i got a chance to test some of the basic sensors. tps voltage sweep seemed normal. there was a spot though that kept OL on the meter. it would only do it during a full sweep. just about 4V. if i tried to pinpoint exactly where it never lost signal. the ECT sensor was about 600ohms off. i replaced that. voltage on the map sensor was good but thats while it sat. not during run time.
i think i have access to a diacom this weekend if i can make contact with the guy. i might also be able to borrow a computer from another guy that has the same era 350. im wondering if my computer got reprogrammed with the wrong map. maybe from a 8.1 or something. even then the fuel burn seems excessive.

after that im going to consider repinning my ECU to utilize the mefi4b i have. we will see what the results are.

Well, I got the boat on the water. I timed it and it ran great. 3800 on the tach. Still seemed a hair sluggish. I'm betting the 3800 was more due to the cold as balls temp more than anything else.
I was able to get a hold of another impeller though. It just happened to be the next size down. Threw it on and ran it on Saturday to 4000. Holeshot didn't seem to change much if any.
The only issue I have left is the fuel burn. I didn't get enough hrs on the meter but I'll continue to chip away at the problem. Its possible the change out of the ECT might have fixed the problem.
I was also able to consult with another guy who has this exact same era motor. My low rpm is right on par with what his boat with twins produces. I'm wondering if the rudimentary 1st gen fuel injection system and possibly a lower up motor might e the culprits. Newer 350 efi motors are rated 325-330 typically.
Thanks to everyone that has helped me out along the way. The advice given was greatly appreciated.

The early Gen (i.e. MEFI 1) isn't holding your rpm back. It is likely something else.

Thanks again for the reply trash.

I may or may not have stated the motor is 2nd hand to me and had lots of hours on it. I'm just glad to have scored it for such a price. It works for now. I still plan on selling the boat once springtime comes.

With only 3800 rpm check your knock sensor, you should be into the 4800 range


Either that or your over proped

We typically impeller the boats to around 4000. The exception is the high powered ones with lsa and raptor motors. They run around 4500.

How do you impeller a boat?

Earlier he mentioned Marine Power, so I'm assuming he has a jet boat. I know, assuming will mean i ended up being an azz assuming. LOL.

The manufacturers generally impeller a boat for good fuel economy, holeshot and load carrying capacity.
Which is probably counter productive to the general consensus of OSO.com
My boat new topped out at 45mph. After taking a bump and getting my hull repaired it went 42mph. However, it packs a hell of a load, runs in inches of water and makes class V rapids it's *****.

OK got that also and understand not propping (impellering) for max rpm. Running rapids the impeller can grab air easy and rpms will jump. Only issue with running lower rpm's is your lugging the motor and more fuel use.

Has anyone done a compression test?