Im not a moron, im a redneck engineer. 2 bottle jacks under the manifolds allowed me to pull the gimbal plate. i bought a complete used gimbal assembly locally, for $400, and installed it after tearing it down, cleaning it up and installing a new hoses, seals and such. i had my local marina align the engine after installation of the Gimbal assembly.

Finished all my wiring, fuel and water plumbing, and took the boat out for the first trip this year after tuning it in the driveway. It didn't go so well.....

Engine is starving for fuel! Got 3000 rpm briefly, and then the engine dies. Basically, I can maintain 1200 rpm under load, if I blip the throttle, the it will climb as high as 3000 before the accelerator pump shot dries out. while I was on the water, I tried these here as process of elimination:

Verified had fuel coming out of pump to carb ( couldn't check it for long, as I was spraying fuel into my bilge, so no idea if it was a good constant flow)
Removed inline filter before pump. no help.
Bypassed fuel/waterseperator. no help.
bypassed mechanical pressure regulator. no help.
Removed fuel cap, to see if I had a venting/vacuum issue. no help. replumbed pump to where the pump was 4" away from tank pickup. no help.
rewired pump from switch, to battery 2' away with thicker gauge wire. no help.
Tomorrow, I'm gonna plumb in a pressure gauge so I can see whats going on. I think I have trash in the carb, because this engine easily revved to 5500rpm while tuning it, and breaking it in. today before going out, I blipped it to 5000rpm doing a last minute test before heading to the lake. It revved nicely. I stopped and put 50 gallons of fuel in it(93 octane) before putting it on the water. And thats when I had rpm issues. I think I may have stirred up some debris in the tank while fueling, and either it messed my pump up, or clogged the carb, or both.

Anyone else have a problem with a Holley Red Marine pump and issues supplying fuel? I know electric pumps push better than they pull, but I know I'm not the only one using this pump and drawing fuel from the pickup on top the tank.

Damn man...you are one stubborn SOB...I'll give you that.

I had a similar problem on my starboard engine last year. I put a re-built Q-Jet from National Carburetor in Jacksonville on it and it ran like a raped ape.

I vote for carburetor.

If you think it's a tank issue, rig a temporary 5 gallon Jerry can with a suction hose to the pump and try it...but I think it's the carburetor.

I'll take that as a compliment! (I am a hard headed SOB! ) LOL

Yeah, I'm thinkin carb issue too. This is a new refurb, that I purchased from National Carbs. They expoxied a few of the top cover screws to prevent tinkering on it, but I'll get in there. I noticed last night that the primary flow looked weak, so its prob debris in the jets. Ahh, it felt like a completely different boat night light leaving the launch. Steering is so much tighter and responsive with the new gimbal assembly. And those brief few seconds of giving it throttle till the carb clogged up was oh so satisfying!!

Tore the carb down, yep! It had some tank sludge in it. Gave it a good cleaning, reassembled, installed on boat and back in service.

Got home a bit ago from another test and tune, and the results are:

Have to replace the inline filter every 45mins to hour as it is catching a lot of tank sludge. (good thing I brought 3 spares with me)

Ran like a champ mostly, no issues outside of tank sludge being in filter. If that doesnt clear after after another trip or 2, may have to pull the tank for a thorough cleaning.

Been running it with a 14.5x19 pitch, and got 54.6 mph/GPS @5400rpm.(may have had more rpm to go, didnt turn it any harder than that)
After a bit of running, swapped to my 14 x23p, and dropped to 46.7 @4200rpm. seems odd, I should have enough engine to pull the 23p at 4800to5000 rpm. I think I will get a calibration kit, and do some tuning. Its a stock 750 marine carb, and I'm thinking I may need some more fuel. running 33 degrees timing, distributor is locked out.

That's great news!!!

I think the right 21" may be the prop you need...maybe a Bravo 21".

Is this with the 302 in it? I doubt you will be able to spin a 23. I am stinning 23's on my 311 with 420hp per side. The RPM's you are getting with the 19 is about correct. Try a 21 but my guess is you will be back to a 19. How much trim did you run with the 23?

@Sprink- yeah, I think the 21 will be the way to go also. If I woulda have brought a torx set with me, I could have pulled the carb on the water from the get go, and not tried all those other "fixes". A lil more info on the "bravo" prop, vs, perhaps a Mirage or mirage + ?

@Audiofn- I played with the trim a lot with the 23, 47@4200rpm was the best I could pull

Im running a slightly warmed over 454:
Gen V454 forged internals and square port heads
Gen 6 502 425hp Merc roller cam installed on a 106icl(cam is ground on a 109 icl)
Cam Dynamics full roller rockers
Merc Aluminum dual plane intake with center divider milled out
Msd Distributor and box
750 Edelbrock carb
GLM manifolds

I could have turned it harder with the 19p,but backed off. I've been told that with the bottom end, and valve springs, I could turn this engine 6k rpm all day without any ill effects. I'd rather keep it closer to 5k rpm.

I've found a 21p aluminum that I can borrow for the next test session, and if it performs well, think I will try to locate a 21p Mirage plus Stainless and see if that will be my final prop choice

23 alluminum would be closer go ghd 21 mirage.

I hear you on the 6000 RPM...tell you the truth though, I think the drive would go before a strong well balanced BBC.

I don't run my equipment like that...unless some bad a$$ with bigger guns than mine is chasing me!!

Sprink- Yeah< I don't want to run it that hard either, especially since its a Alpha drive. I'm really hoping the 21p will be the ticket. On a side note, my Stainless 23p, is originally marked as a mercruiser21p. And then right besdie that, is a hand stamped '23p'. maybe somebody repitched it? or screwed it up? who knows. gona try this known 21p, and see what happens I guess.

Boat is still dirty, but heres a small clip of it idling:
http://www.facebook.com/video/video....51864424240057