1998 Optimax 150 starts then stalls.

[Gccon]

Been a member for a fews years now but never had the need to post until now. I hane a 1998 optimax 150 hp Ser: 0G681404. The problem that I'm having is whenever I put the boat in the water(cold start) it would start, run for few seconds, then stall. I would have to restart it anywhere from 4 to ten times until it stays idling. After that the boat runs great and starts up first try. The weird part of it all is, when I have hooked up to the muffs at home, it starts first try and stays running. I've had the boat now for approximately 3 years nows and have only put 60 hrs on it.
Brief history: When i got the boat I changed all filters, new t stats, water pump, serp belt and plugs. Last year I had tps go bad on me so I replaced both of them and while I was at it I decided to change both temp sensors thinking my start up issue is related to temp but that didn't help. Fast forward to this year(recently) I replaced the starting battery, primer bulb and rebuilt the pulse pump. All of my fuel and air pressures are within spec. Fuel 90 psi air 80 psi. Low pressure pump 9psi. I've checked the tracker valve for any tears , all good. I inspected the compressor reed plate and all looks good to me. Sorry for the long post. I am stumped. Any help, would be greatly appreciated. Thanks in advance.

[lpugh]

Are you pumping the bulb up every time
Is the motor trimed up when you back it in to water and is the idle exhaust port out of the water when starting,
Double dose the Quicklean for one tank and add about 4 oz. of premium plus for every 10 gallons. Then permanently use the Quicklean at 2 oz. and premium plus per 10

[Gccon]

Thanks for the response Leon. Yes I am pumping the bulb everytime (until hard). Yes the motor is trimmed up when backing up. Not sure what you mean about the exhaust port. I have the motor trimmed down while starting. I do use a can of seafoam with every fill up. Are suggesting its fuel related? Thanks

[lpugh]

Thanks for the response Leon. Yes I am pumping the bulb everytime (until hard). Yes the motor is trimmed up when backing up. Not sure what you mean about the exhaust port. I have the motor trimmed down while starting. I do use a can of seafoam with every fill up. Are suggesting its fuel related? Thanks

On the lower cowl, back of motor there is a exhaust port that lets the exhaust escape with less resistance at idle and when starting, the exhaust mid and lowers are completely filled with water under this condition which creates a resistance. This port should be out of the water at idle, just trim to neutral or higher when starting and at idle. This could be a contributing factor though not likely the sole cause
I would stop using the sea foam entirely. The injectors could very well not be allowing proper fuel flow due to age and coking.
Read this regarding fuel and additives http://www.bbcboards.net/showthread.php?t=20401
There is a fair chance this may help after a couple of tanks of fuel is ran thru it

If never done it would be wise to send the complete rails to European Marine to be validated

[Gccon]

I took a look at the exhaust port and dont think it is submerged when I start it. When I got home last night I decided to start it in a big tub of water as opposed to the muffs. And sure enough it stalled on me twice. First stall I did notice it" sneezed" out of the exhaust port. Restarted it , ran for 10 seconds or so. While it was idling, I did have a drop/stumble in rpms for a split second. Any thoughts?

[JOE54]

got a way to test fuel psi at start up,=gages glycerin filled

[Gccon]

Yes, I've tested both pressure's not with glycerin filled gauges though. Yesterday when I started it, I had gauge on the fuel side and I when I turn key on, guage jumps to 60psi, then when I crank it and its runs, it jumps to 88- 90psi.

[JOE54]

did it drop before it died

[Gccon]

no, it didn't

[EuropeanAM]

Look at the bottom cowlings and adapter plate. Are they "gritty" (lot of sand and grit if you wipe across them)?

[Gccon]

Hi Don, Thanks for responding. Quick update, I decided to remove the air handler assy and inspect the reeds, all checked out fine except for a few of them that weren't within .20. So I replaced them all with a set of carbon fiber reeds. Dropped the boat back in the water, and fired up first try and didn't stall at all. Boat ran great. Don't know the reeds were the problem all along or maybe it was a coincidence, but I will try again this Friday. Fingers crossed!!!
Don, when I did have the cowlings off, there was no sand or grit, just a bit oily. Thanks

[EuropeanAM]

Make sure there is absolutely no debris, grit, grime, sand, belt leavings, tie straps, leaves, etc. inside the cowling- they WILL end up in the engine (likely in the reeds) resulting in damage or excessive standoff (which causes your symptoms, especially on the earlier 2.5L models).

[Gccon]

Back to square one , took the boat out on the weekend, and sure enough it stalled on me 5 times until it would idle. Any thoughts? Don... if the temp sensor was bad( even though I replaced a year ago) would it not set a trouble code? Thanks

[EuropeanAM]

Depends- sensors can fail "in range" in which case there is no fault. Example: 85 Degrees F outside, but the Intake Air Temp sensor is faulty and reporting that it's -18 Degrees F. That is a valid (and possible) temp, so likely there would be no fault.

Given dozens of possible sensors, don't try guessing and throwing parts at it. Back up, start with the BASICS (Compression Spark and Fuel) and take a FRESH look at the entire engine.

Don't overlook the flywheel (and rust or flaky paint on the lower teeth can cause irratic CPS signals).