Unless you just changed your plugs i would buy a set to replace them. Put someone on watch and do a throttle chop in the middle of the lake and replace one or two easy to get to plugs with the new ones, if stuff turns sideways and your drifting on the rocks I would fire the boat up for a secondor two . Make sure you number where they came from , this will give you some insight even though its only 1/8th of the cylinders. If there is something major going on you'll have a better chance to see an abnormality when you replace them all, don't forget to number them.

I wouldnt go messing with fuel pressure unless you have an O2 sensor. A tweak here or there on one end is messing up the other end and you wont be able to wing it at a recommended 40 PSI and get excellent results. However, with the age and model, you might want to take the injectors off and have them flowed and cleaned. Some cool fuel units throw paint chips into the fuel rail.

Does your boat have the stock fuel pump and fuel regulator?
Were you ever able to attain the speeds the old owner got? Are you sure you got the same prop? When I got my boat it ran 73 on trial, upon arrival, 64 becasue the seller took the labbed props off and threw a used set of bravos on. Just sayin...

Change plugs Plugs, see what they look like.
Wires - stock wires on a 496 last to a long long time but you can change them

CarNuts,

Drifting is not what spooks me. I have an anchor It's the sudden thrust dump when I kill the engine at high throttle and what the boat will do. I've just never done that. I guess I can always try just a throttle dump and see what happens. I've just seen boats swerve pretty hard when the engine dies or whatever.

I also think a new set of plugs might be in order, just because I'm sure they are fouled after all the overly rich run time.

Thanks. Brad.
(937)545-8991

Keith,

I think we've worked out the fuel pressure for now. I'm hoping/expecting the fuel pressure to return to the recommended 62-65 psi when we get the boost back up to normal.

As I stated in the opening post, I'm fairly certain the 71MPH on the TattleTale is honest. We got a solid 67-68 out of it with 4-5 people and a half tank when we first got it, and I'm sure that 71MPH was with a minimally loaded boat. As for any midnight parts swaps, we did the sea trial, exchanged funds and rolled away with it. No chance for any shenanigans there.

To be honest, I don't know for sure whether it's a stock fuel pump and/or regulator or not. I guess, since the ProCharger was a factory build/install from PQ, and it's run as expected until now, I'd assumed that all the appropriate parts were installed when the ProCharger went in. I will get a closer look at it and get some pics if I'm not sure.

Thanks. Brad.
(937)545-8991

Just curious if anyone thinks new plugs will get the lost 3lbs of boost back?

UnderPsi,

Not sure if this was supposed to help, or where you're going with this, but, no... Nobody, including me, thinks changing plugs is supposed to recover the lost boost. I am in the process of installing a new blower belt and possible new idler tensioner. Trying to cover all bases, I am planning to install new plugs when I pull the old ones for reading burn patterns.

Thanks. Brad.
(937)545-8991

Guys,

I need a little help. With the ECM having been sent to Whipple for the stage 2 tune, I spoke with Dennis and he sent me their "Custom Calibration Test Results" form to fill out that will help them determine if any tweaks need to be made to the tune. Problem is, I'm a little confused as to how to fill it out. Obviously, I know what the RPM column is for, but the graph has me puzzled. I'm hoping some on here might be familiar with it, as I can't upload the PDF.

Any help would be appreciated.

Thanks. Brad.
(937)545-8991

If the boat ran fine before, then the ECM should not need to be touched and should not be recalibrated until the root of the problem is found.

FYI, Chopping the throttle back and turning off the engine is really no different than coming off plane normally.

Griff,

Completely agree on the ECM. My only interest is in the potential that I might have indicated a 5lb boost system to Whipple, on my tune request form, instead of the 3lb that the ProCharger kit I’ve got actually is, just as I did in my initial post. I can’t remember if I was thinking wrong then as I did here. I just wanted to be sure. In the meantime, I am, in fact, working to resolve the core issue.

I don’t think I’m going to have to change the idler pulley tensioner. I just tried changing the belt, and couldn’t get the tensioner off the belt enough to even come close to getting it off the pulley. That mother is STRONG. Now my only concern is the pulley itself. I’m wondering it it’s not what caused the wear groove on the non-working side of the belt. I’ve checked and rechecked. Nothing else is touching the non-grooved side of the belt. I need to get a longer breaker bar and enlist a second set of hands.

So…. No violent lurch, swerve or attempt to roll should be expected when/if I kill the key at throttle? I’m assuming the prop will free-spin with the oncoming water?

Thanks. Brad.
(937)545-8991

Guys,

Got the belt changed. Had to make a cheater bar for the breaker bar, and had my nephew hold the tensioner off the belt while I changed it. Only dropped the breaker bar into the bilge once.




It certainly looks like something was rubbing on the outside of the belt, but I'm positive there wasn't. This doesn't mean there wasn't something rubbing on it in the past, before we bought the boat.

This doesn't look like a ton of wear on the belt, but I don't really know what to look for. There is some glazing in the valleys, at the bottom of the Vs, so that could be an indicator that the Vs themselves were worn to that point. The new belt was considerably tighter getting back on the pulleys. The old one came off with the tensioner still pulled back. Getting the new one on required relaxing the tensioner, getting the belt over the rims of the pulleys AND over the tensioner, then pushing the belt to the side, pulling the tensioner, working the belt around it, then releasing the tensioner while ensuring the belt was still between the rims of the pulleys.

Next comes the compression test. I picked up a remote starter switch. Now I gotta find the starter...... God, that's gonna be a PITFA......😡

Thanks. Brad.
(937)545-8991