87 GT 150 cuts off WOT

[va1968sh]

I have a 1987 GT 150 which I have had since it was new. This spring I went out and it started ok but at WOT it started skipping-cutting off at about 2500-3000 RPM's. I ran the boat for several minutes and it cleared up, but at WOT, about 4500 RPM's, it would shut off then back on, just like the switch was turned off and then back on. Also, the plugs look wet. I thought maybe a fuel system problem like trash or a fouled plug\s that cleared up. It got better as the day went and I thought all was well.

I found one of the power packs defective and since they both are 21 years old I replaced both. Of course it stared up and I could hear the differance with the motor flusher attached. Went to the lake and as soon as I hit WOT and\or it got to 3000 RPM's, it would do it's on-off thing. It sounds almost like a loose wire or a bad kill ot ign. switch. You can idle all day as long as you are not at WOT or under 3000 rpm's. It runs ok in thoses ranges. It's trying to come alive but cannot.

Any ideas????

 

[R.Johnson]

Re: 87 GT 150 cuts off WOT

Do a compression, ignition , fuel test, or you can throw more part's at it. I wish I had the market on pulse pak's, and VRO pump's.

 

[va1968sh]

Re: 87 GT 150 cuts off WOT

I am. 105 average on all cyl.

this did come about after being storaged. At WOT, it pulses list you are patting your foot to music............garrrrrrr...........boooooo.........garrrrrrr.......boooooo

just like you are shutting the engine on and off.............almost like the timing retards and advances but I don't thinkj it's a timing issue.

 

[va1968sh]

Re: 87 GT 150 cuts off WOT

This evening I did some testing; just for the heck of it, I checked with my timing light to see if each cyl. was firing. Some times it fired on both sides and other times it was only firing on one bank then the other. kind of like it was switching from power pack to power pack.

I think it may be the ign. switch or the emergency stop switch. Anyone have any thoughts??

 

[emdsapmgr]

Re: 87 GT 150 cuts off WOT

I'd probably start by checking the output of the stator and the timer base. You need a factory service manual and a peak-reading voltmeter to check this.

 

[va1968sh]

Re: 87 GT 150 cuts off WOT

I checked the charger coil output while cranking; one side was 160 volts, and the other was 105 volts. Ohms test were 667 and 970. The 105 reading is on the bank that drops. According to CDI's trouble shooting info and the factory service manual, it's out of specs.

I think the stator assembly is the problem so I have ordered a new one. I've checked everything else and all is in specs.