5.0L MPI power loss

patchkit123 said:
I'm not a IO marine mechanic but I have had a small engine Biz for about 25 years. You are getting some great advise. I would check the basics.
1. You could have a valve train issue and still show good compression. Make sure the cam, pushrods and rockers are ok.
2. You could have good fuel rail pressure with a bad injector.
3. Run a vacume test for a possible intake gasket leak.
Good luck!
Click to expand...


Been gone for a few days, I'm back now to confront my perpetual headache. Thanks everyone for the good advice

1.How would I check the valve train without tearing the head apart
2.How would I check for a bad injector
Thanks,
Waterboy
 
waterboy, I read everything in this post and noticed you didnt answer SR Tech questions if you had any alarm. I did have a power loss because I had a faulty sensor (water pressure) go bad and the engine guardian was activated which would not let me go over 3600 rpms.
 
papogator24 said:
waterboy, I read everything in this post and noticed you didnt answer SR Tech questions if you had any alarm. I did have a power loss because I had a faulty sensor (water pressure) go bad and the engine guardian was activated which would not let me go over 3600 rpms.
Click to expand...

No alarms, SmartCraft computer says water pressure is OK.
Replaced the waterpump about 200 hrs ago.
Thanks,
Waterboy
 
I would first do what SR Tech said and hook that baby up to cds or ddt. What would it do if you went wide open throttle 3600 and then trimmed to the point of blowing the prop out? Would the rpms go up or stay at 3600. Seems to me that if it were a safety or protect mode, the rpms would not go up no mater what.
 
I agree with patchkit....you need to take your boat in and have it hooked up to find the exact cause.
 
Yeah I agree with myself as well:lol:

New MPIs are much harder to diagnose than a traditional carb/TBI setup.

Mainly because when something goes wrong, the computer makes changes right away to get back to normal operating procedure. Giving you no chance to hear the noise or experience it at a certain RPM or temperature.

You can throw parts at it all you want, even still...you have to reset the fault after you fixed the problem or your still going to be in guardian.
 
Will the smartcraft display if it is in guardian mode, or will everything appear normal on the computer?
I will take it in, but now I'm wondering if I have fixed the problem and all it needs is to reset the computer.
Thanks,
Waterboy
 
No, it will not display that you are in guardian mode. Take it in, explain what you have done to correct the problem but you are still experiencing the power loss. They will hook it up to the computer to find the source. I dont know if they are going to charge you for that but be prepared.
 
I would think you should be able to get it out of guardian (or fail safe) mode by disconnecting the batteries. Can't hurt to try, although this will erase any saved fault data. If you have already corrected your problem, (i.e. does it still vibrate or feel like it is misfiring) this should clear things up.
 
^^ yes it will. And you have a PM^^

But I'm sure the O.P. would like to know what faults he may have as to what caused guardian in the first place. Atleast I would...:grin: but thats just me.
 
So finally, two technicians and about a grand in parts later, the problem has been resolved. A faulty distributor cap, which I had already replaced. Our second mechanic said that all symptoms were pointing to a bad cap, then he told me that Quicksilver had gotten a couple bad batches from china. The bad ones have microscopic pin holes or air voids when they poured the molds which is just enough to throw the spark out of time on one or two cylinders. Put another cap in and problem solved. Whodathunkit.
Thanks to everyone for your input.
Fairwinds and following seas,
Waterboy
 
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