454 mag W.O.T Question

[2ifbyc]

I have a 1990 mercruiser 454 mag 7.4L on a 26ft Cobalt. I just got the boat this year. My question is this... At wide open throttle I am running at 4100-4200rpms and about 36-38mph. Does that seem right? (I have a bravo 3 outdrive with the dual props.) Also, at WOT only i have some hesitation. It runs beautifully from idle all the way up to WOT. It seems like a clogged fuel filter or something but its only when shes wide open. Any help is much appreciated. Thanks!

 

[Bondo]

Re: 454 mag W.O.T Question

It seems like a clogged fuel filter or something but its only when shes wide open.

Ayuh,... So did you Check,+ Change the fuel Filters,..??

They stutter,+ die at WOT because that's when it's using the Most fuel...

 

[2ifbyc]

Re: 454 mag W.O.T Question

Yes, the fuel filter was just changed. The guy I bought the boat from claims he got some "bad gas" from somewhere. I figured that was probably a cover up for a bigger more serious problem. Any other ideas or steps in eliminating this? How about the rpms and speed at wot? Do they seem right?

 

[Bondo]

Re: 454 mag W.O.T Question

Any other ideas or steps in eliminating this? How about the rpms and speed at wot? Do they seem right?

Ayuh,... Click right Here...

 

[QC]

Re: 454 mag W.O.T Question

How about the rpms and speed at wot? Do they seem right?

Seems a little light on both, but doesn't really matter until she is running right. After that you should post up your RPM (must be accurate), GPS speed, prop pitch and gear ratio if you can get it (we can get to the latter but best to confirm especially with a 20 year old boat).

There is sticky at the top of this section, Must Have Technical info. Check that out. #13 could be a help, but you should poke around the whole thing.

Good luck!

 

[Fun Times]

Re: 454 mag W.O.T Question

Did you try trimming the drive up a little while at speed, Or did you leave the drive trimmed all the way down?

What did the old owner tell you the boat should run at?

 

[Philster]

Re: 454 mag W.O.T Question

This issue screams, "The drive was never trimmed up".