Thread: 01 GTX DI Fuel Pump/Compression
07-31-2011, 09:10 PM #1
- Join Date
- Jul 2011
01 GTX DI Fuel Pump/Compression
Hello all, great forum you guys have here... I have been spending some time doing some research on what I should do.
I am considering buying a 01 GTX DI from my cousin. He has had it parked at our pier for a few years and he is not going to be able use it due to med. school, so he is trying to sell it. It is a very clean machine, and has very low hours.. I think it has in the 70 hour range, maybe less I'd have to double check..
I haven't officially bought the ski yet, so thus far all I am out is my time.
Anyway, the machine has run great up until this year, when it stalled on him and wouldn't restart. We towed it in, he took it to a shop that works on PWC's, and they replaced the spark plugs and called it good.. The ski would then start and run, but would randomly stall after some time of running. Usually it would stall and you could get it started again eventually.. It currently does not start or run. It will fire and stumble for a second but will not idle.
I obtained a copy of the service manual and after some reading, suspected the fuel pump and/or plugged strainers/filters... I tested fuel pressure after the fuel filter and by plugging the lanyard in, i would get about 22 PSI. During cranking I would get about 85 PSI.. One time the pressure jumped up to about 98 PSI and it started and ran. I believe the spec is about 106 PSI at idle.. It would flutter around 100 PSI when it idled.. I assume it would flutter like that because the fuel pressure regulator is trying to regulate at 106 PSI, so the fluttering is from the pressure drop on the fuel injectors opening..
After removing the fuel pump and inspecting the pieces, nothing seemed amiss. The bottom of the tank is clean, the little sock on the bottom of the pump was fine, the strainer inside the pump looked clean, and when I dumped out the fuel filter into a jar it didn't have anything dirty inside, just nice clean gas... So after that diagnosis I assume my fuel pump is shot..
I came across this thread and noted there might be some other alternatives to the $800 fuel module that Bombardier wants to charge.. I will pursue other options...
For grins, i decided to check the compression.. I got no compression on the front cylinder, and the back cylinder has probably about 125 PSI or so.. I confirmed the no compression by sticking my thumb over the plug hole while cranking.
I'm wondering if somehow something could be preventing compression? When I took the plug out of that cylinder, it looked dark like it was running rich.. The ski was always maintained and proper oil was used.. I would think it'd be hard to imagine that it would bust a piston or a ring after less than 100 hours?
I shined a flashlight inside the cylinder and from what I could see the piston looked like it was in good shape...
I checked compression by removing the spark plugs, opening the throttle all the way and cranking the engine over..
08-03-2011, 07:00 AM #2
- Join Date
- Jul 2011
Any ideas? Thanks
08-05-2011, 02:06 PM #3
- Join Date
- May 2011
A piston is toast. If you can not see a hole, that does not mean the edges of the piston are ok. You won't know how bad it is until you pull the head off. My guess is that it rings are gone and the piston is tore up and most likely the head will be pitted from metal debris.
Did you notice any oil in he bottom of the engine compartment?
I am about to try my hand at a DI. I am picking it up in a little while (if the body is perfect). If so I will start posting the tear down and build-up of the ski.
08-06-2011, 01:01 AM #4
- Join Date
- May 2011
well, that project will just have to wait, that was a total Flower Pot!!! Ain't No way I am paying for that project. I would have only taken it on for free!!!. sorry bud
10-05-2011, 02:16 PM #5
- Join Date
- Oct 2011
- Littleton, CO
I don't know if you have already completed your repair, or are waiting for more info.
Your first description was leading me to think fuel pump. If your fuel filter is OK then you need a new pump assembly (about $700).
However, when you said no compression on the Mag cylinder, it means there are mangled rings and most likely a hole in the side of that piston.
Just remove the RAVE valves, 4 small bolts, leaving air hoses attached. Then with spark plugs removed just rotate the PTO flywheel so you can visually inspect the sides of the pistons.
You will most likely see the PTO (rear) piston is OK, but the MAG (front) piston has mangled rigs and possibly a hole. In my experience it is usually the Mag piston that gets to hot and melts, and it is always on the exhaust side so you can easily see it through the RAVE port.
You can actually do the partial (1 piston) top-end rebuild leaving the motor in the hull, if you have good mechanical skills and the correct tools (nothing you can't buy at Harbor Freight or anywhere).
When you get the head off and cylinders pulled you can see if there is enough damage to require cylinder re-sleeving or just honing.
The trickiest parts:
You can actually unbolt the fuel/air rail and push it back and out of the way without disconnecting the fuel lines, just the injector plugs, and removing a water temperature sensor behind it.
Before removing the bad piston from the rod, "mask off" the crankcase so you don't drop anything down in the crankcase (like needle bearings, clips, etc.), then push out the piston pin with a short piece of dowel to hold all the needle bearings in place in the rod, for reassembly.
Installing the piston pin circlips with small needle nose pliers can be a little tricky, since they aren't as easy as the automotive types.
Compressing the rings on both pistons and pushing them back into the cylinders is the last tricky part. I used a couple of lubed hose clamps, and of course liberally lubed the cylinders and pistons. It is easier with a helper.
The pistons can get pretty hot with extended high speed WOT runs. I back off WOT after about 1 minute to cool them off and prevent detonation.
10-05-2011, 08:46 PM #6
I would really take a look at that machine before you put any time or money into rebuilding it to figure out why it broke. Otherwise, you can end up right back where you are now if you don't remedy the issue that toasted the piston in the first place.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By Elloello in forum Sea Doo Open DiscussionReplies: 2Last Post: 06-25-2010, 04:00 PM
By n20junkie in forum 2-Stroke PerformanceReplies: 0Last Post: 06-08-2010, 09:31 AM
By XtRmn8 in forum 2-Stroke PerformanceReplies: 3Last Post: 11-16-2008, 06:52 PM
By johnsonmtz in forum Polaris Open DiscussionReplies: 1Last Post: 08-24-2008, 10:13 PM
By Vagaondracing103 in forum Sea Doo ClassifiedsReplies: 2Last Post: 06-05-2008, 12:31 PM