QBhoy
Well-Known Member
Hi guys
Posting in the slim hope that there is an MPI Merc or GXI Volvo expert on here or someone has had the same issue.
At the risk of sounding gallas...I’m not new to the GM engine and might also boast that I spent 10 years as a marine engineer on rather larger vessels...but these new fangled electrically biased MPI engines are and have been troublesome on occasion to me.
The symptoms...
Boat has not generally been running to full potential for the last season or more, but frustratingly only intermittently making it difficult to diagnose on an amateur level. At further risk of coming across a smart arse, I’m fairly well aware that the MPI and GXI are well known for certain faults like Diz cap, IAC, TPS and others. I’ve been through these problems early days and rather foolishly thought I was one of the best placed to judge and diagnose faults on these engines...often giving fine advice to others on faults I have already been through.
So....the boat was running well this evening and even managed into the 60’s gps after replacing the Diz cap and plugs last week. Vast improvement from a steady 52/53gps the months before hand, causing original concern. At this time she was defo just lacking that top end grunt she used to have. As I say the power loss was not all the time. But...tonight, after running well and as mentioned into the 60’s with hood up and dirty hull...I was so pleased....only to be almost to the point of getting a tow home an hour later. She lost significant power and almost failed to plane. I turned the straight through exhausts on to listen to it out each side (4 stbd cylinders exit from one side, 4 port the other) and she was defo down on at least one, if not 3 cylinders out the port bank. Also an alarming smell of unburnt fuel and even rainbow in the water from the fuel. So logic would tell me it’s an ignition problem.
All leads in place...all leads on Diz cap. Diz cap 2 weeks old. Plugs the same. Oil in sump stinks of fuel. Clearly washing down past rings. Pretty sure not down on compression, but what else could cause no ignition on only 1-3 cylinders on one side of the V. It’s a common ignition coil. Obviously going to try the basics tomorrow with testing spark etc.
Just posting in the slight hope someone has come across this before. As with all MPI owners..it’s a steady learning curve of known faults...I thought I was well versed but clearly not.
Thanks in advance.
Posting in the slim hope that there is an MPI Merc or GXI Volvo expert on here or someone has had the same issue.
At the risk of sounding gallas...I’m not new to the GM engine and might also boast that I spent 10 years as a marine engineer on rather larger vessels...but these new fangled electrically biased MPI engines are and have been troublesome on occasion to me.
The symptoms...
Boat has not generally been running to full potential for the last season or more, but frustratingly only intermittently making it difficult to diagnose on an amateur level. At further risk of coming across a smart arse, I’m fairly well aware that the MPI and GXI are well known for certain faults like Diz cap, IAC, TPS and others. I’ve been through these problems early days and rather foolishly thought I was one of the best placed to judge and diagnose faults on these engines...often giving fine advice to others on faults I have already been through.
So....the boat was running well this evening and even managed into the 60’s gps after replacing the Diz cap and plugs last week. Vast improvement from a steady 52/53gps the months before hand, causing original concern. At this time she was defo just lacking that top end grunt she used to have. As I say the power loss was not all the time. But...tonight, after running well and as mentioned into the 60’s with hood up and dirty hull...I was so pleased....only to be almost to the point of getting a tow home an hour later. She lost significant power and almost failed to plane. I turned the straight through exhausts on to listen to it out each side (4 stbd cylinders exit from one side, 4 port the other) and she was defo down on at least one, if not 3 cylinders out the port bank. Also an alarming smell of unburnt fuel and even rainbow in the water from the fuel. So logic would tell me it’s an ignition problem.
All leads in place...all leads on Diz cap. Diz cap 2 weeks old. Plugs the same. Oil in sump stinks of fuel. Clearly washing down past rings. Pretty sure not down on compression, but what else could cause no ignition on only 1-3 cylinders on one side of the V. It’s a common ignition coil. Obviously going to try the basics tomorrow with testing spark etc.
Just posting in the slight hope someone has come across this before. As with all MPI owners..it’s a steady learning curve of known faults...I thought I was well versed but clearly not.
Thanks in advance.
