Fuel Related problems 2005 Mercruiser 5.0 Bravo CW344212

[sessasails]

The engine starts and idles. It will rev to the point where the alarm sounds in idle, BUT, when in gear (forward or reverse), the engine will not go past 2000 rpm. I think it could be a throttle sensor switch or fuel filter issues. I think I have resolved any fuel contamination issues with seafoam additive and fresh non-ethanol fuel. I have pulled a few plugs but not all and they do not appear to be fouled. The engine acts as though it want to go, but either is not getting enough fuel or as if the motor is loading up. The Smart gauge screen is not functioning, so do not know if there are any codes.

 

[alldodge]

First digit of your serial number is a zero, not a C

It may be the "in gear" switch, if the alarm also sounds when in gear at 2000 rpm

If it only sounds in neutral then thats not it

Do you have mechanical or digital throttle shift?

What is the fuel pressure at the rail?

 

[sessasails]

thanks for the Serial Info. Mechanical shaft to the throttle body. I have not checked the pressure at the fuel rail, but will do and report back. Another thing I noticed is the water temperature only moves to just above 100* and I recall it usually ran at about 150-160*

 

[alldodge]

Might also have a thermostat stuck open

Verify temp with IR temp gun to make sure you don't have a issue with the gauge or sender

With it not getting over 100* the PCM may be limiting power until it warms up, but thought that was only with PCM09 models. You should have a PCM555

Would be best to get the motor scaned for codes

Hey muc what do you think

 

[sessasails]

I was able to get my hands on a fuel gauge. The pressure at the rail is 42 lbs in neutral, and stays within a few pounds in all throttle ranges. In gear, the pressure is still over 40, and increases slightly as throttle increased. As the engine approaches 2000 rpm, it begins to bog down or load up (misfiring) and the pressure increased to 50-55 lbs. Any help would be appreciated.

 

[alldodge]

The fuel pressure increase is the issue. Your regulator is either dirty or bad. Disassemble item 14, and see what it looks like

https://www.mercruiserparts.com/bam/subassembly/31750/11681/120

 

[sessasails]

Will do, but confused why higher pressure in the fuel rail, would make the engine run rough, is it pushing too much fuel to the injectors?

 

[alldodge]

is it pushing too much fuel to the injectors?

Yes
Injector opens and more fuel is released because of the extra pressure.

 

[sessasails]

Getting the clip off was easy, but the regulator is very hard to pull out...am I going to damage is by pulling? What should I be looking for once I get it loose? Thank you

 

[alldodge]

It should come out easy enough, but since yours is stuck you may have found the issue

Look at link in post 6 for what's inside and part number
Can find aftermarket for the item under $40

 

[QBhoy]

Sw pressure sensor....IAC.....Diz cap failure would be my targets...if it’s an MPI.

I think you’re on the wrong track with the fuel regulator. I think you are in guardian mode from one of the above or having failure because of the diz cap causing misfires.

 

[muc]

You really should be looking at manual #31 p/n 864260300 this manual will cover disassembly and repair of the cool fuel module.
Also manual #36 p/n 8M0160555 will cover how to test fuel pressure, it sounds like you might not be doing that correctly.

Pretty sure the fuel pressure regulator is on the Gen III Cool Fuel Module. The one on the fuel rail doesn't have anything to do with regulating pressure.
Some ECM models use a "dummy" fuel pressure regulator on the fuel rail. This is a GM supplied part that does not regulate the fuel rail pressure. The vacuum line attached to this regulator is a possible vacuum leak source and a possible fuel leak source if the regulator’s diaphragm should fail. Only the Cool Fuel regulator actually controls fuel rail pressure.

4. If fuel pressure exceeds 44 psi (303 kPa), replace the fuel pressure regulator.

It would be best to get the things you have found that are wrong (low engine temp and high fuel pressure) and then you can move on to whats keeping you from getting over 2000 rpm

 

[sessasails]

QBhoy I am not sure what an Sw pressure switch is, but I did take off the IAC and checked for carbon deposits, (it is an MPIi system) but I didn't think it had anything to do with engine after idle. also not sure what a Diz cap is..(Distributor cap?)

muc Is the Cool Fuel Module located on the starboard side under the alternator? I replaced the fuel filters under 1 of the covers and was told the electric fuel pump is under the other cap (are there 2 fuel pumps or 1 fuel pump and the other is the fuel regulator)..It will go over 2000 rpm in neutral, but is only an issue going over 2000 rpm in gear, which makes sense if Safe Mode works only in Gear. What sensor would put motor in Safe mode or am I jumping too far ahead?

Thank you all for the info, this is all valuable information. The line at the repair shops will keep me from boating this season.

 

[QBhoy]

QBhoy I am not sure what an Sw pressure switch is, but I did take off the IAC and checked for carbon deposits, (it is an MPIi system) but I didn't think it had anything to do with engine after idle. also not sure what a Diz cap is..(Distributor cap?)

muc Is the Cool Fuel Module located on the starboard side under the alternator? I replaced the fuel filters under 1 of the covers and was told the electric fuel pump is under the other cap (are there 2 fuel pumps or 1 fuel pump and the other is the fuel regulator)..It will go over 2000 rpm in neutral, but is only an issue going over 2000 rpm in gear, which makes sense if Safe Mode works only in Gear. What sensor would put motor in Safe mode or am I jumping too far ahead?

Thank you all for the info, this is all valuable information. The line at the repair shops will keep me from boating this season.

Yeah it’s the distributor cap. It’s such a common thing to fail on the mpi. Internet is literally flooded with its issues.
The SW pressure sensor is also a common failure by all accounts. I haven’t had that issue yet.
I’m just thinking of things that would cause this. The cap would be the top target for me. Just to rule it out if nothing else. It can cause all sorts of things to play up from not starting to poor running and anything in between with miss fire on some cylinders.

 

[muc]

muc Is the Cool Fuel Module located on the starboard side under the alternator? I replaced the fuel filters under 1 of the covers and was told the electric fuel pump is under the other cap (are there 2 fuel pumps or 1 fuel pump and the other is the fuel regulator)..It will go over 2000 rpm in neutral, but is only an issue going over 2000 rpm in gear, which makes sense if Safe Mode works only in Gear. What sensor would put motor in Safe mode or am I jumping too far ahead?

Yes, the cool fuel 3 is on the stbd side near the front of the engine. There are 2 pumps inside. The regulator is on the top and is visible without disassembly. It will have a small vacuum hose attached to it.

Reving the engine in neutral means nothing (your engine will go over 2000 rpm even if only 4 cylinders are working) guardian works in neutral and in gear. My guess is that is why you get a warning horn when you rev it in neutral. The computer knows what a bad idea doing that is and is trying to stop you.

All of the sensors (and more) will put the engine in guardian mode.

I understand that you don't want to pay/wait for a professional to fix this, and that's fine. But you do need to understand that without the knowledge that is in the manuals I listed earlier. You have a better chance of wasting more time and money, than you do of fixing it.

 

[sessasails]

Thank you for suggestions, I will get in line