hauling ass-a

Ihave a 2000 502 mpi, installed new stainless marine exhust, vortec flame arrestor, and arizonia speed ecu and vortec flame arrestor. Here is the questions I changed the fuel pressure from whatever stock was to about 46lbs, and Iam getting water in the rear cylinder, has anyone else changed the pressure when they installed headers???? Ireally think 46lbs is a little much and that the rear cylinder is fouling out then it starts sucking water. Whent on the board before and no one knew what pressure was stock or what to set it to. Call arizona speed and vortec and both say about 46lbs to start and some may need up to 52lbs. If you installed headers and flame arrestor PLEASE let me know if you also had to change the pressure or if you left it stock.

ursus

stock is 43 psi, seems unlikely the change to 46 would foul out a cylinder seems more likely reversion from new headers or a gasket leak etc.

Basically for 30 more hp the engine needs that much more fuel.

liquid asset

Arizona speed and marine told me I was fine just doing the ecu

ursus

Oh I thought they told you to increase fuel preasure to since stock is 43 psi

"Call arizona speed and vortec and both say about 46lbs to start and some may need up to 52lbs"

wildcard

I have the same set up as you do. Stainless marine exhaust, flame arrestors and ecu reprogram.
Arizona speed & marine told me that there should be no need to adjust the fuel pressure in the area I boat in which is 100' above sea level. They told me that at high altitude it is sometimes necessary to increase the fuel pressure. I never installed the regulator, I just verified that I had 43 lbs. on the stock one. I had a surge in speed when I shifted in and out of gear so Jim advised me to set the IAC's to 35 with the boat in gear. This solved the problem. I have never had reversion with stainless marine exhaust. I have installed 9 sets. I capped my Y pipes with 3"pvc plumbing caps and went straight out the transom. I don't know if you have captains call or not, but you could be getting some water sucked up from the Y pipe. I picked up 250 rpm with the add on's and 2.5 MPH. Good Luck

tommy v

have a 31 formula twin 502s did manifolds ecus vortech and regulators im running 50 psi no water you have other problems i gained 8mph on gps

liquid lounge

Tommy V- Your results are stunning to say the least....now you should try the runner extensions and additional programming for another 8 mph gain.

hauling ass-a

I have straight exhust with no silent choice. Really wanted someones elses opinion. Ran the boat the first time and found water in the manifold, pulled the exhust on the one side where I found the water on the plugs, air tested both the riser and manifold, found no problems or leaks! Install the manifold ran the boat for a good hour pulled the plug and found no water. I'm thinking that I fixed the problem. Then I take the boat out this past weekend run the boat about 12 hours in three days pulled the plugs and found water again. Now i'm like what the f*** could this be. The only thing I found and I don't know if this matters is the riser clamp came a little loose? Checked all the bolts, (good) tighten the riser clamp and changed the plugs. Now I ran the boat at idle for about 2hrs (changed the oil 4 times) and found no water. I really appreciate all of your help, I needed to hear from someone else to see how theirs ran with the same set up. Does anyone really think that if the riser clamp came a little loose that it would cause reversion. (not loose enough to wiggle, but not as tight as the other side with no problems) Also have you guys with the same set as me ever tried the ac rapid fire plugs?

tommy v

liquiod lounge where do i get these runner extensions ???email me the info at [email protected]

Drew

Running a 97 502mag MPI with AC rapid fire plugs. No real performance gains noticed as I can tell but it does seem to idle better and help with black transom some.