I bought this boat from a guy that let it sit up for 4 yrs. He had taken the motor apart and it had surface rust all in it. I replaced the entire gasket kit, new impellar, new set of plugs, rebuiltall four carbs, replaced the stator, trigger, low oi warning module. I had to replace the remote controls, cables and steering piston. I reset the timing, it trying to run 18 degrees off. It runs good, no missing, good take off. Smooth acceleration, however it will not reach top speed. At 30 mph it will hesitate and try to run on up but falls back.
I bought this boat from a guy that let it sit up for 4 yrs. He had taken the motor apart and it had surface rust all in it. I replaced the entire gasket kit, new impellar, new set of plugs, rebuiltall four carbs, replaced the stator, trigger, low oi warning module. I had to replace the remote controls, cables and steering piston. I reset the timing, it trying to run 18 degrees off. It runs good, no missing, good take off. Smooth acceleration, however it will not reach top speed. At 30 mph it will hesitate and try to run on up but falls back.
I would appreciated any advise you guys may have.
How did you set the initial timing?
Are the injectors on 3 and 4 clean and operational.
Is the accelerator pump setup correctly and is it delivering fuel to the injectors.
When you rebuilt the carbs did you mix any parts or did you keep them separate.
Are all the carbs back in their original positions?
Did you perform a link and synch?
The carbs (probably WME's) are jetted according to cylinder and only the top two have idle adjusting screws. Yours may actually be marked with a sequence number, some were and some weren't.
Wow, you already replace the stator, trigger AND switchbox, only thing left is spark plugs and coils!
You cannot assume that ALL new parts are good.
Test spark on all cyl's
DVA test stator high speed windings (@ 25 V at cranking speed)
Test compression
I'm really curious as to this 'timing 18 degrees out' statement.
Spark plugs out, plug wires grounded throttle WIDE open. If you have a Fast Idle lever then remove the prop, shift into Forward gear, WOT, and use a remote starter button. Crank the motor and observe WOT Timing with your timing light on the top cyl (#1)(Removed the prop so you don't bash your ankle as it spins)
At an idle connected to #1 cyl it was hitting at 18 degrees instead of 0. After adjusting the spark advance back to 0 on #1 it smoothly acceleerates and at what is now full throttle I'm at 27 degrees on #1, which is what my service and repair manual says ( could be mistaken). Have replaced the pluggs. Carbs, I was very carefule to keep everything seperate, rebuilt one at a time, replaced the jets and all. Fuel pump, I have not tackled that yet, was hoping I wouldn't have to but since I've come this far I guess I should. I have begun to question the voltage reg. my voltages is squrrily, it will start out at 12v and smoothly climb to around 17v, which I don;t think is correct so I have order a new voltage reg and rectifier. Will be here tomorrow.
Check the fuel pump output with the clear hose, running out/low of fuel will limit top end, too long that lean and you will scorch a piston, and it don't take but a minute.
Either a weak pump or air leaking in before the pump, you GOT TO find it and fix it.
Since your seem to know your way around your engine pretty well now, under the oil tank there is a filter between the accelerator pump and the injectors on 3 and 4. Change that filter and while your at it, pull the injectors, take them apart (they are really just basic check valves), clean them and lube them up with WD-40 (per merc manual). Re-install and replace all the hoses making sure you clean all the fittings. The hose size for the injectors is 7/64 i.d. the rest you'll replace with 3/16" i.d. and use a 1/4 lawnmower filter. In 3/16 hose that comes after the last injector you will find a brass plug. Be sure to extract the plug and put it in your new hose.
Since you and I have nearly the same exact engine, I suspect you may be experiencing the same problem I was with Ethanol destroying the old style fuel lines on the injectors. Nobody ever checks these since they don't understand how important the Accelerator pump is on one of these 2x4 engines. Check out page 4 of my resto and you'll see exactlywhere the injectors are located.
I have to say, you guys are great. I have a business trip starting on Staurday and will be out of town for a week. I have two days to work on this. I will post again with my results asap. I have to say this has been a blast and a sever headache, but I wouldn't have missed it for the world. Two years ago my son and I built a 16' wooden jon boat.
I had exact same prob. I also rebuilt everything including the Accelerator pump. diaphrams were all shot. Also check to see if you got the right fuel pump kit. My 115 90' has 2 part#'s listed. Parts folks gave me wrong one.
I had exact same prob. I also rebuilt everything including the Accelerator pump. diaphrams were all shot. Also check to see if you got the right fuel pump kit. My 115 90' has 2 part#'s listed. Parts folks gave me wrong one.
Yep, one uses a inline check valve and one has the check valve in the 90 degree fitting. From the outside they look nearly the same but they sure aren't when you get them apart.
Yu guys were right on the money. I pulled my acceleartor pump and it was clugged. I tried to clean it out but no go. I ordered a replacement pump and hope to back on the big blue this coming weekend.
'89 Mariner 115hp 4 cyl 2 stroke no high end
Linear Mode
