320 EFI matted to a Alpha One drive
 

Hi there, new to the boating world..just bought a very solid 88 larson senza with a 320 EFI matted to a Alpha one drive. I took it out last week for a water test and it ran out great. My one conern was there was a slight rev studder at WOT. This happened several times in a row. The present boat owner is a licenced mechanic and said he would make it right. My fear is this sounds like it might be ECU related? I have been reading much on this forum regarding the 320 EFI but nothing that touches this issue. Can someone advise if this boat is just a big problem waiting to happen or if it should be a good one. Any suggestions on where to start to solve this problem is apprecaited. I love the boat but have 30 days to return it, if I need to..

what kind of money are we talking to fix a ECU for this motor?

thanks

Re: 320 EFI matted to a Alpha One drive
 

what do you mean by slight rev studder?????????

Re: 320 EFI matted to a Alpha One drive
 

how may rpm's is the tach showing at WOT ??

Jim

Re: 320 EFI matted to a Alpha One drive
 

Does the boat slow down, shudder and shake, what is the WOT fuel pressure should be around 40-43#.. need the 411...

Re: 320 EFI matted to a Alpha One drive
 

sorry guys this is all new to me, what I can tell you is the studder only happens at full out..RPM's are around 5000 it sorta feels like someone pulls back on the throttle for an instant, and each time it happened I too pulled back on the throttle just after it happened..

Re: 320 EFI matted to a Alpha One drive
 

Sonic I have read most of your history with these 320 efi - if you could do it again with something differnt would you?

you asked if the boat slowed, shakes and shudder? yes alittle bit, the boat defineately slowed briefly but I pulled it back to fast to experience the shake or shudder.

Re: 320 EFI matted to a Alpha One drive
 

Are you sure its not a rev limiter kicking in?????????????

Re: 320 EFI matted to a Alpha One drive
 

Is it this engine in this thread??????

http://www.offshoreonly.com/forums/s...hlight=320+efi

Re: 320 EFI matted to a Alpha One drive
 

I had one of those engines in a 20' Donzi Minx.
The intake rotted through so had to go with a carb.
Be careful, they are cool, but everyone seems to have the same story... :(

Re: 320 EFI matted to a Alpha One drive
 

I will check on the Rev Limiter...thank you..Have you guys heard of any trouble having this type of hp's matted to a Alpha one drive? seems like too much..any suggestions

Re: 320 EFI matted to a Alpha One drive
 

320HP/350 small block on an alpha is fine if the drive is in good shape... :cool:
Merc still sells the 300HP/350 hooked to an alpha today... :drink:

Re: 320 EFI matted to a Alpha One drive
 

Thats a tough call as far as doing something differnt, I don't know. On one hand they are very unique (read cool), most people have not seen them before, and when they run they run well. However the lame ass stock engines I put in are so reliable that I have had the best season of boating since I've owned the boat. All in all I'm a gearhead (glutton for punishment) so most likely I'll rebuild and DYNO them before they go back in this time so I can be SURE they will run correctly and not have to spend any precious boating time tinkering (at least on the motors). :D

First thing I would do on yours is to go back to basics, change cap,rotor,plugs,wires, fuel filter...just a good tune up.
Make sure your tach is accurate the built in rev limit is 5600 rpm. BE SURE to check fuel pressure @ WOT (lost one to this). You can get a good EFI fuel pressure tester at NAPA, it will screw onto the schrader valve on the fuel rail/bypass block and it has a rubber hose so it will quell the pressure pulses from the fuel rails. You need two people to do this while running, one to sit and watch the guage and one to drive. Do not leave guage on all the time just run your tests and remove it.
Good luck

Re: 320 EFI matted to a Alpha One drive
 

I have read much about the rev limiter...since Griffs suggestion ( thanks ), it really sounds like this might be what I'm experiencing. Is it the Mirage prop that is causing the boat to hit the red line at WOT? I cant believe it would be set up so I cant put the throttle all the way without it hitting the rev limiter. I am putting all new gauges into the boat and hope this will give me an accurate RPM reading after which point I will know exactly what RPM it is kicking off at.

Any suggestion on what I should be doing to correct this REV Limiter problem?

BTW I love this boat and I dont even have it in the water yet..lol

Re: 320 EFI matted to a Alpha One drive
 

If it is the prop, ask the owner if it was changed to a lower pitch. If the they used the boat for skiing, tubing, etc they may have changed props so it pulls better.
Either way we still need to know at what RPM this is happening.

Re: 320 EFI matted to a Alpha One drive
 

Check the props for some numbers, I could pull 5500 with 14 3/4 X 21 pitch Mirages.

Re: 320 EFI matted to a Alpha One drive
 

My first thought is rev limiter as well,,,, dont trust the tach to be acurate.

if its consistant ,,, thats probably what it is.

See if you can get your hands on a larger prop just to check.

Re: 320 EFI matted to a Alpha One drive
 

When I first bought my boat I had this happen - I never got a chance to figure out what it was because the motor (302 EFI) blew on me. My orignal engine LOOKED clean but once i took it apart it was in horrible condition. My problem was not a limiter issue, I was only hitting 4200 RPM at WOT.

I would have someone else look over the boat (besides the guy you bought it from) to let you know what kind of condition it's really in. If you have to spend a couple hundred to have it done its worth it in the long run.

Re: 320 EFI matted to a Alpha One drive
 

OK the boat was finally put on the Dyno last night and it is the REV limiter thats engaging to early...So now I need to get my hands on a new ECU for this boat??

any body have one available anywhere?

thanks

Jeff