Ryanw10

Im leaning towards it being an exhaust shutter restricting flow. I think im going to pull the riser off and see what I can find. I also have not replaced the ignition coil yet, so im going to do that as well. Everything else in the ignition system is new.

Ryanw10

I still haven't been able to get this figured out. Also, just noticed in my original post that I said the boat was a 1997, when in fact it is a 1999.
I pulled the riser off the starboard side and found that the exhaust flappers were torn off. I got my bore scope in there as far as I could but I did not see anything. Unfortunately this is a slipped boat and does not have a trailer. Otherwise I would be pulling the drive off to see if I can find the missing flappers. I put the riser back on and also at this time replaced the ignition coil. All ignition components are new now, and were still not getting the power and RPM we should out of the motor. Today I emptied the fuel filter to see if there was any in there and found no signs of water. I think my next step is going to be checking fuel pressure with my gage hooked up where the factory fuel pressure sensor is.

Ryanw10

I took the boat out yesterday to test fuel pressure. The gage pretty much stayed at 39 psi the whole time, no matter how much load on it. While running with the hatch open, it sounded almost like its dropping a cylinder on the top end. When I try to get on plane, it sounds like its running on all 8, and running great for only about a second, then you can immediately hear power getting cut back after that, without pulling back on the throttle. This time I stuggled to get on plane at all and almost would lose speed with the throttle all the way down. Next step I think im going to do is pull all 8 spark plugs again to inspect, and probably do a compression test at this time too, One other thing to note after this run was that the starboard riser is still getting significantly hotter than the port riser. Temp gauge stays at about 190 all the time. Also something to mention, timing is still jumping up to 28 degrees under full throttle, then pretty much immediately dropping to 20 degrees

AllDodge

iTrader: (1)

If your gauge is accurate then 190 is to high.
Loosing power I'm thinking one injector is going lean. Be nice if you had a go-pro or mount the phone above the TB and watch

Ryanw10

I did take a video while running under load of the injectors. From what I could tell the starboard injector was spraying more fuel than the port injector. The starboard riser is the one that is getting hot, not the port.
For the temp, ill have to check next time im at the boat, but the gauge is definitely reading 1 or 2 marks above 175.

Ryanw10

Compression test results:
Cylinder 1: 150
Cylinder 3: 140
Cylinder 5: 145
Cylinder 7: 135
Cylinder 2: 135
Cylinder 4: 135
Cylinder 6: 145
Cylinder 8: 135

Spark plugs looked rich, with cylinders 1 & 2 pretty much fouled out. The starboard side plugs all looked richer than the port side plugs, which makes sense from what I could see the injectors pushing out. The port side injector looked like it was putting out less fuel than the starboard in my video.

Left to right: Cylinder 2, 4, 6, 8


Left to right: Cylinder 7, 5, 3, 1


Top to bottom: Cylinder 8, 6, 4, 2


Top to bottom:
Cylinder 7, 5, 3, 1

AllDodge

iTrader: (1)

Your pressure should be 30 psi from manual 24
Running at 39 will make the motor rich. Look at the regulator and see if it has a Pink ring where the vacuum line connects to it. If its Blue its a 43 psi Reg

DrFeelgood

The 43psi regs on my 502s had neon green rings, FWIW.

Ryanw10

Thank you for the information, I will check to see which regulator I have. Here is the link to the one that is in there, looks like its maybe for the MPI motors and not TBI?
Also another thing to note, the temp gauge on the dash is definitely reading 190, maybe even closer to 200. But when it gets up to that temp, it stays there and doesnt move. Maybe I have the wrong thermostat in?

SB

iTrader: (1)

As a heads up, your engine uses a 2bbl dual plane intake and an adapter thst also is divided. Because of such, each injector feeds 2 cyl’s on bank 1 and 2 cyl’s on bank 2.

1,7,4,6 fed by pass side injector
2,8,3,5 fed by driver side injector