Low PSI alarm at idle

Liberty44140

my buddy has an 04’ 340 DA with twin 454 v drive and is having an alarm issue. She fires up fine but as soon as he puts it in to gear he gets the low psi alarm on both the sea ray monitor and the smartcraft for the port motor. Local dealer changed out the sensor and put the computer on it. He still gets the beeps. The alarm goes away when he is running above idle and again it’s fine in neutral, alarm is only in gear at idle. Thoughts? Thinking about Wilds wild story I told him to have the mechanic backflush the manifolds and risers first. Figured I’d post this for other ideas... thx 

aero3113

Sounds like the pump possibly, idle is lowest at idle in gear. When he gives it some throttle the pump spins faster giving more psi and flow turning off the alarm.

aero3113

What's his RPM's when in gear at idle? It could be as simple as an adjustment.

Liberty44140

aero3113 said:

Sounds like the pump possibly, idle is lowest at idle in gear. When he gives it some throttle the pump spins faster giving more psi and flow turning off the alarm.

Thanks- but wouldn’t he have an overheat if it were the pump?

I will ask him about the rpms 

aero3113

It could still have enough flow to not overheat but give an alarm.

Liberty44140

Alswagg said:

Hold on.   You are talking about an old 454.  In a Sea Ray V drive.   That means is has MEFI 2 or 3 controller.   When you mention low pressure, that would be either low oil pressure for the motor or low oil pressure for the V Drive.  MEFI 2 and 3 does not register low water pressure like the Motorola pcm 555 controller does.   

My mistake, they are 6.2s which I’ve been calling 454 but I’m probably wrong. 6.2 MPI. This is a 2004 sea ray. 

Liberty44140

He doesn’t remember the rpm at idle but he knows it’s too low, he is able to manually increase it at the helm which he does often but it resets itself when he restarts the engine. What should it be?

Liberty44140

Thanks, will have him check 

Liberty44140

So Marine Max got on my buddys boat, again its an 04, 6.2 MPI. They say that the RPM's are too low at idle, they are 400 rpm, so they are upping to 600 rpm which makes sense. They also found that the distributors on BOTH engines are cracked. Whoever did them over tightened the screws and cracked. Mechanic says that could be part of the problem but I dont know, could that cause the PSI alarm or low RPM? I'm going to recommend the distributor rebuild kit that has been posted here as he should not leave them cracked

Michael T

Depending on model there are PSI sensors that can fail - not expensive - but if they fail they throw a code and trigger engine guardian. Ones I have seen are in-line gray clip into place sensors.

Liberty44140

Coming back to this, my friends problem persists and he is being told he needs a new ecm. To recap this is a 2004 sea ray 340 with 6.2s and v drives. Continual low water psi alarm at idle speed. Has had sensor swapped and replaced, distributors were cracked so he had them replaced on both engines. Finally pulled the water pump on the engine with the alarm and found major grooves and while all impeller vanes were there there was obvious melting. So the tech installed the wear plate kit with a new impeller. Tech was marine max and they felt that the wear plate kit would be fine. They see the code in the computer and say the computer is bad. Does this add up to you guys? Can the ecm be re flashed or codes re set? Thanks 

Liberty44140

Thanks, very helpful. He is not sure on the psi reading but will check. Will post back anything new.

Liberty44140

So the merc dealer called merc who said that (as al said) it is not the ecm. They said that this is consistent with a particular wire harness failing. I’m trying to get the name of it. At first they thought they could splice in a new wire and save money, but now they say the $1400 harness needs to be replaced. My friend is trying to decide what to do. Boat runs great, he uses it every weekend. 

Liberty44140

So I thought I'd follow up on my buddy's SR 340 with the low PSI alarm. He did not change the $1400 wire harness that he was told to after all of the above trial and error. Decided to wait. He did nothing and the alarm is now gone this summer. So here is my theory on what happened to him:
Spring 2018 he had a local goofball try to repair his old radar/gps system which ended up going nowhere and never working. He launches boat last spring to find a new problem, low PSI alarm, and chases the low PSI alarm all summer 2018. Spring 2019 he has a good, real professional come in and install a new Garmin GPS system just before launch. Zero PSI alarm issues this year. I think that the goofball disconnected a ground or something that the pro properly re-connected and thus problem solved. 

rasbury

Like Al said, start with the basics...I'm the first one to think any noise is sign of a major failure. It's hard to take a boat to someone else to work on- it's a crap shoot for sure even if they are very experienced.