Still not running right

[msojjo]

For thoes of you who have been following my threads, thanks for the help and encouragement to go on. I took my boat out this past weekend for the second time after i had all of the work done, and it didn't seem to run very well. Thoes of you that haven't read my previous posts, this boat has been repowered this spring with a merc long block, and have been troubleshooting ever since. I've replaced plugs, wires, cap and rotor, fuel pressure regulator, and all of the injectors plus both exhaust manifolds and when i took it out 2 weeks ago it seemed to run better than it did this past weekend. I have trouble getting up on plane again, but once i do it goes like you wouldn't believe. I did finally go wot with the boat now. I'm hitting 4900 rpm and the spedo says 56 and i'm runnign a 17 pitch 3 blade ss prop, the boat is 3300lbs empty. The boat is running great a higher rpms, no popping, backfiring, loss of power, which would happen i believe if i had a fuel or ignition problem. (Right?) I'ts just when i try to get the boat out of the water it really bogs down and there is a dead spot as i give it more throttle. Do i replace the plugs again, as there are only 3 hours on the ones now. I do notice that when i give throttle out of the hole i can only max 3000 rpm until i get the boat up. Is this normal? I just don't know where to go next. I did find a line comming out of the throttle body disconected, on the port side, right side looking at the motor. What is this. Vaccum line?

 

[msojjo]

Re: Still not running right

Sorry for the long post, i have done some checking around, and i found that that vaccuum hose that i found disconected is for the fuel pressure regulator, anyone think that this could be my problem? Also i have done some reading and i have a dual battery set up, and i have been running it on " all or both" to charge my batteries, i have found out that this in incorrect and should be running it on either "1" or "2", meaning only one battery at a time. Could this be my other problem. It does say that in the manual that if you do have both batteries on that it could "reset" the system and you will feel what they say is a "miss". And that could be what i'm feeling when i'm trying to get under way. Any one have any experience with these problems?

 

[whit101]

Re: Still not running right

First, running on both batterys will not damage anything. All it does is split the charge from the alt. between the two batterys. Second, The poping you are talking above is called lean pop, it means you are running a lean fuel/air mix. That is a bad thing for your engine. It sounds to me all you need is to put that vac line back on and have a fuel pressure test done. I think your fuel pump might not be able to handle the load at take off but when you get on plain it does not have to work as hard to stay there. It sounds like a fuel pressure issue.

 

[msojjo]

Re: Still not running right

First, running on both batterys will not damage anything. All it does is split the charge from the alt. between the two batterys. Second, The poping you are talking above is called lean pop, it means you are running a lean fuel/air mix. That is a bad thing for your engine. It sounds to me all you need is to put that vac line back on and have a fuel pressure test done. I think your fuel pump might not be able to handle the load at take off but when you get on plain it does not have to work as hard to stay there. It sounds like a fuel pressure issue.

I'm hoping it's just a fuel pressure issue, that means all i have to do is connect that vaccuum hose and i should be good then. I just had the fuel pressure regulator replaced

 

[msojjo]

Re: Still not running right

When i'm getting up on plane i don't hear a popping sound, i feel like a dead spot, or what was more accuratly explained a "miss" in my owners manual caused by running the 2 batteries, so i'm hoping that that's the problem for that. As far as the fuel pressure regulator, i'm hoping that i just need to reconnect that vaccuum line, and i'll be good. I just replaced the fuel pressure reg. and all injectors, so i'm hoping.

 

[Tail_Gunner]

Re: Still not running right

As to this rebuild...Was it a fresh marine long block...or did someone tear down the old block and rebuild it...If some rebuilt this block did they ad lib some items such as a cam

Who put the thing together..Vacum line is a pretty big thing to miss..

It sounds like you boat is mpi 350 that is having a hard time getting on plane and misses or hesititaes at 3000 rpm...troubles under a heavy load...And no you dont have a prop issue


Can you determine if the FI is a mefi 3 or a 555

 

[msojjo]

Re: Still not running right

As to this rebuild...Was it a fresh marine long block...or did someone tear down the old block and rebuild it...If some rebuilt this block did they ad lib some items such as a cam

Who put the thing together..Vacum line is a pretty big thing to miss..

It sounds like you boat is mpi 350 that is having a hard time getting on plane and misses or hesititaes at 3000 rpm...troubles under a heavy load...And no you dont have a prop issue


Can you determine if the FI is a mefi 3 or a 555

Just to be clear, it wasn't a rebuild. It was a reman marine long block from merc that i paid 4000 bucks for.

Had it done by a local dealer that i don't know if they knew what was going on.....had a lot of troubles with them.

Yes it is a 350 mag with the mpi and bravo 1 drive.

How do i find out the difference in the fuel injection, a mefi 3 or a 555?

 

[sqbtr]

Re: Still not running right

With that vac line disconnected it will cause high fuel press and should be running rich, wich would explain the bog.

 

[msojjo]

Re: Still not running right

With that vac line disconnected it will cause high fuel press and should be running rich, wich would explain the bog.

Ok, good to know, thanks for the response. All i need to know is that all i needed to do was put that hose back onto the throttle body. Too bad i didn't spot the problem while i was still on the water, so i could test it. I'll try it out this weekend.

 

[airdvr1227]

Re: Still not running right

I had to check to make sure this wasn't a continuation of your other thread. Man you've had a time with this one! . Hope you get it straightened out.

 

[QC]

Re: Still not running right

Check your prop thread. There is bad data here!!!! I agree there are engine issues, but you also have a data issue which is screwing everything up too . . .

 

[Tail_Gunner]

Re: Still not running right

Between 2500 and 3000 rpm. That's when i'm trying to get up on plane. and i can peg it at 3000 and it stays there until the boat is up, and it seems to take a bit longer when that miss occures. In a previous post i thought it was a dead spot, in the throttle range.

Here is the problem or a suspected issue..When the motor is under a heavy load it experiences a slight miss or stutters..Not good sounds like detonation


(and i can peg it at 3000 and it stays there until the boat is up, and it seems to take a bit longer when that miss occures)

Again that sounds like the ecm is retarding the timing..which effectivley lowers the engines output

-----------------------------------------------------------------------------------------

What you need is a manual so you can verify that the vacum system is setup properly...EFI is touchy stuff it needs to be done correctly...Stay with it can be frustrating but there is a answer and it will be simple i hope..Just elusive for now......................


Try posting your engines serial number that would be a good start...There are some here that will not guess at things...But if and when they post listen carefully..

 

[Wingnutt]

Re: Still not running right

Test the knock sensor. If it detects knocking or pinging it will tell the ECM and the ECM will then retard the timing. First however, put that vacuum line back on the regulator and make sure that the mixture is correct. Recheck the base timing with the dizzy disconnected from the ECM. Your owners manual should tell you how to do that. Also, if so equipped, have the crank position sensor tested. I'm not 100% sure what sensors your engine has on it, I'm just going by what I know is on automotive ECM controlled engines. One last thing, does your engine have O2 sensors on it? If so, they could be sending screwy readings to the ECM which can cause all sorts of problems.

 

[QC]

Re: Still not running right

Almost 100% positive, that vintage does NOT have a knock sensor . . .

 

[Tail_Gunner]

Re: Still not running right

Almost 100% positive, that vintage does NOT have a knock sensor . . .

Model CID / # CylYear Range Serial RangeKnock Sensor 350 Mag MPI 350/V81999-20010L340000-0M2999999-33503

Im just not sure if he has a mefi 3 or the 555 system..Using the serial number im sure someone knows which type he has

http://forums.iboats.com/showthread.php?t=329915

Maybe some infor there

 

[QC]

Re: Still not running right

I said almost . . .

After noodling about this as I should've before I posted I was thinking O2 sensor as they are not "closed loop", sorry :redface:

In my best Emily Litella . . . . never mind.