Optimax stalling after warming up

[dancollins111]

Hey all,

looking for assistance. This thing is kicking my butt.

https://vimeo.com/949590195
https://vimeo.com/949590195

2001 Optimax that stalls out after warming up when trying to put load on it. Checked VST and it was clean. Replaced both water separators and it was fine. Starboard motor running off same fuel tank ok.

checked compression - 105 every cylinder.
checked temp sensors, within spec.
checked wiring to ECU and pinned out harness, confirmed sensor grounds ok.
Replaced spark plugs
replaced one coil with broken connector body
had leaky thermostat gasket - replaced gasket.
warning sensor works upon key up, does not indicate a fault when shut down
fuel pressure appears ok
pumped bulb during acceleration to try and bypass lift pump/siphon valve and got no change
everything appears clean.

any ideas? This thing has got me feeling pretty down. I caved and ordered diacom to try and get more info, which will be here Friday.

thanks

dan

Smartcraft does indicates a fault of low oil and also no temperature input. I don’t know if this means anything.

[dancollins111]

https://vimeo.com/949590979

pressure drop test at idle

[lpugh]

Need the air/fuel pressure while problem is occurring. Must have dual glycerin filled gauges to test, also need leak down readings taken as soon as motor is shut down at. 5, 10, 15 seconds

[EuropeanAM]

Check temp of outlet on low pressure pump when acting up.

Check fuel delivery passage for high pressure pump (this "hidden" passage is directly across the front chamber from a threaded pipe plug). Often found restricted with old congealed fuel or debris and a BOOGER to diagnose.

Check belt tensioner (use an INCH pound torque wrench) and make sure that you have at least 70 lbs/in tension before the end of tensioner travel.

Make sure belt has not been stretched (if 4+ years or 400 hrs since replacement, now is a good time).

Check lower flywheel teeth for rust or flaky paint. If present, remove and repaint with no rust remaining.

Check crank position sensor for cracks or "rattle" when shaking it.

That should at least get you started....

[dancollins111]

Hey Leon, thanks for replying.

i have leak down info in the second video I just responded with, but not with glycerine gauges. Do I really need the $800 mercury diag gauges?I’ll try to get someone to help with running the motor and I’ll film the gauges specifically.
Thanks

dan

[dancollins111]

Will bust this out tonight. Thanks don

[dancollins111]

Belt ok, belt tension ok checked with snap on 1/4 torque wrench, fuel pump output 85 degrees, no rust on flywheel, crank position sensor checked out ok

any other ideas? Spark related?

[Savage]

Need diacom to test

[dancollins111]

wanted to get back to everyone in case someone else has a similar issue:

wanted to reply in case someone else had a similar problem.

Kept going through motor, connected diacom, everything looked ok, but…

symptoms still seemed temp related. Measured motor with infrared temp gun, ECU was cool, fuel pumps seemed cool. Checked engine harness, looks like it was replaced recently which was interesting.

plugged in with diacom. As motor would shut down, I would get a freeze frame error with diacom/loss of connection to ECU. Ecu would beep but not always communicate upon key up.

pinned power supply harness, pinned out grounds, all checked ok. Checked MPRD relay, shook it and noticed a rattle inside of it. Swapped relay with one from starboard motor and it seems to have fixed the problem. Brutal.

With that said I’m little afraid this is a symptom rather than a cause, could a shitty harness/key switch have burned up this relay or is this problem common on these motors?? Ordering a couple from the parts store before we head out for a sea trial.

[lpugh]

Key switch cannot cause relay failure, they simply wear out over time, replace the trim relays as well, same as master power relay, Key switch can cause non op not failure.

[dancollins111]

Well I’m back. Same problems, main power relay did not solve it. Still ended up stalling when coming on plane. I poked around more and removed the yellow wire to the slave solenoid and there was some gunk on the back side and it picked way up. Boat planed off and ran for 3-4 minutes, in which case it then shut down again with the same symptoms. Any other ideas?

[JOE54]

Need the air/fuel pressure while problem is occurring. Must have dual glycerin filled gauges to test, also need leak down readings taken as soon as motor is shut down at. 5, 10, 15 seconds

have you done this test on the water under acceleration ?????? please verify you dont have a fuel press problem under load

[EuropeanAM]

have you done this test on the water under acceleration ?????? please verify you dont have a fuel press problem under load

+100!

BTW... the yellow w/red stripe wire on the solenoid was not related to the problem you are describing. That is the starter activation circuit, which functions only in the START position of the key switch.

[Savage]

Why is there 92 minutes of Break-in Remaining?? Who reset the Break-in Timer?

https://www.bbcboards.net/attachment...8&d=1716854799

[gcaustin3]

why is the lake/sea temp 433F ? Hey where did you get the diacom from did you have to buy one, or rent it?

[JOE54]

why is the lake/sea temp 433F ? Hey where did you get the diacom from did you have to buy one, or rent it?

default sensor info not available

[EuropeanAM]

default sensor info not available

Plus a few hundred degrees, perhaps.