Mercruiser 5.0 MPI Won't get onto plane after Top end Rebuild

[IM Buddy8]

Hello, this boat (2003 Sea Ray 240) ran fine this spring, until a pinhole rotted between the water jacket and the valve area in the head which made it hydrolock when we tried starting it after it sat for a few hours trickling in.

So we replaced head gaskets, heads (new remans with the same cast #), intake gaskets, exhaust manifolds, risers, exhaust flappers (the ones that stop water from coming in from a wake), intake gaskets, spark plugs, wires, cap, and a few other things while we were in there.

When we reassembled we followed the procedure fro pre-loading the lifters with one full turn after lash was removed. This felt like a lot, but it seems that Mercruiser manuals state this spec. Although on most small block chevy's I see 1/4,1/3, and 1/2 more commonly so I'm curious what others have done in their Mercruiser.

Set distributor to point at #1 cylinder with timing mark lined up with Cyl #1 at TDC. Started up well, idled well after a little bit of learning out from excess priming and runs excellent at idle and up to mid-speed. We thought we were all set, then took it out on the water (it's docked at a marina) and couldn't get it to more than 3100RPM's. Just two of us on it, it usually gets on plane in less than 10 seconds 90% of the time and it was calm with minimal wind, wave, current. Shut it down, checked oil level (good) tried loosening distributor and moving it as much as I could clockwise and counter-clockwise (it's the flat cap so it only turns a little bit in each direction) and it didn't seem to do anything. I have the 48 pin ECM-555 so I think if you're close to #1 at TDC that's all you need to do and the computer does the rest of the timing but correct me if I'm wrong.

Did a compression test, got between 165-175 in all cylinders so they are pretty well balanced with what I think is a respectable number.

No weird noises, normal oil pressure, doesn't overheat but lacking power. What could it be? The boat ran 100% strong this spring before the water leaked into the cylinder and stopped it from being able to start.

Any help would be greatly appreciated, located in Providence RI.

Thanks,
Ryan

 

[alldodge]

What is your serial number?

Don't know what manual your using but manual 32 list no valve lash adjustment on the MPI motor. The Rocker arm bolts are torqued to 22 lb-ft

Set distributor to point at #1 cylinder with timing mark lined up with Cyl #1 at TDC

You should have the HVS distributor and that isn't how to set timing. See pic below

 

[Bondo]

Ayuh,...... Examine the Contents of the fuel filter, for anything but clean fresh gasoline,......

 

[IM Buddy8]

What is your serial number?

Don't know what manual your using but manual 32 list no valve lash adjustment on the MPI motor. The Rocker arm bolts are torqued to 22 lb-ft



You should have the HVS distributor and that isn't how to set timing. See pic below

The motor serial is M615345
Are you saying the valves are supposed to just be set at 0 lash with no extra degrees of rotation to add preload?

The image you posted on how to set the timing is the same mark I used, I just did it the harder way by looking where #1 wire plugged in, traced down the side of the cap looked inside and found where it should be pointing. This would have been easier to know ahead of time but that's where it's pointing. If it's between those lines, no need for a timing light or to set it with a scan tool, it should adjust timing automatically by the computer?


Thanks Bondo I'll check the fuel filter out.

 

[nola mike]

The motor serial is M615345
Are you saying the valves are supposed to just be set at 0 lash with no extra degrees of rotation to add preload?

Yeah, at some point they upgraded to a full roller rocker that you just torque to spec.

 

[tpenfield]

Any help would be greatly appreciated, located in Providence RI.

Thanks,
Ryan

OK, we'll be right over after we stop at Dunkies

Not sure about the valve lash thing, but it would be worth checking into, making sure you have the correct manual for the engine. Just for kicks you could re-do the lash and go 1/4 turn to see if that makes a difference. Of course, if the valves were floating a bit, the compression test should be lower . . . :noidea:

I know my Merc 454 (Mark IV) was spec'd for the full turn, but that was an older engine.

 

[Howard Sterndrive]

With conventional rockers on a boat, I always fine tune them with the compression gauge. Tighten until compression starts to drop off cranking. Then loosen until rocker can wobble. Split difference.

 

[alldodge]

The motor serial is M615345
Are you saying the valves are supposed to just be set at 0 lash with no extra degrees of rotation to add preload?

My mistake, I was using manual 32 (V6) and said that above, and should have used 31 and there is a valve lash adjustment. Its 1 full turn after zero lash

 

[IM Buddy8]

So do you think for my serial that it's 360 degrees from zero lash? If so that can't be the problem. Open to other ideas thanks!

 

[alldodge]

So do you think for my serial that it's 360 degrees from zero lash?

Yes

Its either timing, or fuel
Need to scan motor to see if there are codes
Hope you beeper is working

If the timing is close then it will run, but if its not exact them the ECM will not respond correctly.

 

[IM Buddy8]

Yes

Its either timing, or fuel
Need to scan motor to see if there are codes
Hope you beeper is working

If the timing is close then it will run, but if its not exact them the ECM will not respond correctly.

It beeps once when I turn the key to on and the fuel pump cycles. Is that the same one that beeps if there is an issue or are there two beepers in the dash?

 

[alldodge]

There may be one at the helm, but I was wondering if the beeper worked, and it does. If it didn't work the the ECM may be indicating a problem but it could not be heard

 

[QBhoy]

Confused by the idea of setting the timing mark and all that to cylinder one. These mpi just need the diz put in between the two lines and the ecu sets the timing.

 

[nola mike]

OK, we'll be right over after we stop at Dunkies
.

Dad lives in mashpee. Early in our relationship I tried to explain this to my wife (she's southern). Driving back to Boston I set the over/under at 22 for how many we'd pass. I won easily on the over. She still doesn't know how to order though.

 

[IM Buddy8]

I went yesterday and did the following, still same issue won't go over 3100RPM.

Changed spark plugs (again...)
Triple checked firing order
Double checked fuel injector plugs to make sure they were on the right injectors
Replaced fuel/water filter (drained in to clear glass absolutely no water or debris in it, although it probably only had about 12 hours on it)
Put injector cleaner in the gas tank
Felt bottom for growth (almost none it's pretty clean/smooth)
Replaced PCV Valve
Changed oil and filter with OEM checked level to be sure we're right at the right level
Ran the following tests with spark arrestor off and boat "hood" up so air could get in there without issue

I also hooked up a fuel pressor gauge to the fuel rail. At idle it's nice and still at around 38PSI, when you get on it it doesn't dip lower than that and at WOT 3100RPM it is around 40-42 with a light flutter here and there but overall pretty stable and returns back to 38psi at idle without any drastic spikes or drops.

Then I hooked a vacuum gauge up to the intake manifold T'd it in. At idle it pulls vacuum down to around 13. If you rev it in neutral it will go up to around 5, then to around 22ish and then settle back down at around 13. With idling it up to maybe 1500RPM it will stay around 18-20. At WOT under load moving it will go to around 3 to 0 and then settle back down around 13 when you go to idle. It also is nice and static and stays at 13 when idling no fluttering and no slow drop or gain while idling.

I'm not sure if these results are good, I think maybe the rings are a little worn (motor has a decent amount of hours on it, the boat has 7XX and not sure if it's the original block but probably) and that's why I'm not getting 18-20inches at idle. Also not sure what the spec should be on fuel pressure, just know that if the numbers are good it was acting as it should.

I'm waiting on Rinda to send back my scanner that needed a new screen repair. The dash beeper beeps when I turn the key to on, so if that's the same alarm that would go off if it's in guardian mode for some reason then it's not sounding. Will report back with codes when I get scanner back but time is of the essence so I'm open to other ideas while waiting.

Thanks,
Ryan

 

[IM Buddy8]

Problem solved in case anyone else runs into this. I rescheduled valve lash and timing for the third time. Noticed prop had some barnacles on it but the boat itself was relatively clean. What do you know cleaning the props and outdrive with a scraper in the water and it planes as it should now. Can’t believe just 3 weeks of sitting causes so much growth that it couldn’t get on plane... can get 4250 rpms out of it now.

Thanks for your input and suggestions.

 

[QBhoy]

Hi

good it’s running better. How are you doing the timing here. It’s just a case of lining up the distributor between the two lines and that’s it.

You are also way short of the rpm range too. You need to be between 4600-5000 and preferably nearer the top I’ve found, on these engines.