2Valve

water temp hit 70 yesterday.....finally. Boats didn't hit the docks 'til 9, so we waited a few minutes and ran our sets under a gorgeous MI sunset.

@escmanaze I like the InTow tapered handle. I'm running 6,8 passes in succession with no forearm issues like existed with other handles. Add the HeadGuard is cheap insurance too.

@MISkier he even barks when the skier falls. A hoodie might be in the works. I like it!

@DaveD On the positive side, the cool water is keeping most of the other traffic at the docks and allowing our club to do some 'four legged spotter' training.

@oldjeep Nice looking bike.

my buddy and I have been getting out every night after work. The water's at least 10F under norm for this time of year, but my wife has been getting in serious driving time with nobody else on the lake.

looking forward to my set with Nate in July. 2V

lost my concentration as I watched our spotter (my dog in training) sitting on the Observer's chair, head held high with a big smile moving his gait back and forth like at a tennis match, eyes glued to me. I started cracking up and just couldn't run that 41 off pass. (yeah, right)

wanted to post an update. We found the problem. Apparently, there are two different positions to install a thermostat in a 350 Chevy for that year. This boat had both thermostat's installed for some reason (previous owner?) One was installed in the T hose connection junction and the other in the intake manifold. The T location t-stat was bad and was replaced, and we removed the intake manifold unit as this is a non-LT1 engine. Problem solved. No more limp mode, temp at 140-150F. Except.......the MC dealer may have sold us a bad t-stat, as we skiied last night and our last set in the course, the temp gauge stayed around 100F. My buddy took out his rubber mallet to tap on the housing and the gauge moved to 160F. LOL! Thanks everyone for your help. We'll remove this one and return it to the dealer, with the assumption it's sticking open. On a better note, my dog is becoming quite the spotter. Sits in the Observer Seat, head slowly moving back and forth with a smile on his face. Officially part of the club now. 2Valve.

@Rednucleus they have not to my knowledge

@skiinxs Yes. Agreed. I don't have a IR, but do have a dual channel Fluke digital thermometer, that I should be able to sample water temp's in isolated areas. And we do plan on checking the thermostat at many different water temp's.

@skiinxs Not 100% sure of anything to be honest but with the temp gauge going hot and back down to normal intermittently, and the engine appearing to go into limp mode (rpm drop), when the temp gauge goes full, we think that's the path we should be following. Everything up to the main water pump has been inspected with no issues, so our thinking is that if both the temp gauge and limp mode sensor's are working (rare to have both fail), then it must be overheating. We may be wrong, but that's the direction we're headed.

@skiinxs 2nd that. I carry one of these all the time. https://shop.antigravitybatteries.com/products/micro-starts/xp-1/?gclid=EAIaIQobChMI3J6U2ILB4gIVhLfACh30FwV-EAAYASAAEgIatPD_BwE

OTOH, we have my boat to use in the meantime. Excellent conditions last night. Had the whole lake to ourselves, and not a ripple anywhere.

@skiinxs We're going to pull the thermostat tonight and run the engine without it. If it still overheats, we'll tear into the main water pump, and possibly the exhaust manifold to look at the water jackets. Hopefully, they're not plugged. Thanks,

@skihacker We checked that it and we're not sucking any air. Thanks

@jpwhit Thanks JP, I'll investigate this issue. Not hard to pull the main pump on a small block Chevy. If I recall, there's a cover on the back that once removed, gives access to the metal vane inside. Should be easy to verify that it's not slipping. 2Valve

The crazy thing is, at normal engine speed, why does the temp gauge go up and down?

@Andre "There's a temp sensor for the gauge and a a second one one for the ECM. For the needle to go 220 and for the engine to go into limp mode you must have a real overheating problem.But the gauge shouldn't go back to normal instantely when pulling back the throttle... Weird...Could the rubber impeller spin on the brass hub under certain conditions...? " First thing we did was pull the thermostat and test it in boiling water. Appears to open and close smoothly, (switching to colder water). We then installed a new 160F thermostat and drove around the lake. Now the temp gauge is acting even goofier. Regularly goes up and down between 160 and 200 or so. When it hits the 200+ range, the engine instantly starts bogging down. We then removed the sensor on top of the thermostat and noticing it didn't affect the temp gauge operation, concluded it must be the one talking to the ECM. (Limp mode) Accelerated as normal and within a few min. the temp gauge started dancing and sure enough, started bogging down. Re-connected it and drove back to the lift to inspect the impeller. Removed it and it's perfect. It's not disconnected from the metal inner sleeve so no issues of it not spinning. We removed all coolant hoses between the strainer, peered into the transmission cooler (perfectly clear) and up to the raw water pump. totally clear. I agree Andre. I think it's overheating as it would be rare for both temp sensor's to fail. The main water pump rotate smoothly, with no bearing issues, no leaks. Is it possible there's some restriction in the block itself and would it be prudent to pull the main water pump and somehow flush the block? Thanks, 2Valve

thanks everyone. The plan is to look at the impeller first, then the thermostat, under the assumption that the boat is really overheating intermittently.

The saga continues. New TPS didn't solve the problem. Pulled a skier last night and the engine bogged down as before. However, THIS time I was able to observe the engine temp gauge do something very weird. When the engine started to bog, the needle went all the way to full hot (220F). I watched it as I left the throttle in the same position and it stayed there, until I pulled back to idle. As soon as I did that, the needle came back to it;s normal position a bit below 160F. We then tried duplicating without pulling a skier and it happened again. Same thing. Nice smooth power planing out to 34mph and then a couple min. later, temp gauge goes full. Stays there until I pull back throttle and then the gauge returns to normal. My first thought is a bad temp sensor, telling the ECM that the engine is overheating. I'm guessing the algorithm is to reduce power at that point until the engine temp returns to normal. Or maybe a thermostat that's somehow opening and closing intermittently? 2Valve

@BraceMaker Thank You, We're going to swap out the TPS first and see if that does it. I have a MityVac that I use to bleed brakes with so if needed, I can use your suggestion to troubleshoot the MAP. Now let's ski!!!

Got back on this late last night. Using my handy dandy Fluke meter, I disconnected the TPS and measured the resistance on the TPS. Varying throttle position revealed values all over the map, from 2kohms up to infinity, back to 5 ohms, back to infinity. Also did some voltage checks with the connector plugged in (5vdc reference) and the output voltage was very inconsistent as well. So we'll be replacing the TPS. Also found the fuel pump relay housing (which was laying on the intake manifold), was burnt. Even though the fuel pump powers up, we're replacing the relay and will route it away from any heat sources. Thanks for your help everyone. I'll report back once we get it installed. 2Valve

In the minority here, but the Goode Power Vest let's me ski twice as long, with zero lower back issues.

@BraceMaker Thanks for the info. Then as a possible technique, could we disconnect the MAP sensor and see if the problem occurs? If not, then conclude that the MAP sensor is sending an incorrect signal to the ECM when the fault occurs?