Seriously running out of ideas on things to check for bad holeshot with 225 promax

[90 5.0]

All right , here is the deal.

My 225 promax that normally screams out of the hole has developed a slow get up issue.

It is a 15” offshore 225 promax ss just Incase you were wondering what mid, it that it matters in this case.

Boat didn’t get used much for a while, due to more priorities with life etc.

took boat out, idled bad and would not get on plane at all.

Had fresh gas, believed to be stator issue. Had 16amp electronics on it.

Put all 40 amp electrics back on it, was fine. Sat for a good while again.

Fresh gas, slow holeshot. Bogged like it was loaded up and slowly built rpm. As soon as it hit 3k rpm it comes on like crazy.

Checked the normals, timing , compression , stator , etc. all seem good.

Tried getting up on plane , letting it clear out and setting it back down and immediately trying again.
Better, but not perfect. Ok, it’s loading up on fuel, injectors are need of service.

Yank injectors and swap in another known good set.

Much much better, but still not like it should be, still gets up going slower than normal , and hits 3k rpm and comes on like crazy.

Very responsive and snappy after 3k rpm anytime you punch it or roll into it all the way to the limiter.

As soon as I load the video of the hole shot I’ll post it here.

I’m scratching my head on things to check next.

Replaced flywheel, stator and switch boxes
checked timing etc
replaced injectors.

Would map sensor going out on ecu cause this?

[silverbullet02]

You know anybody with one of those motors you can try their ecu?

[kkelley]

The stator does have a low side and high side. It sounds like you are having issues on the low side of the stator. The serial number would be a big help on this. How was the spark on cylinders ?

[90 5.0]

You know anybody with one of those motors you can try their ecu?

I have my drag ecu I can throw on there, worth a try. Especially if it’s the map sensor going out, might point to that.

[90 5.0]

The stator does have a low side and high side. It sounds like you are having issues on the low side of the stator. The serial number would be a big help on this. How was the spark on cylinders ?

Possibly, but it had a bad stator and it would not get on plane at all.

Swapped them and now it does this , it was fine when I first swapped stators and it sat for a while.

It it doesn’t feel to me like it’s a low side stator issue but I suppose it is possible.

Serial number is absolutely no help what so ever in this case, all 225 promax motors are the exact same besides some 15” motors had one piece adapter plates and some had two, of it was a cooling or water related issue in this case serial MIGHT help, assuming that part of the motor WAS still factory.

[onttr22]

Fuel pressure ?

[90 5.0]

Fuel pressure ?

I haven’t checked it when running and punch it, but I suppose I should dig a gauge up to see what it’s doing

If it was too high I could see it being fat and lazy, but that would be fat and lazy all over I suspect.

But it you are correct I do need to check that while running.

[silverbullet02]

My first thought was weak stator on the low side but since you've had 2 different stators on there it's odd they'd both have a bad low side.

[leonreno]

Have you checked for a loose tuner or bad reeds?

[JOE54]

^^+1

[90 5.0]

Have you checked for a loose tuner or bad reeds?

I looked at the reeds when I had the plenum out to swap injectors, just a quick glance but they looked fine.

I thought of this but normally a bad reed will have poor idle quality. Since i swapped stators it’s been idling perfect.

I suppose it’s still possible , however.

[JOE54]

check tuner ????

[minnowlimo]

check tuner ????

this was my next thought after a fuel issue. Is the very first holeshot off the trailer any better than the others when its cold? Also have you tried to run wot? I wonder if it' still consistently running find on the big end? If you need help loading holeshot video let me know I might be able to help. Good luck

[cajunrgfm]

The stator does have a low side and high side. It sounds like you are having issues on the low side of the stator. The serial number would be a big help on this. How was the spark on cylinders ?

He has already changed all the electrics with known good stuff,from 16 back to 40 amp. Have you checked fuel pressure @idle ? I'm thinking fuel delivery ,since an injector swap improved things, with all the sitting the motor has experienced,have you considered tearing the vst apart for a good cleanup ? Those fuel systems do run better with a bosch pump and bridgeport 39psi gold regulator, with vst delete. I'd send a set of injectors to Tony/Rich ,while i cleaned the vst and replaced all the bleed lines. Inspect reeds for any frayed petals ? Are the butterflies opening properly from idle ? Could be a cracked reed block (not uncommon )or air leak, it's gonna be somethin simple. It runs/idles and hauls the mail, up top,as you say. 15" mid wont matter, adapter plate should be a 2pc. Not a 260 1 pc.it would be rare to have a 15" mid with a factory 2 pc. Unless your motor is a factory SS steel bore ? they didnt build many. Most came on 260/280.

[JOE54]

agree gotta be simple running that good

[cajunrgfm]

I looked at the reeds when I had the plenum out to swap injectors, just a quick glance but they looked fine.

I thought of this but normally a bad reed will have poor idle quality. Since i swapped stators it’s been idling perfect.

I suppose it’s still possible , however.

You should have checked the gap, mercury had a spec for worn /used reeds,back in the day, personally if they dont lay flat,i dont reuse them,regardless of lapping. air flow is critical on that xri front,in real time flow testing , only the inner reeds actually get decent air,the outer reeds suffer,due to a very short plenum, thats why they have a horn on the race motors. do you have a spacer on it ? Is the linkage opening the butterflies properly,after reassembly ?

[90 5.0]

He has already changed all the electrics with known good stuff,from 16 back to 40 amp. Have you checked fuel pressure @idle ? I'm thinking fuel delivery ,since an injector swap improved things, with all the sitting the motor has experienced,have you considered tearing the vst apart for a good cleanup ? Those fuel systems do run better with a bosch pump and bridgeport 39psi gold regulator, with vst delete. I'd send a set of injectors to Tony/Rich ,while i cleaned the vst and replaced all the bleed lines. Inspect reeds for any frayed petals ? Are the butterflies opening properly from idle ? Could be a cracked reed block (not uncommon )or air leak, it's gonna be somethin simple. It runs/idles and hauls the mail, up top,as you say. 15" mid wont matter, adapter plate should be a 2pc. Not a 260 1 pc.it would be rare to have a 15" mid with a factory 2 pc. Unless your motor is a factory SS steel bore ? they didnt build many. Most came on 260/280.

225 ss promax 15” motors did come with both one piece (it’s a special one piece promax plate,slightly different from a 260 and 280),
mine came factory with a 2 piece, I had a one piece on it at one time and it has a 2 piece back on it now.

I put everything back to stock for the tournaments I’m fishing again, so the fuel system swap is out for this motor.

I have another on another boat with a Weldon pump and a black 56psi regulator. But i can’t set this one up that way.

The vst needs some love I’m sure. I’ll do that and recheck the ecu vaccumm fitting again and bring another ecu to the lake with me.

The butterlfies and the throw etc have all been checked.

[90 5.0]

Slow holeshot before injector change, better now but not right but did not film




Throttle response over 3k

[Jasonrs]

It sounds like its not firing on all 6 cyl on holeshot?

[90 5.0]

Kid wanted to go fishing a little today haven’t had time to jack with much like I wanted too.

I shot some more contact cleaner in the ecu fitting and hit it with a little air real quick before we went out.

Seems slightly better, got off and back on plane real quick once today and it was noticeably quicker back on plane.

Dropping some injectors off this week, really starting to look like the set I put in need gone through too, but weren’t as bad as the ones I took out.

Anyway. Still fighting it just progress has been slow with life in the way of boating lol.