Mercruiser 7.4 LX MPI EFI problem

scoflaw said:
B2 is no tougher than 1 and 3, same upper, Bravo's weak link. Spins a much larger prop, made for heavy boats with no intention of going fast. Had one on a 2000 245 weekender with a 5.0, top speed 32 mph
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Weird. Was it the 19.5" prop? Our 7000 lb 245 hits 40 mph with a carb'd 5.7 and B2. The drive is 2:1 with a 17.75x21 ss prop. My cousin has a '98 EC250 that came from SR with the same package as mine. It also runs the same numbers.
The B2's are pretty popular up here. Not far behind the B3's. Maybe due to the corrosion issues in their earlier models? Fewer moving parts allowing a heavier shaft and bearings(?) in the bottom was my understanding for being tougher.
My point was based on getting it on the water quick for a "right" price. Can always keep an eye open for another lower down the road if not happy with it.
 
The 5.7 was probably the difference mine was the 5.0. Not popular here at all, Ma or Fl. Not sure about the heavier shaft since the top gears are the first to go.

Agree whatever it takes to get on the water quicker.
 
Update:

Well, I’m still waiting on the only “Mercruiser” approved mechanic in the State to complete a rebuild of a Bravo 3 from spare housings he has in his shop and God only knows when the one yard I can use will allow me to schedule a haul out for the outdrive but I suspect boating for me this summer will be limited at best, if happening at all. At least I can sit in the slip and dream of boating while getting drunk I guess.

Meanwhile I finally got the parts in to change the circulation pump and the sea water impeller. Everything came off easy enough miraculously but as always if it weren’t for bad luck I’d have no luck. The pulley for the circulation pump turns out has deteriorated to the point that upon taking it off the old circulation pump it literally began to crumble on my hands from corrosion. $160 for a new one and another 1-2 weeks waiting for it to get here, at least the shipper was kind enough to flat rate it rather than make me spend $100 for fedex to get it here in about a week and call it second day.
 
Update:

Finally got her hauled out and sure enough the gimbal bearing was beyond done, the U-joints had failed, and corrosion was presenting it's own issues on the outdrive. The mechanic got the old outdrive off and about half the remains of the gimbal bearing. Hopefully he can figure something out to get the rest of it out as both of us were pounding on the slide hammer for about an hour and it would not budge. On an unrelated note I found that the previous owner had used a steel plumbing plug to plug the drain hole and the bronze fitting for the drain hole had been secured with machine screws and was essentially held on by the paint. Had to clean that area up and fill the old holes with epoxy, drill new holes, seal it with some 3M 5200 and put a proper brass drain plug back in with a healthy coating of plumbers tape. God willing I may get to use this boat this summer.
 
After much ado the outdrive has been replaced with an entirely rebuilt one and she’s back in the water. Got it out offshore and it was handling reasonably well for about 15 minutes. Then a loud double beep started to go off every 30 seconds or so and the engine lost power and began to run really rough. Was able to limp back to my slip and discovered the alarm is for the outdrive oil supply and found the sensor wire had disconnected from the bottle. Got that reconnected and now I have a single beep every 30 seconds or so and engine doesn’t seem to be running great. Anyone know what the single beep is supposed to mean? The engine isn’t throwing any codes other than 12 for the sensor wire coming loose. Do I have to reset it somehow out of limp mode or something?
 
Update. I am exhausted with this boat. The alarm turns out was for sure only the loose wire on the gear oil bottle and it has no limp mode as best I can tell. So, I began to go through everything, again, and found the number 7 cylinder spark plug fouled black with carbon. Did a compression test and once again found there is zero PSI in that cylinder. There is maybe 5 hours on this engine since the last time I pulled that head and it tested fine for compression then. This motor is going to drive me completely insane and broke. And there are no mechanics in my area willing to work on it at all so I either fix it myself or not at all. I just want to go out on the water and have a nice day on a boat. All maintenance and no fun is not at all enjoyable.
 
Now do a leak down on that cylinder. It must be a valve sticking open.

Possible causes -

1. Water ingestion (not likely since no issues with others)
2. Bent valve stem
3. Sticking valve due to insufficient ream on the guide
4. Improper valve grind on valve face or seat
 
Finally got the machinist to come take a look last week and he figured that the cylinder in question was the one he had to lap down extra to get it to seal again. Well apparently he lapped it enough that the back end moved up enough to change the geometry enough that the rocker arm was holding the valves open. Got it shimmed up and compression was restored. Went to go try and take it for a sea trial yesterday and the starter motor crapped out. At some point I’d really like to be able to do something other than get greasy working on the engine with this boat.
 
Got the starter motor swapped out on Saturday and it started and ran great. Came down today to take her for a sea trial and of course it won’t start. No idea why either. As far as I can tell it has fuel and spark. I’m really starting to hate this boat.
 
Well after much work and frustration I think I found the culprit. I pulled the distributor cap and found all the contacts badly pitted. Which is weird because the cap, rotor, wires and coil are all brand new. It doesn’t make sense that they’d fail after only being used for a few hours. Hopefully I just bought a defective part and it just failed. I cleaned the old rotor up a bit and got the engine to start but it would rev past 2000 under load. I think it’s time to find a different boat.
 
Aint buying the guys story about "shimming the rocker arm". If he ground the seat so much it whacked the geometry, he destroyed the seat. He should have re-done the head and installed new seats so they are all the same, + or -. Rockers are adjustable, BTW.

But, then again, trying to troubleshoot / visualize through a keyboard has severe limitations and based on interpretations and assumptions working around sometimes vague or misguided info.

You need to find a mechanic that knows BBC's inside and out. Only fly in the ointment would be the Mercruiser MPI and ignition system. Other than that, it's just a Big block Chevy. With all the motor heads on that rock, can't imagine there aren't any willing to do some side work. Get the base engine done 100% correct and then move to the fuel and ignition systems and sort them out one at a time.

I would invest in the PC based diagnostic software, if in your situation. You may even be able to pay for it doing diagnostic reads for others, because describing what you are experiencing, there is a critical need on the island for someone who can do that.

When I was stationed there, you couldn't swing a dead cat with out hitting a Chevy motor head. Maybe things have changed..
 
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@Bill Curtis since the state forced the race track to close in the early 2000’s the Motörheads have slowly dissipated to almost non existent. Even the classic car cruise nights have been pretty much ended as the state scared any business willing to host one with liability concerns so there are pretty much no parking lots willing to host anymore. For whatever stupid reason the marine mechanics on this island refuse to work on gas engines and there aren’t that many of them. For decades Hawaii has been ranked last in the nation in the marine industry. Which is insane considering we are surrounded by ocean 2000 miles in every direction. Another year and a half and I can retire and hopefully leave this place. Just gotta figure out where to move to.
 
Sorry to see that happen. Used to be a fun place.
 
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