2003 40hp TLDI issues

[Vwsandcar]

I am helping a friend attempt to repair his boat engine. I have experience on older carburetor 2 strokes. He took it to a shop and they gave it back no change due to not being able to repair the engine. His original problem was the boat wouldn't idle and when it would stall it would restart and would be flooded with wet spark plugs. He operated the boat like that for a few trips. When he brought it to me he said the boat wouldn't turn over and I found the air compressor was locked up. I cleaned out the compressor hose and air rail with compressed air and carb cleaner. He ordered the compressor parts and installed the new piston, cylinder and gaskets himself.
he said the engine still would not start. I went and found the lower 2 spark plugs wet with fuel. When I pressed the air shrader valve with a screwdriver fuel poured out. I removed the air rail to find the air side fuel in it. With the fuel line connected and the fuel injectors installed we cycled the key and fuel poured out of when the compressor hose port. I then removed all the fuel injectors and inspected the orings. The all looked ok to me but 2 injectors had slight corrosion on the end. I reinstalled the injectors and the n the fuel would only drip a few drops when the key was cycled. We reinstalled the air rail and the engine started and didn't run right then the compressor locked up again. He said he coated the cylinder wall with motor. So my 2 question are
-do you think fuel got into the compressor and washed the oil out causing the cylinder to lock up again?
-Is there probably a bad injector or oring causing fuel to leak into the air side on the rail?
And last he removed the oil pump without remove and lines connected a drill to it with the lever in the full oil position (all the way down) and it doesn't seem to pump any oil. The tank is full and we bleed it like the manual said to. How much volume should the pump move?

 

[pvanv]

You probably have an MD40B. Model is important, while year is irrelevant.
Using the Factory service manual as a guide, you can put the ECU into diag mode and see what the motor thinks is wrong.
I would also check the fuel and air pressure regulators.
He may have turned the oil pump backwards.

 

[Vwsandcar]

I actually just bought the boat from my friend since he gave up on diaging it. Nsd40b 3t4-1 is the model. I confirmed the oil pump is working. I have to get the right adapter for my fuel gauge to check fuel pressure and air pressure. One problem I know it has for sure is when the compressor discharge line is removed fuel come out of it. My buddy changed the injector o rings hoping to solve the air rail internal fuel leak. Tomorrow i am going to put it into diag mode and take apart the air rail to see if i can find. Anything in particular I should look for for the fuel leak?

 

[pvanv]

I have seen this on an MD50B2. Bad fuel regulator. Fuel washed down the air line, washed the rings of the compressor, and I had to change the cylinder, piston, and rings, as well as the offending regulator. Remember that those high pressure hoses require oitker clamps. There should be 10 psi differential in air and fuel pressures. When assembling the compressor, use TCw3 oil or DFI synthetic 2 stroke oil.

 

[Vwsandcar]

Ok so I removed the air line going to the fuel pressure regulator. The regulator was leaking fuel into the air side. I replaced the regulator and was sure to put a Oetker hose clamp on the hose. Put everything back together attempted to start the engine and it starts then dies in about 3 seconds. I put it in diagnostic mode and it has no codes. I ordered the adapter for my fuel pressure gauge tonight so I can check air and fuel pressure. I did use an air chuck to hook my home compressor to the air rail and started the engine and it ran well until I removed the air chuck. So I know it is an air problem. Question I have is should the air rail hold air pressure? Mine does not hold air pressure so I think I have an air leak. What's the best way to leak test the air rail?

 

[pvanv]

Sounds like you are getting there. If the fuel regulator was allowing fuel into the air side, that could wash down the compressor rings/cylinder and game over -- new piston and rings (comes as a set) and cylinder. Good idea to do the valves in there as well at that time... or a compressor, but I believe they are BO right now. If it runs OK with shop air, but not on its own, you now have an air issue, . Yes, air pressure should slowly bleed off over time, but should be right up there when you turn it off. A leaky injector or bad o-ring could leak. Soapy water is a good way to find an air leak. Or bad reed valves in the compressor. Couple drops of dish soap in a quart of water should work.

 

[Vwsandcar]

I appreciate all your help. Tonight I'm going to do a leak check with soapy water. The compressor already has new rings cylinder and piston. Valve was not replaced. I opened it up and coated the piston and cylinder with DFI oil. I suspect the valve may be the problem. Hoping for a pinched o-ring. I'll report back my findings.

 

[Vwsandcar]

Here is the valve when I put shop air to the air rail it forces the compressor to turn to the bottom of its stroke then holds pressure. I pull the valve off and looks like 1 exhaust valve does not close. Picture attached. Do you agree?

 

[pvanv]

Hmm. Could be. The leaves aren't available separately; you would need to get a valve assembly for almost $90. They are presently out of stock.

 

[defrag4]

Here is the valve when I put shop air to the air rail it forces the compressor to turn to the bottom of its stroke then holds pressure. I pull the valve off and looks like 1 exhaust valve does not close. Picture attached. Do you agree?

did you ever get this one figured out @Vwsandcar, having a similar issue with air pressure

 

[Vwsandcar]

did you ever get this one figured out @Vwsandcar, having a similar issue with air pressure

I did fix it. I bent the thicker piece of metal on top of the exhaust leaves down just a hair and that worked. The engine has ran great for a year and a half now.

 

[defrag4]

I did fix it. I bent the thicker piece of metal on top of the exhaust leaves down just a hair and that worked. The engine has ran great for a year and a half now.

thanks! Ill have to give that a try, i suspect the valve is the problem as well as I have replaced everything else at this point (piston, rings, and gaskets) and shes still not building enough air to run right

fingers crossed!