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low power lots of black smoke 4jh2m-ute

buick430

Regular Contributor
Hey guys having a hard time figuring whats wrong on an engine I just re-assembled. it was torn down for overheating but made full power before. Wile apart we had the injectors rebuilt, injection pump rebuilt, turbo rebuilt and all heat exchangers boiled and cleaned. All seals and gaskets were also replaced. The engine had 950 hours but lots of sitting. It is in a 19' RHI with a Hamilton jet. Right now I am getting a MAX RPM of 2600 and large amounts of BLACK smoke. The idle quality is good with easy starting it revs freely to 3400 RPM with the shaft disconnected. I have tried adjusting the throttle stop on the injection pump but makes no further gains. at 1500 RPM I cracked the injector lines loose one by one and noted equal drop offs between cylinders. The boat is at half tank of fuel and empty bilges. Before the work it had no problem reaching 3400 RPM. and clean with little smoke. Any help is greatly appreciated.

Will
 
Hi, just a wild guess but sounds like injection pump out of time or if the timing gears were removed , possibly one is off. Does turbo spin freely by hand ?? Has some varmint built a nest in your exhaust pipe ?? Does the jet turn free ??
Charlie w
 
Hey thanks for the response. I am pretty sure the injection timing is correct. I checked a re-checked before puting the front cover on. Is there a was to check without pulling it back apart?

The turbo spins freely and produces the audible whine of spooling up.

The jet drive seemed easy enough to spin with one hand while attaching the shaft.
 
Buick 430, try loosening the three inj. Pump mounting bolts, rotate the top of the pump towards the engine. Tighten bolts. If rpm improves there is a timing issue. I believe this engine has an auto advance on the inj. Pump drive gear if this doesn't work it could the problem.
Note : Before you move the pump make sure there is a reference mark on one of the slotted holes and the mounting cover, if not make one with a perm. Marker or scratch one.
Hope this works for you, charlie w.
 
Thanks for the tip Charlie. I will try that tuesday morning when I get back to work. The engine had marks already when taken apart. so I am good to go.

Again thanks for the help

Will
 
Hey guys thought Id give and update. after pulling a fuel sample it was full of algae and water. A new tank is going in and the injection pump is being rebuilt again as per the yanmar techs suggestion.

Will keep you all updated.
 
Well the new fuel tank and rebuilt injection pump (by yanmar techs) didnt solve anything. They are saying low compression and high engine hours is the likely cause. I re-checked valve clearance all good. While in the shop, the jet drive was also gone through.
 
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