Mercury 150 XRi stalling out, won't plane boat

[tatage0201]

I am attempting to revive my dad's old bass boat that has been idle for the past 2 years. The outboard is a 1994 Mercury 150 XRi which I have been working on for the last 6 months. The serial number is 0G052141.

The first thing I did was to disconnect the line from the tank and ran it into some fresh gas. I also replaced the spark plugs. The engine wouldn't crank so I began tracing the fuel to find out that the VST tank needle was stuck. I cleaned this up and finally got the motor to turn over and start running. I removed the old gas out of the tank and filled the tank with fresh gas. I launched the boat and began to start to plane out. The motor ran like everything was in tune and I was going good for about a minute or so. All of a sudden I lost power (not completely) and the boat came off plane and would not get back up past half throttle even though I had it pegged. It would run at half throttle and occasionally jump like it was going to take back off.

I returned back home and suspected that something had clogged the fuel line somewhere so I then rebuilt the pulse pump with a new diaphragm kit and I replaced the fuel/water separator. I pulled the injectors and cleaned them (they didn't look dirty at all). I tested the injectors with 9 volts per the SELOC manual I have and each one clicked and emitted some fuel so i assume they are all ok. All spark plugs seem to fire when I turn over the engine. I pulled each one and connected back to the coil to test for spark as someone turned the key switch. I replaced the primer bulb as well.

I went back out on the water and started exactly where I left off. The boat did not plane at all and would actually start to stall at full throttle and kill. I would pull off the throttle a little bit from full and the boat would run steady at mid throttle and occasionally slightly jump like it would try to take off.

I came back home frustrated and looked for any other things that might could be the culprit. I noticed that the electric fuel pump comes on sometimes when I turn the key and it somewhat noisier than I would think it should be. Should this pump come on every time I turn the key to on? I don't know if I have exhausted the fuel problems and it could possibly be the electrical system? I noticed in one forum where someone mentioned the stator as possibly being the culprit but I don't know if that would be it or not. My last resort will be to take it in to the repair shop, but I don't want to spend that money if I don't have to.

 

[Faztbullet]

Re: Mercury 150 XRi stalling out, won't plane boat

I noticed that the electric fuel pump comes on sometimes when I turn the key and it somewhat noisier than I would think it should be. Should this pump come on every time I turn the key to on?

Yes and run for a few seconds and shut off. Need to check the pump pressure and throw the Selco manual away. The test on injectors was not a good test as internal filter could be clogged or pintle stuck and flooding, these need to be sent off and flowed and balanced(Brucatosvs.com). A noisy fuel pump could be cavitation of pump as filter on bottom of it is clogged.

 

[tatage0201]

Re: Mercury 150 XRi stalling out, won't plane boat

Yes and run for a few seconds and shut off. Need to check the pump pressure and throw the Selco manual away. The test on injectors was not a good test as internal filter could be clogged or pintle stuck and flooding, these need to be sent off and flowed and balanced(Brucatosvs.com). A noisy fuel pump could be cavitation of pump as filter on bottom of it is clogged.

There are times when I don't hear the fuel pump come on at all when I have the cover off. When I was running it yesterday with the muffs on, it killed on me a couple times. When I went to restart it, I would turn the key to "On" and the pump wouldn't come on. I would do this maybe 10 times and still the pump would not come on. There are times when it will run for a long time (20-30 seconds) and then shut off and then there are also times when it will run for a few seconds and then turn off as well. Do I check the pump pressure at the valve above the fuel pump?

 

[Faztbullet]

Re: Mercury 150 XRi stalling out, won't plane boat

Do I check the pump pressure at the valve above the fuel pump?

yes

 

[tatage0201]

Re: Mercury 150 XRi stalling out, won't plane boat

Took the boat to a buddy that works on motors on the side. Tested compression and all 6 cylinders good ranging from 125 to 130 psi. Tested ignition and it also was good.

Gonna meet up with him on Tuesday next week and take the boat on the water. He said he wanted to test the switch boxes and some other things on the water. I'll update back as we get closer to either weeding more things out or a resolution.

 

[tatage0201]

Re: Mercury 150 XRi stalling out, won't plane boat

Took the boat to a buddy that works on motors on the side. Tested compression and all 6 cylinders good ranging from 125 to 130 psi. Tested ignition and it also was good.

Gonna meet up with him on Tuesday next week and take the boat on the water. He said he wanted to test the switch boxes and some other things on the water. I'll update back as we get closer to either weeding more things out or a resolution.

Finally got what we believe are the correct tools to test the motor (dva meter and a Mercury analog diagnostic tool). We tested the stator and trigger and they passed. Then tested the switch boxes and they passed. Boats till runs the same. We hooked up the diagnostic tool to the ECM (old analog box with dials to turn for different test selections; found my ECM in the manual and ran the tests). First we tested the TPS and it passed. There were 5 tests to run for the ECM to determine if it is faulty. WE ran then once through and then ran them again to make sure. The ECM failed 2 of the tests. The first test was looking for a reading of 1.13 with a variance of +/- .04. We got a reading of 1.02 which is -.11 variance. This test failure dictates the ECM is faulty. I want to make sure I am making the right decision to purchase an ECM/rebuild mine as this is a lot of money. I feel like we have exhausted all other tests.

 

[tatage0201]

Re: Mercury 150 XRi stalling out, won't plane boat

We also tested the motor on the trailer in the water at the dock. We hooked up the dva meter and we would get low to high surges on all 6 cylinders we tested ranging from 140V and spiking to 200V as the motor revved up and down while holding the lever almost at full throttle. If I pushed the throttle all the way down it would bog down and kill. Would the ECM have any effect on the voltage spikes up and down?

 

[Faztbullet]

Re: Mercury 150 XRi stalling out, won't plane boat

Would the ECM have any effect on the voltage spikes up and down?

No....what you where seeing was stator output as voltage would increase as engine sped up/down. ECU only controls injectors not ignition. Send the ECU to Brucato and have tested(about $50) and if bad get his PCU as it a heck of a lot better than Merc's.

 

[tatage0201]

Re: Mercury 150 XRi stalling out, won't plane boat

No....what you where seeing was stator output as voltage would increase as engine sped up/down. ECU only controls injectors not ignition. Send the ECU to Brucato and have tested(about $50) and if bad get his PCU as it a heck of a lot better than Merc's.

Thanks for the help here Faztbullet. If I am interpreting what you are saying correctly, I will still have a problem if I have a bad ECU. Is there something on the flywheel or stator that I might have missed to check? The motor purrs like a kitten idle through mid range. When I hit the high range to start planing out is when the voltages start to spike and then drop down causing the back and forth surges.

 

[Faztbullet]

Re: Mercury 150 XRi stalling out, won't plane boat

When I hit the high range to start planing out is when the voltages start to spike and then drop down causing the back and forth surges.

What is the charging voltage as if excessive you have a regulator bad causing stator to act up. If its at the 2800-3000 rpm range thats when switchboxes internal rectifier flip to the high speed side of stator. I doubt both boxes have a problem so check rectifiers,stator high speed output and disconnect advance module as can cause boxes to act goofy.