What would cause a motor to "gag" when you trim it up?

Last time I ran my Triton with the 50HP Merc, I noticed when I was running at speed and went to trim it up, it acted like the engine almost cut off, almost like I had hit the choke or something.

It did that a couple of times. I noticed it didn't do it when I trimmed it down, only when I tried trimming it up did it do this.

I've never seen this happen before. WTH? What would cause that? Any ideas? My gut says there could be some kind of short between the trim and the electric choke. But, since it doesn't do that at low speed, I have my doubts about that theory.

That is weird - and it only does this at high speed? How high a speed before it start?

Pretty much at 3/4 throttle and above. Like I said, it didn't do it at low speed. maybe it was a fuel surge, I'm not sure. I'm going to run it some more and see if it continues.

Is it cavitating or actually trying to die?

Does the motor seem to jump when it happens?

I had a situation once on an older boat where at higher speeds, the motor would hesitate like it was cavitation problem but would run normally at lower speeds. It turned out to be the shift cable. It was a tad too long and wouldn't allow the shift lever on the side of the motor to stay in the fully forward position at faster speeds.

fuel line getting kinked when trimming up maybe? or carb float not adjusted right posibly

hunterguy86 said:

Is it cavitating or actually trying to die?

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More like it's choking or flooding out, not cavitating.

nomowork said:

Does the motor seem to jump when it happens?

I had a situation once on an older boat where at higher speeds, the motor would hesitate like it was cavitation problem but would run normally at lower speeds. It turned out to be the shift cable. It was a tad too long and wouldn't allow the shift lever on the side of the motor to stay in the fully forward position at faster speeds.

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It does jump a little, but not like it's coming out of gear, it's more like the choke being applied. As soon as I let off the trim button, it runs normal.

Haven't had a chance to run it, as this tropical system off the coast has the water conditions pretty rough right now, it's not much fun trying to run a johnboat in 25 mph wind and chop.

i hear ya about the tropical system, I am here in Jacksonville and it is coming right at us, glad we went out yesterday!!!!! Even then it stated getting rough fairly early. Anyway i would definitely check all connections and lines/hoses. Probably something simple.

If this is a new problem than it's most likely an electrical problem cause by a bad connection or corrosion. When you trim up it uses more current causing a voltage drop and the ignition cuts out.

I would start at the battery and check the connections. Remove, clean and re-install then check the connections at the motor.

JaxJonBoat said:

i hear ya about the tropical system, I am here in Jacksonville and it is coming right at us, glad we went out yesterday!!!!! Even then it stated getting rough fairly early. Anyway i would definitely check all connections and lines/hoses. Probably something simple.

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Yep, it's pretty snotty here today. Didn't go boating, instead, we ran my girlfriend's VX110 and my Super Jet, went out in the ocean, the waves had to be at least 9 feet. Even got a little video of it and put it on my youtube channel.

Anyhow, I might try to run the boat early in the morning, and see how it does. I'll also take krawler's advice about the electrical connections....that does sound like a possibility. So, I'll check those to be sure.

BTW, jax, my girlfriend thinks that dork fish avatar is huh-huh-huhlarious! LOL We thought it was funny when Bill Engvall talked about the dork fish in his comedy act, now we know what one looks like. :mrgreen:

I don't know how many years Mercury used them, they may still be in use, but my 1979 40HP has a relay that if the motor get's tilted too high it will kill the motor. This was designed to prevent the motor from burning up if it got out of the water. If you have this relay it could be malfunctioning since it is only happening when your raising the motor.

PSG-1 said:

As soon as I let off the trim button, it runs normal.

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I had a similar problem at KY Lake one time. When I went to trim the motor,it sputtered a couple of times then died. Turned out to be a bad battery connection.

nimmor said:

I don't know how many years Mercury used them, they may still be in use, but my 1979 40HP has a relay that if the motor get's tilted too high it will kill the motor. This was designed to prevent the motor from burning up if it got out of the water. If you have this relay it could be malfunctioning since it is only happening when your raising the motor.

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Ok, that also makes sense. My motor is a 2007 model, not sure if that part is still used, but I'll look into that, as well.

S&MFISH said:

PSG-1 said:

As soon as I let off the trim button, it runs normal.

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I had a similar problem at KY Lake one time. When I went to trim the motor,it sputtered a couple of times then died. Turned out to be a bad battery connection.

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I did run my boat late yesterday afternoon, to see if the problem repeated, and it did. Again, it only did it when I was trimming the motor up.

I checked battery connections, and the positive battery cable felt like it was not fully tightened, I was able to move it some. I tried to tighten it with my hand, but couldn't get the wing nut on the battery terminal to tighten down much more. I'll take a pair of pliers on the next run, and also check the connections under the cowling, to make sure those aren't loose, either.

I thought it may have been a fuel issue, especially with the long fuel hose going to the tank in the front of the boat. Based on that, I tried running on the rear tank, which has a short hose....same problem. So, I think I can eliminate that as a possibility. I think it may be a loose electrical connection, like at the battery.

PSG-1 said:

JaxJonBoat said:

i hear ya about the tropical system, I am here in Jacksonville and it is coming right at us, glad we went out yesterday!!!!! Even then it stated getting rough fairly early. Anyway i would definitely check all connections and lines/hoses. Probably something simple.

Click to expand...

Yep, it's pretty snotty here today. Didn't go boating, instead, we ran my girlfriend's VX110 and my Super Jet, went out in the ocean, the waves had to be at least 9 feet. Even got a little video of it and put it on my youtube channel.

Anyhow, I might try to run the boat early in the morning, and see how it does. I'll also take krawler's advice about the electrical connections....that does sound like a possibility. So, I'll check those to be sure.

BTW, jax, my girlfriend thinks that dork fish avatar is huh-huh-huhlarious! LOL We thought it was funny when Bill Engvall talked about the dork fish in his comedy act, now we know what one looks like. :mrgreen:

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Yeah thats where i got the idea from, it has been an inside joke with my wife and i for a long time, she calls me dorkfish when i put my fish sun glasses on. Thinking of naming my boat that with a pic on the side too lol. Google a hog fish and look at the pics, i swear that it where the idea came from!!!

Yeah, the spanish hogfish is a funny looking thing, for sure.