Second new Merc motor issues...

watching the videos you are not making the hp to plane off. Couple of thing to check .The spark plug firing order. usually reversing 5 and 7 is the cause.
does this have a standard cap or a flat cap?
have all the wires to each plug been verified,tracing out each individual wire to each plug
has the throttle cable been checked for wide open throttle
 
Could the timing somehow be stuck in base mode? That would prevent advance and cause the boat to bog down.
 
Could the timing somehow be stuck in base mode? That would prevent advance and cause the boat to bog down.
 
Yup, always check spark plug order. AND, what type distributor do you have.

Forgot to mention the gas smell...but usually any excess gas is easily consumed at full throttle WOT. The other possibility of the high pressure fuel line leaking needed pressure.
 
The gas smell is from the exhaust. No smell in the engine bay.

It's a flat distributor (I think that's what you call it - the wires all come out parallel the the deck, rather then up like the older ones)
 
The Smell - sounds like the MPI is delivering fuel that the ignition isn't firing. That'll slow you down.
 
the plug order is in my other post for a flat cap . a mistake people make is thinking the flat cap is 2,4,6,8 on the left side and 1,3,5,7 on the right side.It`s not.
188069_98k1500fireorder_1_zpszng76bqx.jpg
 
Lordy! I looked at that diagram of the CAP. How'd They Do That?

Anyway, REAL good time to verify Firing Order again... That thing gives me headaches.
 
internal connections so the plug wires have a nice neat setup not crossing each other.
Now if the dist was a round one he could have a 6 cylinder rotor in it instead of a v8 rotor
 
These MPI engines - They don't have a Firing Order, or do they? I used to think they did, each provided fuel only on the intake stroke of its assigned cylinder. Now I believe there was/is Sequential Electronic Fuel Injection (SEFI) that does that, but the MPI's provided fuel to all cylinders all the time. I was wondering if the Ignition could be in the correct timing and the MPI was not.
 
The dealer that installed your engine should be able to verify all the live data with a marine scanner. If you like i could scan it for you. I keep my boat at CYC and im down that way alot on the weekends if your interested.
 
quote:
Originally posted by Al_Prisco

The dealer that installed your engine should be able to verify all the live data with a marine scanner. If you like i could scan it for you. I keep my boat at CYC and im down that way alot on the weekends if your interested.

Click to expand...


That's a great option, thanks.

I do have an update - Just got an email from the yard - "We did some more testing & it seems to have an intermittent # 2 cyl." that's all they got as it started raining and they had to button it up. Hoping they will be working on it more tomorrow.

I don't know about the intermittent part, as it hasn't run right since new, but that explains the gas smell in the exhaust and lack of power. Hard starting? Not as sure but probably too.
 
Latest:

Dealer said they were able to get 4900rpms and a good hole shot yesterday. WOT range is 4800-5200 btw. I asked (all via email) what they did and they said:

It seems the wires were the culprit. Although we also changed cap, rotor, & spark plugs. However the IAC valve is still working to hard. I’m going to talk to Merc again today & see what can be done.

Not sure what they mean by "IAC valve is still working to hard" but I'll let them talk it out with Merc and see what they come up with.

Maybe I'll have a boat this weekend!!!
 
I had similar issues with my 5.0, it turned out to be a loose spark plug in the #2 cylinder, they tightened up that and the boat ran great for a week, then I noticed with 3 skinny people aboard that it was struggling to get up on plane, it struggled and finally topped off at 27mph for 5 minutes before the engine blew, looks like a connecting rod pierced the oil tank. Looking at a 10 grand replacement...why this happened I don’t know, I always maintain it well.
 
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