787 RFI low power

[mattrourke]

Hi everyone,

New to seadoos and I just bought two 2004 seadoo 3d RFI units. The one runs quite well after an initial 5 minutes of running really rough and smokey... I think it was just burning some buildup from storage.

The second one is causing me some issues, seems to run about 1/2 the power. Fairly smooth throttle in the first 1/4 but after that I can hold it wide open and it very slowly gets on plane and cruises but nowhere near the speed of the other. It also misses randomly while cruising.

After reading on here for the last few days I changed the battery out with a new one from seadoo and tried disconnecting the rectifier to eliminate that as an issue. Also changed the plugs. Compression reads 135-140 psi on both cylinders. I know it is a little low but they are equal and most people seem to suggest if they are equal it should still run ok. I did notice the temp sensor has melted at some point but the wires look good and so does the plug contacts.

What is next? I'm fairly mechanically inclined but seadoos are new to me.

 

[Ckrawiec]

Strip away all the "extras" around a gasoline engine and it all boils down to FAST.....fuel, air, spark & timing.

Just "guessing" on your problem, based on the description.....it really sounds like a fuel delivery to the pistons related issue......if she starts and runs but doesn't perform quite right......I'd hazard to say that fuel delivery is the most likely culprit.

NOW, fuel delivery is a "vague" diagnosis as that could involve many things.......partially plugged filter, varnish in the lines, tank vent is plugged, water in the fuel, etc......it really comes down to a process of elimination......do one thing at a time, test to see if that changed anything.....move on.....can be tedious but doing TOO MUCH all at once might mask the solution (but if it gets you back on the water quicker....I get it!). Good luck.

 

[mattrourke]

Since I have two of them and one seems to be running well, I was thinking of swapping the fuel sending unit/pump from the good one into the bad one and see if that makes a difference. I've ordered the main bottom filter but it won't be here for a week or more.

I know exactly what you mean about trying one thing at a time, just a pain when everytime involves a drive out to the lake. I wish it would fit in my hot tub haha.

Is there an easy way to test the injectors to first see if it is a fuel pressure issue and then I can try and find out which component is causing the pressure issue? I saw someone say the injectors are a real PIA to get to on the 3D.

 

[Ckrawiec]

Since I have two of them and one seems to be running well, I was thinking of swapping the fuel sending unit/pump from the good one into the bad one and see if that makes a difference. I've ordered the main bottom filter but it won't be here for a week or more.

I know exactly what you mean about trying one thing at a time, just a pain when everytime involves a drive out to the lake. I wish it would fit in my hot tub haha.

Is there an easy way to test the injectors to first see if it is a fuel pressure issue and then I can try and find out which component is causing the pressure issue? I saw someone say the injectors are a real PIA to get to on the 3D.

Sorry, I'm no help on the injector side of things.....I'm a carb guy myself......I haven't had to mess with injectors on my newer skis, so no direct experience with them on a seedoo YET!

 

[mattrourke]

Sorry, I'm no help on the injector side of things.....I'm a carb guy myself......I haven't had to mess with injectors on my newer skis, so no direct experience with them on a seedoo YET!

No worries! Thanks for the reply. I'll switch the pumps and maybe siphon out the fuel and try that before moving on.

 

[mikidymac]

You really need to do both fuel filters in the tank. They are cheap and available at any auto parts store.

Listed here The RFI Spot.

 

[mattrourke]

You really need to do both fuel filters in the tank. They are cheap and available at any auto parts store.

Listed here The RFI Spot.

Thank you for that link. I found 2 of each in town and will change the filters as I swap them over. Also found a replacement pump in town which I may purchase as well. I don't mind having a few spare parts on the shelf. I don't live in a very big city so finding parts locally is pretty lucky!

I think I saw that a rivet gun is needed as well to reassemble after drilling out rivets to get at the internal filter so I will pick one of those up too.

I will report back.

 

[mikidymac]

I don't think I replaced any rivets.

I wouldn't mess with aftermarket fuel pumps.

 

[mattrourke]

So, update for the day. The filters available locally were the wrong ones but I swapped the fuel pumps anyways since I know one works well. No change. The good seadoo was still running well and the crappy one was still crappy. Not sure what is next.

Any suggestions?

 

[mattrourke]

I'm wondering if i should pull the injectors and see what the fuel spray looks like. Do you think i would be able to notice if something was wrong? How difficult are they to pull? Is it worth swapping them over from the good doo over to the busted one?

 

[mattrourke]

I have been reading about RAVE valves and how they can cause some issues like I am having. I took a picture of the one I pulled apart and it was quite oily under the cap. Does this suggest that maybe the diaphragm is ripped?

 

[Poormanracing]

Look around the bellows to see if it is blowing past plastic cap.take a volt meter and put it on battery and try machine.to see if it starts to mess up and the voltage at the battery starts climbing or dropping or going crazy.then you can count out the charging side.make sure your grounds on the block are good.and make sure your battery is 100 percent.not one that has been sitting for a few years and just charged up.and thinking it's good because it is not good.

 

[Poormanracing]

Also what rpms is it messing up at not throttle position in the ECM has different default settings for different problems.that ignition runs off of battery not the charging system and people get messed up Diagnosing them when it's the battery the whole time.the charging system is just really designed to maintain a good charged battery.not a weak battery.hope this helps out

 

[Pedec]

I am also having similar problem with my 3d will start great but will not rev above idle barely will not get on plane just bogs and smokes a lot. Have 155psi on both cylinders. Checked oil pump is set correct right which it is.The fuel rails are not that hard to remove only two bolts but a lot is done by feel. I changed my fuel filters and to change the one I had to drill two rivets out no big deal. Cleaned tank out which was actually really clean. I also checked my fuel pressure while ski was running on the water hose 58psi which is good and did not change psi when bogging. I took injectors out cleaned and tested and seemed good. Checked spray with rail off and cranking motor and spray looked fine on both injectors. I put a new battery in 3d no difference and every time I try testing ski I make sure battery is fully charged. While running 14.1 volts at battery and also disconnected rectifier while running with no difference. Check all sensors with multi meter and all checked out good. Checked all fuses and all seem fine and tested good and clean contact. Exhaust system doesn't leak water or fumes in hull no melted looking pieces. Took most hoses off to check for blockage and none found. No engine lights and took to dealer and Budd system said no problems. Reset TPS while on BUDD system at dealer but seemed fine before. Found out ski has 189 hours on it while on computer. I let engine sit for 4 days then took spark plugs out and held paper towel over spark plugs hole while cranking engine for 5 seconds. No signs of to much oil on paper towel and repeated test 2 more time after right away and looked the same as first time. So thinking test proves crank seal or rave valve seal is not leaking. I have found a used ECU that is suppose to good I bought and going try it since I am out of idea just waiting to get it. The first time I took 3d out it ran great for a hour on the water a week later right off trailer problem started like a switch was hit but I did not change anything. Let us know if you figure out problem.

 

[Poormanracing]

I am also having similar problem with my 3d will start great but will not rev above idle barely will not get on plane just bogs and smokes a lot. Have 155psi on both cylinders. Checked oil pump is set correct right which it is.The fuel rails are not that hard to remove only two bolts but a lot is done by feel. I changed my fuel filters and to change the one I had to drill two rivets out no big deal. Cleaned tank out which was actually really clean. I also checked my fuel pressure while ski was running on the water hose 58psi which is good and did not change psi when bogging. I took injectors out cleaned and tested and seemed good. Checked spray with rail off and cranking motor and spray looked fine on both injectors. I put a new battery in 3d no difference and every time I try testing ski I make sure battery is fully charged. While running 14.1 volts at battery and also disconnected rectifier while running with no difference. Check all sensors with multi meter and all checked out good. Checked all fuses and all seem fine and tested good and clean contact. Exhaust system doesn't leak water or fumes in hull no melted looking pieces. Took most hoses off to check for blockage and none found. No engine lights and took to dealer and Budd system said no problems. Reset TPS while on BUDD system at dealer but seemed fine before. Found out ski has 189 hours on it while on computer. I let engine sit for 4 days then took spark plugs out and held paper towel over spark plugs hole while cranking engine for 5 seconds. No signs of to much oil on paper towel and repeated test 2 more time after right away and looked the same as first time. So thinking test proves crank seal or rave valve seal is not leaking. I have found a used ECU that is suppose to good I bought and going try it since I am out of idea just waiting to get it. The first time I took 3d out it ran great for a hour on the water a week later right off trailer problem started like a switch was hit but I did not change anything. Let us know if you figure out problem.

I am also having similar problem with my 3d will start great but will not rev above idle barely will not get on plane just bogs and smokes a lot. Have 155psi on both cylinders. Checked oil pump is set correct right which it is.The fuel rails are not that hard to remove only two bolts but a lot is done by feel. I changed my fuel filters and to change the one I had to drill two rivets out no big deal. Cleaned tank out which was actually really clean. I also checked my fuel pressure while ski was running on the water hose 58psi which is good and did not change psi when bogging. I took injectors out cleaned and tested and seemed good. Checked spray with rail off and cranking motor and spray looked fine on both injectors. I put a new battery in 3d no difference and every time I try testing ski I make sure battery is fully charged. While running 14.1 volts at battery and also disconnected rectifier while running with no difference. Check all sensors with multi meter and all checked out good. Checked all fuses and all seem fine and tested good and clean contact. Exhaust system doesn't leak water or fumes in hull no melted looking pieces. Took most hoses off to check for blockage and none found. No engine lights and took to dealer and Budd system said no problems. Reset TPS while on BUDD system at dealer but seemed fine before. Found out ski has 189 hours on it while on computer. I let engine sit for 4 days then took spark plugs out and held paper towel over spark plugs hole while cranking engine for 5 seconds. No signs of to much oil on paper towel and repeated test 2 more time after right away and looked the same as first time. So thinking test proves crank seal or rave valve seal is not leaking. I have found a used ECU that is suppose to good I bought and going try it since I am out of idea just waiting to get it. The first time I took 3d out it ran great for a hour on the water a week later right off trailer problem started like a switch was hit but I did not change anything. Let us know if you figure out problem.

If you disconnect voltage reg and you have no difference then you have a charging problem if you undo rectifier your voltage should climb and not stay at battery voltage

 

[mattrourke]

Also what rpms is it messing up at not throttle position in the ECM has different default settings for different problems.that ignition runs off of battery not the charging system and people get messed up Diagnosing them when it's the battery the whole time.the charging system is just really designed to maintain a good charged battery.not a weak battery.hope this helps out

I put a brand new OEM battery in a couple days ago and tried it with and without the rectifier attached. There is no tach on the 3d. Is there a way I can connect one to get rpm readings for diagnostics?

 

[Poormanracing]

I put a brand new OEM battery in a couple days ago and tried it with and without the rectifier attached. There is no tach on the 3d. Is there a way I can connect one to get rpm readings for diagnostics?

You can put one of those cheap mighty tach on it.or a dealer can put budds on it and see what's going on or again put a volt meter on machine and run it on the lake to see if it is jumping around or drawing voltage instead of maintaining voltage.rfi run good 90 percent of the running problems are voltage related or ground related

 

[Poormanracing]

Also run another ground from battery to the block the ground cable either runs under the motor or to the starter mount and they break apart under the heat shrink.i worked at a dealer when these where being made and they can be hard to figure out

 

[Poormanracing]

And your new oem battery believe me when I say don't mean squat.when I went to Doo school we spent a full day of class work just on battery's and storage procedures.did the stealer fill it wait an hour to settle acid then top it off then let it sit again then charge it as slow as possible for the right length of time.no they filled it and prob just handed it to you saying it's all set then you assuming it should be good to go just thru it in.meanwhile your ski is not seeing the voltage it needs because your new battery doesn't have the right amps in it.sorry for the rant but I've dealt with this happening for years and it just wastes people's time and money

 

[mattrourke]

And your new oem battery believe me when I say don't mean squat.when I went to Doo school we spent a full day of class work just on battery's and storage procedures.did the stealer fill it wait an hour to settle acid then top it off then let it sit again then charge it as slow as possible for the right length of time.no they filled it and prob just handed it to you saying it's all set then you assuming it should be good to go just thru it in.meanwhile your ski is not seeing the voltage it needs because your new battery doesn't have the right amps in it.sorry for the rant but I've dealt with this happening for years and it just wastes people's time and money

I will check it again today. They filled it and put it on trickle charger all day and then I picked it up and put it on a 2 amp charge overnight before I put it in. But I won't argue... Im happy to run some voltage tests on it again in hopes of tracking down the issue. I really appreciate your help!! I can also pull the battery from the seadoo that is running properly and swap it in if that helps eliminate the variable. I'm lucky to have two of the same units sitting on the trailer.

 

[Pedec]

Sorry I meant the ski still had the bog did not improve the way ski ran is what I meant.

 

[Pedec]

You can put one of those cheap mighty tach on it.or a dealer can put budds on it and see what's going on or again put a volt meter on machine and run it on the lake to see if it is jumping around or drawing voltage instead of maintaining voltage.rfi run good 90 percent of the running problems are voltage related or ground related

Mine bogs all the time doesn’t improve then get worse again. The ground idea is a good one.

 

[Pedec]

Also run another ground from battery to the block the ground cable either runs under the motor or to the starter mount and they break apart under the heat shrink.i worked at a dealer when these where being made and they can be hard to figure out

Great idea. I have checked ground and seem good but all by feel. So just hook a wire from ground terminal to bolt on block. I heard you do not want to hook up battery backwards it will fry ECU.

 

[mattrourke]

These are battery readings on the trailer, no water.

Battery readings:
On the bad seadoo:
Before starting with new OEM battery: 12.65v
With lanyard attached: 12.5v
Started and running at idle: 14.02v
WOT: 13.97v
After shutdown: 12.85v

On the good seadoo:
Before starting with aftermarket battery: 13.08v
With lanyard attached: 12.96v
Started and idle: 14.4v
WOT: 14.39v
After shutdown: 13.15v

 

[mattrourke]

These are battery readings on the trailer, no water.

Battery readings:
On the bad seadoo:
Before starting with new OEM battery: 12.65v
With lanyard attached: 12.5v
Started and running at idle: 14.02v
WOT: 13.97v
After shutdown: 12.85v

On the good seadoo:
Before starting with aftermarket battery: 13.08v
With lanyard attached: 12.96v
Started and idle: 14.4v
WOT: 14.39v
After shutdown: 13.15v

@Poormanracing any thoughts on those voltages?