After discovering & fixing a prop strut alignment issue, our engine will now die when shifted into gear. It runs fine in neutral, is firing on all 3 cyl., idle seems high enough. You can turn the shaft by hand, so alignment/tightness does not appear to be an issue... It has a Max prop (3 blade feathering) but that seems to be working alright. We found that the engine will crank & briefly run if started while in gear (!) but it dies almost immediately. It motored from the slip to the sling fine, no tranny issues noted. The mechanic thinks possible fuel gov problem$$$, but it ran fine before. Any ideas what could be causing this? The engine is the original-- Universal M25... Any help is appreciated!
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Wow
First, I love these engine quizzes! Sorry for your situation, though; I know it can be quite frustrating. Based on the fundamentals, I agree it could be fuel management. The governor is supposed to increase the fuel input when the engine slows down when the load is increased. It seems that when you load the engine up by shifting into gear that the engine quits due to lack of power, which is because there isn't enough fuel. First, can you rev it up and down all the way in neutral? Second, what if you slam it into gear at say, 1200 RPM? The Hurth gear coupling these engines to the shaft are designed to take this. Alternatively, if you can turn your alternator's regulator on and off, or switch a fairly dead house battery in and out you should be able to hear the engine load up and the speed regulate. You could check the fuel supply and return system - lines for kinks, filters, etc. A constriction in a line or filter could be such that the engine has enough fuel to idle, but is starved under load. Beyond that, the speed control (governor) and injection pump might be at fault.
First, I love these engine quizzes! Sorry for your situation, though; I know it can be quite frustrating. Based on the fundamentals, I agree it could be fuel management. The governor is supposed to increase the fuel input when the engine slows down when the load is increased. It seems that when you load the engine up by shifting into gear that the engine quits due to lack of power, which is because there isn't enough fuel. First, can you rev it up and down all the way in neutral? Second, what if you slam it into gear at say, 1200 RPM? The Hurth gear coupling these engines to the shaft are designed to take this. Alternatively, if you can turn your alternator's regulator on and off, or switch a fairly dead house battery in and out you should be able to hear the engine load up and the speed regulate. You could check the fuel supply and return system - lines for kinks, filters, etc. A constriction in a line or filter could be such that the engine has enough fuel to idle, but is starved under load. Beyond that, the speed control (governor) and injection pump might be at fault.
The really weird part...
Thanks for the ideas, jviss.. Unfortunately no help. We can run the engine up to 3500 rpm in neutral & it purrs like a kitten. The REALLY weird part is if you uncouple the shaft from the transmission it will shift fine. It still stops dead when coupled & shifted. And no, the bolts aren't interfering. I think we are hitting our frustration limit and are down to calling in a Universal mechanic, if we can find one. Stay tuned-- my next post might be "BOAT FOR SALE CHEAP"
Thanks for the ideas, jviss.. Unfortunately no help. We can run the engine up to 3500 rpm in neutral & it purrs like a kitten. The REALLY weird part is if you uncouple the shaft from the transmission it will shift fine. It still stops dead when coupled & shifted. And no, the bolts aren't interfering. I think we are hitting our frustration limit and are down to calling in a Universal mechanic, if we can find one. Stay tuned-- my next post might be "BOAT FOR SALE CHEAP"
Must be the shaft
The clue here is that work was done on the shaft and strut, and after that it won't work. I assume you meant that immediately afterwards. Perhaps it turns by hand, by how easily? The shaft could be bent, and it will turn slowly but binds up at speed?
The clue here is that work was done on the shaft and strut, and after that it won't work. I assume you meant that immediately afterwards. Perhaps it turns by hand, by how easily? The shaft could be bent, and it will turn slowly but binds up at speed?
does the shaft turn freely now?
Jviss has a good point. Does the shaft turn freely now, with the boat in the water and the shaft disconnected? Is their any chance you could have fouled the prop when the boat was put back in the water? If the shaft turns freely when disconnected since then, then I agree it probably is in the fuel system. Another problem that acts the same is a vacumn leak in the engine. You could have knocked loose a air hose on the engine that allows un-meters air into the engine and thereby leans the fuel supply down. Good luck and please post the results of your adventure. Ray
Jviss has a good point. Does the shaft turn freely now, with the boat in the water and the shaft disconnected? Is their any chance you could have fouled the prop when the boat was put back in the water? If the shaft turns freely when disconnected since then, then I agree it probably is in the fuel system. Another problem that acts the same is a vacumn leak in the engine. You could have knocked loose a air hose on the engine that allows un-meters air into the engine and thereby leans the fuel supply down. Good luck and please post the results of your adventure. Ray
I can turn the shaft easily.....
I agree that something seems to have gotten messed up during the work that was done. I don't think it is the shaft though. Part of the alignment fix was to install a new dripless seal and ss shaft. When that was done & the boat refloated this problem surfaced. The yard realigned the strut & I can easily spin the shaft by hand now. For what it is worth, the mech. also removed an engine driven fridge compressor. Full RPM in neutral would seem to rule out a fuel problem, or am I wrong to assume that? I don't know if there is a safety switch that could have gotten cross-wired, or if a vacuum leak would do it, but when the engine kills it almost seems like it has been cut out. No lugging, no laboring-- it just stops dead. I appreciate the input on this, guys. I am way out of my depth here! I will try to trace the fuel lines, etc tomorrow & let you know what I find...
I agree that something seems to have gotten messed up during the work that was done. I don't think it is the shaft though. Part of the alignment fix was to install a new dripless seal and ss shaft. When that was done & the boat refloated this problem surfaced. The yard realigned the strut & I can easily spin the shaft by hand now. For what it is worth, the mech. also removed an engine driven fridge compressor. Full RPM in neutral would seem to rule out a fuel problem, or am I wrong to assume that? I don't know if there is a safety switch that could have gotten cross-wired, or if a vacuum leak would do it, but when the engine kills it almost seems like it has been cut out. No lugging, no laboring-- it just stops dead. I appreciate the input on this, guys. I am way out of my depth here! I will try to trace the fuel lines, etc tomorrow & let you know what I find...
Line wrapped around shaft?
Is it possible you have a line fouled around the shaft? One or two wraps might allow you to turn the shaft by hand relatively slowly, but bind up tight when you shift into gear and the shaft turns relatively quickly. Randy
Is it possible you have a line fouled around the shaft? One or two wraps might allow you to turn the shaft by hand relatively slowly, but bind up tight when you shift into gear and the shaft turns relatively quickly. Randy
good call Randy!
I think Randy speaks from experience. That was exactly what had happened to me this year. Find a buddy to dive under for you. Make sure you have a 6 pack to give him (afterwards!).
I think Randy speaks from experience. That was exactly what had happened to me this year. Find a buddy to dive under for you. Make sure you have a 6 pack to give him (afterwards!).
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