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"Hot soak" to "limp mode"; 2016 TXI with 350 monsoon engine

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Above noted boat has a HOT SOAK condition that results in a LIMP MODE condition.  We've used the boat for several years so something has changed.

The condition started "all of a sudden".  Root cause remains TBD and the boat has been at the dealer for........EIGHT (yep 8) weeks (good thing we have my boat to ski behind).

1. Initial diagnosis was a low fuel pressure issue.

2. Dealer ordered and installed a new fuel pump (6 weeks).  Owner picks up boat, goes to lake, and the issue repeats itself (Engine is run for  5 min, soaks, restarts, immediate limp mode (with a high coolant team).

....Yes the impellor has been replaced and entire inlet (lake to impellor) is free of debris/system pumps TONS of water.

3. Boat is returned to dealer, who then has tech and owner go to a lake to reduplicate the issue.  Tech collects data and advises he will send logs to Malibu & PCM. 

4. Dealer then diagnosis issue as a bad fuel regulator (on the fuel rail).  Orders & installs is.  Issue is not fixed.

5.  Dealer advises they are awaiting Malibu's help.

* Sure seems similar to the "high temp air intake" issue i've heard some Malibu owners discuss.  Are there any threads on this that have a definitive root cause?

* I suspect the dealer is focused only on the fuel issue.  I have to pause here and ask "Is the PCM system designed so that a fuel pressure issue (high or low) has the entire engine control system to go into a limp mode"?  I am of the understanding that only high coolant temp or low OIL pressure" can result in system limp mode.  Would appreciate someone who knows the answer (not guessing) to advise on what are the conditions that will cause the engine control system to go into limp mode.

* Appreciate learning from those who have actually experience these symptoms and what was the root cause/corrective action ?

Thanks, in advance.



Edited by Fullmer
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Posted (edited)

spacer.pngDealer to provided the fault code(s)/screen shot via his pc connected to the engine (app is Pleasurecraft Crusader GCP ETC 4 Engine Data )  during their water test. 

"SPN: 94  Fuel pressure Fault
FMI: 1 Fuel pressure low data is valid but below Normal Operational Range

Click here for freeze frame data"

The dealers focus remains on the boat having a low fuel pressure being below spec.  While i understand why he is chasing the fuel pressure issue (a code is set),  i would like some validation the PCM design is to set the engine control system into limp mode for a fuel pressure issue (historically limp modes are to protect the powerplant from damage, such as low oil pressure or high engine temp).  

I've asked the dealer if they captured the engine team at the time it goes into limp mode (awaiting feedback)



Edited by Fullmer
added pic
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Low fuel pressure can cause the engine to run excessively lean.  A very lean engine is prone to piston damage, so the limp mode is justified.

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A lean condition can also cause cylinder, valve, and piston damage.  I remember back a couple decades ago, during Volvo Penta training, when they recommended to always verify compression and ignition component function before moving on to fuel system diagnosis.  There are a few times I neglected doing that during a repair and later wished I hadn't.  Verifying proper compression is a very important first step in finding a potential running issue.

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Dealer replaced fuel pressure sensor (after replacing fuel pump {6 weeks at the dealer}, then the fuel pressure regulator {3 weeks} to no avail.   Dealer states they water tested it and it was fine.  Owner picked up boat from dealer saturday, and at FIRST test experienced the same condition (get engine to operating team, pull a skier, turn off engine, wait 5 min, restart engine and temp spikes and goes into limp mode.

Now what?????  Suggestions??



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If high coolant temperature is causing power reduction there should be fault codes for those sensor circuits, like SPN 110, SPN 441, or SPN 442.  Those codes can be caused by an actual overtemp condition in the cooling or exhaust system, or a wiring or ECM issue.

The SPN 94 FMI 1 you posted about eariler indicates fuel pressure that is lower than normal.  Low fuel pressure could cause running issues, but the code itself should not cause power reduction mode from the ECM, just a MIL alarm.

Coolant and exhaust overtemp codes like SPN 110, SPN 441, and SPN 442 will cause a recommended power reduction from the ECM by at least 50 percent or more and will cause a MIL Check Engine alarm.

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Posted (edited)

appreciate the info. 

Dealer has contacted Malibu and is awaiting direction on next steps

(FYI....the operating fuel pressure is 55 PSI....the tech noticed it drops to 52 PSI "only for a few seconds"...apparently this has caused the SPN 94 code.   Last Saturday the boat was run for about 5 min, shut down...sat for 15 min....(watched the engine temp gauge climb to 190)...powered the ignition/blower came on, then MIL light and audible sound came on as soon as the engine was started.  This time the engine did not go into limp mode.

Edited by Fullmer
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Issue resolved.  

Dealer installed a new/different fuel pump (apparently the first one installed was "not robust enough".

i have to assume that the 2nd pump has a different part number than the first (also assume manufactured by a different company.


That entire process took 12 weeks.

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