Just picked up a 1990 251 gtx 502, last owner claims some sort of original 450hp package. Boat has only had a few owners but last owner had it for around 7 years and didn't seem to know much about it. Anyway I had it out for a second time today and noticed that when full out at 4600 rpm when I would try to trim it out for more speed the engine would cut out when pushing the trim button?? As I'm typing this I'm thinking maybe I was at the limit of the trim settings and needed to use the trailer trim to get any more trim out of it or is it possible the trim pump can short the engine?
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New boat, first question for help
- Thread starter cjcs
- Start date
Boat has a old nordaskeg speedo which reads 60, prop is 25 mirage 3 blade. I don't think it is the rpm limiter because the engine only cuts out when the trim button is pushed to trim the drive higher. I only made two full speed runs though . Probably only able to use the boat 1 or 2 more weekends this year.It would be nice to have a good idea if this is even an issue or not.
boatman4021
Well-known member
You have got a bad ground somewhere. When you hit the trim, its killing power to the coil. Had it happen on an older Baja one time, the only one I have ever owned. I traded it off before I even looked into finding the problem, but the dealer I traded it to was a friend of mine and one of his employee's took it to ride on the weekends and found the problem. Don't remember exactly where the problem was, just that it was a ground issue.
After thinking a bit, it may have been a hot wire in the trim wiring going to ground or a ground wire from the trim making contact with a + wire.
After thinking a bit, it may have been a hot wire in the trim wiring going to ground or a ground wire from the trim making contact with a + wire.
keith4216
Well-known member
4600 turning a 25 around 60mph all sounds about right. You might want to try a 23.
Check the wiring on the trim pump. Take a close look at where the pump grounds on the block with all the other major components. I had a bad ground there once and motor wouldn't crank every now and again. Should be a simple wire issue.
Check the wiring on the trim pump. Take a close look at where the pump grounds on the block with all the other major components. I had a bad ground there once and motor wouldn't crank every now and again. Should be a simple wire issue.
Thanks for the quick replies! I will check the wiring over on the trim pump real close. It does feel like the prop is almost to big when the boat is loaded up with gear and fuel. I may install a new transom assembly over the winter. I want the steering to be tight. If that happens I may just end up cleaning up the wiring the best I can and that could solve any other issues. Thanks again
if your not able to trim without the engine dying.....i would def find that issue before changing props or anything else for that matter. its safe to say you may not be getting all the performance out of that engine with the ignition or some other major system having a short in it somewhere.
good luck! wiring problems are simple enough to fix...but can be a bitch to track down. get a buddy and a voltmeter and if you can get a wiring schematic of the boat and engine that would be great too.
good luck.
good luck! wiring problems are simple enough to fix...but can be a bitch to track down. get a buddy and a voltmeter and if you can get a wiring schematic of the boat and engine that would be great too.
good luck.
Hope to be able to get out tomorrow and check it out. The only thing that puzzles me is the boat only does it when running full out. The boat only cuts out when you press the trim button. It is just like it is hitting the limiter but runs great until you trim the last bit. Thanks, again
Interesting. Hmmmmm........
It is funny that you mention that. I have only been able to use the boat once and never found the cause. I will only be able to only get out once more so the problem may have to wait until spring. The reason I said this is the voltage only reads 12.5 on the guage so I thought the alt was going but when I checked it with a voltmeter it showed 13.5. The alt may just be on it's way out. I will have that looked at over the winter. Thanks!