Little high
32-34 at idle@ sea level, you may have to fine tune for your altitude. After make sure you do a WOT plug reading.

 

At 3500 ft would it be less?

 

I would say too high if you have a vacumn/boost reference that turns it up when you go into boost. If you dont have a reference and the fuel is controlled strictly by the computer you may need the high pressure to have enough pressure at WOT. I believe im at about 50psi all the time, but dont quote me on that I didnt tune it. Im sure it has an adjustable regulator and they can turn it down at idle to see if it solves the problem. This is a boat youre looking to buy right? I think the dealer needs to take it to someone who knows what theyre doing on a blower motor.

 

Ya, this is the same boat. I gave him tyle crocketts phone number to call to help him with the boat. I hope he called him. He also said that the pressure does climb when it gos into boost. Can too much pressure cause the plugs to foul? This mpi stuff is a little new to me. This is probably a stupid question, but would more pressure force too much fuel trough the injectors?

 

Ive learned a lot about EFI since I bought this boat this year so im going say what I "think" for what its worth and id like to hear someone correct me if im wrong. There are two ways to set up fuel pressure correctly with a blower. First is with a boost/vacumn reference. You set the pressure at a certain amount at idle and as you go into boost it will kick up the pressure. The other way is to keep the pressure high all the time and have a fuel line dump the excess fuel back into the tank. With this set up you need a different MAP sensor called a 2bar MAP sensor that reads boost and vacumn so when you go into boost the MAP sensor tells the ECM to give it the extra fuel and the pressure is already there. I "think" if you buy a procharger the only thing they do is tell you to put there fuel pressure regulator on and crank it up. This would lead it to be rich at idle and probably still be lean at WOT. I dont think on a stock setup fuel is dumped back into the tank so the extra fuel pressure is what makes it rich at idle. I do notice on my boat when I turn the ignition key on the fuel pump kicks on and builds pressure for a few seconds, as soon as the pump stops the pressure drops back to zero because the fuel has gone back to the tank. This way the injectors only use what they need instead of having all that pressure all the time.
This is how I understand it but I learn more every day about this stuff mostly from this site so would anybody like to correct me?????

If they want to sell the boat they have to figure out the problem. I think you said a leakdown and compression test are good so maybe you can get the deal of a lifetime on the boat the way it is and bring it to Tyler to tune......if the price is right of course.

 

Again, thanks dagah2x. This is very frustrating to be trying to help the dealership figure out whats wrong with the boat I want to buy. The guys at the dealership are great guys and are doing all in there power to fix it, but i think your right it my be more than they can pinpoint. I have thought of offering less "as is" but i am scared that it might be something more serious and i would be stuck with i high priced row boat. :confused1

 

Hi Boatnutt,
I have a natural asperated 540 w/ holley mpi fuel injection and run approx. 50psi all of the time. I was told by holley to check the plugs at different rpms(idle, mid, wot) and if all are the same you can adjust fuel pressure for fine tuning. I will have to get my manual out to give you pressure numbers but they said if it is lean accross the board to increase the fuel pressure by like 4 or 5 psi to gain a certain % of increased lbs/hour of fuel delivery and apposite for dropping the pressure. If I am very far off i am going to take it to Tyler Crocket, but if close I will probably play a little with it myself. I am not going to mess with it myself if it is not the same all accross the rpm band. Hope this helps. If you need more specifics with pressure/lbs per hour of fuel let me know and i will look in my manual. If Holley is the same or close to the merc mpi.
Rod

 

Interesting 23 concept, the boat i am looking at has stock injectors. I wonder if they are not as pressure friendly than the holleys or the high flow injectors. The boat now is set at 45 psi and has a boost valve that cranks it up from there when the motor gos into boost. Not sure at 6psi of boost were it tops out on the fuel pressure, but i am sure its over 50psi.

 

Hey Boatnutt,
I am not sure how close they would be to each other. How many horse power is that 502? Mine is around 560+Hp. I could very well be wrong but as long as you are not running lean on the big end I would think they could fine tune the fuel pressure to lean your idle out a bit. As long as it picks up when the power comes on to feed the engine. I think my injectors are 46 lbs/hour. If you would like I can confirm that. I am not really sure of the difference with a blower motor, but my holley manual specifys different injector sizes to match the horse power. Like I mentioned if you would like me to check those numbers out in the manual I will, and maybe you could check those with the horse power the 502 is making. Maybe someone oversized the injectors, or messed with the fuel pressure. My fuel pressure regulator is adjustable, and is maxed around 52psi. I assume yours is also adjustable. Just my .02
Rod

 

I don't know about your setup but I know a little about injectors in other boost applications (motorcycles). If you are pushing your injectors to their limit (duty cycle) they can start doing all kinds of weird things that don't make sense. Find out if your injectors can support your horsepower for starters.

 

Hi, does anyone know were the fuel pressure should be set on a procharged 502? Now the pressure is at 45 at idle. Is that too much? keeps fouling plugs. Are having the injectors checked now, but could excessive pressure cause the nossles to squirt too much gas? Hmmmm, anyone?

The fuel pressure your going to run at idle and off boost depends on how ecu is programmed. I can tell you when I first put together my first blower motor in 2001 it was a 2000 502 mpi with a m3sc procharger. I had the ecu re-done for top end but at idle the computer program was stock. Procharger reccomended running 35 psi at idle and when not in boost,set timing down from 10 degrees at idle to 4 degrees,run cold, non-projected tip plugs and higher octane gas. Even at 35 psi My boat was a pig and would load up around the dock and in no-wake zones,I ended up backing pressure down like roccard mentioned to about 30 psi at dead idle and just the slight voltage increase when you brought it up to 1000 rpm's it would run 32-33 psi. I ended up giving it a few more degrees of timing then reccomended plus added a msd box and ran ac 43 plugs vs the 42's they said you should run. Most likely this is what you are facing also. Sometimes if crockett or someone does a real serious re-map on the ecu they will re-set the fuel tables all the way from idle up to work at a higher pressure but I doubt this has been done in your case. If your idling at 45 psi and it needs to be 32-35 your motor will definately load right up and completely foul out the spark plugs because as fuel pressure goes up your injector flow rating goes way up too. Now I think what I'm telling you holds true on the 98 up 502 mpi's with mefi3 ecu's and 42/43 lb factory injectors,if yours happens to be older and has the smaller 37lb injectors it may need more fuel pressure as the mefi 1's and 2's (before cool fuel) ran a higher fuel pressure in stock form. What year is the motor your looking at? If its a marina they should already know this but the early efi 502's that had the crappy VST on the back of the motor near the efi upper plenum instead of the cool fuel ,the have ALOT of problems with floats sticking and diaphrams leaking,the extra fuel (I think) is dumped to #8 cylinder. To identify if you have a older mefi1 or 2 , look for a screwy fuel exspansion tank with fuel lines going to it on the back of intake manifold near the distributer. Those motors also have a belt driven mechanical fuel pump that boost the fuel up to the vst tank that the electric pump pulls from. If you are dealing with a newer mefi3 mpi than most likely lowering base idle pressure to around 32-35 will clean this motor right up along with a set of plugs and a immediate oil change to get all the gassed up oil out of the motor to prevent internal damage. If you do buy it and are playing with fuel pressure just be careful when you first start driving it,listen very carefully for lean mis-fire in case you need more fuel pressure,READ your plugs. I went thru a 1/2 dozen sets of sparkplugs until I got my fuel pressure/idle cleaned up then it would go a season at a time on plugs,Smitty

 

If you are looking at buying this boat I'd highly recommend having a leak down test done to make sure the engine is healthy. Then negotiate into the deal having it tuned/remapped by someone like Tyler Crockett. The fuel pressure was probably set that high to keep it rich enough at WOT. If you lower it to clean up the idle, it also leans out the top end. Spend the money up front to get it done right.

 

Re: Re: fuel pressure on a procharged 502?

The fuel pressure your going to run at idle and off boost depends on how ecu is programmed. I can tell you when I first put together my first blower motor in 2001 it was a 2000 502 mpi with a m3sc procharger. I had the ecu re-done for top end but at idle the computer program was stock. Procharger reccomended running 35 psi at idle and when not in boost,set timing down from 10 degrees at idle to 4 degrees,run cold, non-projected tip plugs and higher octane gas. Even at 35 psi My boat was a pig and would load up around the dock and in no-wake zones,I ended up backing pressure down like roccard mentioned to about 30 psi at dead idle and just the slight voltage increase when you brought it up to 1000 rpm's it would run 32-33 psi. I ended up giving it a few more degrees of timing then reccomended plus added a msd box and ran ac 43 plugs vs the 42's they said you should run. Most likely this is what you are facing also. Sometimes if crockett or someone does a real serious re-map on the ecu they will re-set the fuel tables all the way from idle up to work at a higher pressure but I doubt this has been done in your case. If your idling at 45 psi and it needs to be 32-35 your motor will definately load right up and completely foul out the spark plugs because as fuel pressure goes up your injector flow rating goes way up too. Now I think what I'm telling you holds true on the 98 up 502 mpi's with mefi3 ecu's and 42/43 lb factory injectors,if yours happens to be older and has the smaller 37lb injectors it may need more fuel pressure as the mefi 1's and 2's (before cool fuel) ran a higher fuel pressure in stock form. What year is the motor your looking at? If its a marina they should already know this but the early efi 502's that had the crappy VST on the back of the motor near the efi upper plenum instead of the cool fuel ,the have ALOT of problems with floats sticking and diaphrams leaking,the extra fuel (I think) is dumped to #8 cylinder. To identify if you have a older mefi1 or 2 , look for a screwy fuel exspansion tank with fuel lines going to it on the back of intake manifold near the distributer. Those motors also have a belt driven mechanical fuel pump that boost the fuel up to the vst tank that the electric pump pulls from. If you are dealing with a newer mefi3 mpi than most likely lowering base idle pressure to around 32-35 will clean this motor right up along with a set of plugs and a immediate oil change to get all the gassed up oil out of the motor to prevent internal damage. If you do buy it and are playing with fuel pressure just be careful when you first start driving it,listen very carefully for lean mis-fire in case you need more fuel pressure,READ your plugs. I went thru a 1/2 dozen sets of sparkplugs until I got my fuel pressure/idle cleaned up then it would go a season at a time on plugs,Smitty

That there is good chit.

 

Re: Re: Re: fuel pressure on a procharged 502?

That there is good chit.

Yep, Smitty is the man!

 

excellent, info guys thanks!!!!!!!

 

hey guys, the boat i am looking at is a 98. Would that have a mefi 3?

 

hey guys, the boat i am looking at is a 98. Would that have a mefi 3?

I'm not 100% sure but I can tell you if its a mefi3 the intake plenum will look identical to the one in the pic I posted and there will be a small rubber/nylon braided fuel hose going from the center of the injector rail down to a plastic covered cool-fuel module on the right hand side of the motor as you face it down near the motor mount . One other thing about the fuel pressure,the 30-35 I'm saying it should run is going to be at idle and light throttle,when you start getting into boost it should go up to 60-70 psi,the fuel regulator needs to be boost referenced to do this. If the fuel pressure DOESN'T go up under boost you will detonate the motor,good luck and as was mentioned a leakdown test would be a VERY good idea in case someone ran it so rich the rings got ate up or at some point burn't the valves,Smitty

 

Not only is programming important, but the rigging is too. As Smitty is eluding too.

ATI's installation intructions and rigging instructions are typically not the best way of doing things, if correct at all.

Having someone who has installed these a bunch of times is whom should be looking at it. They will know what works and what doesn't work to get these to perform correctly. Seriously.

Someone that sells them but has never installed a few, will not know.

BTW: I'm speaking of installing same system on same generation + specific engine, not a ATI system in general. Every system has it's own quirks and such.

I remember running 38-40psi in mine. WOT was at 60psi or so. If I turned up PSI to 45 idle would be real rich but top end would be faster. I ended running an ignition box because the 45psi would foul plugs. I had the GEN V 502 with extrnal mech pump. MEFI III.

Back then, there really wasn't a whole lot of programmers that I new of.

 

Smitty, not to hijack this thread but what type of breather system are you running on there? It looks like just a pop on breather on the left bank, is it the same on the right? Do you get any oil mist from them? I ask because I have a push-in breather filters and I get an oil mist from them, not a lot but enough to make a mess and smell after a high speed pass. I was thinking about either mounting the filters remotely somehow of getting a puke tank. Ive heard the puke tanks filters dont breathe enough though. Any ideas?

 

Smitty, not to hijack this thread but what type of breather system are you running on there? It looks like just a pop on breather on the left bank, is it the same on the right? Do you get any oil mist from them? I ask because I have a push-in breather filters and I get an oil mist from them, not a lot but enough to make a mess and smell after a high speed pass. I was thinking about either mounting the filters remotely somehow of getting a puke tank. Ive heard the puke tanks filters dont breathe enough though. Any ideas?

I had oil mist/blowby problems on my 502 too,when I built it again and built my 540 using the same valve covers I used conduit nuts for 1" conduit and 1" pipe about 10 inches tall with 1 1/2 circle track breathers PLUS zero gap rings,no oil mist at all,Smitty

 

pics won't load for some reason

 

Question. What is the difference in price between a Pro Charger or any Turbo and a Whipple. Looking at pics of both, I think the Whipple is a much more cleaner installation.. Not trying to stir the pot..

 

I had oil mist/blowby problems on my 502 too,when I built it again and built my 540 using the same valve covers I used conduit nuts for 1" conduit and 1" pipe about 10 inches tall with 1 1/2 circle track breathers PLUS zero gap rings,no oil mist at all,Smitty

Thanks, thats what I was thinking too just raising them up and using a clamp-on. :winker:

RJ, I think the prices are similar, the whipple may be a bit more. I dont know for sure cause like yours it came with the boat. The procharger seems to be a great system if set up properly, as good or better then the whipple but I think the whipple is cleaner looking too. The prochargers boost comes on smoother and its suppose to be better on the drives plus the oiling system is self contained so theres no oil lines.
....Come on now show us a pic of the whipple.....

 

Daga,lets see if the pics will load now,you can see the tube (minus breather) in the left hand corner of the pic.

 

heres another,you can see the tube with the breather near the blower intake. I used a close 1" nipple,threaded the original breather hole invalve cover with a 1" pipe tap,used a coupling on top,nipple thru v.c with a conduit jamb nut inside cover. I also ended up using a couple off set conduit fittings to gain clearence arounsd stuff. When I was done I crinkle painted it all and it barely looks cobbled to a normal person,Smitty