1993 2.4 Engine Woes..... LACK of POWER

[lakesmodified]

Ok guys I'm really pissed and starting to wonder if I got taken on this deal I aquired. I traded for this 1993 Advantage Banshee with 1993 Mariner 2.4 with many mods, including "Old" style race injection. Light-weight flywheel, N20, etc. Anyways, due to the purchasing of another home and other priorities, I hadn't had the opportunity to take my boat out for a run. Well, I went out for the weekend early Saturday morning, and after driving for over three hours to get to Smith lake in Alabama, I had the misfortune, of having one of the lousiest days I've ever had on the water. The engine fires right up and idles fine, but when you put the lower unit in drive and step on the accellerator pedal, I get a lot of nothing! The RPM's just don't climb as quick as they should, and they stay at approx 3000-3200 RPM until after about 20-30 seconds, then they start to climb. It's like the engine doesn't have the power available to spin the 28 cleaver out of the hole. Once it finally starts running, then it "Sling-shots" and will run up to approx 7200-7500 RPM. It definitely isn't cavitating, because if it were, the engine would just rev. This thing is running like it just doesn't have any power available. My buddy and his open bow 18 FT Sea Ray with 150 Merc power, can pull away from me and get about 75 yards ahead of me, before this engine starts to wind out! What I don't understand, is that when it finally "opens" up, you can back off, and then mash the accellerator pedal again, and the power is there. But go back to a complete stop, or idle, and the whole thing starts over again. The other problem I had, is when it was running at speed, I can only run it for approx 4-5 mins, and my over heat alarm will sound. I was checking the water pressure, and it barely got above 12 PSI(I know that's too low) It's set up with the low water pickup nose cone. Standing still at idle, it has approx 5 PSI with plenty of water coming out of the discharge hose, so I would imagine the impeller isn't the problem with the low water pressure? The centerline of my propshaft is approx 1.5-2" above the bottom pad of the hull, so I immagine I need to drop the engine for the water pressure problem? But I was so disapointed with the output of this engine, that I put the rig back onto the trailer and spent the weekend on the Sea Ray. I will try and get some compression numbers in the next day or so.. All along, the engine seemed to run smooth though... ie.. not rough like it was missing on some cylinders.... Damn, my first outboard, and I'm already having trouble and second thoughts about getting into them... Some one please help! Thanks in advance. Ivan

[Dave S]

That your trigger wire is holding back, sometimes they get hard with age. Pull off the throttle cable while motor is not runing, and work the arm from slow to fast and see if the upper arm is getting rite to the stop screw. If the motor has been sitting around you should put in a water pump,they get week and check the gasket under the plate, they can cause probs.

[Alan Power]

Ivan, I'm having a very similar problem. Still no luck finding it yet though.

My thread;
http://forums.screamandfly.com/forums/showthread.php?s=&threadid=60775

Another good thread;
http://forums.screamandfly.com/forums/showthread.php?s=&threadid=8955&highlight=testing+switchboxes

[lakesmodified]

Alan and dave, thanks.. unfortunately, I'm completely NEW to OB's, and EVERYTHING is foreign to me. Trigger wire? I do know what the switch boxes are though... Of course, I have no idea how to actually check them. I will be buying a manual within the next couple of days, but for now, I was hoping for that "Magical" fix from some one that knows these things like the back of his hand. I guess my worst fear has materialized... I know that OB's run hard and are normally trouble-free, BUT it's time like these, when they're not operating correctly, that can get extremely expensive rather quickly. Is there anyone on the Memphis area that can help me out? Thanks, Ivan

[Alan Power]

Ivan, I'm only getting to grips with outboards too, but if you want to learn your in the right place.

To explain what Dave S meant
On the port side of your engine remove the throttle cable while the engine is not running. Push the lever I have marked 'push' untill the limit screw hits it's stop marked by the two arrows.

[lakesmodified]

Dave, OK, so I move the throttle arm until the arm contacts the stop, but what am I looking for at the "trigger"? and where is the trigger? I was reading your posts, and I noticed you have a rough idle as part of your problem. Mine idles as smoothly as I could expect, just doesn't accelerate past 3K. The boat just sits there pushing a wall of water, until it finally starts to plane and then the engine slowly accellerates until about 5K, then it sling shots up to 7500... I sure miss my blown BBF jet boat!

[Dave S]

That bigblock will accelerate like no outboard. :eek: To get your outboard to break free migth take some getting used too. If it's a real tunnel the water washs the prop real good and with a big prop that can be hard to break loose. I wiggel the wheel back and forth to break loose, that may help. Also check your total timing. Alan Power gave a good pix but push the lower part of the arm and watch the top part, the top should get rit too it, no hesitation.

[MercNovice]

The trigger is the pick up coil that is under the flywheel. It rotates when the throttle opens advancing the timing. You will be able to see the wires coming out it going to the switch boxes. These wires should move when you advance the throttle. Looking at the pic of the motor, and that you can hit 7500 rpm, I would say that it's been tuned for top end, not low end torque, with two strokes you get one or the other. A 28 is a big wheel to spin, when starting try making a turn to lean the boat on a side, this helps clear the prop and picks up the rpm's once you hit the power band straigthen out trim it up. Turning a 28 and hitting 7500 rpm's tells me your motor is puting out some serious Hp.

[lakesmodified]

OK guys, trigger mechanism checks out good. Disconnected throttle cable and actuated throttle arm through entire range of motion, the trigger mechanism is tight(No slop in the connections) and it moves the coil through the full range of motion... Tomorrow I will buy and install some new plugs, but unfortuntely, I can't take the boat out for testing until next week at the earliest. What next? A few of mentioned about the prop pitch and lack of torque on an OB, BUT I really doubt this is the case. This engine as ZERO holeshot out of the hole! You can step on the hotfoot, and it will take upwards of 30-45 seconds before the RPM's start to climb past 3000. Yet, once they reach the 4500-5000 range, they sling shot they're way to 7500 RPM... HELP!!!

[outboards4life]

try different engine positions. mess with the jack plate, up or down, play with the trim a little. My 21 Daytona v8 did the same thing your talking about when I first got it. I had the motor down way to far. its not like a vee hull. try bringing the motor up a little. It made a huge difference for me.

[lakesmodified]

OB4Life, thanks, but the engine is actually at the top of the jack-plate(Centerline of prop shaft 1.5-2" above the bottom of the pad) As is, once I'm turning top RPM, I'm only getting approx 12 PSI water pressure.

[mendo]

Sounds to me like the exhaust chest is way hogged out.

Kills the bottom end, breathes hard on the top.

[Talon2.5]

wow thats the old downdraft EFI, havent seen one of those in a while!!

did ya do the compression test yet?

check each plug wire for fire with a timing light, ya may have one cylinder down, could be coil or switchbox, i built a motor for a friend of mine, he got it all together and called me after a day on the lake......... plowed like a truck when he ran it, he brought it to my house so i could check it out and the number 5 cylinder hadnt fired a day in it's new life, it was the switchbox

sometimes the low side of the stator will cause that to

checking the trigger travel was a smart thing to do, that also causes that kind of dilemma

the other thing that comes to mind is the TPI (throttle position indicator) the old ones were mechanical and had a perameter setting that if it got outa whack could cause a bunch of grief, the newer stuff has digital ECU's so the old mechanical TPI is no longer used

this TPI stuff can be tough to mess with for a novice on outboards so i suggest if all other stuff checks out you get the ECU and TPI checked out at a shop that has the tools, you may end up going digital if any of that checks out bad

tony brucato is the EFI guru here on S&F

it does sound like something small, but ya never know till ya get things checked out and eliminated as suspected problems

[ChrisXS2003]

That sounds typical for the way a cleaver runs. Try a 26 ET or roundear.

How much does the boat weigh as tested.

[tozlakes]

3 things!
Verify that you low end stator is putting out, Supplies power to the ignition coils from 0-2000 rpm.
TPI's can definetely cause this type of problem.
Eliminate TPI and ECU as problem by sending ECU and $500.00 to Rapair 1-800-467-3371 x.226 to have them change out internals to digital. This eliminates the use of the mechanical TPI that your motor has along with fixing possible ECU problems. Don't give up on outboards just yet. Once this problem is solved you'll never go back to a lousy pump!

[lakesmodified]

Unfotunately guys, this is my weekend to work, so I won't be able to do any T/S until my next day off(Monday) I realize the Cleaver type props aren't quick out of the hole, but what I'm experiencing(out of the hole) is the acceleration of a 9.9 HP outboard! The boat just drags in the water for quite a while, as even an old aluminum 16 FT boat with an "OLD" Johnson 40 HP, can blow me away for the first 75-100 yards! I'm sure this isn't "Normal" for an outboard, regardless of prop! I haven't done the compression check, and I'll also check the firing of each wire when I'm doing the compression check. I'm going to buy a new set of plugs, because I noticed a few times, while running between 6000-7500 RPM, a slight miss from time to time. I figure I'm losing at least one cylinder at lower RPM's and it comes back intermittently at the high rpm's. Now as far as my ECU goes, I have no idea what's been done to it, BUT I do know that it has a "Rapair" sticker on it, as well as some writing on it by them as to a serial number or maybe indications as to the mods. As soon as I have a couple of days to play with it, I'll get all the info off the ECU and try and get some info on it from RAPAIR. How do I verify that the low side of the stator is putting out power to the ignition coils? Thanks again, Ivan

[Talon2.5]

heres a link to a past discussion........

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=54372&highlight=checking+stator

i did a search for some old scans i did of the merc manual stator test, i knew alot of people downloaded them after i posted them and i have a new computer now and havent loaded the scans back in this one yet, i found them in this post............

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=53980&perpage=15&highlight=stator%20test&pagenumber=1

[lakesmodified]

Talon, thanks for the T/S info and hyperlinks.... Hopefully I can get to it Monday, and run some checks. I've just been so damn busy refurbishing a house we just bought, that I haven't had any free time for the boat. Ivan

[lakesmodified]

OK guys here goes... Unfortunately, my online server "Roadrunner", has been down for two days so when I was off yesterday, I couldn't get online to check what some of you had written about T/S my problems. I was only able to accomplish the basic T/S yesterday afternoon. Here goes:
First I did a compression check: All cylinders were between 125-132 PSI. I then ran the engine with three "Inline" spark function jumpers(To check spark at each cylinder) I ran the right bank and then the left. All cylinders are getting spark. I then removed one wire at a time and checked for RPM drop, hard to tell, but it "Seemed" that # 6 cylinder wasn't causing any change to the rpm. I did noticed while I was running the engine on the hose, that between 3000-5000 or so RPM, that the engine seems to be running a little rough. It accelerates smoothly from approx 1000-3000, but then it becomes rough (Definitely not as smooth) from 3000 on. It feels like it isn't advancing as quickly. While running at idle, I looked with a flashlight up into the offshore exhaust housing and found water squirting down the copper supply line from the top area(Can't look exactly where it's coming from, but I think this might be the reason I wasn't getting enough water pressure? I believe there's an "O" ring up there? One of you wrote about the TPS sensor, I did notice that there is one installed on this engine, so as soon as I can find where my problem lies, I guess I'll send my ECU to RAPAIR and have it changed out to digital. So where do I go from here? Thanks, Ivan

[ken medendorp]

I would put a new set of injectorrs in it My 1990 2.4 bp would runn ok at first but when it starting to get warmed up I had a some injectorsthat were not operating correctly put new ones in and it ran perfect

[Talon2.5]

pull the fuel rail off and disconnect the wire to each injector and fabricate a wireing harnes for the injector thats connected to 9 volt battery

turn the key on so ya have fuel pump running and connect that 9 volt to each injector one at a time (that will fire the injector) and check to see if it sprays right, drips, sticks and doesnt spray etc.

replace as ken said

[lakesmodified]

So you guys are thinking it can actually be fuel related versus electrical? All along, I figured electrically related, possibly the trigger itself, since it seems like the ignition might not be advancing(At least that's the way it would rev were it an inboard engine). I'll have to check out the injectors as you stated, but I was wondering: If the injectors are at fault, would the engine still rev to 7500? What keeps the injectors on the rail(From popping off)when you remove the fuel rail and have the fuel pump running?(While checking the operation of each one?) Thanks again, guys..... I'll be checking the injectors next. Ivan

[tozlakes]

Dont feel bad. I have the same low end problems but with twin 2.4s hanging off the back of my 21ft Daytona Eliminator. Close to 600 HP and I can't get the thing on plane. Both of my ECU's are on there way to Rapair for the digital mod, removal of the rev limiter and TPI's to the garbage can. I'll keep you posted on my results. As for your water supply tube you need to drop your lower unit and pull the copper tube from the power head. Its not uncommon for these tube to leak at the point where it plugs into the powerhead. I usualy seal mine with a little sealant being careful not to get any on the inner tube. Also look for splits in the tube at the seem. The lower portion uses a rubber disaster bushing to help "control" leakage from the pump connection. They will leak no matter what from this point. The key is to control excessive leakage.

[tozlakes]

Remember that the ECU can directly effect fuel delivery through the injectors. If you decide to rework your ECU this will at a minimum eliminate the signal from the ECU to the injectors as a problem. In addition, the elimination of the TPI when you digitalize the ECU will take the TPI out of the loop as a culprit. I agree that the injectors should also be tested using the recommended method in the Merc manual. I would think this would include the step of disconnecting your injectors from the ECU as to not back feed any voltage to the unit before suppling power to open each injector? Only 9v but play it safe!

[Talon2.5]

sounds like after re-reading what you checked as far as spark, you checked it with it running?

i like to check it with all the plugs out, fresh battery, one wire at a time and pull the throttle arm slowly all the way from idle to full throttle while the motor is spinning to see if a cylinder drops (or comes in) and use a spark tester or a timing light, you can have a buddy turn the key for you, or what i do is hook up a remote starter switch to the solenoid with the key in the "on" position, this lets ya go through the whole throttle sweep without actually having the motor screaming on the hose

check the max throttle timing, should be at 25 degrees

the tpi (throttle position indicator) you say is on that motor, is it on the butterfly shaft on the starboard side? if so it sounds like the old manual TPI and that alone can cause alot of grief if it gets outa whack sending the wrong info to the ECU, i had one on a bridgeport 2.4 that got outa whack so bad it caused all kinds of grief, i switched it out with the later style black box, then they came out with the digital, rapair can fill you in on the way to go with that, but be sure through meticulous checking that the electrical is in fact working right so you can move on to other parts of the motor with confidence that the electrical is operating correctly

check to be sure by having someone in the boat (motor off) pushing the throttle to wide open and see if the butterfly is wide open on the intake, being a downdraft style you may not be able to see up in there so if you cant, take a marker and put a line on the end of the port side butterfly shaft horizontally then when ya hold the throttle wide open it should be vertical

usually if the stator goes bad either high side or low side it wont "clear up" and go, it usually just doesnt work

the injectors can cause grief if their "sticking" or "dripping" so if there dripping and not totally closed it can cause a rich condition and if there sticking it can be either stuck open or closed and both can cause alot of grief so checking the condition of the injectors is a good thing

take your time and be thorough on everything you check, usually whatever it is will show it's face if ya pay close attention to detail

however, check this story out...............

we did have a motor one day out on the lake (2.4 carbed) that plowed like a truck took awhile to get on plane, didnt sound crisp, so we stopped at the dock and checked spark by pulling all the plugs and then grounding them one at a time then spinning the motor with the key and had spark on all 6, well we started to suspect the stator and got to looking at what we had to do "out on the lake" we were standing in the water drinking a beer not all that ambitious and decided hell, lets change the switchboxes first they are the easiest thing to do out here on the water (even though they had fire on all 6) well........once we changed them with 2 boxes that were at the house we were docked at......she planed right out and never looked back ;)

some of that **** will fool with your head :rolleyes:

it says in the manual.........

intermitent, weak or no spark at TWO plugs (one from each bank) is usually caused by a bad trigger

intermitent weak or no spark at THREE cylinders ( a complete bank ofcylinders) is usually a bad stator or switchbox

intermitent weak orno spark at at any one cylinder is usually a bad coil or switchbox

hehehehe they need to put in there even if ya have spark change the switchboxes hehehehe

went out to the garage and got my old 2.4 book and in the book on injected motors the troubleshooting chart says.......

poor acceleration-idles ok, top speed ok......

*improper EFI setup
*water covering idle relief exhaust slots
*TPI failure
*MAP sensor failure
*RFI problem (thats for digital ECU's)

and...

engine surges between 4000 and 5000.........

*intermitent switchbox failure
*final filter clogging
*TPI improper adjustment
*injector connector problem

and....

engine down on power or RPM.....

*failed switchbox
*failed stator
*failed coil
*low compression
*broken reed
*fuel delivery problem
*manifold fuel leak

[Rickracer]

...why not go ahead and send them to Tony Brucato, Brendan Power, or Kinsler and have them cleaned and flowed. Then you can forget about that as a problem, and be sure you won't have any problems with them for some time. If an injector stops flowing fuel at speed, kiss that cylinder goodbye. :eek: Checking them with a 9V battery will tell you if they are spraying, and if they shoot a decent pattern, but it won't tell you how well or how much. If you have any doubts, send them out and have them checked, it's cheap insurance. Also, once they are flowed, you can put the highest flowing ones in the leanest cylinders. :cool:

[Talon2.5]

heres a good thread of answers from tony....

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=42983&highlight=injector+test

another with flow suggestions.........

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=10539&highlight=injector+test+procedure

http://forums.screamandfly.com/forums/showthread.php?s=&threadid=28921&highlight=injector+flow+test

theres alot to read if ya type in the search injector flow test

[lakesmodified]

Tozlakes, Talon and Rickracer: Guys, thanks for all the info, but to say the least, I find myself completely flabbergasted with all the possibilities. Bottom line, faced with the symptoms I've described, what would you guys do next? Yes, I will get my injectors flowed and replaced if needed. Yes, I will get the ECU modified for full digital operation to do away with the TPS, but right now, it's Summer, and I would like to get this boat running, before the entire season passes me by. Unfortunately, we don't have a High Performance capable Mercury dealer in my area, if not, believe me, I would bite the bullit and get it repaired. I normally would do all of my mechanical work, but Summer is here, and I don't want to spend the entire season T/S this problem. I plan on carrying out some in-depth T/S on my next days off, and would like to have some course of action as well as direction. Talon, I did in fact check the spark while the engine was running. I will do what you said next: Pull out all the plugs and while spinning the engine check each wire for spark, while actuating the throttle. The TPS is on the throttle shaft, starboard side, just as you mentioned. I would imagine that the TPS can be checked just like on an automotive engine, by disconnecting the leads and checking the resistance along the full travel. It should move smoothly without any jumps or drops. As far as the switch boxes go, is there an actual way to check them? I would hate to run out and spend the money in order to T/S their operation. If things weren't screwed up enough, my online provider (Roadrunner) has been down for 4 days now, so I can only access this website while I'm at work. Again, many thanks... I'll keep you guys posted. Ivan

[Talon2.5]

myself, if it were mine, the first thing i would do is change the switchboxes, but thats me

[lakesmodified]

After re-reading the following: went out to the garage and got my old 2.4 book and in the book on injected motors the troubleshooting chart says.......

poor acceleration-idles ok, top speed ok......

*improper EFI setup
*water covering idle relief exhaust slots
*TPI failure
*MAP sensor failure
*RFI problem (thats for digital ECU's)

I have a few questions: What does it mean by water covering the idle relief exhaust slots? I have an offshore exhaust housing, any relavence? Is the TPI the throttle position sensor(Indicator?)
Are both the MAP and RFI problems only on digital ECU's?
After reading this paragraph again, I keep wondering about that throttle position sensor... I definitely will check the resistance on it asap... Would be nice if that were the problem..

[lakesmodified]

Aren't we talking about $250 for the two? Just hate to start T/S by replacing parts. Don't get me wrong... I would gladly spend the money in order to get it repaired....

[Talon2.5]

dunno how much they are i always have spares ive picked up cheap along the way

ive seen 2 boats plow like a truck and there were 2 different end results of diagnosis but came down to the switchboxes, saw another that acted like fuel and it was a switchbox, then saw the same one do some **** that seemed electrical and when i went over to his house i found 3 injectors bad

tough to say man, just gotta dig in and bear with it ;)

[lakesmodified]

Talon, I will go ahead and "Bench" check the injectors just to make sure the spray pattern is the same. I realize this won't tell me the flow, but on automotive FI, once the flow deteriorates, the spray patterns shows it. I'm sure it's the same here. How many different switch boxes are there? Would switch boxes from a smaller V6 Merc work? Just asking because I do a have a friend with a carbureated 150... Damn, I need to get this thing running...

[Talon2.5]

borrow the ones from your bud and give them a shot and see if she planes out ;) :D

[Talon2.5]

i'm at home now and looked up some part numbers for ya...........

downdraft EFI serial number OA168043 and below.......

switchboxes.........

2.4 EFI part # 7778A3

injector.......
part number 98818

injector seal.......
part # 94219

injector grommet.....
Part # 99123

the TPI for yours is part #11199A2 (not made anymore)

sensor on top of air intake is #96718A1

injector harness part # 98866A1

Newer TPI (not digital, black box) #17814A7



the MOD VP switchbox number carbed or EFI is....7778A4 (incase ya wanna know)??

i do have all the part numbers for that downdraft motor if ya need them ;)

switchbox part number for that 150 you mentioned is.......7778A9

[lakesmodified]

Talon, damn that's alot of info... Where can I get a copy of the software with all the p/n's? Is there any difference in the swbox's? I noticed they're all 7778A* I take it my originals should be 7778A3? One other thing, my ECU has been modified by RAPAIR, but I have no idea what was done to it. Do they keep a record of mods and work done to ECU's by serial #'s ? It also has an adjustable fuel curve with an adjustable dial at the drivers side... All this was done way before I acquired this boat.

[Talon2.5]

yep your switchboxes are the A3

dunno about rapair keeping records, you would have to call them

i may be wrong but i would lean toward the switchboxes, those damn things cause more grief than anything on the mercs, the other is the stator

[Dave S]

I think the parts are the same Merc just adds a 1-2-3-9# whatever when theres an update. I think the injectors would be a good starting point, and safe too. Keep asking for HELP here, you'll get it.

[Talon2.5]

i would think it has to do with highRPM electrical frequency on the switchbox part numbers

the higher reving motors i suspect would not perform as well with the standard box part number

just my "educated guess" there

[lakesmodified]

I wanted to thank all of you that supplied all the info for T/S the lack of power on my ride. I finally called Sean at RAPAIR, and he was thinking a Stator problem, so I was getting ready to check the output of the coils on the stator assy when Sean mentioned a guy by the name of Dennis Hoffman at Ultra Performance just about 10 miles away from my home. So I decided to give this gentleman a call, to see if he was willing and could fit me into his schedule. First I would like to say, that he was willing to take all the time necessary in order to hear everything I had to say about my problem, and then took time from his busy schedule, in order to talk to me about my engine/boat. This guy is truly ONE OF A KIND in this day and age of money making mongers. He was genuinely interested in my problem, and was willing to get right on it. I'm glad to say that he was able to trace my problem to a faulty wire/terminal connection coming from one of the low speed coils on the stator. This guy could have easily sold me a stator, but instead, he repaired the connection, and called me to explain what he found. If any of you are in the Memphis area, and are in need of an outboard mechanic that can T/S and repair, as well as build complete high perfomance engines, this guy is your man! If anyone would like to contact him, he can be reached either at 901-853-0602 or on his cell phone 901-277-2151 Tell him Ivan sent you..

[Talon2.5]

SWEET!! glad to hear from you on what ya found wrong with it and glad to hear your up and rippin!!