GTX 4 tec runs rough at idle for 5 minutes

[spicymemelord1]

Hello, I have a 2003 Seadoo GTX 155 that runs rough at idle initially when the engine is cold. it runs as if it is going to die then catches itself However, if I give it gas it seems to clear up. Then after maybe 5 min once the engine is warm it seems to run fine or at least way better. I have no issues at speed and the ski runs about 55mph at 7400 - 7360 rpm.

Here are the things I tried to fix the issue.

1. New plugs TWICE (resulted in no change)
2. new OEM idle bypass valve (no change)
3. new non ethanol fuel (no change)
4. cleaned fuel injectors and checked spray pattern (no change)
5. replaced BOTH fuel filters they looked good (no change)
6. swap coil packs from a different working ski (no change)

 

[ski-d00]

Do a leak down test when it is cold. I suspect the results will be down a little and then when everything heats up it seals better. Have seen this a few times on the original 4tecs.

 

[spicymemelord1]

Thanks for your response. I have never done a leak down test before. Is it hard to do? Would a compression test also show low numbers?

 

[spicymemelord1]

Hey just providing an update I did a compression test and it was 190 for all cylinders however when I took the plugs out (they have about 30 minutes on them) they had a white layer on the end that could be scratched off with my finger nail. Is it possible that the fuel pressure could be to high? It also smells a bit off while it's running.

 

[mkov608]

A Leak down test is easy, but you'll need a good quality leak-down tester and and air compressor. 190 sounds a bit high for an 11:1 compression engine. I've heard of intake manifold leaks causing poor running conditions when an engine is cold; as the engine warms up, things expand and the leak gets sealed. I'd suggest a smoke test of the intake when the engine is cold.

 

[spicymemelord1]

oh my, I'm sorry I meant 170psi. I will most definitely want to do a leak down test as you said as well. As for doing a leak down you would need to have the cylinder you are testing at top dead center? will defiantly consider doing a smoke test as well what would you recommend using for the "smoke" without buying one of those fancy machines?