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99 scarab starboard engine not making the power the port one does
Guys I have a 99. 29 scarab with twin 350 mpi mags and a set of m1sc prochargers. As far as I can tell the port engine makes what seems like double the power the right engine makes. Went as far as to replace the fuel pump didn’t help. Left engine will make 5000 rpms easy, right now only makes 4400. No water in oil, no backfiring. Need some advise on what to look at. |
Compression test. Ign timing at ~3000 RPM. Props look OK? Were they ever running the same RPMs at WOT?
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Yes they did when I bought the boat at the start of the season. Haven’t tested compression due to the difficulty yet. I’ll try and test the timing on the hose. |
Anyone else have any ideas? |
is boost the same at matching rpm's? I mean at 4000rpm on both motors do you have the same or close reading on the boost gauges? Maybe the belt is slipping on the one motor?
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I don’t have a boost gauge but that’s easy enough to see if the belt is loose. That would be great if it’s that simple. |
Good call on the blower belt possibly slipping.
Fuel pressure at WOT would be a good thing to check but it's not that easy to do unless you have fuel pressure gauges on the dash, which very few boats have. When I first got my current boat, it had fuel press issues on both engs. I installed fuel press gauges near the carbs, then had to rig up a gopro and a light to illuminate the gauges. Do you have the service history of the engs? Any idea when the injectors were last cleaned and flow tested? |
No service history. No clue on the engine history less than 100 hours on the chargers I was told and the total time on the engines is 265 hours each. Would pull 5000 on both first trip out but hasn’t again on the right engine. Fuel pressure specs out at idle, haven’t tested under load. I need to do the compression test but my arms are big and there isn’t much spare room between the two. |
maybe try unhooking bolth blowers and see is the motors both perform the same without any boost on them....
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Never even considered that. That would rule out the ProCharger completely. Or expose it. |
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