Please help

[Ghaa66]

After so many problems with my 1995 GTX 657x engine, I finally hit the lake yesterday. It ran like a bat outta hell for an hour and a half, then just died like someone jerked a wire loose. After that, it wouldn't fire a lick. I swapped out plugs, now it tries to fire but just won't run. I have compression, fuel and fire.
Any ideas ???

 

[Dr Honda]

If you have "Fire, Fuel, and compression"... it should run.


SO... one of those things aren't what you think it is.


1) Fire: Did you check to see if your spark is right? The flywheel could have slipped, and the timing is WAY out.

2) Compression: What is it? (Give us a number) We get guys all the time that just stick their thumb over the hole, and say it's OK... but in reality, it's not. It only takes a few PSI to push your thumb out of the way.

3) Fuel. How do you know? OK... generaly fuel doesn't cause a quick shut off... but its hard to tell if fuel is actualy coming out of the carbs.


So... with that said....... The things that will shut you off while running....

1) Melted piston(s). a real compression check will show you that.

2) A destroyed Rotary Valve. (or gears)

3) Ignition. Could be a bad flywheel, bad CDI, Bad lanyard post... or anything in between.

 

[jimmaki]

If you run pump gas and it has been sitting for a while due to "so many problems" you might have water in your tank. If it phase separated you may have just gotten down to the level where the water is. Switch to reserve and pull some gas from the hose connected to the fuel pump and put it in a glass jar and let it settle out to see how much of it is water.

If you don't see a separation line between two different liquids you could be looking at all water. So keep pulling from the tank until you see a line or put some gas in the jar and mix it and see what settles out.

Also check all your electrical connections making sure they are not only tight but clean.

 

[Ghaa66]

Thanks guys. Engine, carbs, fuel lines, pretty much entire boat has been rebuilt and refurbished over the last month. I'm thinking Dr. Honda nailed it with the fly wheel or stator timing. I'm gonna pull the cover off here in a few and check that. It just stumps me how it was running so perfect then just died, now all it does is try to start but won't run. It always bump started before and ran like a top.

 

[Ghaa66]

BTW, compression test results 91 lbs on both cyl. Taken on a Harbor Freight Tools Compression Guage, which "as you know" may not be completely accurate.

 

[jimmaki]

WOT plates open all the way?

When you get the mag cover off check the trigger coil bracket for cracks/failure.

 

[Ghaa66]

I gave up on this thing. I'm putting it in the shop tomorrow. I'll post what he does to fix it.

 

[XP 787]

In your other post you said you were having problems with water getting into your engine from a bad cylinder base gasket where you said you fixed it by making your own. Pull the head and take a look at your pistons, if all looks good there I'd recheck that base gasket.

 

[Ghaa66]

Already did that, all looks good. I've been making my own gaskets on all types of engines for many years. It's very easy, I can't figure out why so many people are afraid to do it. Took me about 4 minutes to cut out that one, once I verified the thickness was correct.

 

[96spxpos]

Hey man if that's 657x is as close to a 717 as other ppl say, 91 psi in both cylinders is way low. Especially on a newly redone motor. I'm wondering if that gasket has anything to do with it. No seal=air leak=less/low compression, no?


Sent from my iPhone using Tapatalk

 

[Coastiejoe]

BTW, compression test results 91 lbs on both cyl. Taken on a Harbor Freight Tools Compression Guage, which "as you know" may not be completely accurate.

If the number is even CLOSE,,, there is your problem. 120 is the LOW acceptable number. Once you hit 120 psi you will be doing engine work in the near future..

 

[Ghaa66]

Ok, obviously, Harbor Freight China tools SUCK ! I borrowed 2 more Compression Guages. One said 122 psi, the other 128 psi. Harbor Freight Gauge reads 90 psi.

 

[Ghaa66]

Thought I would give you guys a follow up on this issue. PWC has been sitting at boat shop for over a month, I finally get tired of waiting for him to look at it and go pick it up. Needless to say, I had it running in about an hour. Turns out the rotary valve jumped time. I can't figure out how it jumped, everything was perfect. I reset timing, went to the lake, and ran perfect for 2 hours, then it decided to throw a rod bearing !!! I'm so freaking sick of this damn thing !!! Can anyone elaborate on how to replace a rod bearing the right way on this piece of junk or would it be best to just kick $800 on a new engine ???

I started a new thread on this subject at... http://www.seadooforum.com/showthread.php?80621-Rod-Bearings&p=489957#post489957