I have the above mentioned engine 0W666xxx, as clean and pretty a 13 yo engine as you'll ever see, and here's my problem. Fuel injectors 5,6,7,8 don't fire. Using a DDT, I cylinder drop all eight and those four don't drop. I load test the injectors, and the back four, two either side, don't test. DDT says "unable to perform test" or something to that effect. 1-4 click happily away when tested.
Studying manual #36, I see that the injectors fire in pairs, 1-6, 2-3 4-7, 5-8. There is 12v power to all eight, and the ecm grounds them to activate. 2-3 apparently works fine. 5-8 accounts for those two, if, for instance, the ecm has failed. But how do I account for 1-6 and 4-7, since 1 and 4 work fine?? It would require several different harness failures to account for it all. All eight injectors have all been cleaned, and while they flow a little better after cleaning, they all worked on the test bench before they were cleaned. I really expected four bad injectors, because this motor suffered from a large dose of water from the fuel tank. CF3 fuel pumps survived it. Motor actually runs deceptively well until you push the throttle, and it won't push past 3k rpm as you might expect.
Do any of your mercruiser gurus have any insight into what I might be looking at here? Sure doesn't seem like it should be an ecm. Seems strange also the pattern of failure, back 4 vs front 4. Thanks, Mark ZZ03
Studying manual #36, I see that the injectors fire in pairs, 1-6, 2-3 4-7, 5-8. There is 12v power to all eight, and the ecm grounds them to activate. 2-3 apparently works fine. 5-8 accounts for those two, if, for instance, the ecm has failed. But how do I account for 1-6 and 4-7, since 1 and 4 work fine?? It would require several different harness failures to account for it all. All eight injectors have all been cleaned, and while they flow a little better after cleaning, they all worked on the test bench before they were cleaned. I really expected four bad injectors, because this motor suffered from a large dose of water from the fuel tank. CF3 fuel pumps survived it. Motor actually runs deceptively well until you push the throttle, and it won't push past 3k rpm as you might expect.
Do any of your mercruiser gurus have any insight into what I might be looking at here? Sure doesn't seem like it should be an ecm. Seems strange also the pattern of failure, back 4 vs front 4. Thanks, Mark ZZ03