1996 SL700 Hot Start Issue

[MA-Chris]

So, I abruptly entered the world of Polaris jetskis this week with a free SL700 that I picked up from the local "buy nothing" facebook site.

It doesn't seem to have of ton of hours on it. I changed the spark plugs to NGK BRP8ES and put a brand new AGM battery in it. I put some fresh fuel, yamaha ring free and fuel stabilizer in it and it started almost immediately and idled well. The trim motor is dead/seized so I need to address that next. I took it to a local lake and it ran like a scalded dog. I hit 42 MPH with the jet trimmed all the way down which i think is pretty good. Plenty of power throughout the throttle range. I verified that the oil tank level was dropping.

Anyway, I have a strange "hot start" issue. Everyone wanted to go for a ride and half the time, the engine would not restart but would crank and crank and crank. If I let it sit for 3-5 minutes it would finally start. I could smell the engine was getting flooded.

I am not sure that PWC-00-05 applies as the starter will engage and crank over, I just don't seem to have any spark. I am not sure if the CDI was rewired or if I have the updated ignition, but will check that in the morning.

What do you guys think? Is the symptom of PWC-00-05 turning over but not catching or should I look at something else?

Chris

[K447]

The engine will crank with the Start button pressed even if the CDI is not providing spark.

You can validate the thesis that PWC-00-05 applies by disconnecting battery power from the CDI for a moment (say, 10+ seconds). Reconnect and see if the hot engine will now immediately restart. If battery disconnect allows the engine to promptly re-start every time, the service bulletin wiring change probably applies.

Or you can just build the jumper wire and route the CDI to Orange wire terminal (per the service bulletin). If the hot engine now restarts every time, good.

http://polarispwcknowledge.shorturl.com/first-things-to-do

These engines really, really want the fuel system to be 100% good. You will read advice to clean/rebuild the carburetor and go through the rest of the fuel system. Even if the engine seems to be running well.

[MA-Chris]

I opened the electrical box this morning and it appears I already have the jumper installed.

Is disconnecting the battery to check if restarting is easier still a needed test?

What is the next step in troubleshooting? Restarting seems worse with two people on the ski and what I assume is more back pressure on the exhaust?

I have rebuilt a bunch of carbs in the past, where do you get the rebuild kit?

I forgot to add, while troubleshooting the trim motor, I figured out that it has a dead short. I wonder if that is backfeeding power into the CDI and keeping it powered on? Maybe I will disconnect the trim motor and see if that helps?

[K447]

Back pressure in the exhaust outlet with two passengers aboard is not going to prevent the engine from starting.

Something else is going on. Methodical diagnostics will help.

Figure out if the problem cause is spark loss or something with the fuel/carb system.

If it is spark loss during warm restart, does the CDI have proper voltage in (Red/Purple wire to Black wire voltage) during cranking?

The LR module is powering the entire CDI through the Orange wire ÔÇÿaccessoryÔÇÖ circuit. If the LR module is not delivering reliable full battery voltage onto Orange then the CDI will not be happy.

[MA-Chris]

Good to know about the exhaust pressure, I am trying to eliminate issues.

Thanks for your advice. It seems like I have two next steps:
1 See if I have spark during the period it won't start
2 see if the battery voltage is over 10.5v during cranking

The engine seems to turn over very quickly/strong so I doubt I have battery issues. I did buy a cheap 16 size AGM from Amazon, so who knows. I will speak to the old owner again today to see if he had the hot start issue.

The fuel lines are not original, regardless maybe I should swap them all out? It does not have an inline oil filter either.

Chris

[K447]

 see if the [CDI input] voltage is [well] over 10.5v during cranking 

Battery voltage cranks the engine.

Voltage directly into the CDI module powers the ignition.

You want the voltage powering the CDI (during engine cranking) to be well above the minimum.

[casey67]

As K447 mentioned, you need to test the voltage on the Orange circuit while cranking, that is what powers the CDI now.
The LR used on the SL700 was not the most robust, If in fact it is your issue, look into getting the LR31.
Disconnecting the other orange wires could show a problem with the bilge pump or trim system.

The very first "update" kits did not have the newer 2 wire ignition coil and newer style plug wires. It looks like you have the the "non-updated coil". The very few PWC we have seen running that set-up had exploded capacitor in the CDI. I dont think the 'updates"used a reprogramed 404 CDI. There could be a 3 digit number written on the back ( 448 or 449 ). But I suspect that is already a replacement CDI.
I would look into replacing the coil and plug wires.

[MA-Chris]

Hi casey67

While trying to troubleshoot the trim motor, I noticed that the trim motor had a dead short. I may take it for a ride today and I certainly will disconnect the trim motor to eliminate that from the equation. I think it is just the green/white and blue/white wire that head to the motor, I will pull those before going out.

The bilge pump seems to run well, not noisy and comes on when the motor is running.

What is the LR31, is that a rectifier?

Is this the one I should buy?

https://www.ebay.com/itm/251911237624?hash=item3aa7146ff8:g:fYQAAOSwy~JbtPo Y&amdata=enc%3AAQAHAAAA4FWVThVhA1EU7wFjSudeP85mN0u 0CrD84PhxZ0Ue9%2BUbGuIRFjrOGYMmXbx3OUPIl39F6aXWZn4 PRefL6AYX7cFa5Jftb4mgr4JbdK1XmNadn%2F%2BxNoGaN%2By AFXXbKkEKJJ%2FmToj92eaK%2BTZ6AXjOJkFyqKnlK%2Fo9jLO 6uq3F2lbtLLrtUkcofAODwDazDRAFWsow7ljNMD51%2Fry%2FE vhzb%2BhgU0u2GG0qfM8tBGzm%2F537kNwfoAv96K7pSz59GhH lCof93bxRJrMpIf9fQh3fxh5ZlSyU%2BeYm0kN%2BepqpS8Uy% 7Ctkp%3ABk9SR567maXvYA

So you think I have some updated components and I should replace some parts? It is not clear what parts I should be replacing.

Forgot to add, the fuel gauge is totally dead. Not sure if it is related, but I have not started troubleshooting that yet.

Thanks,
Chris

[casey67]

As K447 mentioned, you need to test the voltage on the Orange circuit while cranking, that is what powers the CDI now.
The LR used on the SL700 was not the most robust, If in fact it is your issue, look into getting the LR31.
Disconnecting the other orange wires could show a problem with the bilge pump or trim system.

The very first "update" kits did not have the newer 2 wire ignition coil and newer style plug wires. It looks like you have the the "non-updated coil". The very few PWC we have seen running that set-up had exploded capacitor in the CDI. I dont think the 'updates"used a reprogramed 404 CDI. There could be a 3 digit number written on the back ( 448 or 449 ). But I suspect that is already a replacement CDI.
I would look into replacing the coil and plug wires.

Need to test power on Orange circuits.

Original has LR 21, charging regulator. And LR52, switch for 12v orange circuit, voltage regulator for fuel guage (IIRC 3v)
Could be converted to LR31-x. Charging regulator and 12v switch (orange), would the require 12v fuel gauge or voltage mod.4010302

Polaris parts numbers can be found here: https://parts.polarisind.com/Browse/Browse.asp

Ignition pictures can be found here:https://www.shopsbt.com/jet-skis/sbt...r-polaris.html
"update" is pretty much 2000 and newer parts, with stator made to fit 1996 housing. Other parts could be found on 2000 and newer 700's.

The trim switch toggles power and ground for the trim motor, one direction "up", other direction "down".
At rest, looks like switch will be grounded.(green/blue w white stripe) Power is on orange wire.

[MA-Chris]

Well, good news/bad news.

Disconnecting the trim motor seemed to fix my warm start issue. As I stated earlier, the trim motor was a dead short so it must have been powering the circuity when off? I was able to stop/start the engine almost 20 times.

Problem now is the engine will not get much above idle without missing terribly.

I tried to take a video of it in operation, but I dropped my phone in the lake.

I am wondering if my addition of yamaha ring free (basically Techron) knocked something loose.

How do I find the proper carb rebuild kit? I think that is my next step?

Thoughts?

[Beernutz]

Both Watcon and OSD Marine carry the correct OEM kits. You will need two of them.

[MA-Chris]

I forgot to ask, what fuel lines and filters are everyone using? I don't seem to have an oil filter right now.

Is standard reinforced 1/4" line appropriate?

[MA-Chris]

I think I solved my rough acceleration issue. Before investing too much much into this ski, I want to have it run fairly well. I did not want to rebuild the carbs just yet.

I noticed that the water separator had over an inch of water in it. I think it will reduce fuel flow when it is full. I went ahead and drained the fuel separator and replaced both fuel filters. Interestingly enough both filters looked original. The reserve filter looked brand new but the main filter was full of chunks and dirt. I now have clear filters I can inspect.

So what caused this?

I was dorking around with the main/reserve valve on the side of the ski. I assume my tank is full of water that the main fuel pickup isn't deep enough to pickup but when I switched to reserve, it quickly overflowed the separator. I guess I should run the ski out of gas and then drain whatever is in the bottom of the tank.

I will test that theory tonight hopefully.

[K447]

Run the ski out of gas - How are you going to do that?

If there is water in the fuel tank then the tank should just be completly emptied, then wiped clean inside.

Blow out all the fuel hoses up to the engine. Or just replace all the fuel lines with decent quality new hose.

You really want the entire fuel system to be 100% good. No dirt, no water, no old hoses.

Wanting it to 'run well' before cleaning and rebuilding the carbs seems kinda backwards.
These engines really prefer the entire fuel system to be 100%

[Beernutz]

Standard 1/4" line will work, however most will recommend getting a minimum of USCG B1 rated marine fuel hose. I always use automotive hose and haven't blown up yet. Most (myself included) will also tell you to remove the inline fuel filters and just use the water separator. This is how they were built after 1997 or so.

Being that your SL700 is a 1996, you can actually remove the fuel tank through the bow/hood opening. I'm not going to lie and tell you that it is easy, but it's better than 1997 and later where you have to pull the engine. I would say that pulling the tank, then doing as Keith recommended and draining and wiping it clean is your best course of action.

And of course, just rebuild the dang carbs. If you have good compression, and good spark, then there is absolutely no reason to worry about spending the extra $140 on it.