1990 GT // Progress Thread

[nickandrisin]

Hey everyone! I have just joined the forum after buying my first Sea-Doo, a 1990 GT. I am running into some problems with getting it started. I've been trying to troubleshoot this on my own with no luck so far, so I'm hoping someone can help me here.


Background

I purchased this 1990 Sea-Doo GT last Friday from Facebook Marketplace. The previous owner told me it ran perfect last year when he had it out on the water. He also told me it started right up. When I was picking it up last Friday, I confirmed that it started up and ran. I brought it back to my house and I was also able to get it to run in my garage, but only for about 10 seconds before it died. I haven't been able to get it to start since then. The engine turns over strong, just will not start.


Battery
After taking a look inside the hull, the first thing I noticed was the positive battery cable had a chunk taken out of the side of it, about 1 inch long, and the wire inside was starting to corrode. I pulled that out and I am in the process of replacing the cable.



I still need to get it fed through the MPEM housing hole, but I am waiting on some lugs since currently the lug is too big to fit through the hole, so I need to cut the cable, feed it, and put a new lug on it. So for now I have the battery running like this during my testing.


Spark Plugs
I pulled my spark plugs (BR7ES) out and they don't seem to have any carbon buildup on them. They did however have what looked to be oil on them.

MAG: PWM:

I sprayed these with carb cleaner, wiped them off, and then put them back in. I cranked it a few more times and pulled them and they were dirty again. I do have new spark plugs I can use, but these seem to be in good condition other than getting covered in oil.

I did pull the plugs out and cranked the engine to see if anything came out of the holes. I had a rag over the holes and a very small amount of black residue (oil?) came out, but not a lot. I took the rag off and nothing was coming out of the holes during cranking.


Compression
I picked up a compression gauge and tested compression on both cylinders. Compression was tested by pulling one plug at a time, holding the throttle wide open, and pressing the start button. My readings were MAG: 145 / PWM: 145.


Fuel System
I am wondering if the problem could be the fuel system, but if it is, how was the Sea-Doo able to start at the sellers house and at my house fine, but not now?



I initially looked at the fuel filter and saw that the bowl was only half full; is this supposed to be full? I pulled the fuel bowl off and it looks like there is no O-ring and I believe there should be one in there. Could this cause no fuel pressure?



I emptied the fuel bowl and reinstalled it. I cranked the engine a few more times with the fuel switch to "ON", and the bowl did not fill up at all.


Kill Switch
I'm not sure if my kill switch is original; it doesn't look likes ones I have seen in videos.



I assume I am using it correctly, but I might not be. The button is not pressable until it is pulled out. So I pull the button out, attach the lanyard clip. Now I am able to press the button (I can hear it click). The cap on the lanyard doesn't seem like it engages the button securely, so I usually just hold my finger on the button when I am trying to start it.




Drain plug
I took a look at the back of the Sea-Doo and saw there was a hole there on the bottom-right side. I believe this is where the drain plug should be, but it is missing.

I reached down inside the hull to see if maybe it was inside of there, but I didn't find it. I did find some extra pieces though. Does anyone know where these belong to?




Conclusion
So that's where I'm at currently. I am assuming it is fuel delivery related. Do I need to rebuild the fuel pump and/or the carbs? Hopefully someone will be able to help me get this thing running!

 

[mikidymac]

There has to be an o-ring on the fuel strainer or it will not pull fuel.
I would pull the spark plugs in and check for spark.
If you have spark you can put a little premix down the carb as see if it fires, this will tell you if it is a fuel issue.
Your compression is good.
Your kill switch is broken and/or wrong. That red cap should not be on it and the lanyard with the red wire is wrong, it should be the black cap.

Be careful if you replace the kill switch as the newer skis function differently and will not work. One is normally open and the other is normally closed but I don't remember which is which.

That teardrop shim you found was for engine alignment and it is not good if it fell out. Check all engine mounts.

 

[nickandrisin]

Thank you Mikidymac for the thorough response.

For the o-ring replacement, I found this: WSM Sea-Doo 580-951 Fuel Filter O-ring 006-510-01, 275500090, '89-'05 | eBay

I am going to order an inline spark plug tester so I can verify spark.

This is my first time doing any engine work, so I want to confirm this next step. For putting premix down the carb. Do I remove the blue box (air box? air intake?) that is above the carb, and then pour premix (what ratio do you suggest?) down the open holes of the carb?

Yes the kill switch looks like it was replaced in the past as I can trace the wires and found non-factory splices and connections. I plan on replacing it if I can get this running. Does this look correct as a replacement? https://www.amazon.com/Safety-Tether-Switch-Models-1989-1995/dp/B06XPSFZM8. I would also need to find a new lanyard/tether I assume?

For the engine alignment shim, what is the course of action here? Check the mounts and see if any look abnormal? Am I able to re-insert the shim without any problems?

Thank you for your help.

 

[mikidymac]

40:1 premix is fine and just a little down the top of the carb, don't flood it.

The fuel filter o-ring is Seadoo part number 275500034

The kill switch is Seadoo Part Number 278000129 and the retaining nut is 278000099.
The black lanyard you have should be fine.

 

[nickandrisin]

Thank you. I have ordered a replacement o-ring. I will order a new kill switch if this runs.

Do you have suggestions on what oil I should be using? The oil in the Sea-doo currently is a blue-ish color. After reading a bit on the forums I have seen that it should be a lighter brown color. Is the wrong oil in it?

Also, 87 gas correct?

 

[mikidymac]

IF the kill switch is wrong it will no spark so verify you have spark first.

The general rule of thumb is if the oil is blue or green it is wrong and most people use the incorrect TCW-3 outboard oil because they just don't know.

The correct oil is API-TC rated oil and on yours it does not have to be synthetic or even semi-synthetic but it is better.
Most use Seadoo XPS Mineral Oil

This Lucas is also good, just make sure it is this one and not the TCW-3 one.



You should drain the tank, replace the rubber grommets, inline oil filter and bleed the system whenever changing oil as different brands do not play nice and can gel and plug the system.

 

[nickandrisin]

Perfect thanks for the oil information. I plan on draining the full oil system and replacing with the correct oil.

Regarding the kill switch, I do believe I have spark as I saw the sea-doo running at the sellers house and I was able to get it to run briefly at my house after bringing it home. This leads me to believe it is fuel delivery related.

 

[mikidymac]

I will say, that has to be one of the cleanest 90' GT's around.

I would also suspect the fuel On/Off valve on something of this age. the rubber internal parts rot then it will suck air instead of the system drawing fuel from the tank.

 

[nickandrisin]

I was very surprised at how clean the GT was when I first saw it. I got it at an amazing (I think) price, I assume the seller knew it wasn't running properly, but just didn't disclose that to me. He said he had it running all last summer, but seeing as there is no o-ring in the fuel filter, I don't see how that would be possible.

Since the fuel selector valve is so cheap, I might as well replace that while I am in there. I'm just waiting on the oil to arrive so I can pour some premix into the carb to see if the engine starts again. If it does, I'll get to work on replacing the fuel filter o-ring, fuel selector valve, kill switch, and I'll completely drain the oil system and replace with new.

 

[nickandrisin]

Update:

I tested the spark, and I was receiving spark even without pressing the kill-switch. I assume this is not correct.

I had spark without pressing the kill switch, and with pressing the kill switch. So I'll be replacing that.

Also it started up on me and ran for 3 seconds which was odd. The kill switch was not engaged, choke was in, gas was off, fuel filter bowl still empty. I pressed start button and it ran. Very bizarre.

 

[TheGTIjetguy]

Update:

I tested the spark, and I was receiving spark even without pressing the kill-switch. I assume this is not correct.

I had spark without pressing the kill switch, and with pressing the kill switch. So I'll be replacing that.

Also it started up on me and ran for 3 seconds which was odd. The kill switch was not engaged, choke was in, gas was off, fuel filter bowl still empty. I pressed start button and it ran. Very bizarre.

You’re on the right track with the kill switch replacement. Don’t want to ride without a working lanyard.
Spark is good, it is definitely having trouble pulling fuel from the tank. If it is running for a second or two it is just sucking the residual from inside the carb.
Get that fuel selector and bowl o-ring replaced. I fill the bowl with premix before installation, seems to help the carb pull fuel. Mine will pull from the tank with a dry system in about 15 seconds of cranking.

 

[nickandrisin]

My 1990 GT is still not firing up. I have it connected to a spark tester and I have attached the videos to show you my results. Does it look like weak spark?

I have brand new spark plugs (BR7ES) installed and they are both gapped to 0.024in. I removed the spark plug boots and trimmed the cords 1/4".

What else can I do to troubleshoot?

MAG Spark Test:

PWM Spark Test:

 

[Spider4real]

Is it getting fuel? Have you tried putting some premixed gas directly in the cylinders (or carbs) and see if it fires up?

 

[nickandrisin]

Update:

I installed a new o-ring in the fuel filter and it started filling up after cranking a few times.

The kill-switch was definitely wired improperly, someone added a '93-'94 (I believe) fuel gauge to the ski and wired it into the kill-switch/stop button:



I have disconnected the wiring from the gauge for now and re-wired the kill-switch properly. The switch is currently operating backwards (I have spark when it is not engaged, but I have no spark when it is pressed). I have also reversed the two wires coming from it with the same results. The correct kill-switch comes on Wednesday.

I installed new spark plugs and I trimmed the spark plug wires 1/4". I did a spark test and these were the results:

MAG Spark:

PWM Spark:

Is this weak spark?

I removed the plugs and poured a bit of pre-mix into the cylinders. It fires up and runs for about 2-3 seconds, but does not want to start after that. I did this about 3 times. I do have a new fuel-selector that I will install tomorrow.

After the 3rd time of adding pre-mix into the cylinders, I noticed oil on the floor, dripping from the rear of the Sea-Doo.



There is oil on the washer pictured, but it doesn't seem to be coming from there. It looks like it is coming from slightly below it or near that area. There is no oil in the bilge that I can see.

Any ideas on it still not wanting to start and the oil leak?

 

[TheGTIjetguy]

Your oil problem is a common issue. When these skis sit for a while the rotary valve seals leak and fill the crankcase with oil. When you crank it all that oil is forced out the exhaust which is what you are seeing.
Remove your plugs, ground the wires, and crank with the throttles wide open for a couple tries. It will make a mess, so hold a rag over the plug holes until you don’t get much out.
It will probably take a couple tries to start. When it fires and the crankcase vacuum rises, it will pull more oil up fouling the plugs. Just keep removing the plugs and recleaning them, it will start eventually if you got your fuel issue figured out.

 

[TheGTIjetguy]

I think your spark looks fine. When it starts the mag will start producing stronger spark. Cranking is less than half the speed of idle, so mag can’t provide as much juice.

 

[nickandrisin]

Remove your plugs, ground the wires, and crank with the throttles wide open for a couple tries. It will make a mess, so hold a rag over the plug holes until you don’t get much out.
It will probably take a couple tries to start. When it fires and the crankcase vacuum rises, it will pull more oil up fouling the plugs. Just keep removing the plugs and recleaning them, it will start eventually if you got your fuel issue figured out.

I have checked a few times, but I haven't been able to find any grounding posts for my spark plug wires on this engine. I know there are usually two metal posts to ground them on, but I haven't found anything like that on this model.

 

[nickandrisin]

A few images for reference:

 

[mikidymac]

It is flooded with oil and fuel. Once you get the correct switch and selector and you can keep it running it will blow and burn all that crap out.

 

[TheGTIjetguy]

Doesn’t look like you have plug grounding posts. No big deal, just plug the spark plugs back in and lay them on a metal surface. Should be fine to prevent damage to the coils, just keep them away from a fuel source.

 

[nickandrisin]

Update:

I installed the new fuel selector valve; it turns much smoother now. The last one wasn't too bad, but who knows if it was ever replaced.

I pulled my plugs and I cranked the engine a few times with full throttle (I did not ground the spark plug wires). I had a rag over the plug holes and nothing came out. I removed the rag and I also did not visually see anything come out of the holes.

I cleaned and reinstalled the plugs. I cranked about 10 times in intervals of 6 seconds of cranking and 60 seconds of cooldown. I also cleaned the spark plugs off every few times. They weren't too bad, just lightly wet with dark liquid. The engine started about 5 times, but only for about 3-6 seconds each time. My process was, pull choke, sometimes pump throttle a few times while cranking. Also pumped throttle a small amount while engine was running for the 3-6 seconds.

After this I couldn't get the engine to start anymore. I checked my battery's volts as it was cranking and it was bouncing between 10 and 11. The battery is from the previous owner and is a 280CCA/235CA. I went and purchased a brand new battery that is a Duralast Gold EXT16L; it is a 325CCA battery. I installed the battery and hooked up my in-line spark tester; the spark was much much lower on the new battery. The light was very dim, with maybe 1 or 2 bright pulses over 6 seconds of cranking. I then charged the new battery over night.

The new kill switch came in and I installed it. The new kill switch works correctly, verified by the in-line spark tester. I scrubbed my negative battery cable end on the battery side with a mixture of baking soda and water. The positive end on the battery side is brand new. I tried cranking the engine again with the new battery and I was still receiving extremely minimal spark. The new battery drops to 10-11 when cranking. I reinstalled the old 280CCA/235CA battery and I received the correct amount of spark again verified by the in-line tester, but the engine wouldn't start.

Any thoughts? Obviously I'd like to have the newer and better battery hooked up, but why would the spark be significantly lower with it? And even with the old battery, it still isn't starting consistently or running for more than 3-6 seconds. What more can I try?

I have completed:
- New positive battery cable
- New gapped spark plugs
- New fuel selector valve
- New fuel filter o-ring
- New kill switch
- New fully charged battery

 

[nickandrisin]

After swapping the new battery back in a 3rd time, the spark seems to be back to normal. Consistent strong spark through the tester, but still dropping to 10-11v during cranking. The engine does not want to fire up unless there is some premix down the spark plug holes.

Update:
After swapping between ON and RES on the fuel selector a few times, I finally got it to run for about 20 seconds before I finally killed it. Looks like I just need to keep running it intermittently to burn out all the sitting fuel and oil. I will update the thread as I make further progress.

 

[mikidymac]

Something is up with that new battery, I have seen bad new ones.
On these the battery voltage should never drop below 12V when cranking and at 10 volts you will loose spark.

 

[nickandrisin]

What do you suggest for the battery? A load test at the place I bought it from?

 

[mikidymac]

Yes, it should be performing much better than your old one.