06 indmar 325 fueling issue

[Brian_289]

Hey guys, fresh rebuild here on this boat and I have most of what I need to run. It is MEFI 5 for starters, I have spark, it cranks over, timing is correct, fuel pressure at the fuel rail. My injectors are not firing. I put a fuel injector test light in the plug on all cylinders and no light is coming on when cranking. I have a solid ground to one side of the injector plug, and the other side I would imagine delivers +12v to activate the fuel injector. For some reason they are not working. I’m not sure what else to look for, I’m going to go back and check all grounds. Any ideas?


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[Turbinesurgeon]

Is the fuel pump kicking on for 2 seconds when cranked over? Is the fuel pump on during cranking? Now I’m not sure if the kill switch shuts off the pump or injectors so make sure you have continuity there as well. The computer tells the injectors to fire so if the crank sensor doesn’t work then the engine doesn’t know it’s turning and doesn’t tell the injectors to inject :)


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[Brian_289]

Is the fuel pump kicking on for 2 seconds when cranked over? Is the fuel pump on during cranking? Now I’m not sure if the kill switch shuts off the pump or injectors so make sure you have continuity there as well. The computer tells the injectors to fire so if the crank sensor doesn’t work then the engine doesn’t know it’s turning and doesn’t tell the injectors to inject :)


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Yes the fuel pump primes, and then while cranking it runs also. I did go back and look again and I do have +12v on one wire for each injector. The other wire is dead even when cranking. I discussed with a few mechanic friends and they want me to try for spark again but with the crank sensor unplugged, if I still get spark then that rules out needing crank and cam angle signal for spark. I might try calling indmar today to get some solid info.


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[michael hunter]

The injectors get their signal from the ignition primary through the ECM . It sounds like the ECM may be the problem . You don't have the equipment to test it . You may want to talk to the dealer at this point.

[Brian_289]

Update, I got my hands on the rinda scan tool after striking out for a few days. Turns out my “brand new” crank position sensor was bad out of the box. Replaced it and it runs now with no issues.

The ECM does tell the injectors to fire, but the ECM still needs signal for when to do so. If the ECM was bad, I wouldn’t have the fuel pump turn on to prime, have spark, or be able to watch the drive by wire throttle body move.

If anyone has a spark but no fuel issue and has good fuel pressure at the fuel rail, check the crank position sensor! I still can’t believe MEFI-5 will spark in correct time with just cam signal. I have worked on a lot of modern cars, and this blows my mind. Without crank position on most newer stuff you get nothing.


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[CJD]

Sorry I'm late to the party. My first thought was cam or crank sensor...and the diagnostic tool takes you to the correct one. Think position sensor anytime you have nothing on the fuel. For spark there are a couple other items that could also cause it.