Baja 272 454 mag EFI RPM issues

I'm chasing down an RPM issue with a fresh rebuild 454 mag EFI in a Baja 272. I've just eliminated the manual fuel pump and the VST and replaced with an external Aeromotive electric fuel pump, adjustable regulator and all new plumbing. My first question is, what do you do with the factory fuel regulator at the end of the fuel rail? Do you leave it in place? I am regulating the fuel on the return side of the fuel rail and returning the fuel back to the tank.

Second question and a little more history; I purchased the boat with a spun bearing so I did not hear the boat running before hand. A complete rebuild was done with some modifications. Cam, H-beam rods, Scat crank, .60 over (due to water laying in one cylinder) .100 dome pistons and everything ballanced. After rebuild it labors around 3k rpm's and tops out at around 3500. I had the ecm reprogrammed to match the modifications but still little to no improvements. Timing set at 8 degrees using a timing tool. I have a constant fuel pressure now of 43 psi. I just sent the injectors out to be reconditioned by Bill Johnson at Mr Injector. (Very nice guy and reasonable) He stated that the injectors were not off enough to create that much of a loss so I can rule out the injectors. The engine idles great and runs good up to 3k rpm's. I'm at my wits end:facepalm: and almost at the point to scrap the EFI and bolt on a carb. Any help would be greatly appreciated at this point.

Re: Baja 272 454 mag EFI RPM issues

Well, I'd be pissed and saying 'nice rebuild' :facepalm:

8 degrees BTDC (right?) . . . I'd like to know more about the cam that was put in . . .

If it is not a fuel delivery issue, which it may not be, swapping over to a carb will still leave you with a problem.

It seems like it is not even reaching the RPM range where you would get maximum HP and Torque. Does the boat get up on plane OK? I know my boat has to get up to about 3200 - 3500 RPM to get up on plane and then can hold it at about 3K.

I'd check the timing and see if changing it a bit gives you any improvement. Also, depending on the cam & timing chain set, I wonder if the timing chain was set to '0' or advanced or retarded settings . . .

Re: Baja 272 454 mag EFI RPM issues

The boat is a little slow reaching plane and only reaches about 45 mph. My thought behind going to carb was also it would eliminate the ECM. But I would prefer to fix the problem with the EFI. I used a Comp Cams Xtreme Marine (Duration @ .050 is 230 for the intake and 236 for exhaust) Valve Lift: .547 for both intake and exhaust. Part# CCA-11-451-8 Comp Cams roller rockers, ajustable rocker kit. The cam was installed at 110 degrees.

Re: Baja 272 454 mag EFI RPM issues

TTT Any other suggestions?

Re: Baja 272 454 mag EFI RPM issues

Did you do your own mechanic work? If so how were the valves set? If they are too tight the engine will not rev up under load.

Move the timing 2 deg at a time and check to see if it affects your rpm.

You need to figure out if the old regulator is affecting the pressure.

If that's not it Id be suspicious of the "tune" in the computer.

Re: Baja 272 454 mag EFI RPM issues

I really dont know what efi system you have but i am very sure you cannot manually time your boat. Without going into a bunch of stuff give these guys a call tell them exactly what you have and what they can do for you. http://www.obd2allinone.com/sc/details.asp?item=mefitune

You will never straightn out that motor without a good tune and those guys are very good.. they can actually tune your boat on the fly if you have a laptop with a wirelss connectio. Who did the tune and do you know what type of system you have aka merc 555 or mefi? not to many can tune either of those system's..very few actually

Is it worth doing yes you can do things with a mefi controller that no carb or std ing sytem could ever do..Set your fuel tables rich for launching..lean them out for cruising and again fatten them for wot...Have a hot cam and rough ilde no problem just advance the timing say from 600- 1200 a few degree's and tighen it back up up above that..its all on the fly and once set and burned your golden. Lots of fun when you start getting a handle on the whole process and its a lot to understand.....Im still lost most the time...

Dunno how much you like to tinker with thing's but this product is very intresting and affordable...but it does not burn a tune it just corrects afr on the run..more of toy but fun and fairly cheap

http://www.dynojetcmd.com/cmd_marine.aspx

Re: Baja 272 454 mag EFI RPM issues

I'm thinking you don't want 8 degrees BTDC. You want 0 in the "service mode".
If your timing is too far advanced the "knock sensor" is getting that signal to the ECM which is holding the WOT. Not like rev limit but just not letting it get up & run.

The knock sensor gets rattled & sends a signal to ECM which then adjusts the timing to where it doesn't knock. Originally they wanted 87oct. run in those engines. It compensated for low octane, thru the KS/ECM.

Re: Baja 272 454 mag EFI RPM issues

Ok, while in the process of eliminations I decided to see if the problem might be in the fuel tank so I disconnected the tank and ran the fuel line from a gallon fuel can to the fuel pump. It sucked down the one gallon in less than a minute at idle! What would cause this?? ECM, even though I had it reprogrammed? I found the rich condition by mistake when I changed the fuel filter and put it on empty which caused a lean condition. It ran great or at least until the filter filled up. Has anyone ever had a bad tune after sending the ECM for a re-tune?

Re: Baja 272 454 mag EFI RPM issues

Large fuel comsumption could have been from not also returning fuel to portable fuel tank. Duh. Still cannot figure rich fuel condition other than a bad ECM tune. Any suggestions?

Re: Baja 272 454 mag EFI RPM issues

Do you have the Merc serial number for your engine. Right now, no body knows what you have. There were several different EFI systems used.

Re: Baja 272 454 mag EFI RPM issues

Baja272 said:

Ok, while in the process of eliminations I decided to see if the problem might be in the fuel tank so I disconnected the tank and ran the fuel line from a gallon fuel can to the fuel pump. It sucked down the one gallon in less than a minute at idle! What would cause this?? ECM, even though I had it reprogrammed? I found the rich condition by mistake when I changed the fuel filter and put it on empty which caused a lean condition. It ran great or at least until the filter filled up. Has anyone ever had a bad tune after sending the ECM for a re-tune?

Click to expand...

That happens more than you would imagine..As Don asked what is the serial number on the engine...there is also a code on your ecm post them both...Who did the tune was it mail order

Re: Baja 272 454 mag EFI RPM issues

Engine serial# OF130452 I'll have to pull the ECM to get that number. I had Total Marine Performance ( totalmarineperformance.com )
do the tune but I think he sent it to someone else. I'm waiting to get that info from him.

Re: Baja 272 454 mag EFI RPM issues

http://www.boatfix.com/merc/Techbk/95/95HGB4.PDF

That should answer you timing question its all preset with efi..cant monkey with it.. your ecm takes over from there with pre plotted curves its all been mapped out and set in stone...Hmm i wonder if they plotted new curve's

These people who changed the tune..did they know you changed the fuel pumps and pressure if not set the pressure back to factory specs. You just cant monkey around with efi as much and in a boat engine..they go boom quite quickly remeber there a high stress engine

http://www.summitracing.com/parts/CCA-11-451-8/ Is that the cam...

Re: Baja 272 454 mag EFI RPM issues

Baja272 said:

Ok, while in the process of eliminations I decided to see if the problem might be in the fuel tank so I disconnected the tank and ran the fuel line from a gallon fuel can to the fuel pump. It sucked down the one gallon in less than a minute at idle! What would cause this?? ECM, even though I had it reprogrammed? I found the rich condition by mistake when I changed the fuel filter and put it on empty which caused a lean condition. It ran great or at least until the filter filled up. Has anyone ever had a bad tune after sending the ECM for a re-tune?

Click to expand...

If i read that right your injectors are stuck open....your fuel pressure is out of sight....Or the tune is well not right. That's fourty gallon's a hour.....

You have a PM..

Re: Baja 272 454 mag EFI RPM issues

Actually the reason for the gallon per minute as someone on another site informed me was that I did not return the fuel to the temporary tank I was using for the test. I believe it is a tune issue.

Re: Baja 272 454 mag EFI RPM issues

Are you sure the tach is right? How are you getting your speed? A 27 footer that planes at all AND only reaches 3500 RPM sends up red flags for me. Prop pitch? Ratio? I just want to do the math.

Re: Baja 272 454 mag EFI RPM issues

I'm not 100% sure of the tach but know enough to know it's not that far off. 45-50 MPH on GPS. 23P / 1.50 ratio. The prop pitch and ratio has nothing to do with the problems, I'm 100% sure of that. Most of the test described above are on a hose and only reaching and flat lining at most 3800 - 4000 rpm's, engine laboring after 3200 and black soot at the exhaust.

Re: Baja 272 454 mag EFI RPM issues

Are you saying this thing won't run past 4000 RPM in Neutral? These numbers all matter. How do you know what file the ECM is flashed to? Stock 454 Mag is only a 385, and if they flashed the 7.4L that's only 310. I would not expect even the 385 to push a 272 much past 50, so personally despite the fact you shouldn't rev that high on muffs almost sounds like you hit the rev limiter. I'd still confirm the tach to get that out of the way. Again, any boat that planes AND maxes at 3500 RPM has me questioning the tach. a 1.5 ratio and a 23P takes some serious horsepower to turn. My .02.

Also, is it 50 MPH on GPS or 45? What RPM exactly at each?

Here's a post for the same with a 310 454:
272 Islander 310 454
OK I bought the boat last fall but I am just getting around to getting thing going. Ran the boat for two weekends now and I have not been able to get the RPM above 4100. 52mph on gps with full tank two adult and two small kids. I am spinning a Bravo 23" 3 blade prop. When I trim the motor excessively I can get more RPM but I loose speed on GPS. The chart from Baja says I have the right prop. But I think I should be getting more RPM out of the motor. Is it possible the RPM gauge is not accurate? Or do I need to try a different prop?

Also I had the local marina (resurface) ie. media blast and paint the outdrive. Not a pretty job. LOTS of pitting and a rattle can finish. Flat Grey What where they thinking? Could this be robbing me of RPM's or just speed?

Thanks

Lt.

And I am finding 415 bhp 502s with a 23P. Something is off here. and I am not convinced it is mechanical Not saying it isn't, but I'd want to confirm things. I wouldn't assume anything.

Re: Baja 272 454 mag EFI RPM issues

Tail_Gunner said:

That happens more than you would imagine..As Don asked what is the serial number on the engine...there is also a code on your ecm post them both...Who did the tune was it mail order

Click to expand...

The ECM model# is 16159919 so that would be a MEFI-1?

Re: Baja 272 454 mag EFI RPM issues

Engine serial# OF130452
ECM model# is 16159919

Any ideas what to try next? I'm still waiting in the contact info for the guy that did the tune on the ECM.