New to me xb2003 w J Smith 225 Promax... Having issues.. Long technical thread warning!

[aj06bolt12r]

FYI this is also posted on scream and fly...

Allison xb 2003 with a Jay Smith built 225 ProMax 30 HRS on engine, assembled about 1 year ago.

I bought the boat knowing the engine is not running correctly and the P.O. who is a stand up guy put me in contact with Jay Smith via text. Jay told me to give him a call.. So I did.

Now, to be clear Jay has never made a penny off of me.. but he took my call and proceeded to talk to me on the phone for over an hour on a Sunday evening! I find that amazing. That kind of customer service is above and beyond and exceedingly rare to find. I'm not even technically a customer.. yet. Cannot thank him enough for taking the time... I have 2 pages of hastily scribbled notes in which I tried to capture the flood of technical knowledge he gave me for nothing! Hopefully I'm capable of putting that knowledge to good use and isolating the problem.

Other than a public thank you... (sent him a gift card as well ) the reason for this post is to try to understand something he told me and hopefully get some opinion for you all.... I forgot to ask him to clarify some things during the conversation, it was moving fast and I was trying hard to get good notes. Anyway...

I was telling him that with the engine idling I was performing my version of a cylinder contribution test by pulling plug wires with the engine idling while using my timing light for a tach to see how much each cyl was contributing. I have #1 and #4 doing virtually nothing... #2 and #6 make a small difference when unplugged... #3 and #5 appear to be doing most of the work and I loose about 150 rpm if either of those two are unplugged... Probably I misunderstood or am just confused but he stated that the results of this test basically mean nothing. Having certain cylinders contributing much more than others at idle is of no consequence.

Would anyone be willing to take the time to explain how or why this is? I'm a lifelong mechanic but a newb to outboards... so I'm just not understanding... I would like to know the theory as to why this is the way it is.

Later in the conversation I brought this up again and he did mention that having #1 and #4 so weak could point to a bad trigger.. which is a new CDI unit instead of a Merc part. I'm going to take his advice and order a Merc trigger as well as a stator. The stator is a 1 year old merc part installed by Jay himself but it is OHM testing bad.

Stator results. OHM test...
BLUE to RED leads should be 3500-4200 mine reads 2309
BLUE/WHITE to RED/WHITE leads should be 3500-4200 mine reads 2373
RED to BLACK should be 90-140 mine reads 32.4
RED/WHITE to BLACK should be 90-140 mine reads 32.1

Incidentally those readings are exactly in spec with a CDI stator? Maybe I actually have a good CDI stator?

Also I forgot to ask him what might cause such a new Merc stator with 30 hours on it to go bad... another ignition part possibly?

He gave me a ton of other stuff to check as well but I wont type it all here, I think I have my head around most of the rest of it...

Oh yeah, he mentioned Mercury "blue" oil... anyone know exactly what that is? Premium plus maybe?

I cannot possibly call him back and ask him this myself... I already took too much of his time for no return on his end.

 

[aj06bolt12r]

So I got my hands on a DVA and did a bunch more research and got around to checking a lot of things Jay suggested.

First thing I discovered is that I have slight/ trace voltage on the kill wires to the packs when the key is on. Way less than 1 volt. But its more than nothing. Are the kill wires supposed to have exactly 0.0000 volts or there is a problem? I was not sure so conducted all tests with the kill wires disconnected.

All tests at cranking speed. With plugs in and plug wires on plugs.

I'm told by the P.O. that the stator is a Merc part installed by Jay. Visually is appears brand new. But when testing it fails the mercury testing parameters. But if you look at the specs for a CDI stator it is perfectly within spec. All ohm readings in spec. All cranking DVA readings in spec. So I guess I should assume its a good CDI part? I cannot tell by looking at it, there are no part numbers on it anywhere.. other than PLA-0108.. which comes up empty on a google search. Stator low speed and stator high speed DVA tests within spec at cranking speed.

Switch box stop circuit test ( done with kill wires attached) is slightly out of spec... Should be 200-300... I get 180 on one box and 181 on the other. Because of the trace voltage present in the kill wires? Indicative of a bad switch box?

Coil primary cranking DVA test is within spec on all coils...

Switch Box Bias DVA test is within spec

Trigger appears to be brand new visually.
Ohm testing for the trigger is all within spec, But DVA test is out of spec. Should have 4 volts to switchbox when cranking but....
Brown w-out yellow sleeve to white with yellow sleeve is 2.6
White w-out yellow sleeve to violet with yellow sleeve is 3.0
Violet w-out yellow sleeve to brown with yellow sleeve is 2.8
These tests were performed with all of the leads still attached to the switchboxes. Switchboxes grounded to the block.

Would this be enough for you to replace the trigger? I guess I need to repeat the trigger tests with the leads disconnected from the switchboxes and see what I get?
What about the trace voltage on the kill wires? Is less than 1 volt trace voltage normal or should it really be 0.000?

I don't want to just swap on new parts and see what happens. I don't want to set dollar bills on fire and or have whatever caused the old part to fail instantly nuke my new parts.

Thanks for any advice.

 

[aj06bolt12r]

Obligatory pictures

 

[SlowHayden]

Stumbled upon this boat on IG a time or two, it came out of Chattanooga area didn’t it? Also I’m probably going to be of absolutely no help here but when you say it’s not running correctly, what exactly do you mean?

 

[aj06bolt12r]

Yep out of Chattanooga. I have never put the boat in the water. Bought it with known issues and want to get it running smooth on the hose before running it down the lake. I don't have any experience in a performance v bottom like this Allison, when I do drive it I want to concentrate on what I'm doing and not have half of my brain analyzing the engine.

But not running correctly description... PO reported loosing power/ RPM at top end. Also the engine not sounding normal at light load, neutral throttle positions, it kind of sounds blubbery, not firing on all cylinders at all times. Seems super rich.

What I have experienced is that it does not sound right on the hose either. You can hear that it is not running on 6 all of the time. Sounds like certain cylinders are dropping in and out. If you put an inductive timing light on any of the 6 plug wires it shows that they are all sparking. If you put an in line spark checker on any of the 6 plug wires at cranking speed it shows that they are all firing. But if you let it idle and pull plug wires one at a time certain cylinders make a big difference and certain cylinders make no difference, this is better explained in my first post.

Engine currently has Brucato ACU installed. I also have the stock Merc ECU and I have tried it with no noticeable difference.
Has 6 new NGK resistor spark plugs gapped as recommended by Brucato

Compression test with 2 different gauges shows 130psi or more on all cylinders.

 

[aj06bolt12r]

One more piece of the puzzle. My air temp sensor OHMS correctly when compared to the air temp vs resistance chart. However with the engine idling if I unplug the air temp sensor I hear no change in how the engine is running. Should I notice a difference when unplugging the air temp sensor at idle?

 

[SLOmofo]

As you are cranking (ignition killed) does it sound even = Quick and Dirty compression test. Compression test and Leak Down test. Mark each cylinder for TDC on the flywheel so you can see that each cylinder is firing approximately when it should. You know, basics first. Good compression, spark when it should and correct air/fuel ratio.

 

[aj06bolt12r]

Yessir, sounds normal when I crank it. I'm waiting to get my hands on a leak down tester. Compression test shows over 130psi on all cylinders. Jay Smith had already marked the flywheel for each cylinder. I checked all of them at cranking speed with my timing light and the timing arm maxed out. Timing is close on all cylinders. 25*

 

[ssv1761982]

Yessir, sounds normal when I crank it. I'm waiting to get my hands on a leak down tester. Compression test shows over 130psi on all cylinders. Jay Smith had already marked the flywheel for each cylinder. I checked all of them at cranking speed with my timing light and the timing arm maxed out. Timing is close on all cylinders. 25*

What was the timing at idle?

 

[aj06bolt12r]

Dead on zero... Only checked idle timing on #1

 

[SLOmofo]

Yessir, sounds normal when I crank it. I'm waiting to get my hands on a leak down tester. Compression test shows over 130psi on all cylinders. Jay Smith had already marked the flywheel for each cylinder. I checked all of them at cranking speed with my timing light and the timing arm maxed out. Timing is close on all cylinders. 25*

I figured Jay would have marked them. Also figured you being a wrench you would unconsciously hear the low hole (starter spins faster against low or no compression). I am a retarded.... I mean retired grease monkey. Many years ago I bought one of these. https://www.screamandfly.com/showthread.php?350205-Anybody-interested-in-buying-Leakdown-Testers-(Covid-19-Boredom)&highlight=Leakdown+Testers+/+Balz+to+the+Wall+Racing+Website+Here:+BALZ+TO+THE+WALL+RACING

 

[gmorgan]

I have noticed the same symptom as you when pulling spark plug wires off an idling engine. Go on to something else. I can’t explain it, but that is normal for a Mercury V6.

 

[SlowHayden]

I had an entire bank dead on my 200 ProMax earlier this year. At idle it really didn’t seem any different, the sound was different but not like a typical misfire sound or vibration so I def could see pulling plug wires not making a difference on certain cylinders. Only noticeable difference I had is it wouldn’t even plane out.

 

[aj06bolt12r]

If I could pull any individual plug wire one at a time.. and not have it make that make much of any difference I could understand that.

But in my case, if I pull the plug wire off of cylinder 3 or cylinder 5 it makes a big difference... cylinders 2 and 6 make a small but detectable difference.. cylinders 1 and 4 make virtually no difference.... The disparity between the effects of killing certain cylinders is what I am failing to get my head around...

But if this is typical of a good running 2.5 merc EFI then so be it... I'd still like to understand the theory behind why this is.. but maybe nobody knows?

 

[stuart gary]

might have more fire at idle than the others because the fuel may be different at different rpms that way its not loading up all 6 while idling. another thing Is if you look at the wires going to the power packs you will notice 3 wires going to one pack and not the other. that has something to do with how it idles when you pull certain plug wires might have something to do with fuel and fire also . I look at and try anything when my motor doesn't sound correct

 

[gmorgan]

If I could pull any individual plug wire one at a time.. and not have it make that make much of any difference I could understand that.

But in my case, if I pull the plug wire off of cylinder 3 or cylinder 5 it makes a big difference... cylinders 2 and 6 make a small but detectable difference.. cylinders 1 and 4 make virtually no difference.... The disparity between the effects of killing certain cylinders is what I am failing to get my head around...

But if this is typical of a good running 2.5 merc EFI then so be it... I'd still like to understand the theory behind why this is.. but maybe nobody knows?

I’m not sure about the theory, but that is the way a healthy Mercury does. One plug wire removed and it makes no difference, pull another and it dies.

 

[aj06bolt12r]

So I got to do some more DVA testing today with the engine running at idle.

Coil primary voltage at idle is within spec at all coils.

Ignition timing is correct and appears stable.

Spark will jump a significant gap on all 6. Thin blue spark that is difficult to see in bright sun light. All 6 look the same.

Switch box stop circuit reading is within spec.

Stator low speed test is within spec.

Stator high speed test is NOT within spec. Spec calls for 120-160 volts at 1000rpm. I have about 85-89 volts on both red leads and voltage reading is not very stable. Tested with kill wires unhooked from switchbox... Same result. Swapped switchboxes with another pair of known good ones... Same result.

So I guess I do need a stator.
When I look up the Merc part number via Serial Number 0G367321
It calls for this stator 9610A27... which is on backorder apparently.

However stator 9610A19 is available all over the place... It appears this is the correct stator for other 225 promax engines with different serial numbers? Does anyone know the difference? I'm not sure why it wouldn't work.

 

[aj06bolt12r]

In case anyone finds this in a search in the future. The A19 stator will work in place of the A27. They are both 40 amp and set up for dual rectifiers.

 

[silverbullet02]

Find somebody with a stock ecu and try it, those acus seem to be hit and miss. I’ve not been impressed by them.

 

[aj06bolt12r]

I have the stock ECU. Nothing wrong with it. Was just removed in favor of Brucatto for higher rev limiter. I installed it and ran the engine. It acts and sounds about the same. But I think I will re-install it and try grounding out the air temp sensor to see if it has any effect with the stock ECU.