Help! P-29 dies when put into gear??
 

I had both motors and drives pulled over the winner to fix oil leaks and clean up the bilge. Fixed laundry list on the boat of miscellaneous things that needed to be addressed to put it back in top mechanical condition. Nothing on the engines were changed except spark plugs, oil pans, seals, gaskets and timing covers.The boat is a 1996 Merc 350 Mag Gen+ coupled to Black Hawks 31p props. They are both doing the same thing now drop them into gear and one out of two or three times dies. When I was looking for a P-29 to buy I wanted all factory. A lot of people had trouble putting carbureted motors in front of the Blackhawks and dying when you put them in gear. I knew that a factory power set up what's trouble-free engine package and thats what I wanted. I'm waiting in line to get back in the shop to get the rest of these bugs worked out but this one has us scratching our heads. By asking here I'm hoping to save some trouble shooting and go straight to the issue. Thanks for any help...

try the neutral safety switch common merc problem

also called the shift interuppter switch

Staging on the carbs might be the issue too. Had that prob on my cig. Put it into gear and the carb wasn't adjusting to keep fuel level up under load. But kinda weird both are doing it at the sane time. Even with the neutral safety switch. Should be both going out.

I heard those blackhawks were giving fits going into gear.If it can be fixed he will .It's in good hands. hf...

Engines are MPI.

I would be looking at the shift interrupt. It should momentarily ground ignition coil out to let it go in and out of gear. Immediately after it engages, the rpm should bump up a bit so stalling does not occur. If engines were out, and both doing the same thing, maybe some plug in connection for both was missed? It is also a possible cable adjustment issue and due to play/misadjustment, the interrupt and actual shift are not sequenced correctly.

I don't believe a Blackhawk drive uses a shift interrupt switch since its a Bravo based drive.

Check the ignition timing.

Black hawks don't have a shift interrupt switch. That's only on the alpha drives
The neutral safety switch will not cause the engine to stall. It only prevents the engines from starting in gear

If the engines do not stall do they run normal and pull proper wot rpm?

Everything else is normal. Thanks for everyone's input so far. I'll be dropping it off soon to straighten it out. I've been very pleased with the service I've received it's just dotting an I and crossing a T to finish it up.:drink:

MPI engine with bravo based drives. My guess would be the IAC motors are not plugged in. They are in the same position when the engines were shut off

100 % CORRECT - All Blackhawk's and Bravo's outdrives do not use or have a shift interrupt switch nor an adjustment for one.

Is these engines TBI or MPI being a 1996 vintage ?

In the water or on the water hose throttle only NOT in gear can you rev these engines up - Just asking if you have silent choice or just straight thru transom exhaust. how does engines run and shift into gear on the water hose - unloaded ?

I would scan the engines and what is your idle RPM's showing on the tachs and on the scan ? Blackhawks needed to be set at a bit higher idle,

My bad. I thought they were utilized in the Blackhawk application due to the dual prop load and higher in gear idle speed. That being said, slightly off topic, but due to same, would adding them be a good idea?

P-29s all came with MPI

Both idle at 600rpms in neutral.

Whenever engines are pulled, bilges cleaned/painted, and there are running problems afterwards I always think "bad ground". Not sure a ground problem makes sense in this situation, though. IAC's were also my first thought. Get the ECU's scanned and see what comes up.

When the bilge was cleaned is it possible moisture caused some corrosion under the distributor caps? I have heard they can be a problem sometimes. Seems to be a timing or ignitition issue to me from what you are describing.

Engines were pulled then bilge was cleaned up. We'll find out soon I'm dropping it off Thursday:D

adding if a digital tach and or the scan can verify your engine idle is really 600 rpms before you shift into gear - that is too low. Not saying this is your exact 100 % problem but 600 rpms is not helping either. You have to find out (the problem) why your rpms are only 600 if in fact your tachs are showing the correct readings.

Possible fuel restriction first thing comes to mind.

BUP - I have twin 2006 6.2 MPI's and SC5000 vessel view. Ran both engines the other weekend on the hose to dewinterize. After warmed up I bring them to idle and they both are right at 600 rpm according to the SC5000. That is where they normally idle for me. Just telling my experience.

Yes sir that is correct. I have not seen or touched a Blackhawk drive app in years. For some reason I thought a fully warmed up MPI with a BLACKHAWK app was idle min at 650 to 700 RPM's.

I went to look back in my service notes and it was listed for bravo and Blackhawk apps a 350 MPI should have an idle of 600 rpms. SO MY BAD. I POSTED INCORRECT INFO.

With that said somehow I could of sworn that idle with MPI engine and Blackhawk app was 700 rpms / 650 rpms bare min.. If I ever find that info and what app w/ Blackhawk that applies to, I will post it. But again I still might be totally wrong.

Have you verified the factory Idle RPM spec, 600 sounds low, there is a limited amount of rotating inertia at that RPM. You state none of the rotating parts were changed, but it is common to replace with a lighter flywheel, such as aluminum. You mention the props are 31", but have they or the gear ratio been changed.

Personally, I believe in heavier, not lighter flywheels, and would raise the RPM in 100 RPM increments until the shift can be made without stalling. Testing in such a manner may help with the solution.

My guess... loose nut behind the wheel.

:party-smiley-048:

I still would verify rpms with a digital tach and or scan.

I think my boat has the same problem.

IAC sensor maybe, 2004 Formula 6.2s did the same thing would idle but dye going into gear but it also had the warning beep going off. When they first went bad they use to go out really, close to each other hour wise.

[ATTACH=CONFIG]540232[/ATTACH]I still think the IAC motors are not connected. From the picture it looks like the connection for the IAC motors is under the intake. It would be easy to forget to connect it. (I know, I have forgot to attache it on my Vette when taking the TB off). The other thing Nova26 is did the shop that did the work remove the throttle bodies? Im not sure about these throttle bodies but I think the gaskets between the throttle boy and intake have to go on a certain way to allow the air passages to line up correctly. Not 100% that is the case, but I remember that from my days of working on the old TPI Vettes and Camaro's Firebirds

Advance throttles to 3,000 RPM and then shift. Report back! :drink: Sorry, just remembering my buddies back in the 70's with wimpy cars that wanted to do burnouts. Neutral drop!

Could be anything from TPS to IAC in which both are installed at the throttle body. Throttle linkage and or throttle cable - worn or adjustment off.. I would look into a scan to see voltage at the TPS within spec and IAC counts - 0 thru 40 - Throttle blade position also is determining factor for the IAC pintle position and counts.

Forgot the TPS is installed on the bottom in conjunction with the throttle linkage and the IAC is installed upper back side of the throttle body itself. Not that hard to see if they are connected.

What is your idle quality and starting the engines like. Hard starts and very poor idle can be linked to IAC. Poster never mentioned any of this. So ???? mark - how is starting and idle quality ?

I did notice it was a little harder starting they normally start right up. They do not light off as soon as you hit the key now. But I can't say it was bad. Idles smooth. I'm going to put some fresh gas and run it in the morning before dropping it off tomorrow. I really don't think the gas will make a difference I ran it into November last year with 91oct.

Will your engines accelerate in throttle only (not shifting into gear ) ???

Adding some info for whomever and a simple try for yourself. .

RVP of the gas blend itself. Its a big deal for boats. RVP has different blends in the spring, summer, fall and winter gas. It ranges in values from 7 to 13 + depending what part of the country and whether conditions that take place during.

I would take a portable outboard gas tank and new fuel line with current fresh gas - hook to inlet fuel engine side and the run the engines to see if anything changes. I say all the time you have to separate which side of the boat is the problem child.

RVP = Reid vapor pressure - google it, everyone just might learn something. It is highly taught in OEM Marine schools for the past 35 years. THE JIST - Winter gas blends do not lite off in hotter months and summer gas blends does not lite off very well in cold winter months. This is very common in my neck of the woods.


Also just went thru this last week - and every year from winterization time to spring commission - boat hard to start along with not so great ide - accelerate throttles - engine dies imnediately. Run motor on my shop portable gas tank and fresh gas - taking his fuel and tank out of the mix - motor runs great - throttles very well, sample his gas from his gas tank - looks perfect - no water (NONE) plus, I winterized the boat in DEC 100% properly and the complete fuel system.. Customer bought gas in DEC the day he brought me the boat. Its 85 degrees out now. Has nothing to do with E-10 and all to do with RVP blend value of the gas itself. Just saying because if you are not taught this whether it applies to you or not - it will someday, especially if you own a boat.

This is a broad post for everyone - and worth a try but I am not saying this is your 100 % problem. I see it a lot here because of our huge temp swings and gas blends that change at the pumps during different times of the year. it causes minor to poor to very poor engine starting and running conditions.

If you work on boats - A Portable fuel tank with a quality fuel line and primer bulb using fresh gas is a another tool in your tool box. I promise - it is a great tool for testing and problem solving.

Ok the story book is finished now. I have to go crawl back into engine compartments myself. Good luck

Does it die instantly when going into gear or does it struggle at all then die? You can safely bump the RPM as a test. carefully bump it to 800-900 RPM and see if it does the same thing.

IAC or possibly a vacuum leak are the obvious culprits.

No problem! For some reason I was really paying attention to where my 6.2 MPI's were idling. Over the winter I changed spark plugs and put in fresh IAC filters in the throttle bodies. The old ones were pretty dirty.

This was running on the hose with no props installed. What's interesting is I put them in gear, both forward and reverse, and for a brief moment during shifting the engines they would drop to 500 rpm then go back to 600 rpm (according to the SC5000 digital tach). Engines sound and run perfect and no sign of dying during the shift. I even saw it drop to 450 rpm once. The cam in these engines is sooo mild. Just another observation.

Update: I've been traveling with the MTI BatBoat attending the OPA races and haven't had much time to spend with the P-29. So this is where I'm at with it, did find the props were out of time, fixed that still dying. We put new IACs both motors cleaned the throttle bodies still dies. I've run about 300gal threw it everything is great but dying when put into gear. Someone mentioned to me that the motors are tired, but it was fine before we pulled them. They don't smoke don't use oil the oil is still clean. Fires right up and sounds strong. Motors have around 440hrs. It still runs 74mph with two guys cooler 1/4 tank and all the other junk in the boat. 76.6mph is what Power Boat Mag ran it in 1996. I'm trying to find my water ears now to try in on the trailer.

Simple Blower Surge..

Great advice if he had blowers:rolleyes:

I had 22 Donzi Blackhawk edition with the 502EFI doing the same thing. Turned out had to reset the timing.

Actually my point of jest was to add Blowers and then shift during the "up surge". Sometimes laughter isn't the best medicine..

Not familiar with the MPI engines but do they have a distributor? If so could the advance plate/springs be broken and the bump of going into gear wacks out the timing killing the motor? Used to have an older chevy engine that would run perfect other than the occasional stall or backfire (which was bad enough to blow off all vacuum lines) and after many hours found a broken piece on the advance mechanism.

Yes they have distributors. They do not have any type of springs in them. The advance is all electronic and in the module.

A friend of mine has a p29 with the same problem the iacs work fine and the timing is correct still wont shift right

I put water ears on the trailer today and gave them both a try. When you put both of them in gear there is NO rise in RPM. They both drop about 20RPM then back to 600RPM, there's no way you will kill it on the trailer.