socalstone

I'm chasing my own tail here. Trying a Shorty to gain a few..... need an external pickup which costs a few.... WTF!!!

Wild Card 09

First of all find out what the water pressure is actually doing. Borrow (or buy - $400) a Rinda Scan Tool. Real easy to use. You can check, and erase all failure codes, and monitor all of the ECU inputs in realtime or at the dock (freezeframe).
Once you see at what point the Guardian is activated at, you know how the ECU is programmed, and may be able to drive around it , or even solve the problem with the prop.
What prop are you running?
Water pressure iincreases with speed. Too little prop, and too much slip means you are getting up to the upper end of the rev range ( and the smartcraft gets pickier the higher you go) before the water speed can shove enough water up the pickup.

Dean confirms what Ron (at Imco) told me, that their lowers mostly produce too much, and not too little pressure. The same motor/drive settup in a 27 Cat would be running 90 mph before it hit 5000 rpm, and there would alot of water pressure.

Longer prop to drop your revs, is my first guess, buddy!

Whipple Charged

If you have smartview, monitor water psi and see what rpm/water psi it goes into guardian. If not, then borrow scan tool like wildcard said, then you can see a freeze shot when it goes into guardian. 2" might be too much for boat, might only need 1" or 1.5".

Thanks,
Dustin

socalstone

Thanks Dustin,
My x is a sickening 7" w/stock xr, so 5" with -2Shorty.
The Imco intake is below the tip of the bullet, so as you start adding trim, the intake "dissappears" from the ram effect.

I do have smartview. The pressure starts at 30psi then drops into the 20's around +4 trim the pressure was down at 25 or less, and guardian kicked in. Fault said "Eng overspeed" but was only at 4800rpm or so.

I could open up the intake more but don't see the issue going away.
The boat needs a lot of trim to run, and right when you start getting there that intake falls away from the leading edge.

socalstone

Thanks Stephen,
I still have the 30B1 which I had labbed at bblades.
It's a little too tall for the boat as it is, but works pretty well.
I was hoping the -2 shorty would help me gain a few hundred rpms with this prop.
Then, I want to try Dustin's mod and see if I could gain more.

After both mods, if I could not get the labbed 30 to 5400+,
I figured I would tweak the 30 again, or try other props from there.

make sense?

Wild Card 09

That makes lotta sense. However, it would be good to try a couple of different props, both four and five blade (I say that as though they are just lying around on the dock!) to see what the settup reacts to. IŽm really surprised with almost every new prop IŽve tried.

Engine overspeed at 4800 doesnŽt make sense, though! My fault manual is in the boat. IŽll check tomorrow.
Low water pressure is the fault you should be seeing, if anything!

socalstone

I wish I wasn't seeing anything!
After reading your post I was thinking maybe something was awry with my systemview or guardian.

But I spoke to Merc today... they said systemview looks at a number of data before throwing a fault. Water pressure, temp, throttle position etc. Overspeed commonly trips first... even though the water pressure dropping below 25psi was the culprit.

First time at around 4600rpm, then after opening up the intake a bit, it gained some rpm but still happened again around +3-4 trim. I could open it up more, but the trim had a ways to go before good speed was found.
With the stock lower and a horrible 7" x, best speeds occur with the trim cranked up to a ridiculous +7 to +8.
I'm concerned that I'll continue to open it up and still have the same issue as you get into positive trim. (where I am sure I will still need to be)
With neutral trim I could spin the prop to 5150 or more and still see great pressure, but of course the speed wasn't there yet.... not even close.

So, I'm still looking at the external p/u.
Just wondering what the next obstacle will be!

pkspx

I have this same exact problem, I'm also looking into external pickup. WOT with my IMCO same thing.

Wild Card 09

That the Smartcraft monitors and relates a number of parameters to each other and then throws an alarm "only" when defined boundaries are crossed sounds good. The combination of say 4800 rpm, full throttle setting and a drop in water pressure trips the alarm.
A freezeframe record of ALL the parameters at the moment that the alarm was triggered, would be good. Can the systemview give you that, or is that a speciality of the Rinda unit?

In what way have you opened up the intake? The upper edge towards the point on the bullet would make sense to me.

@ pkspx, what hull and drive settup do you have? Are you running a 600 as well?

With a problem like this (and because Imco, and Dustin W say that HIGH water pressure is more usually the issue) it is worthwhile making sure that there are no other factors contributing. Impeller, or a loose fitting (causing air to be sucked into the cooling circuit) could cause a problem. Check that the S hose that runs from the drive to the transom is not jammed up between the belows and the gimbal ring.

On my settup, lifting the drive beyond about 6 on the 10 scale of my mechanical indicator is unnecessary ( unless a roostertail is on the programme). As I said, the pressure does drop dramatically when trimming out.

I would stay away from the transom pickup first of all, unless there is no other solution.

socalstone

I'm going to see if I can drill a new hole through the top side of the bullet on the IMCO.... If it is possible without getting into the bearing support areas, that would allow it to take in water when in positive trim mode.

My prop to pad measurement is 7" with the stock lower and 5" with the shorty, so it is still plenty deep!!!

Not sure if it is possible but will take a look this weekend.

I want to wrap this up in the next week or so, do some testing and then try the whipple upgrade....