El Campo, Texas. They apparently did not have the experience to enable them to find an intermittent electrical issue. As a result, I spent $1200+ dollars at their store and got little for it (regulator and new filters). I would not go back there again. They were not interested in helping with the cost of the real repair in Louisiana. Share this post Link to post Share on other sites
obedb Report post Posted April 21, 2017 The harness and labor probably wasn't cheap either. Maybe one of our resident Cat experts could tell us why an electrical issue could be turned into a pressure regulator replacement and two filters? We have a 3126E model Cat, that is why I have some interest in your experience. Glad you finally got your problem solved. Share this post Link to post Share on other sites
shardonnay Report post Posted May 22, 2017 Hi. I thought I replied, but for some reason, the answer did not "take". I believe that Mustang's thinking was that the injection system would be prone to tripping a code on the weakest-performing cylinder if the system pressure was low. They had found pressure regulator problems on other CAT engines, and mine showed some indications (pressure was in the mid-60 psi range, when it should be in the low 70s). The same reasoning applies to the filters.....common problem if you get a load of bad fuel, lowers the system pressure, etc. In retrospect, they were barking up the wrong tree.....all the indications were electrical on cylinder #2. But since they couldn't find an electrical problem, they looked in other areas. The injector harness itself was not that expensive ($121)......it was the labor that ran up the total bill (just shy of $1500). Share this post Link to post Share on other sites
