Hi guys,

I have a 2005 Sea Ray signature bowrider with a 5.0 MPI and Alpha drive. The engine has only 240 hours, one third on idle and almost no WOT time. I have it at a shop in SFL that have been good to me before. Has been run in saltwater but it is a clean boat.

They have tested compression, 165-170 all over. Replaced coil pack, wires, spark plugs, fuel filter, oil, oil filter. No fault codes in the computer. Last thing was that they pulled the drive to check for debris in the exhaust, but nothing there.

The symptoms is that it runs really good up to 2500 rpm, them it just wont rev anymore. It starts to misfire, and I cant get the rpm any higher. The shop says it sounds like it runs lumpy when running it on the hose, but in the water it runs perfect to me.

I am stumped, just fresh out of ideas. The shop likewise. So, question is if any of you guys could help us ut? Looking at it from a fresh perspective?

Any elp would be very appreciated!


Regards.

Johan

looks like a fuel pump problem had a similar problem last year

May also check the fuel pickup and supply line.
pressure and flow are needed to make rpms. Sounds like you are dealing with part changers, not mechanics or technicians.

Agreed!

It's real easy to bust out the parts cannon, but it takes experience and ability to find the root cause. Fixing the problem is easy, finding the cause usually is not.

So.....a couple of things I can suggest....in order.
1: pull the vac line off of the fuel pressure regulator, then the horseshoe shaped keeper. Fuel will spill onto the intake, so stuff a rag under it first. This is located just port of engine center, on the front of the port side fuel rail. Once removed, look at the screen on the internal part......looks like a peace sign. Spray with non-chlorinated brake cleaner and reinstall......even if it looked clean.
2: put a gauge on the fuel rail. The schrader valve (like on a tire) in just behind and to stbd of the regulator. You need to maintain a minimum of 35psi....or you will see that the engine will exhibit every complaint you mentioned above 1k rpm......lower takes longer, higher with a load takes no time at all. Best is to check the pressure while loading the prop.....so in water.....one guy/gal driving, the other diagnosing.
3: if you see a fail in pressure, the problem can be only, and I mean only......a collapsed supply line due to ethanol OR a plugged tank vent, or a bad pump.
If there is no drop, it can only point to water in the fuel, or clogged injectors.

If the tps, cps or another sensor were failing, the guys you are using would be able to see it with their scan software. If they aren't using rinda/diacom/merc scan.......run away. They are competent only to the extent of oil changes and that may be questionable.

All good points listed above so check them out and you did not mention anything about the distrib cap and rotor being change out. These caps can be problems cross firing between 5 & 7 even new right out the box.

Also if this distrib has been rotated or pulled out, it all has to be properly phased including the rotor, ECM 555 is non adjustable timing but the distributor and rotor have to be clocked / phased properly. I have seen the distributor hold down bolt slight loose and techs while work on the motor side will accidently grab the distributor rotating it slightly not knowing causing sometimes this exact problem you are having,.

Hi guys,

Thought I should let you know how this was sorted! I missed out a few things above; the fuel pressure was checked, and the caps and rotor was replaced. Basically they checked all the normal stuff, replaced all the usual suspects and then started to look at other things, like blocked exhaust and such longshots.

It turned out to be the distributor, as BUP suggested above. The shop moved it just 1/16th of an inch, while running it in the water, and all of a sudden it revved 4600 rpm's! But, they could not get it running on the hose or even backed down the ramp on the trailer. It needed to be driven in the water.

Maybe this info could help someone save some money.

So I am a very happy man now. I got a lot of things replaced for a very fair price.

I just feel bad for the PO who sold it cheap because some fraudulent mechanic told him the engine was shot and needed replacement....

Thanks all for your help!


Regards,

Joham

Thanks for the update and your time coming back up here to let everyone know the fix. I have seen this problem a lot with rotor / distributor phasing in correct or it was moved. I hope you gave them the info that I provided to help save you some labor costs thru them as it was your complete fix. Good luck with your boat. thanks again for the follow up. I think we all like to keep track of the complete fix that gets everyone back out on the water.

Also it does not take much movement at all for the HVS distributors to be moved out their properly phased position to cause poor running conditions.

I can not believe that someone told the old owner the engine was shot. Jeepers.