Logo
FULL SITE MENU

2004 Bayliner 350 with twin 5.0 MC MPI Bravo 2 wont turn over 2200 rpm

S

Snakeriversailor77

Contributing Member
Been trying to diagnose what is stopping this Bayliner from turning more rpm. Initially the boat would run over 35 mph at WOT. The starboard engine sucked up some water (bad manifolds and lack of flapper) and had to have the top end rebuilt. After getting it back together, the engines start and run great, no missing or sputtering. The props have not changed, no extra weight in the bilge. The boat idles and will rev without load but will not turn over 2200 rpm at WOT under load while in gear. The throttle plates are wide open yet no more rpm. Neither engine is revving above that 2200 mark. The port engine was not worked on at all and isn't turning either. The Rinda diagnostic tool indicates 100% power available. Only codes that come up are "pitot level ckt", "fuel level ckt low" and "steering ckt low". It does say "Guardian active unspecified" on both engines but does not clear when codes cleared. the only thing other than that shows up as a 32F temp on both the port and starboard head temp. Obviously wrong with the raw water temps in the 70.s F. The trim is going up and down on the outdrives and the tabs are working as well. This I don't think would stop the engines from cranking up to higher rpms anyway would they? The boat will only get up to about 8 or 9 knots at the maximum rpms of 2200. Good compression, all cylinders firing. We swapped the ecm's side to side on the motors, no change. Props have not been altered from when it ran 35 plus rpm. Help!
 
My swag.... Ecm is limiting engine rpms since it thinks it too cold. Find out why temp to ecm are crazy. Since both engines,not likely sensors themselves.
 
Try this: In gear, open one engine throttle at a time and read the maximum rpm achieved. Then compare. If one is lower than the other, find out why.

BOTH engines have to be putting out for the boat to plane. If one of them is dogging it, the other (good) one is dragged down with it.

Jeff
 
Thanks for your interest in helping me with the problem. Don't have the serial number as the boat isn't here and the numbers are not on the engine covers. I do know it is twin 5.0 MPI's. Both will not turn more than the 2200 rpm I mentioned before. It seems to be something that impacts each engine. Not sputtering or coughing at all. Fuel looks and smells good, no indication of water or contaminates. New filters on both engines in any case.

Compression is good on all cylinders and within 15% of each others. All cylinders are firing and it appears that the fuel injectors are firing as well. The only thing I questioned was with the static test of the fuel injectors. test fired each of them, #1-4 but would not cycle #5-8 as the diagnostic tool said the ECM said it did not support the test on those cylinders but #5, 6, 7, 8 shows up in the diagnostic itself, but is not supported by the ECM.

I keep thinking it is something simple that is causing both engines to be in the "Guardian cause unspecified" state.

Thanks!
 
I am concerned about those temp # too. Seems odd the both engines have a similar problem though and at the same time. Does anyone know if I can just disconnect those temp sensors and have the ECM not include that as a input. Will it default to a too cold condition which it is now or will it "think" its hot? Or perhaps nothing and just run and allow it to increase revs as it can.
 
fastjeff said:
Try this: In gear, open one engine throttle at a time and read the maximum rpm achieved. Then compare. If one is lower than the other, find out why.

BOTH engines have to be putting out for the boat to plane. If one of them is dogging it, the other (good) one is dragged down with it.

Jeff
Click to expand...
Thanks Jeff, we will try this. I know that when we go to the firewall on the throttles both engines are running the same rpm. We will try to see if we can get more speed out of one engine without running the other. Seems like even with one engine dragging it should go faster than 8 kts at 2200 rpm though.
 
Checked the compression check again for both motors - Found one low cylinder on the port side (still over a 100 psi however), rest of the cylinders were between 155-and 175.

Both engines are showing the same codes and similar outputs. Ignition on, not running...
0 RPM
0.00 Fuel Flow gpm
429 F Lake/Sea temp
0 Hx Paddlewheel
0# Pitot
1023# Trim Position
4.99 VDC Trim volts
1021# Fuel level 1
4,98 Sensor Power Volts
14.2 VDC Battery voltage
32 F Port Coolant temperature
32 F Starboard Coolant temperature
39.6 psi Block Pressure
8.0 Spark advance
.4 Oil Pressure
0.0 IAC duty cycle
0.6 TPS #
.61 TPS # voltage
80 F Manifold air Temperature
14.7 Barometric Pressure
14.7 Manifold Pressure
77 F Coolant Temperature
Guardian Cause Not specified
Available power 100%

Current codes
Fault 94 Pitot Crt Low
Fault 75 Fuel Level Crt Hi
Fault 119 Steering Crt Low
Fault 130 Trim Circuit Hi
 
Your water pressure Should read Zero. Sensors are probably bad.

Can you see the shift event happen when you shift into gear?

There is a TSB on indexing the HVS(distributor) with and older engine due to timing chain wear. If the indexing is off it will cause your problem.

Change the Dist Caps and the rotors, When you pull the caps try to turn the rotor sometimes the reluctor wheel that hold the rotor will slip on the shaft.
 
Docksidemarineservices said:
Your water pressure Should read Zero. Sensors are probably bad.

Can you see the shift event happen when you shift into gear?

There is a TSB on indexing the HVS(distributor) with and older engine due to timing chain wear. If the indexing is off it will cause your problem.

Change the Dist Caps and the rotors, When you pull the caps try to turn the rotor sometimes the reluctor wheel that hold the rotor will slip on the shaft.
Click to expand...

Is the water pressure/block pressure sensor on the block somewhere or is it part of another sensor Should/could both pressure senders go out at the same time or do they both use the same sensor somehow? Would a problem with distributor reluctor wheel show up on both engines at the same time? Thanks for the reply, this is getting the better of me for sure.
 
The other question that keeps coming up is why both engines are showing such high seawater/lake temps and low temps on port and starboard. What causes this? The sensor or sensors or ECM's for that matter don't seem likely to fail at the same time and why on both motors and why only after one had a water intrusion issue? Just doesn't seem likely or even plausible to me. A reminder is that prior to the water intrusion event, both engines were running good and the boat would plane out and was capable of over 35 mph. Now with a rebuilt top end on the starboard side, with new manifolds and a flapper, plugs etc., neither engine will turn more than 2200 under load and not get up to plane nor even get over 8 mph now!
 
If you have not tried, try disconnecting all connectors, look and make sure the pins/contacts are good and not corroded.
Maybe add a little electrical grease (dielectric) and reconnect the connectors and see if the issue goes away....

Have seen many issues that the connections were just not good altering the resistance/signal back to the ECM
 
kghost said:
If you have not tried, try disconnecting all connectors, look and make sure the pins/contacts are good and not corroded.
Maybe add a little electrical grease (dielectric) and reconnect the connectors and see if the issue goes away....

Have seen many issues that the connections were just not good altering the resistance/signal back to the ECM
Click to expand...

Thanks Jack, we will give this a try. Do you or anyone else know where the ECM gets the temp reading for the sea/lake water temp. from? Or where the senders for the port and starboard temp are? The only temp sender we can find is the one on the thermostat housing and that temp is right on compared to the infrared heat gun anyway.
 
Seems like incorrect data from the scan tool you are using. The sea water temp is unimportant, this would be fed to the ecm through the 4pin flat connector that you are using to access the ecm. You do not have Head temp senders on your engines.

Sounds like your engines are hitting the rev limit for neutral over rev. Like I asked before can you see the shift event with the scan tool you are using?
 
Docksidemarineservices said:
Seems like incorrect data from the scan tool you are using. The sea water temp is unimportant, this would be fed to the ecm through the 4pin flat connector that you are using to access the ecm. You do not have Head temp senders on your engines.

Sounds like your engines are hitting the rev limit for neutral over rev. Like I asked before can you see the shift event with the scan tool you are using?
Click to expand...

Im not sure what the term "shift event" is . The neutral over rev is not showing as a fault in any case. Could you explain what "shift event" is. Thanks
 
That makes sense. What is it Im looking for then? A code on the diagnostic or some other event I can observe or document. What is the solution for this, new shift switches or ecms? Why would this occur simultaneously with both motors after the water intrusion on one?
 
If you have problems on both engines, check the electrical grounds. I've seen engine ground wires wired engine to engine and then to battery ground. Not my favorite way to do it.. Also saw boat w twin engines, one battery.
 
Last edited:
Capt Bob,
Thanks for the reply. I will check the grounds. Additionally I will run a jumper ground from each engine to the batteries negative posts, hopefully if this is the problem we can easily find the solution. Interestingly enough we did find a partial connection on the main switch to the port engine but this is on the positive side only. Found that even though all batteries are over 12 vdc, the port engine main switch will not turn the engine over unless the emergency switch (both batteries) is also in the on position as well. This is a three switch system. This is not true for the starboard engine.
 
fastjeff said:
Ah-ha! Low voltage can cause all kinds of problems.


Jeff
Click to expand...

Jeff
Another bit of complication is the boat is on a canal and takes a bit time at slow speed before ever having the chance to find out if it will turn higher rpm. Can't do it in neutral obviously and blazing away through a slow no wake zone is both dangerous and a bit rude as well. Not to mention it would raise the ire of the many other people on or along side the canal.
 
Back
Top