2005 Sea Ray Sundeck 240 350 MAG MPI - no power over 3500 RPM, random alarm beeps

[spunkyman]

Back for another season of troubleshooting ! Still can't get my boat running properly.

BACK STORY: upgraded block from a 5L to a 350 MAG (MPI). I solved all kinds of issues and now while closing in on everything, while I'm on the water, I can't get this boat to go past 3500 RPM or about 30 MPH. The boat gets bogged down, and if I push it, it back fires or "knocks" AND a random alarm starts beeping, but then shuts off once I go back below 3500 RPM.

I had a mechanic come out and run his scan tool - said there was an issue with #7. He though might just be a spark plug. I changed that but it didn't do anything. It's never been able to get past 3500RPM with about 9 hours of run time on the new engine.

My question is - am I looking at a fuel problem, or a timing problem ( timing is regulated by the ECM, can't change it), or maybe something else on #7? Perhaps an injector? Anyone else having this problem? Is this a protective/safety mode issue?

 

[spunkyman]

Another video

 

[Bondo]

My question is - am I looking at a fuel problem,

Ayuh,...... Sure sounds like it's goin' lean, to me,.....

 

[alldodge]

Which ECM, MEFI-3 or 555 or PCM 09?

 

[QBhoy]

Firstly I’d ask if the ecu was changed to suit the new engine.
If it was, I’d then be looking promptly at both the fuel quality and more crucially, the problematic dizzy cap

 

[spunkyman]

Which ECM, MEFI-3 or 555 or PCM 09?

I installed a brand new correct ECM Part # 865840T02 which is the correct ECM for the 350 Mag. Distributor is in the right position. If she's going lean, how might I approach that ? Or troubleshoot from here........ thx

 

[QBhoy]

I installed a brand new correct ECM Part # 865840T02 which is the correct ECM for the 350 Mag. Distributor is in the right position. If she's going lean, how might I approach that ? Or troubleshoot from here........ thx

I was perhaps more meaning to check the cap for integrity again, or change or swap for a known good one. I had one fail out the box and I’ll admit on one occasion I cracked one when tightening down, slightly against the lip it sits on Easily done.

 

[alldodge]

Thanks 555

Check your in gear switch. If motor thinks its not in gear it won't allow the motor to pass 3500 and will reduce power to 40 %. This fault will not be recorded by the ECM

 

[spunkyman]

WOWzers ! Great suggestions... I'll look into this this morning and report back ! I have the Bravo 3, so I will check the gear switch. Not sure what to look for with that... maybe just get a new one? or check to see if it's plugged in?

 

[spunkyman]

I was perhaps more meaning to check the cap for integrity again, or change or swap for a known good one. I had one fail out the box and I’ll admit on one occasion I cracked one when tightening down, slightly against the lip it sits on * Easily done.

I will also get a new Flat Distributor Cap & Rotar Kit to rule it out.....

 

[alldodge]

Check continuity of the switch when in neutral, if memory serves it should show a connection. When in gear it should show open circuit.

If open when in gear, disconnect switch and take it out for a spin

 

[spunkyman]

Bought a new switch AND got a new cap and rotor just to rule that out. I'm gonna go take it for a rip and see what happens. Does anyone know what thread size the Fuel Pressure tester fitting is? Can't find that info anywhere, and thought I would test the fuel pressure while I'm out as I think this is a fuel issue and not the other issues, but I want to try it all, so I throw more $$ at it ! ugh.... I hav a tester, but no end that fits.

 

[alldodge]

That is the standard schrader valve. If normally comes with the pressure gauge kit and many times its called a Ford Schrader adapter. Inside the adapter it has two sets of threads, the first threads are larger and match Fords, the next threads are schrader

The fitting on the gauge without adapter is for GM

OTC model is JC0180-1280

 

[spunkyman]

That's gonna be a hard find up here in the great white north (cruelty 90F - no igloos). I'll have to order one I guess and wait it out... I'll go for a test drive and report back.

 

[spunkyman]

Back from a test drive and same thing.... random alarm beeps right at 3500RPM and a brick wall to going any further. Is there anything else I can try while I wait to find that shredder valvue to test the fuel pressure? I switched out the cap and rotor AND gear switch. Same old.... Would the alarm through a code on why it's alarming?

 

[alldodge]

Did you check continuity of the gear switch?

 

[spunkyman]

Yes.. Works fine, but I put a new one in anyway... and it's engaged when the shifter advances. Maybe the wiring harness end needs to be tested? Meaning switch is good but maybe that info isn't being send down the harness?

 

[alldodge]

This is the thing with the gear switch, it will be closed in neutral and open in gear. So disconnecting the switch tells the ECM its in gear. Try disconnecting it

 

[spunkyman]

took it for a test drive, unplugged switch... no change... Still bogged down, alarm, and no getting past 3500 RPM. Any suggestions on where to go from here? many thx y'all

 

[alldodge]

Only other thing is maybe the water pressure switch. The newer 555 and PCM 09 goes from a solid alarm for low water pressure, to 2 beeps per minute. It doesn't throw a code but if the scanner is watching the sensor it can be seen