Quick story, I have twins and last yr was CONVINCED I had a fuel starvation issue (intermittently) with my starboard engine. It would sometimes only get to around 4000 rpm's at wot. I changed all the filters and basically rebuilt the vst...then at my wits end replaced the spark plugs and that solved the problem.
New problem with port engine: It did this twice the last time I was out. After trolling at 1100 rpm's, when I advance the throttles the starboard engine revved up normally to around 4000 but the port engine would only go to 2500-3000 with surging and a lot of shaking. It would gradually smooth out over about 30 to 45 seconds (maybe even a minute) and then run perfectly for 20 miles around 4000 rpm's.
No alarms when this happens but I'm wondering if the engine is getting hotter while at trolling speed and I might have a spark plug or 2 or maybe a coil failing when very hot??? The reason I mention heat is my starboard motor will actually give a overheat alarm if I let it idle too long. I know that impeller is weak because I only have 2.5 lbs of water pressure at idle. The port does have 5psi. Both engines have 20+ psi at cruise speeds but if ones weak I'm sure the other is too. I have water pump kits on order.
I changed the spark plugs last yr but will change them again to see if it solves the problem or at least eliminate them as the problem. I did find something unexpected with these 1 yr old plugs. The center electrode resistance ranged from 3500 ohms to 4400 ohms. I was expecting them to all read basically the same.
Any suggestions? Can you bench check ignition coils? I suspect they will check fine when cold.
I removed and checked the IAB today, it checked out ok.
New problem with port engine: It did this twice the last time I was out. After trolling at 1100 rpm's, when I advance the throttles the starboard engine revved up normally to around 4000 but the port engine would only go to 2500-3000 with surging and a lot of shaking. It would gradually smooth out over about 30 to 45 seconds (maybe even a minute) and then run perfectly for 20 miles around 4000 rpm's.
No alarms when this happens but I'm wondering if the engine is getting hotter while at trolling speed and I might have a spark plug or 2 or maybe a coil failing when very hot??? The reason I mention heat is my starboard motor will actually give a overheat alarm if I let it idle too long. I know that impeller is weak because I only have 2.5 lbs of water pressure at idle. The port does have 5psi. Both engines have 20+ psi at cruise speeds but if ones weak I'm sure the other is too. I have water pump kits on order.
I changed the spark plugs last yr but will change them again to see if it solves the problem or at least eliminate them as the problem. I did find something unexpected with these 1 yr old plugs. The center electrode resistance ranged from 3500 ohms to 4400 ohms. I was expecting them to all read basically the same.
Any suggestions? Can you bench check ignition coils? I suspect they will check fine when cold.
I removed and checked the IAB today, it checked out ok.
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