Sportjet 90 will not start cold.

[responding]

I'll do my best to describe the issue.
I have a 1993 Bayliner Jazz with the sportjet 90hp engine. When the engine hasn't been run for awhile, it will not start. I have tried every combination I know of using choke, and throttle. The primer bulb pumps up solid. When I check the plugs, they have no fuel on them.
If I give it just a quick shot of premix or ether, it starts and idles and runs perfectly from then on out. Until, that is, I let it sit for 15 min or longer... then it will not start again without a shot of something.
Otherwise, it runs perfect while out on the water and is a pleasure of an engine to own.
I've tried searching the forums, but haven't found anyone who's experiencing identical issues, and there are a lot of different starting problems to sort though.
I have rebuilt the carbs. It's getting good spark. I have not done a compression test, as I don't have a gauge yet. I have tried 1/2 turn in and out on the idle mixture screws, with no luck. Any ideas where I should start to chase this issue?
Thanks!

 

[responding]

Re: Sportjet 90 will not start cold.

Woo hoo... did I find a question that stumps even the iBoats members?

 

[ondarvr]

Re: Sportjet 90 will not start cold.

Low compression can cause starting problems just like you described. Some sportjet models were also known to have staring issues, now I just need to remember what the exact cause was.

 

[responding]

Re: Sportjet 90 will not start cold.

Thank you Ondarvr. I will try to get a compression tester today to check it out. I was afraid you were going to say that. I know some had issues with the "small stator", but mines been upgraded along with a few other ignition pieces. This just doesn't seem like an ignition issue to me. Makes sense that low compression wouldn't create enough flow through the carbs to pick up fuel for starting.

 

[Texasmark]

Re: Sportjet 90 will not start cold.

I have the conventional drive 90. Mine sits for a long time between running. It used to take a long time starting the engine when I wanted to use it, using the standard procedure: squeeze the bulb till firm, engine vertical, fast idle all the way up, key on and push in for prime for a few seconds, roll over to start for 10-15 seconds. No start, repeat till it does.

I pulled my carbs and found some black particles in the low speed circuit of #1 and a blob of something black in the high speed jet of #3. No other problems noted. I use Sea Foam and the carbs were spotless otherwise and it's been 10 years since they were serviced.

Since then it starts a lot easier even though it sits for long periods.

If I am fishing and move around on a short schedule, 15 minutes roughly, touching the key and my engine starts right up. If I fish for 30 or so minutes it may not light right off, but a little nudge of the key for fuel enhancement, or running the fast idle up will solve the problem in short order.

HTH,
Mark