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Hard starting RFI - 787 GTX 2001

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oldbugger

oldbugger

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787 RFI with less than 10 hours since re-sleeved cylinders, new pistons, new rotary valve and reworked rotary valve cover. Oil in the injection tank is Quicksilver PWC API-TC rated. First tank of fuel I ran regular 87 octane with about 500 ml of oil in the gas. Plugs are stock BR8ES NGKs. Ski starts great on trailer out of water. during the first tank of fuel I removed and cleaned plugs several times in an effort to do 2 things: 1. eliminate a sputter at 3900 - 4200 rpm and 2. get the thing to start on water without having to crank for 3 - 5 minutes. (if it is warm and I shut it off it will star right back up, if it sits for more that 2 or 3 minutes no such luck). Second tank of fuel was premium 91 octane with no oil added, I ran it briefly (10 - 15 minutes) hoping to see improvement on the 91 octane and "oil free" gasoline. When I didn't notice anything I put in new plugs. the sputter seemed to be better but on water starting still sucks. I have noticed that if I clear the cylinders (hold throttle full, plug in DESS and crank for about 8 seconds) and remove DESS for 3 seconds it will fire right off.

I am starting to think fuel pressure or maybe bad injectors (I did not replace o-rings on injectors when replacing jugs). Any thoughts or other things to try?

One other note is that rotary valve clearance is .002" over tolerance at .016"
 
Sounds like the injectors are leaking. In turn, it can't meter the fuel properly... and it will flood the engine when it sits.
 
Thanks Tony,
I kinda like the theory but why would it start fine out of the water? It does every time all the time. I guess I could pull the rail and let them sit outside of the cylinders and see if they drip? If they do are there any options beside replacing?
 
I am back a season later...
This spring I checked fuel pressure and all is within specification. I also pulled injector rail and did the drip test with pressure on the injectors, I literally had zero drips in the allotted time. Yesterday we ran for a few hours. the same symptoms remain. easy start out of the water, easy start if you shut it off just long enough for some one to board quickly and fire it back up, if they dilly dally you will fight the restart. on the water it runs great, pulled "big mable" with 3 riders no problem, with just me it tops out at about 52 on rough water.

Anyone have any other ides?
 
Im having the same issue hard to start have to give it some gas. 00 787 RFI Newly rebuilt and new injectors fires right up out of the water.
 
griz, thanks for the reply, I did trim wires, forgot to mention, sorry!
I am confused what indicates that the injectors are bad, they passed the leak test and seem to spray a nice pattern although I can not verify total flow.
I can certainly perform a compression test, would a over tolerance rotary valve clearance result in low compression?
Is resetting the tps a standard procedure on engine overhaul or is there a set of circumstances where it is definitely needed and others where it is not?
regarding the engine "before overhaul" I purchased the jetski at the start of last season with a "complete overhaul". long story short the oil injection pump driveshaft was not ever put in. I performed a top end after flushing and cleaning bottom end and installing the oil pump driveshaft. the cylinders and pistons were, of course, scored as was the rotary valve and rv cover, case side was not damaged.
 
griz, got it.. I understand the fuel delivery from the port versus the air/oil delivery from the the starboard. the oil was added to the tank per mfg recommendation and was only the first tank which was 4-5 tanks ago.
 
griz,
Thanks again for the reply. the reluctance to go to the shop stems from a few things...local shop's reputation, the 45 mile drive to the "local" shop and the desire to "do it myself" I will definitely look into the link for injectors, thanks for that and I will give the shop a call to see about scheduling the tps check.

I also want to get my hands on another RV cover to see if I can close that tolerance up some, just to know if it makes a diff.

I will be back to let everyone know how it goes...
 
I have a 2001 GTX RFI, same engine as you and I have the exact same problem except mine was never re-built.
I checked the compression, changed plugs, checked fuel pressures, injectors and nothing. All the readings I got from my checking were within specs according to my sea doo service manual.
I am starting to think it is the Throttle Position Sensor. I did check it as well in my garage by checking the resistance across the three pins and it was within spec but I am thinking since the problem is when the ski is warm it could be causing funny readings at higher temps. The starting easily out of water thing can be due to no drag on the impeller and thus masking the bad readings from the TPS.
I did a little checking and a new TPS is about $125 for the cheapest place so I do not just want to throw a new one just to make sure. Also in the service manual it says you have to adapt the new sensor with a scan tool. Does anyone know of a good way to adapt the sensor without a scan tool?
 
Cant adapt new tps without scan tool. Tps tells mpem throttle position which adjusts injector pulses. Without tps at zero will hard start and can run rich or lean. If u buy at dealer they may set it for free.
 
mrpickles2000 said:
Cant adapt new tps without scan tool. Tps tells mpem throttle position which adjusts injector pulses. Without tps at zero will hard start and can run rich or lean. If u buy at dealer they may set it for free.
Click to expand...

Thats what I came to find out as well.
So a little development on my end. I wanted to make sure that it really was the TPS that was bad before a spent $125 on a new one. I went to the dealer and had them set the 0 stop on the boat and then they set it up to the idle speed that it should have been and this is where the problem was discovered. It turnes out that the idle speed on my ski was way low, it was 1700RPM out of the water and this is what was giving me problems. It was set to about 1800 RPM in the water and I had no more issues. The thing starts even when hot and (knock on wood) the problem went away.

I figured that the main issue was just the Idle being turned way too low, since the engine does not have an Idle Adjustment Control other than the throttle blade opening, since mine was way too closed it was not allowing enough air in the engine to start it at idle.

I will keep an eye on it and if anyting changes I'll report back. My suggestion is to make sure that the idle is adjusted properly.
 
That is exactly it, that bolt with on the throttle blade is the idle adjustment. The ski is suppposed to idle at around 1700RPM to 1800RPM in the water. On land that translates to about 3000 RPM. This setting also gives the factory recomended 6% to 7% opening on the Throttle Positoon (TPS) sensor
 
I'm having the same problem with my ski. If you figure out the solution let me know. I've given up and sent mine to a dealer to try and figure out. They've spent some time on it over a 3 day period so far and they aren't sure what the issue is. Mine idles out of water but won't idle in the water. They tested the TPS and it was fine and they reset the throttle.
 
I recieved a tip from someone else who had this problem and his fix was a coil. The coil couldn't handled the load when the ski was in the water. He replaced it and his idle issue went away.
 
here is my update....though not really any success to report.
I had the rotary valve cover machined to tighten up the tolerance. Unfortunately the result is that the clearance is at the maximum, but within tolerance. I took the ski out tonight on beautiful water and got so brave as to shut the engine off to switch out riders on the tube....and had to be towed back because it wouldn't start. i had two guys lift the back end out of the water and voila off and running
Next on the list is new injectors...if that doesn't work i am not sure if i will go for fuel pump or be brave and try the "local" dealer for a tps setting....
 
Here's what someone told me on another forum. He's the only person I've come in contact with that has found a solution to the problem... and there are a lot of people trying to figure out this same problem with these RFI's. No one has ever suggested a problem with a coil on the 4 forums I've searched. Of course a lot of times people find the solution to the problem and let the thread die instead of posting the solution for the rest of us.

"Mine turned out to be weak spark from a bad coil, it would start in the water if you lifted the jetdrive out of the water. The extra force required to start it in the water was too much for the coil however it would start fine when it was cold.
Hope this helps"
 
WagonPipe said:
Here's what someone told me on another forum. He's the only person I've come in contact with that has found a solution to the problem... and there are a lot of people trying to figure out this same problem with these RFI's. No one has ever suggested a problem with a coil on the 4 forums I've searched. Of course a lot of times people find the solution to the problem and let the thread die instead of posting the solution for the rest of us.

"Mine turned out to be weak spark from a bad coil, it would start in the water if you lifted the jetdrive out of the water. The extra force required to start it in the water was too much for the coil however it would start fine when it was cold.
Hope this helps"
Click to expand...

I have stumbled upon that post as well, I like the theory except for the fact that if mine sits for 20 -30 min (enough time to cool down?) it will start in the water. I think this would be real easy to solve with the CanDoo system. I will test primary resistance in my coil though, maybe it is weak when hot which would point to a secondary breakdown I believe...and with out BUDS or CanDoo, can't test the secondary in our RFI coils :(
 
With a Different battery it will fire up fine the first time, But after that its back to no strating in the water.

I Ordered a Coil Ill Update if thats the problem.

My Coil Has about 110Hr and I bought one with 45Hr
 
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