johnson 110ph wont rev over 2500

[8uzz]

Hi everyone my name is Craig and I am in real need of some expert help.

My cousin and I bought a Nova Craft Half Cab with a Johnson 110hp outboard on it about 3mths ago for $5,000 it?s our first boat. It?s really turning into a dog of a motor, at full throttle in the water will not rev over 2500rpm... (first time we took it out we were at 2000 then 1500 now stuck on 2500)

We have taken it to two marine mechanics several times and have already spent way too much on the motor we are at the point now where we are thinking of selling it for whatever we can get for it and count our loses. I thought might just try one more time to work on it ourselves with help from you guys if possible....

What I can tell you about it is as follows:
Motor ? 1989 (I think) 110hp Johnson v4, vro - (been taken out running oil in fuel) , serial number AJ110TXC,
Compression 100 110 110 120 ( I?m not sure but have been told its bad )
Rectify regulator replaced (when we went to buy the boat, the owner had connected the battery on the wrong way we think and stuffed the r/r, was smoking as soon as it had power going to it. So replaced and seems to be fine)
Brand new battery
When the motor is running the battery is charging at 13.4v
New blub and fuel lines (fuel tank works fine)
Sink and link has been done timing is good
New spark plugs (was running on only 2 piston but worked out that was because someone had hooked up the coils wrong and the timing was jumping all over the place)
New leads
Have done piston drop test and they all are running right, all pistons have good spark
Temp sensors - the wire of the port side has been rip out the other one is fine, when grounded they both will set off alarm
Have been told by mechanic that S.L.O.W is not fitted on motor??
Our next step we were thinking of getting the carby rebuilt and jets cleaned out, just not sure if we should spend any more money on it......... or just get a can of petrol and watch it burn!!!!
I don?t understand that when in natural I can rev the motor up past 2500 but when in the water it won?t........ Any help or advice would really be appreciated. Thanks!!!

 

[Faztbullet]

Clean/rebuild the carbs and yes they will rev up fine with no load on the motor...

 

[emdsapmgr]

The compression on that engine is just fine. The 13.4 volts when charging indicates the rectifier/regulator is working normally. The SLOW (rpm limiting) overheat feature came out that year and was on the single power pack engines, but not on the crossflow family of engines-like yours. (was only on the V6 and 120/140 looper V4's) That engine will easily rev to high rpm's when sitting on the trailer, even if the engine is only running on 2 of the 4 cyls, so that's not a valid test. You have to be under load in the water to determine if it's able to make full hp. Keep in mind that the engine may run just fine when cold, but not when warmed up. Weak ignition components tend to fail, once the engine heats up to normal operating temps. So, I'd start your testing by checking for good spark when the engine is warmed up and the boat is in gear (you don't have to run it on plane do this test,) in the lake. Take the cowl off. Have a buddy drive. Hook an inductive timing light up to each plugwire, look at the light in the gun. The flashes from the gun should show, strong, bright, rhythmic flashes from all 4 plugwires. It will also show misfires, weak firing and no fires. A simple, easy test. Keep in mind that these crossflows can have problem with spark jumping to ground on the two bottom plugwires. If they are run close to the bottom cowling latches, the spark can ground out on them when the cowling is on. You may be able to check this at night-in the dark. If the spark looks good after warmed up, then I'd start looking at the carbs-the more time-consuming job. Depending on how the boat has been winterized over the years, there could be some dried up fuel gel clogging some of the main jets at the bottom of the carb bowl.

 

[8uzz]

hi guys.... i took the boat out yesterday, i got a timing light and fuel pressure gauge from ebay..... I took the cowling off started her up and took off to test all the leads had good spark with the timing light ....... crazy thing happened, it went up to 5000rpm .... i put the cowling back on, and would not rev over 2000rpm.

 

[Bosunsmate]

did you pull a lead off when putting the cowling back on?
If a base gasket breaks then exhaust gas can leak in to the engine area and suffocate it with the cowling on

 

[8uzz]

no didnt pull a lead off...... yeah ill check that one out exhaust gas leak and lead grounding out on the cowling mount this weekend. thanks!

 

[emdsapmgr]

You may not have pulled one of the lower spark plug leads off the plug, but if the plugwire is not routed properly (gets too close to the two lower cowling latches) the wire can ground out on that latch. Esp when the upper cowling is installed. I've seen engines starve for air and not run properly with the cowlings on. That engine ingests air in two places: the vents in the upper cowling and the lower cowling vent just under the bottom carb. Make sure both of these airways are completely clean/clear or the engine can starve for air when running higher rpm's. (You'd be surprised what mice can cram into open spaces when stored in a barn all winter....) Checking for an exhaust leak is a good idea. Usually a leak is accompanied with a visible leak of black tar at the bottom of the engine block. It will run down the midsection, visibly.

 

[8uzz]

hi guys took the boat out today, and yeah it turns out that its earthing out on the mounts i tried hard to move the leads away from the mount but its still doing it. im not sure what to do the cowling is pretty tight on there.

 

[racerone]

??------Replace the sparkplug leads and boots.

 

[emdsapmgr]

The factory uses special wire holders to direct the spark plug wires away from potential grounds. You can look thru the factory exploded parts diagrams at the factory site: epc.brp.com. Check out various years' hp parts lists. For your 110 hp engine, for instance, there is a metal clip, part number: 309322 which may have a rubber tip and will hold the spark plug wire in a specific orientation. Also, check out part number: 310493. This one is longer. They can be bent to conform you what you want.

 

[8uzz]

No Title

ok thank you, they are brand new leads............... i ordered the clips. looks like in the photos i have seen on the internet, the same as my motor the top two coils are facing the other way around, might try that......... ive been having trouble with my steering as well its really tight and dose not look in the best of sharp alot of rust...... could you recommenced a new steering setup for me, right now its just cable.....

 

[emdsapmgr]

Check with your local marine dealership. Most offer Teleflex steering products through any number of their distributors. Likely the cable is going bad. They don't last forever and they are not setup to be lubed by the consumer. There is a part number heat-stamped at the end of the cable. Usually the engine end. Take that part number to the dealership. If it's a fairly current model, they can get you a replacement cable. If the cable is out of production, they will sell you a cable kit-which has a new cable and a new steering gearbox. Usually about $60 more for the gearbox kit. If you cannot find the cable part number, remove it and take it to the dealer with you. They will measure it and come up with the right parts.

 

[8uzz]

ok thanks alot emdsapmgr you have really halped me out alot. cheers