thetridoc

I need some help. I just purchased a 2006 Baja 35 OL with 496 HO’s in it. The boat has 175 hours on it. I bought it out of state and started by having a compression test done. The compression tests were good on both motors. During the tests, the broker suggested to the owner to put new plugs in, which he agreed to. I then went to the boat and checked it out and the broker took me on a ride. The ride was relatively brief, but the motors ran fine. We didn’t take it to wide open, but more to cruising speed. No issues noted, I bought the boat. I took delivery on Friday, which was 3 weeks later. I got the boat home and ran it out on Saturday. The boat runs good, but won’t get above 4100 rpms on either engine. I first thought it was propped wrong. The boat appears very original and I thought the props were factory when I looked at it. On Sunday I drove it again and realized, not only is it running 4000-4100 rpms, it is only running 51 mph wide open. The boat should run 70 mph +. I played with the drives and trim tabs, but cannot get it above 4100. I can drop the motors down to 3000 and get the other motor to rev about 4-500 rpm higher. Both motors will do this, but do not go higher than 4100. The boat is in the water and I can’t see the props, but they do not have damage. The boat has good compression (160 +/- 3 across the board), new plugs and no miss while running. Searches on the web discuss possible plugs, fuel filters, tps sensor and map sensor issues. Any thoughts ideas would be greatly appreciated. I have no info from the prior owner as I dealt with a broker, but the boat is a one owner, in great shape and nothing appears out of place.

Sydwayz

iTrader: (1)

1) Must know the make, pitch, & number of blades of the props before we can tell you anything. It's possible that someone swapped out the props without you, the broker, or the owner noticing. It's stamped on the props.
2) In the mean time, make sure all of the plug wires are firmly connected, and undamaged.
3) Order yourself a scanner from www.rinda.com . I know you don't want to spend $500 on a boat you just bought, but trust me it will be God-send one day. It will allow you check the full health of your engines at any time, on your schedule, not a busy marina's in the height of prime boating season.

NightHawk

70 plus mph in a 35 foot baja with two stock 496s sounds optimistic.

BUP

iTrader: (9)

1. scan both engines and the number one thing to look at is available power % if both engines show 100 % then you are not in guardian mode.

Next if both engines show less than 100 % available power then you need to dig into the scan to see what the cause is and at what rpm the problem(s) happened. Faults and history are the places to look at, also look on the scan if the rpms match the tach's ???? I see some tachs way off the mark compared to the scan. Analog tachs that is. Not all but more than you would think.

Next is does your throttle plate open 100 % fully for both engines ???

next do you have the correct DRIVE RATIO"S for the engines installed and props installed ????

Like Brian said props are they correct ??? or are they rebuilt as some prop repair places are very poor at what they do and have pitch way off. Not uncommon for that to happen. See this once to 3 times a week per boating season - repaired props causing rpms lowered and or planing issues and or decreased performance.

thetridoc

It has 28 pitch props on it. That sounds a little aggressive. Does that sound stock?

blownhammer2000

iTrader: (1)

That sounds like a good place to start, HO's should turn 5-5100, 26's would net you about 3-400 rpm, which is still below your recommended wot range, can you find some 24's? I'm guessing your running bravo props, turning athe 28's at 5k would mean that boat would run near 80, which unfortunately is not realistic on a 35 outlaw with HO's

thetridoc

After researching it, the 28's were the stock props. I have a mechanic coming out this weekend to put a Rinda on it.

thetridoc

Update: I cleaned the hull, as the bottom was very dirty/gummed up with the previous lake residue on it and filled it up with fresh gas. The boat ran 64 mph at 4400 rpms (full tank of gas and 8 adults), which is a 13 mph increase over last week. I had a mechanic coming out, but now I have a motor heating up, kicking the alarm, so I am going to change the impellers prior to letting him take a look.

I can't believe that a clean hull and fresh gas made that kind of difference. I'm wondering now if the fuel was several years old.

thetridoc

Just to follow up and not leave a thread without the final solution, it appears the dirty/gummed up hull was the culprit. I did another run last night with a full tank and 5 adults and was able to hit 67.1 mph on gps. I think 2 adults with 1/2 a tank makes 70 mph possible. It seems crazy that I was limited almost 20 mph on a dirty hull alone. The good news is, it was a $10 fix with some elbow grease! Thanks for everyones help here

Baja Rooster

iTrader: (1)

Dang, what magic spit did you wash it with to get you those gains? and thanks for tidying up the post.

I'm actually serious as I'm chasing a slow boat/high prop slip issue.