Mercruiser EFI engineer recommendation needed in Portsmouth

[EmptyPontoon]

Hi folks.

Well, that was a ruined weekend while leaving Port Solent. Now need a good engineer to diagnose and tune a Mercruiser MPI.

350 Mag MPI, 2013 been running well for previous owner, some ‘water in fuel’ receipts in the full service history and a new o ring on the filler cap. It was recently serviced (late April) before I bought it in early June.

It ran well until a couple of weeks ago, was in Southampton Water at 6kts, been at low speed exploring for some time and it felt like it was missing some cylinders. Hit the hammer to clear it and it really did not want to pull, but eventually cleared and we got home with no further issues. I put it down to me looking for something wrong with a new (to me), unfamiliar boat. And some strong tides running.

Plan this weekend was to go to Poole for a long weekend and explore the coast in what appeared to be brilliant forecast sea conditions, visitor berths booked etc. Left PS and chugged down past Tipner range - 6 kts. Engine started missing, hit the hammer and it died, wouldn’t restart. Had some help from a sailor coming the other way (thank you yacht Tania - please claim those beers) and eventually managed to get it started. There was no way I was going to hit the needles in a tub with a suspect engine even in perfect conditions, so we glumly headed back to PS. Engine sounded odd at low speed and died two more times... just as we were throttling back entering the lock to add a little extra interest! Got the tug to put it back on its berth in case of a no engine situation among my neighbours boats.

It seems like it is choking when running at low revs, maybe oiling plugs. About 1300 revs at 6 kts limit for half an hour seems to kick it all off. So I would really like a good Merc EFI engineer to have a good look and make this thing safe again before the weather changes. Emphasis on the ‘good’ as I really want this right. No faults reported on Vesselview.

Please could I ask for any recommendations for someone with the right equipment and skills that can visit Port Solent? Not just looking for a one off fix, but an ongoing servicing relationship.

Many thanks. Now off to console my really disappointed missus who was so looking forward to this first (for her) little adventure out of the Solent

 

[rafiki_]

Tom Parker of Tompa Marine is the Mercruiser expert.

 

[QBhoy]

Hi
Outwith really bad and old fuel...I can pretty much say with 99% confidence this will be the well known MPI crap cap problem.
To elaborate, the distributor caps on these MPI are world famous for failure in their very design...especially after winter storage and infrequent use. They gather moisture and corrode internally. You only need to type “Mercruiser mpi distributor” or even half of that into google and you will find a million odd posts on forums with the same issue. I’ve had the same issue countless times, having had an mpi since nearly as long as they have been around in 2003 in the U.K.
the now recommended change out is every 2 years and possibly every year if in the sea and things need to be more dependable. Honestly now, this is one of the biggest causes of failure with the mpi. Many have spent fortunes on diagnosis when all it needs is an £80 Diz cap and rotor. Trust me on this.

 

[spannerman]

Can confirm the two MPI s I had problems with were cured with new distributor caps.

 

[AndieMac]

EP, could you post the results of the diagnosis, I'm interested in finding out more, particularly if you get an opinion from Tom Parker.
The comments on the D cap are concerning, I've got the same engine as yourself, but a faultless run in seven years.

 

[volvopaul]

EP, could you post the results of the diagnosis, I'm interested in finding out more, particularly if you get an opinion from Tom Parker.
The comments on the D cap are concerning, I've got the same engine as yourself, but a faultless run in seven years.

Sadly Tom doesn’t Bother much with this forum .

 

[EmptyPontoon]

Many thanks for the responses. I will give Tom a call on Monday.

With regard to the dizzy issue, I would have thought that any tracking issues inside the cap would materialise at high revs and low revs? It had plugs in April’s but no cap / leads etc. The boat seems fine when it has its head, just prolonged periods around 1000 revs or so seem to upset it. Also, fuel in the boat has been replaced by use over the last weeks.

Once Tom has worked his magic I will update as requested. Once again, thanks for the replies and the pointers.

 

[EmptyPontoon]

Just spoke to Tom. He also suggested the cap as the first point of call for a problem like this. Given the apparent fragility of these caps, Tom also suggests carrying a spare on board so I guess there is an issue with these flat caps as pointed out by others.

Could DIY but would prefer him to check it over thoroughly (suspect oil contamination given the colour) so have sent engine details to him. Looking forward to seeing him soon and having a reliable boat again.

Thanks for the responses all. Will update when sorted as requested.

 

[AndieMac]

Just spoke to Tom. He also suggested the cap as the first point of call for a problem like this. Given the apparent fragility of these caps, Tom also suggests carrying a spare on board so I guess there is an issue with these flat caps as pointed out by others. Will update when sorted as requested.

Thanks for the update EP

 

[EmptyPontoon]

Hi AndieMac.

Tom popped in bang on time as planned, had a look with the computer, nothing to concern myself with really, but sure enough, looking at the cap it had a fault. Replaced the cap and all was well, running smooth at idle. Tested in low drive on the berth and all was clear at the revs which brought the fault on, but still a fault coming off the throttle through neutral causing it to stall.

There is an idle motor which was not responding quick enough / fully / at all which Tom will order in and replace. Basically, and I am paraphrasing heavily, that fault could cause it to run very rich - which it clearly is. Should be the end of it we hope, but a little background worry about injectors given the history showing water in fuel some time ago may cause us to have a little run out with the computer attached after fitting it.

Tom is one extremely knowledgable and decent guy it seems.

 

[julians]

The idle air control valve is another weak spot with these engines, and if it fails it can result in stalling at low revs. I think I went through 3 in 6 years when I had mine. I ended up carrying a spare on board, they're easy enough to change yourself.

 

[EmptyPontoon]

I think that is what Tom is suggesting. On the side of the throttle body, the thing you hear sucking when you come to neutral.

 

[julians]

Yes thats it. Before i took to carrying a spare on board i worked out that you can adjust the throttle linkage to keep the throttle open a little which keeps the engine running nicely even with a completely broken idle air control valve.

 

[QBhoy]

Hi

As probably gathered by my previous post, you will probably guess that I have been through all this before. Not sure if I mentioned, but these engines are known for certain weak spots. Most of all being the Diz cap. Best to replace every year. What usually happens next is the IAC. It will have been working hard to control the idle with the poor spark.
Then it will be the throttle position sensor. Next on the list will be the sw pressure sensor and maybe the fuel regulator too.
Another recent discovery after replacing the whole distributor gear in its entirety on a friend’s mpi, was that although the Diz was set up between the two marking lines and the ecu should take over from there with regards to the timing...it became apparent that a slight turn of the assembly by only a mm or two made a huge difference to the running of the engine. There is a 1/2” bolt holding the whole unit on. A slacken of this bolt and a slight turn (usually anti clockwise) will sort it out.

 

[AndieMac]

I'm watching the responses on this thread with interest, thanks for contributing EP, julians and QBhoy. I'm going to compile a list of spares to carry and work on some preventative maintenance it seems, cheers gents