Some advice for first Maxum owner 97 2700 scr

[JrJ01]

Ok, Boat is performing as I thought it should.. took all the advice, took the weekend.. found out my boat is 1.81, my new drive is 1.81
changed out the outdrive, and there it is.. boat is hitting 35-36 mph and cruising nicely at about 28-30.. rpms at wot with 19p prop about 4500 ( if the tach is correct)
I believe the drive I pulled off the boat was not matched in gear ratio and was not the OEM drive, when I pulled it there were yellow marks on the inside that look like salvage part numbers..

so after a day of running it, its beginning to bog down at the upper rpms..similar to running out of gas.. so, I am thinking to change out the filters and check the fuel lines.. but overall, a huge difference.

I know its not a speed boat, but as long as it gets us around close to where the other boats similar to ours are running I will be ok with it until its time to move up to a 3200
Thanks everyone for helping out on this mystery!

[mmwjr]

Jr, glad you resolved the performance and the new drive payed off.

New issue bogging at high rpms, change filters, pour the old gas from filter into a clear container and let it settle and look for signs of water. Also test fuel pump pressure ~7 psi for mechanical pump and ~30 - 40 for electric pump. Could also be time to rebuild carb if has one else dirty injectors? more data will be needed for better advise but start with the filters and look for water in gas.

[JrJ01]

Thank you Mike! The mechanic that was down there told me the carb needed attention so, this is probably what I am dealing with..I will do the filters today if the rain quits and hopefully get the carb off and to a shop for a rebuild, might just purchase a remanufactured one from national carb, i have had success with them in the past.
will keep you posted!!
Thank you all for your interest on this journey

[mmwjr]

Always a pleasure to help fellow boaters

[JrJ01]

So after a couple of weeks of fun boating...the bogging issue returns.. however briefly, because the Raw Water pump went shortly after and chewed up the fuel pump. There was a little chatter and then it ran terribly at all rpms.. I am wondering if this was going all along. I did replace a few things,
the Carb was old and in need of a rebuild, so I decided to buy a remanufactured marine carb, I replaced the fuel pump, lines and water seperator.. all was running just fine.. and the fuel pump started chattering.. got it back in, took off the fuel pump.. the arm was worn down bad and the cam or bearings on the pump was spinning freely. A little frustrating, but ordered parts, a week or so to get here and I hope that solves this issue for now.

[ss3964spd]

Photos of that would be super, Jr, got some to share?

[mmwjr]

Jr, sounds like this could have been the problem all along. So new fuel pump and new or rebuilding raw water pump that drives the fuel pump. If rebuilding pump did you verify housing is Ok and that play in the bushings did not cause the problem? Pictures of the broken parts will interesting to see.

[JrJ01]

Hi There ! I will take pics when I go back down there.. or when I take the pump off. I ordered the Mercruiser replacement Pump Assembly with fuel pump..
$770 with shipping expedited.. dont want to chance a two week down rather than one.. being that it is now August and the warmer weekends are numbered..

Mike I believe this was the problem for the bogging all along.. however not sure about the rpms and the drive issue? or could it be?
Will that engine make more RPMs if it is trying to get fuel? I was thinking about this today.. is that possible?
Thanks!!

How do I post pics to this forum I dont see a picture option here..

[JrJ01]

Trying to add pics just so I know how.. anyway if this works this is my boat..

[mmwjr]

If the engine is starving for gas then it can't make full power. The drive ratio may still have been an issue, hard to say. At this point just need to install new unit and see how it performs.

[JrJ01]

here is the fuel pump look closely at the end of the arm where it is worn...

[mmwjr]

That is worn. Typically a mechanical fuel pump mounts to the engine block and is lubricated by the engine oil. In you case this vintage of the 7.4 was intended for fuel injection for street use. When mercruiser but a carb on it they need decided to use a mechanical fuel pump and mounted it on the raw water pump. Do you know if this section gets filled with a lubricant? If so I guess you need to maintain it's level to prevent this type of wear again. If not you get what you get.

Anyhow good luck.

[JrJ01]

makes sense Mike.. there was no oil or lubricant in there and not sure where or how it is filled.. probably just stupid on my part.. I will look at the pump and see if there is a fill point but there is/was no lubricant there.. again, probably my stupidity..

[mmwjr]

Wasn't sure myself and did a quick google. There is a plug on the unit to check and fill the oil. Sounds like the pump must be removed to do so. Therefore do this service when changing impeller.

Do you have a picture of the pump housing? Sound have a plug where fuel pump attaches.

[JrJ01]

As I can tell the pump takes mercruiser gear lubricant.. same as the outdrive? anyway must be filled.. when the fuel pump goes it leaks into the housing thinning out the oil? the friction disipates whats in there and kills the bearings.. anyway this is from iboats.com.. so here is the reason for my issue I think.. ignorance on my part, costly too.. anyway is this correct or sound reasonable? I will get pics when I get down there to take it apart.. probably not til the rain stops or the parts are here.. dont want to leave it open..

Here is a post from BoaterEd.com
To replace the lube remove both screws. The bottom screw will have a magnetic tip to attract the metal parts from wear. Once you have it drained put the bottom screw back in place. Fill the pump from the top hole until the oil is even with the top screw hole.

.. apparently it takes 2-3 ounces of gear oil

[mmwjr]

Sounds right to me.

BTY: don't sell yourself short I bet most folks with this same set up don't know about the need to check to ensure there is oil here. Once you get the pictures it might be helpful to other to make a new post letting them know.

[JrJ01]

Thanks Mike!! Yea I will do that when I get the parts in and get it together.. they say by next wednesday I should have them, hoping so, the regatta on the river I dock on is next weekend I think.. would hate to be without my cruiser for the fun..

Also I joined the facebook group a while back and just realised its the same group as here.. or from this site..
I have posted pics of some of the adventures we are having this year there.
Anyway cant thank u enough!

[JrJ01]

[ATTACH][/ATTACH][ATTACH][/ATTACH][ATTACH][/ATTACH]

Here are pics of the bad raw water pump... u have to look in there close but, its completely broke up.. the bearing is split in two pieces.. the boat ran like this but no high rpms.. this also caused it to kill the fuel pump.
So, lesson learned for first time owner of this motor.. that raw water pump has a resevoir screw and needs to checked periodically for gear lubricant.

Installed the new pump, filled it.. boat runs good now.

Stupid question here.. what does the SCR stand for?
Thanks!

[mmwjr]

Glad to here you're running again.

SCR: Sports Cruiser