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Help - 1999 johnson 70 hp 4 stroke

B

big dog

Member
Hello,:)

I bought a Landau Pontoon Boat with a 1999 70 HP Johnson 4 stroke From What I hear it was made by Suzuki) it will start and run rough idle but cuts out when trying to run it out.

The Injectors have been replaced, Plugs and Wires also and now I am looking for other culprits. I was told to check spark and compression (will do that tomorrow) also to check fuel pressure? Where do I hook up the pressure gauge? Also pumping the Bulb while running does not seem to help it run better.

When you turn the key on I can hear the electric Fuel Pump cycle for 3 seconds as the manual says it should.

Is there anyway to hook this motor up to a PC to get Codes? Also if so where do you hook it up and where to get the software???

Thanks for your help.

Wes
 
There are a few possibilities, but you may need the diagnostic software from OMC/BRP as well as the diagnostic cable between engine and lap top. At the same time get a factory manual.
I would then start by checking the IAC valve function which controls the idle.
.
 
Docksidemarineservices said:
I would start by changing all the fuel filters.
Click to expand...
Very cheap and the first place I would look. Since you just bought the boat it's a good idea to change these (and any other typical PM item) anyway so you know you're starting with a fully serviced boat.

Another thing to consider is if this tank has an antisiphon valve. Maybe the ball is stuck and is restricting fuel flow?

How old is the fuel? Maybe there's a significant amount of water in the tank and you're just getting poor combustion. Siphon some fuel out of the tank through primer bulb/fuel supply into a glass jar. Allow it to set for a while then see if there is a definite line of gas and water. If there is you will need to drain the tank and start with fresh, water-free gas.

KJ
 
Messing with this engine without a manual and the software is not to be recommended.
The one filter that most likely is 'clogged' if any, is the filter on the high pressure pump inside the vapor tank.
There are however some 'DO NOT TOUCH' items on this engine that one should be aware of.
The only adjustment that may be done, is the idle air mix for the IAC valve, and to be able to set that correctly one need the software. It may even be a 'hard' code stored that needs to be checked out.
 
Hi and Thanks for all your replies. I am a little new to the 4 stroke outboard, this is my first one. Can you tell me how many fuel filters I have on her and where they are located? Also I put new gas in the tank first thing so I know that one is OK. Is regular gas OK that is what I used or is Higher Octane better??
Anti siphon Valve is a possibility is it best just to replace it as to trying to test it? I am not 100% sure it has one but I will check it out. It is a built in tank on the Boat.

Thanks to you and Thanks everyone for the help.
 
Hi and thanks for your help with this motor. Can you tell me where the IAC Valve is and also how to check the filter on the high pressure pump inside the vapor tank.

Thanks
 
It is one filter (plastic in a clamp) and one 'screen' in the fuel pressure pump inside the vapor tank behind the intake manifold!
To access, remove intake and dismantle vapor tank.
The IAC valve is mainly an electromagnet located at the air throttle body. When the trottle is in closed position, is registered in the ECM by the switch at the throttle body, the IAC 'pulses' air to get the correct mixture fuel/air into the engine. It is however an adjustable by-pass for the basic air behind a rubber plug in front of the throttle body. Should if remembering right, be set at 25% IAC operation cycles by using the Diagnostic Software'!!
That is the only adjustment screw on the engine. (Valve lash exempted!)
Do not mess with the throttle body, remove the idle switch etc, they are 'preset by factory' and delivered as complete unit as spare part!!
(However amazing what one may do if knowing the system!!)
 
You need a special adapter to check the high pressure fuel system on that mtr. It was an OMC special tool and works really good with a pressure gauge.
 
The engine has two fuel filters, one in a clamp up front on the lower port side, a plastic unit, and the other is below the fuel vap. separator, below the lowest plenum on the intake manifold. Round black device with in and out lines.

The high pressure fuel pump inside the vapor separator is held in place by a bracket and one phillips screw. At the bottom of the bracket, there is a round rubber grommet that fits between the pump ant the bracket. This is the location of the screen that Morton refers to. I have had a few of these vapor separators apart, and the one screw that holds the bracket is always frozen. You must use a hand impact driver properly to get it out, or you will have to resort to bending the bracket to remove the fuel pump.

Also, in the bottom of that fuel vapor separator, under a metal plate, there is the fuel pressure regulator, a round can shaped part that is about 1" in diameter, and 1.5 inches long. If you have low fuel pressure at the injectors, this may be the cause.

The fuel pressure in the injector rail should be 36psi., and I would measure that first, before you do any disassembly of the vap. separator.
Three secs of HP fuel pump running immediately after power up is correct.

Hey Morton, please shed some light...is the spark on these outboards supposed to jump the 7/16" gap spec just as a two stroke should do? Is there a different spec?
 
daselbee said:
Hey Morton, please shed some light...is the spark on these outboards supposed to jump the 7/16" gap spec just as a two stroke should do? Is there a different spec?
Click to expand...

Have honestly never seen any specs for the 4-stroke sparks. The only thing I remember is they are a lot 'weaker' than the 2-strokes. The only ignition 'part' that caused problems on the 40/50/60/70 4-strokes were the spark plugs (NGK 'R'), that failed much more frequently than on 2-strokes. I even had cases where I crosschecked plugs that 'failed' on the 4-strokes, but 'worked' on the 2-stroke/tester??? This even could happen with brand new plugs. I used a timing light with rev and dwell incorporated and had a pick-up with 'high/low' setting. Gave me the possibility of testing primary to coil using the 'low' setting and when testing coil to plug I got reading in 'low' setting but not 'high' setting - time to change coil! It had spark, but not a proper one.
When putting engines into storage with electric pressure pumps etc, I always ran them with the 'Ficht' storage mix with 2+4 and Fogging Oil added and never had any fuel problems.
These 'new' generation of engines are great when working, but now a lot of them are getting into age where problems starts. Fault search and testing in a proper way in most cases force the owners to 'authorized dealer' with the proper equipment. The old ways may still work, but one has to be a bit careful and systematic.
 
Thanks very very much. I have one (an abused one) in the shop now. Not stored properly, bad, old gas in the HP fuel pump, clogged injectors, compressions at 125, with #4 at zero...(should be 200 on the four strokes)...bad shape.
The bad compression is due to a needed valve job.
Anyway, thanks for the answer.
 
This is what we found today. To resolve the possible bad gas and also a possible anti siphon valve fault in the tank we used a portable tank with Fresh Gas.

Checked the Fuel Pressure it was steady at 39 PSI.

The Spark was Good and I put new plugs in while I was on that. The Neutral Safety Switch is in the right place and checks correct with continuity test also.

The IAC valve appears to work correctly.

The Computer Software my tech has was too new.. They said the software he needs is on a Floppy Disk thats OLD It sounds like. The New Software for OMC would not talk to the motor. He is checking to find a old version.

He feels like it is some sensor or worst case the computer. I am not sure what sensors are on that motor and computer is an Indian word for Expensive.

The Motor starts when given some throttle and runs fair idles pretty good we put it in the lake and it ran out fairly but not perfect to about 3300 RPM and that was it. It still is a bit hard to crank and its not right yet but it seems to not be the Fuel Pump and its not the fuel. Its getting gas and spark but its like a sensor is not letting the air get right. No Vacuum leaks were obvious.

Any thoughts? Also thanks for all your help from everyone chiming on on this.

Wes
 
If your engine does not run above 3000 it may be 'locked' in SLOW.
It may however even be the switch in the throttle body indicating engine in idle, it may be the switch on the gear lever indicating engine in neutral.
 
So is it a possibility there is some stored code or sensor reading that is messing up the ECM? What would happen if the battery was disconnected to clear the volatile memory and any stored codes?

Big Dog,
When you say "It still is a bit hard to crank..." do you mean that the starter spins the engine fine but it is not firing? Or, do you mean the engine seems to be cranking slowly? I wonder if a weak battery could possibily be causing electrical funkiness?

These are just general ideas I'm throwing out since it seems like you're grabbing for straws now.

KJ
 
KJ The battery is near dead we had to use a jump start to help it start. The engine starts with some throttle after it turns over slowly but with jump box starts quick.

IS there anything that could cause the engine not to run out right if the battery is not good?

Thanks
 
Codes may only be read and deleted with the diagnostic software.
If voltage drops below about 10,5Volts during cranking, the ECM will 'shut off'.
 
haffiman37 said:
Codes may only be read and deleted with the diagnostic software.
If voltage drops below about 10,5Volts during cranking, the ECM will 'shut off'.
Click to expand...
Got it. I wasn't sure if the ECM on these were similar to automotive ODB II and disconnecting the battery would clear the volatile memory.

Given Big Dog's answer about needing to jump the battery, I would suggest having the starting battery load tested (after a full charge) to determine if it's good. If you have a weak/dead cell the battery can show 12V in a resting state, but as soon as you start cranking the engine the voltage plummets. So, as Haffiman has stated regarding the ECM shutting down below 10.5V , if your battery is in poor condition it's possible you're losing spark during cranking because of low voltage.

I don't want to predict a miracle here, but I'd bet a new, fully charged battery will work wonders for your engine.

KJ
 
Thanks for the tip KJ....The Boat is at the Marina with the Tech looking at it I called him and told him to put a new battery in it and call me with the results. Hopefully Monday I will know something and post back. The Battery is pretty dead. Fingers Crossed. Worst Case it needed one anyway.
 
Hi everyone. Hope you all had a great weekend.. It was 84 and Sunny in Alabama Sat and about the same Sunday. We were dry docked with the boat in the shop maybe a few of you got out to fish and cruise.

Does anyone on here know where I can buy, borrow, beg a copy of the Older Johnson Motor Software for this motor?? Every shop that was supposed to have it had it on CD and it is too new won't talk to motor. Someone told me that it was on a Floppy Disk from that year model 1999.

Any help please share. Thanks in advance.
 
If not totally mistaken, ou may use a Suzuki software for the same engine. Only difference is the diagnostic cable connector.
The ECM is a simple Mitshubishi unit and I know even some of the Mitshubishi software's 'crack' it.
One 'problem, you need a comp wit access to DOS, XP or earlier.
 
Hi, I Finally got the software hook and connector I am getting 2 codes 1) Crankshaft Position Sensor and 2) Cam Shaft Position Sensor these are the 2 codes I am getting the tech said this is as odd as he has ever seen with both of them coming up and he is thinking it might be the computer.. Any Ideas??? Thanks in Advance. Wes
 
Can you tell me how to go about checking the belt. We put in on a timing light at one time and I was thinking it was right on. Also the motor acts like the timing won't advance.

Thanks.
Wes
 
Take off the plastic top cover.
Turn the engine to TDC, top cyl fireing.
Its should be a mark on the belt-wheel on crank shaft pointing straight on a similar mark on the cam shaft wheel.
Be sure the belt tension is correct!!!
Check clearance of both sensors and everything is clean from belt-dust.
I'm a have no books and not access to the specs, so I'll advice to get one FACTORY manual!!!
 
Hi and Thanks for the info I have an update..... I installed the New Battery and got the boat back from the tech he kinda gave up on it but did try a lot of stuff. The codes that we got was Crankshaft Position Sensor and Cam Shaft Position Sensor and I was thinking timing but the marks are lined up. With it on the DIAG Software it appears not to advance past 5 degrees? Does that mean anything is failing? Anyway I decided to take the boat out and run it as I have not done so yet. It started quick and idled ok little rough. I putted around at maybe 1200 RPM for a few minutes and got it to running much smoother. By now idle was so smooth it seemed to not even be running but was. It would bogg and shake a bit if you opened it up and as long as you bumped it up just a bit at a time or pulsed the throttle Like open up and pumping back and forth it finally climbed to 3300 rpm and 14 MPH. It ran here smooth for 15 mins till I slowed down. I was never able to "baby" it back to 3300 RPM After that but it ran 10 MPH at 2200-2300 smoothly. I ran it for about 2 hours and the longer it ran the smoother it got. At the end of the trip it was idling smooth as a new motor and would throttle up to 2000 rpm like it was a new one but still when you trie to load it up with throttle it Bogged and Popped a bit like a small back fire some of the time.

My observation is that it ran better the longer it ran I kinda feel like this is a Fuel / Air thing not electronic.

Anyone got any info that may help I really appreciate the time you all have taken to help with this. Also I mis-quoted the year this motor is a 1998 4 stroke JOHNSON (SUZUKI).

Thanks.

Wes
 
Your engine may have 'locked' in an 'emergency' mode.
This may happen if some of your sensors partly fails.
Was the codes for CPS and camshaft 'hard', meaning permanent, or could they be erased and did not re-occur?
The 'popping' is due to you opening the throttle and giving more air than the engine gets fuel = running lean!!!!
Try first to remove the faulty sensors, clean all ground connections, re-install the sensors and test again.
If no change, replace the sensors!
 
Hi the codes are Hard I guess as you described we deleted them and then they cam back on the next test. I will try the removal of the faulty sensors, clean all ground connections, re-install the sensors and test again and as you suggested change / replace the sensors if it comes to that. If the sensor is bad and I replace it will it come out of the locked mode or is that require the computer again? Thanks
 
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