Warming Her Up

[rtgogo]

How long do you run your boat before you push her wide open? I noticed this weekend that the 454 Mag in mine must have a govenor to keep me from burnin her up while shez still cool. I'd been out in the early morning for 20 minutes or so and began taking a few passes down the lake. At first run she was only hittin 52 GPS WOT. I stopped becasue I thought she was chokin, killed the motor to make sure the linkage was getting fully engaged. It was traveling the entire range so i started her back up after 10-15 minutes of fiddling with the motor. Well, guess the fluids were cookin while i was tinkering, because she came to life outa the hole and was hittin 69 on my way back. I warmed her up a little longer today, but again, she would not go over 52ish until i killed her and then cranked back up after sitting 5 minutes.

What's your advice?

Thanks!

[The Hedgehog]

I went to an oil temp gauge. Everybody told me that this would be a good learning experience. It is.

Eddie told me to wait to 160 before I start to squeeze it. It takes me about 5-10 min to get there and I have a thermostatically controlled oil cooler. I bet yours takes a good 10-15 min.

[MOP]

That is a weird one, I don't think it has anything to do with temp. Does it run good for a long periods after you did the start stop thing?

[rtgogo]

Yep, she keeps her juice once we have quiet time after warm up...Feels like shes not gettin air or fuel, just chokin out, but then after re-start the throttle is much stronger and top end is 15+ higher. Again, the only times i noticed were during my first runs in the early AM. rest of the day seems fine. There has to be some type of govenor on it that's gettin tripped when i shut her down and restart.

Bill...she aint at 160, but should be plenty warm by the time I'm pushin...I warmed her up a lil extra this morning and got the same thing. Stopped to talk with a friend,started back up and she was back to screamin....

[The Hedgehog]

Yep, she keeps her juice once we have quiet time after warm up...Feels like shes not gettin air or fuel, just chokin out, but then after re-start the throttle is much stronger and top end is 15+ higher. Again, the only times i noticed were during my first runs in the early AM. rest of the day seems fine. There has to be some type of govenor on it that's gettin tripped when i shut her down and restart.

Bill...she aint at 160, but should be plenty warm by the time I'm pushin...I warmed her up a lil extra this morning and got the same thing. Stopped to talk with a friend,started back up and she was back to screamin....

Hmm. Think it is getting hung in cold start mode?

[rtgogo]

That sounds close....any pointers on troubleshooting?

[chappy]

Any soot on the transom?

[rtgogo]

Yes...

[chappy]

Yes...

Had a similar problem, albeit on a 350, turned out to be just like what was stated above, hung in cold start mode, choke was sticking.

[rtgogo]

So how did you fix it?

[The Hedgehog]

So how did you fix it?

You either have a problem with the temp sensor or the ECU. Probably the sensor. The best place to start is to run a diagnostic to see if the ECU is reading the right temp. Beyond that you will need to talk to one of the guys that has some MEFI experience. Last Real Texan has some cool software that plugs into a MEFI and spits out all of the cool data. It will tell you detail logs of exactly what was going on during a run. It kicks out temps (oil, water and air intake), RPM, pulse width, timing, knock, fuel flow and all sorts of goodies. I believe it kicks out autoenrichment detail as well. I thought that owning that might be overkill for me. I will probably get the software too. It was really cool.

There are a number of techy folks on the site that can probably give you a better answer. If you don't get one, give me a call. I am meeting my engine builder today. He uses MEFI systems on all of his big motors and will probably know exactly what it going on with yours.

[BigGrizzly]

Is yours a carb unit? If so The plate is stuck. As for warm up at least 15 minutes. With mine it takes longer because I have a 14 quart oil pan, but I am a closed cooling too. This helps on the warm up.

[chappy]

So how did you fix it?

For my issue, like Griz said, the plate was sticking. I just got a kit and rebuilt the carb. From what Bill said, sounds like you've got an efi, so my solution probably won't help, sorry.:(

[The Hedgehog]

For my issue, like Griz said, the plate was sticking. I just got a kit and rebuilt the carb. From what Bill said, sounds like you've got an efi, so my solution probably won't help, sorry.:(

He has a 454 Mag with a MEFI. The concept that you are talking about is not way different

[rtgogo]

How does the soot on the transom work into this issue?

[The Hedgehog]

How does the soot on the transom work into this issue?

Very sooty transom means the boat is running rich. EFI engines run in cold start mode until they heat up. That means super rich, kind of like a choke being stuck.

It is natural for your transom to have some soot. Merc runs them kind of rich as a safety measure. We call it the "Signature Merc Black Transom". A better exhaust will lean it out some more. You can also have the MEFI reprogrammed to lean it more.