1989 150xp Stalling At High RPM

[rlowhorn]

I have had this boat (Stratos) for a couple of years. About 6 month ago a cylinder blew out and I had the motor rebuild. Rebuild was okay but not sure it was the best job. Have compression and spark on all cylinders. Boat started struggling to plane out. It would plane if I took it slow and continued to hit the choak. Once it planed out it would run okay but only at low rpms. If I pushed it to high rpms it would run about 10 minutes and then sound out with a knocking noise and stall out. If I pulled back quickly on the gas it would start back up and go again with the same problem in a few minutes if I pushed the rpms. If I did not pull back on the throttle fast enough it would not crank the first couple of tries. After waiting a few minutes it would crank but slowly and start. I rechecked spark and compression and noticed that one of the cylinders was sparking at times and not others. Checked coil on that cylinder and it was okay. Checked by swapping out with one next to it. Purchased a power pak and it was not the fix. Also it just sounds bad. The only way to explain it is it sounds like a car does before the oil gets up on the valves. Knocking. Status of motor is I just replaced lower unit, have not cleaned carbs, and do not know it the fuel pump has ever been replaced. What would you recommend?

 

[boobie]

Re: 1989 150xp Stalling At High RPM

Is the hot horn working. Is the mtr over heating ??

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

Is the hot horn working. Is the mtr over heating ??

Did not know it had a hot horn and therefore I would not know about over heating. what would this have to do with it not planing out?

 

[boobie]

Re: 1989 150xp Stalling At High RPM

You said it had a knocking noise and then quit. The motor may be over heating and seizing.

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

What would be recommended? Thermostat?

 

[boobie]

Re: 1989 150xp Stalling At High RPM

No. Checking the hot horn to see if it works and then checking the mtr temp with a temp sensor gun.

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

The horn is part of controls. Being disconnected from the engine how would I test it?

 

[boobie]

Re: 1989 150xp Stalling At High RPM

Being disconnected from the engine ?? Explain ??

 

[ricklow]

Re: 1989 150xp Stalling At High RPM

Being disconnected from the engine ?? Explain ??

Bad use of words. What I was trying to say was since the horn is not working how do I test it? It is at the control panel is there a wire at the motor that I can connect to that should cause the horn to sound? Also, how would this cause the slow to plane. Is there something that happens in the motor that forces it to run at a slow rpm when this horn is not working, or when it is overheating? If so, how does that work?

 

[ricklow]

Re: 1989 150xp Stalling At High RPM

Bad use of words. What I was trying to say was since the horn is not working how do I test it? It is at the control panel is there a wire at the motor that I can connect to that should cause the horn to sound? Also, how would this cause the slow to plane. Is there something that happens in the motor that forces it to run at a slow rpm when this horn is not working, or when it is overheating? If so, how does that work?

This may help me know what to do.

 

[emdsapmgr]

Re: 1989 150xp Stalling At High RPM

The overheat information on your engine is found in your owner's manual or the factory service manual. Your 89 XP engine comes standard with the SLOW system. (not on the basic 150 models) When the engine overheats, the power pack automatically limits the engine rpm's to 2500, to protect th engine, until the overheat condition is resolved or the key switch is cycled. (the hot horn resets itself when the key switch is cycled, but it does not clear the overheat problem.) When the overheat is detected, the engine should also simultaneously sound the horn in the control box. It's easy to test the horn. There are two overheat warning switches, one on each head. Disconnect the tan wire that goes to each switch and touch it to ground when the key switch is on. The horn should sound. There is a bullet connector inside a rubber boot by that switch. It can be uncoupled there. You are actually testing the horn. FYI, the overheat head switches go to ground at 203 degrees. Sounds like at least one of them is may be working since you appear to be getting the overheat rpm limit.

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

Thanks. What steps should I take to identify what caused the overheating? Does it always come down to the pump or are there other things that can cause this?

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

Can someone tell me could the symptoms be caused by fuel problems. Low rpms, slow planing and stalling out if push down on throttle after ten minutes or so?

 

[emdsapmgr]

Re: 1989 150xp Stalling At High RPM

The telltale indicates that the pump is supplying water to the powerhead. That's part of the story. It does not indicate that the water is circulating through the powerhead and out the midsection/lower unit. You could have one/both thermostats stuck shut. When that happens water can't flush out of the block and you'll get a sure overheat. A weak fuel pump can cause WOT running issues. If the pump can't keep up with the carb fuel needs, you'll get a significant decrease in rpm's till the carb bowls refill with fuel. Once at WOT, then can empty again, causing this fast/slow running problem.

 

[rlowhorn]

Re: 1989 150xp Stalling At High RPM

The telltale indicates that the pump is supplying water to the powerhead. That's part of the story. It does not indicate that the water is circulating through the powerhead and out the midsection/lower unit. You could have one/both thermostats stuck shut. When that happens water can't flush out of the block and you'll get a sure overheat. A weak fuel pump can cause WOT running issues. If the pump can't keep up with the carb fuel needs, you'll get a significant decrease in rpm's till the carb bowls refill with fuel. Once at WOT, then can empty again, causing this fast/slow running problem.

Are you saying that is what you think? That thermostats are bad? These are the steps I plan to take. 1) Check horn to see if working by grounding circuits. 2) Run engine and check to see if overheating (125F at idle and 163F full throttle) using temperature sensor. 3) If overheating, replace thermostats. 4) Recheck engine temperature if over heating. What do you think?

 

[emdsapmgr]

Re: 1989 150xp Stalling At High RPM

The thermostats open at 143 degrees. The engine should idle between 143 and 150 after it's warmed up. In the dead of summer, in a warm lake, it might get up to 155. I'd be fixing something if mine ran at 163. The hot horn sounds at 212, then shuts off at 175, which is still way to hot. To answer your question, the stats could be bad. Or, you could have debris built up in the cooling system. Stats are cheap and should have been replaced automatically at powerhead overhaul. Also, the 322411 water diverters (one per cylinder) should have been replaced at the same time-and checked for proper position. The cyl head covers should have been removed to check for debris buildup inside the head cooling passages-as it can restrict powerhead cooling water flow. The pressure relief valves in the stat housings open when the engine gets on plane, providing tons of extra cooling water. Your cyl head temps will actually go down as much as 20+ degrees (when planning) when these valves open.

 

[ricklow]

Re: 1989 150xp Stalling At High RPM

The thermostats open at 143 degrees. The engine should idle between 143 and 150 after it's warmed up. In the dead of summer, in a warm lake, it might get up to 155. I'd be fixing something if mine ran at 163. The hot horn sounds at 212, then shuts off at 175, which is still way to hot. To answer your question, the stats could be bad. Or, you could have debris built up in the cooling system. Stats are cheap and should have been replaced automatically at powerhead overhaul. Also, the 322411 water diverters (one per cylinder) should have been replaced at the same time-and checked for proper position. The cyl head covers should have been removed to check for debris buildup inside the head cooling passages-as it can restrict powerhead cooling water flow. The pressure relief valves in the stat housings open when the engine gets on plane, providing tons of extra cooling water. Your cyl head temps will actually go down as much as 20+ degrees (when planning) when these valves open.

. thanks. Starting to understand. The horn seems to be fired in series to the detectors on block. I disconnected the brown wire and grounded it to the block with the key on. No sound. Assuming I did that right I have s bad horn. Got me an optical thermal sensor. Going to see if motor overheats. If so will order thermostats...if that does not fix overheat will go to water pump. If the motor does not overheat I will look into fuel system to see if I have air in gas.

 

[ricklow]

Re: 1989 150xp Stalling At High RPM (Tested temps)

Re: 1989 150xp Stalling At High RPM (Tested temps)

. thanks. Starting to understand. The horn seems to be fired in series to the detectors on block. I disconnected the brown wire and grounded it to the block with the key on. No sound. Assuming I did that right I have s bad horn. Got me an optical thermal sensor. Going to see if motor overheats. If so will order thermostats...if that does not fix overheat will go to water pump. If the motor does not overheat I will look into fuel system to see if I have air in gas.

Okay. I got an optical temperature sensor from a friend and measured the temperature of each side of the motor. First I ran it at edle speed for 10 minutes. The temperature measured between 130 and 140. Then I ran it at about 1 a third full throttle for 10 minutes and it never went over 150. Not sure what this tells me sense I still have the problem of slow plane, and stalling after running at full throttle for 10 minutes or so. What would be suggested as next step?

 

[emdsapmgr]

Re: 1989 150xp Stalling At High RPM

Ignition components that are weak (in the process of failing) will tend to break down once the engine heats up to normal operating temps (over 143.) Your temps seem to be just fine. Normal for those components to perhaps work when the engine is cold, then start to break down as the engine warms up. Sounds like that's your scenario, so you need to do your testing on the ignition system after the engine is well warmed up. You can check for spark on each plug wire by doing either of two tests: Spark drop test: 1. pull one plugwire off a spark plug with a set of insulated pliers. The engine should slow down. Replace that plugwire and pull off another. It should slow down. If you pull one wire off and nothing happens, that plugwire is probably not firing. 2. You can also test for spark on each plugwire with an inductive timing light. Watch the flashes in the gun for misfires, no fire, or weak firing, etc.

 

[ricklow]

Re: 1989 150xp Stalling At High RPM

I will do these test. Already replaced the power pak thinking that was my problem. So are you thinking more wiring issues? Let me ask another question. I ran the temperature test using muff for water supply. Would that make a difference in the temperature level?