Intermitant fault with Mag 350 MPI on maxum 2700SCR

Below is a cut and paste from 1 of the many forums i'm scouring for help - HELP

Hi & Help, bought 1st boat couple of months ago, Maxum 2700SCR (2003) only 60 hrs on engine, been fun up to a few weeks ago, now 74 hrs on engine 350 Mag Mpi

Problems-
1) Notice leaving marina at idle engine missed a beat every now and again, put on plane @ 3500 revs and seemed fine, out for a hour or so returning on plane felt it miss again, came into marina and ticked over fine
2) Went out from marina and the odd miss again, just onto plane @ 4000 revs when dies, heavy smell of fuel, tried to start would occasionally fire but then splutter to a halt, towed home, back at marina fired up and ran for 15 mins at idle no problem
3) Replaced fuel/water separator filter, on draining fuel from old filter it was very dirty – no water, changed inline fuel filter as well and again really dirty from inlet side, took boat out and tested for an hour ok at all revs, thought problem fixed
3) Went out for weekend, no issues at 1000-2000 revs to destination, stayed the night, next day headed for supplies, all well for 30 mins while waiting to dock spluttered to a halt again, wouldn’t start, 1 hour later got started, running really rough, using high revs to keep running sounded like missing on a few cylinders starting and stopping then all ok, limped back to destination between 700-1000 revs never missed a beat, fired up a couple of time during the night all well, fired up in morning for 30 mins before heading home again all well, loaded up kicked in reverse and spluttered to a halt, tried over an hour to start, would occasionally start but splutter and die, towed home again
4) After being towed back tried to start at marina and wouldn’t so hey hopefully find the problem now, an engineer looked at it and she still would not start, he checked fuel pressure - ok, removed plugs pretty dirty so cleaned and re-gapped - engine now fires up but would shut down after anything from 30 seconds to 2-3 minutes, purring away then just shut off as if you switched the key off, then he phoned back to say engine now running for last 15 mins and not shutting off- arghhh
5) Decided to get Mercruiser dealer to run diagnostic test, he did with no fault codes or issues, he checked the fuel pick up wasn’t blocked says engine running away with no faults and seems to be fine, thinks sea trials required to find fault or breakdown again etc
6) Was down last night, ran engine myself for 20 mins revving etc and purring away nicely – so frustrating

Sorry for the long story but I have lost all faith in her and had the embarrassment to be towed in twice now from the same park rangers, there is clearly something not right and I guess the more information the better so any ideas guys??

Told today mercruiser dealer can't help, i need to run boat until it breaks down again before he can do anything, HELP

I am going to assume that the mechanics have already checked the electrical side . plugs, leads,
caps, vacume pipes etc.

Your problem seem to happen more when the boat tips up at the front, plane or cruising as opposed to sitting still. This will cause any water to run back to where the fuel pick-up is located. Perol will sit on top of water and depending on the shape of your tank may only reach pick-up when tilted.

It sounds like a fuel problem to me. If your boat has been left over a few winters with very little fuel in the alloy tank then condensation can build up in the tank and will only mix when the mixture is agitated. It is best to top off your tank during the winter.

I would try one of these easy things first.

If your fuel is low try and drain the tank using a manual pump through the hole for the tank sender unit just to make sure the tank has no water in the fuel.
remember that old petrol will go off if the boat was not used much and the fuel is old.

You can buy a couple of cans of "Dry Fuel" a chemical that will make water mix with petrol and burn out naturally but this will only work if there is a reasonably small amount of water in the tank. ( up to .5 gallon per 30 gallon tank). Dry fuel can be bought in most motor factors and minimum of two for a big tank.

Of course to completely rule out fuel ask your mechanic to run the boat from a small outboard tank connected to your fuel line.

You also need to check the tank vent hose is clear and has not been kinked as under load the pump can create a vacume in the tank preventing fuel pressure to the engine. this can be checked when your engine cuts and you remove the gas cap, if you hear air rushing in then there is a vent blockage.

It is also not uncommon for electric or manual fuel pumps to loose pressure when under higher demand but i would do the easy and cheap stuff first.

Good Luck

Paul

Hi Paul

Thanks for the tips, as she will purr away today and Neil looked at her i assume the electrics etc are all ok

I agree with you that we think its a fuel problem, my brother who is an ex mechanic and changed the water/fuel sperator and inline filter said he had never seen such dirty fuel in his time in the trade

There was no water in the seprator filter and since she broke down again he came and checked the inline filter which was spotless so were thinking possible still some dirt between the fuel pump, fuel rail and injectors. Need to find out if the electronic fuel pump has a filter

I got the boat with half a tank of fuel, did a 3 hour sea trial with previous owner with no issues, went out with a mate for another 3 hours again no issues, seems to be once i put £250 of fuel in from CH that problems started to occur, i'm sure their fuel is fine otherwise we would all be having problems, she now sits with a full tank of fuel

This tank vent hose keeps getting mentioned so i'm going to look at that tonight, its in the mercruiser manual as a possible, looked ok but i think i need to trace it just to check kids have not stuck something in it for fun or something

I also need to check the flame arrestor as this is mentioned as a possible cause and i'm sure it probaly has never been cleaned

Will keep you posted

Cheers

Campbell

I dont think the issue is only there when the front tips etc as the first time i noticed anything was puttering out of CH at 700 rpm, missing an occasional beat

Hi Campbell

If your tank is full and the fault started after you topped her off its sounding more like a vent issue------------less air quicker vacume----------take the vent pipe off the tank and blow through it, you will be able to discount that one very quickly.

Not sure about the flame arrestor if it was only partially blocked you would not get the poor starting thing you mentioned but keep it clean anyway.

Dirty fuel........I had a problem with a peugeot 306 that several mechanics and two main dealers could not resolve and showed similar symptoms to what you describe. I removed the tank sender/pump and found a large leaf floating in the tank......when the pump sucked in the fuel the leaf covered the pick-up gause when the engine stopped the leaf floated away until the next time..............the owner was filling his car up with a funnel he kept in his garden and cans of fuel " procured " from somewhere !.

I hope you fix it soon................floating aint as much fun as boating.

Paul

Hi Paul

Went down tonight, checked the vent hose from the fuel tank, blowed through no problems, removed the flame arrestor 95%+ clean so not that, checked all the wiring connections all good

Fired her up, started straight away, ran for 30 minutes, revved up and down a few times upto 3000rpm, never missed a beat, set my carbon monoxide alarms off though, maybe thats why i felt dizzy

Arghhh oil pressure spot on, engine temperature spot on, 30 minutes without missing a beat, just have to take her out and put her through her paces and hope all is well or the fault appears again and i can get towed in again

Cheers

Campbell

I had the 7.4 mpi had some issues and it turned out to be the idle control valve. They stick every so often and can kill the engine when returning to idle. It may be one of the sensors. Speak to colin camburn as he has the Rhinda diagnostic unit that he purchased from as I have no need for it on Volvo diesels. He should have the correct hook up lead and you can take the boat out for a test with the diagnostic still hooked. It should show the faults codes and the parameter to which you 350 is operating at.

anjo wrote:

I had the 7.4 mpi had some issues and it turned out to be the idle control valve. They stick every so often and can kill the engine when returning to idle. It may be one of the sensors. Speak to colin camburn as he has the Rhinda diagnostic unit that he purchased from as I have no need for it on Volvo diesels. He should have the correct hook up lead and you can take the boat out for a test with the diagnostic still hooked. It should show the faults codes and the parameter to which you 350 is operating at.

Spoke with Colin but see's no point in doing the diag machine as E Crossan has done this with no fault codes or codes in the history, had a long chat and still sounds like a fuel issue, going to remove and clean the fuel booster pump and take her out on Thursday to see what happens, cheers

Hi Campbell

Never made it up yesterday too busy. How did you get on with your boat ?

Paul

Hi Paul

Did not happen, no one arround, going for Saturday afternoon now, hopefully some helpful boaters arround, will keep you posted


Campbell

Campbell,

Sorry did not arrive at the marina until 18:30 hrs yesterday evening, but will be staying until sunday afternoon.

Give us a shout when you are going out to test.

anjo wrote:

Campbell,

Sorry did not arrive at the marina until 18:30 hrs yesterday evening, but will be staying until sunday afternoon.

Give us a shout when you are going out to test.

Hi John,

Don't worry i'll be stalking your boat from about 2-3pm onwards on Saturday

Campbell

SKYEDEN wrote:

Hi Paul

Did not happen, no one arround, going for Saturday afternoon now, hopefully some helpful boaters arround, will keep you posted


Campbell

Why, oh why, oh why did you not phone me, I txt you to say that was me on the water. Txt'd you when I was back off which was about 5.30-600.

You could've had it out tested & even towed back if needed

BIG ZEBEDEE wrote:

SKYEDEN wrote:

Hi Paul

Did not happen, no one arround, going for Saturday afternoon now, hopefully some helpful boaters arround, will keep you posted


Campbell

Why, oh why, oh why did you not phone me, I txt you to say that was me on the water. Txt'd you when I was back off which was about 5.30-600.

You could've had it out tested & even towed back if needed

Hi Paul

When i got to the marina i assumed you were up the islands and didn't want to put you out, i had just left when you texted and had to head home with dinner for the fmaily, appreciate your offer and if i still aint managed to get her out i'll text you Saturday, Sunday etc etc The other thing being a new skipper i don't have the confidence to take her out the marina on my own so i need a wing man as well as the standby boat, lol or maybe just some mates who aint always so bloody busy

I'm keeping a beady eye on the weather at the moment & there's a possibility I could be going on the water saturday late afternoon & camping till sunday. Probably on North island as the wind is meant to be a good SW so more shelter at north beach.
I appreciate you saying you did not want to bother me as I was on the Island but I know the feeling of what it's like to have a boat that don't run properly & getting that boat to run is top priority or in your case possibly get the fault to happen again so it can be diagnosed by the mechanically minded.
Anyway, no worries, I'll txt you again this weekend when I'm on the water either sat or def sunday.
Hopefully the problem was a bit of dirt in the fuel line from the filters & since the filters are changed maybe the last bit of fuel needs a good blasting through then it'll be happy days again

Campbell I assume you were not at the marina on saturday as I was looking out for you. The weather wasfairly poorly and and a fair bit of wind.Weather got better Sunday pm as I was leaving. I will not be back at the marina until Friday as I an in Aberdeen for a few days.

Hi John

I didn't make Saturday as i was still suffering from a very late night on Friday, i was down at 12pm on Sunday but didnt see anyone arround, by 2pm i was too ocupied with the police as some plonker on a mountain bike decided to leave a couple of dents in my car and then scarper, need to re-think my plan of action to see if i get down this week or leave it until the weekend, cheers

Have you seen the weather forecast for this weekend?



I'll be on inchmoan from Thursday teatime till Late Monday, You've got my number Campbell

Hi Campbell

I will be at the marina from about noon for a few hours to fit a water pump and give the boat a much needed
wash. I should be there for a few hours anyway.

Paul

I'm just about to pack the boat with the camping gear, so I'll be on south Inchmoan in a few hours. I'll be there till monday if this weather holds out till then

Hi All

Hopefully see some of you guys down this weekend, taking the family down to the boat on Friday staying at the marina, maybe even get to test her Friday night, if not on Saturday, have to get this done this weekend as the season is disapearing fast

Hi,

Well took the boat out on Friday night with the family, enough was enough, puttered up at 1200rpm and got to Inchmoan North without missing a beat, stayed Friday night and due to the crap weather on Saturday headed home on the plane full speed ahead with no hick ups

With my confidence restored decided to head back out to Inchmoan on Sunday, up on plane there and back with no hick ups, appears the gremlins have gone for now

Cheers for all the offers of help and Big Z i'll maybe catch you next time for a beer or was that Vodka, Bacardi or does it matter

Campbell

Glad to hear all is well with the boat, must've been dirt in the fuel system somewhere & now it's cleared. I never got your txt till I got home as it was a bit of a rush getting things packed away, my brother txt me saying it was forecast for rain at 7pm on the sunday night & to be heavy rain on the monday so, we packed up coz I hate having to pitch up stuff out the back garden to get it dry. was a lovely day on sunday eh!
I'm sure we'll catch up sometime as I'm on the water as often as I can

ARGGGHHHHH The gremlins have returned

Went out Saturday to North Inchmoan, not that there was much beach right enough, no problems, headed home Sunday morning and that when the gremlins returned

Fired her up while packing up after 5 mins she just cut off, left her for 20 mins while packing the rest of the gear, tried to start and just turned over with no luck, tried about a dozen times and finally fired up, then conked out after a couple of mins, fired up straight away and jumped on not wanting a 3rd liason with the Brigadier

Got to about Ross Dhu point and open up to about 2000rpm ok then missed a beat, then conked out, fired up again and same again, then something new and different, when trying to start again nothing when turning key, 3 times this happened then 4th time turned again and fired up. Ran back to CH at 2500rpm without missing another beat

Just bloody weird, getting Neil to dip the tank for water content, had no electronic issues when Ediie had the diagnostic machine on her, any dirt in fuel must be long gone by now, will check filters again and dip tank, then its time to scuttle her i think

Hi,
With reference to the new fault, when you say 'nothing' do you mean no lights, no alarm or just no crank? For starters are you sure you never knocked the kill switch or were trying to start with control lever in gear still?
If none of above, could be faulty wiring, harness connection, ignition switch, kill switch etc. An intermitant fault with one of these items could also cause / contribute to your other problems.
I can see you have had alot of ideas and advice from the guys. On first hearing this, my first thought would be swop to remote fuel tank for test to rule out boats fuel tank. Anti - syphon valves can malfunction, dirty fuel or foreign objects in tank can periodically block fuel pick up pipe and unblock when engine stops and fuel pump suction ceases. If pick up was permanantly restricted fuel pressure test would usually return low reading though.
I know you have verified correct fuel pressure. Was a static test or running test carried out under normal operating conditions? The regulator is in my mind as another posibility here. What was the recorded pressure at time of test? This can cause strong smell of fuel you mentioned. If fuel condition is rich black smoke will also be evident in exhaust.
This could also be an intermitant basic ignition fault away from all the fancy electronics.
I also have the latest mercruiser diagnostics but I know you have ran diagnostic tests already. I am assuming you hear fuel pump & alarm running for couple of seconds when you switch on ignition when engine is refusing to start.
The list of possible faults is pretty extensive but these ones spring to mind straight away. Remember, as I was taught when I was an apprentice - When faultfinding 'You have to expect the unexpected'.
Nick.

Hi Nick

The new fault was no crank, key turned, pump pressurised, alarm etc then instead of turning got nothing, like a flat battery in a car, did check the kill switch which was ok, can’t remember if control lever was in gear but I'm pretty positive it was not

Yes it seems swapping to remote tank is a quick way to eliminate the old tank & fuel, not sure if pressure test was static or running would need to check with Neil. Not really any issues with exhaust smoke being black etc.

Now the basic intermittent ignition fault away from the fancy electronics sounds good to me and does have a couple of notes pointing it in this direction, earlier after being towed in Neil was looking at it and mentioned it would start but then just switch off 5, 10, 20 seconds later just as if someone was switching of the ignition!! Was this a sign??? And then their was this latest time when the new gremlin appeared in that she never cranked over when turning the key – is this another clue??

Yes every time I turn on the ignition I hear the primary pump pressurise and hear the alarm for a few seconds

As you said expect the unexpected, think I need to get Neil or another engineer out for a mornings blast with their tools and diagnostic gear on board then we will just thrash her about for a few hours to see if she will play up – and knowing my luck probably not

Cheers