I have a Sea Doo x-20 with a Mercury 240 EFI M2 Jet Drive. Engine started missing very badly and smokes more than normal. WOT is fine, but at idle sounds like a muscle car with a hot cam. We ck'd the air temp sensor using an ohm meter, seems ok, also checked the port side temp sensor and it too "seemed" ok. We have good spark to all 6 cylinders. Have not done, but will do a compression ck. Reading in this forum and using google searches seems that the temp sensor w 3 wires is a cause of many problems when it goes bad. Any suggestions? thanks Big Tom
Sea Doo x-20 w 2002 Mercury 240 EFI M2 Jet Drive
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Given we get a good comp ck on all 6, think we will replace the port side temp sensor as its easy and not very expensive. If that does not fix the problem guess we will have to find a Mercury mech that can use the DDT to ck the ECU and the MAP sensor the is integral to it. Still hoping for a few suggestions on the formum. Thanks much for you post.
Dr Honda
Well-Known Member
You can check the temp sender, and TPS with a standard meter. Generally, if the MAP is out of spec, it will trip the engine light. (and it's not a part that normally goes bad) On the sea doo boats... it's the oil light. I know... it's stupid, but sea doo should have labeled it with a bell and not an oil can.
OK here is where we are as on 30 Mar 14, All 6 cylinders have compression of about 90 psi, so I do not see any issue there.
Changed out both temperature senders on the block port and starboard and the one on the fuel
system, think this a an air temps sensor. We ran the boat down to the marina to
refuel and then back up to the house. No recognizable change. Engine is
still running very rough at lower RMPs (not just idle) and smoking. We
noticed this even at about 3000 rpms. Still appears to run great at WOT.
We looked in the service manual and the only way it explains to test the TPS
is with the special tester. However Dr Honda says you can do this with a meter? not sure how since does not apprear in the manual. Any advice here would be appreciated, because as Dr H says, this part is not cheap.
So the only part we haven't replaced is the TPS. We did hear that a leaking reed might be the issue? Anyway we are pretty well stumped right now, thanks to anyone that has an idea.
Changed out both temperature senders on the block port and starboard and the one on the fuel
system, think this a an air temps sensor. We ran the boat down to the marina to
refuel and then back up to the house. No recognizable change. Engine is
still running very rough at lower RMPs (not just idle) and smoking. We
noticed this even at about 3000 rpms. Still appears to run great at WOT.
We looked in the service manual and the only way it explains to test the TPS
is with the special tester. However Dr Honda says you can do this with a meter? not sure how since does not apprear in the manual. Any advice here would be appreciated, because as Dr H says, this part is not cheap.
So the only part we haven't replaced is the TPS. We did hear that a leaking reed might be the issue? Anyway we are pretty well stumped right now, thanks to anyone that has an idea.
Dr Honda
Well-Known Member
What manual do you have? It shows the procedure for checking with a volt meter. I'd have to go look it up... but you are looking for .3v at idle, and 7v at full throttle. (smooth change in the middle)
As far as the compression.... if your gauge is right.... the engine is done. You should be seeing 125 to 130 psi. 90 psi is very low, and I'm surprised it's running.
As far as the compression.... if your gauge is right.... the engine is done. You should be seeing 125 to 130 psi. 90 psi is very low, and I'm surprised it's running.
Wow! we will have to go back and re-ck the comp, its an old gage, so maybe it is off. Would think if comp is off by that much it would not hit the top end speed at WOT. Boat can do about 50 mph at WOT, which is what it did when new. We will ck the TPS w your voltages and relook at our manual, but think its the factoy service manual for the 2002 Mercury 240 EFI M2 Jet Drive. What's puzzling to us is the fact that it runs fine at WOT, but idles very rough and smokes, neither of which it did when running good. Seems to transition from rough running to running fine at about 3000 rpm. Thanks again for all your help.
Dr Honda
Well-Known Member
90 psi is enough to get it to go... but it will be rough. As the RPM's go up... the dynamic cyl filling will go up... and raise the cyl pressure. BUT... the rings will be leaking and overheating the cyl walls, and piston skirts. Normally, the life becomes short, and is followed with a melt-down.
I find old gauges to be the best. The new cheap ones are the problem. But... verify that there aren't any leaks in the hose... and that the O-ring at the sparkplug end is good. Also... when you do the test... the throttle should be wide open, and the battery needs to be strong. A weak battery (slow cranking) or closed throttle can show low compression. BUT... DO NOT put any extra oil in the cyl. That will hide a problem.
I find old gauges to be the best. The new cheap ones are the problem. But... verify that there aren't any leaks in the hose... and that the O-ring at the sparkplug end is good. Also... when you do the test... the throttle should be wide open, and the battery needs to be strong. A weak battery (slow cranking) or closed throttle can show low compression. BUT... DO NOT put any extra oil in the cyl. That will hide a problem.
The manual we have is a Mercury Service Manual 240 Jet Drive Electronic fuel injection, Starting Model year 2002, 90-884822 Dec 2001 and it lists starting ser no. for power head as 0E384500, for Pump Unit 0E379931. We have a 2002 Mercury 240 EFI M2Jet Drive Seadoo X-20, we think this is the right manual. This manual shows specifications for the TPS at idle as 0.19-1.0 VDC and for WOT as 3.45 to 4.63 VDC, but does not show how to test this voltage, it does refer to a Digital Diagnostic Terminal, which I guess is a testing device for this engine. Would assume a volt meter would work.
We will re ck comp w a different comp checker and see what we get. We did not have the throttle open either, so will try to do that, battery is good and we cranked it over 4-5 times.
Could a bad reed valve cause the compression issue or the problem we are seening? Someone has suggested this.
Again really thank you for all the assistance.
We will re ck comp w a different comp checker and see what we get. We did not have the throttle open either, so will try to do that, battery is good and we cranked it over 4-5 times.
Could a bad reed valve cause the compression issue or the problem we are seening? Someone has suggested this.
Again really thank you for all the assistance.
Dr Honda
Well-Known Member
I don't think you have the right manual. Normally the engine will be one year older than the boat. Basically because the engine manufactures give a real build date... and the boat guys will release a "Model year" up to 9 months early.
What does your engine cover look like? (The plastic on top) Is it round, and just covering the flywheel... or is it rectangle, and covers more of the top of the engine??
Even though the 240 efi engine didn't change... there was a HUGE change in the support equipment. (Oil pump, alternator, electronics, etc) And that happened at 2001-1/2. SO..... if your boat is a 2002... it's very unlikely you have the new style engine. (ie, the 2002 engine)
What does your engine cover look like? (The plastic on top) Is it round, and just covering the flywheel... or is it rectangle, and covers more of the top of the engine??
Even though the 240 efi engine didn't change... there was a HUGE change in the support equipment. (Oil pump, alternator, electronics, etc) And that happened at 2001-1/2. SO..... if your boat is a 2002... it's very unlikely you have the new style engine. (ie, the 2002 engine)
You are right we had the wrong manual, I think we now have the right one, let me ck on what the engine looks like for sure, Having the right manual wouild be a good start...... The manual we now have and believe it is the right on is: MODELS 210/240 HP M2 Jet Drive, With Starting Serial Numbers Powerhead 0E373939 Pump Unit 0E370718, 90-877837 NOVEMBER 1999, and sure enough in this manual the votages on the TPS are .2 to .3 volts at idle and 7.46 at WOT. Appears that testing the TPS is a bit complex, so we'll have to read/study the manual. Prior to that however we'll re-do the compression ck. Thanks again, at some point we will get this pinned down.
Dr Honda.
We re-checked our compression with a new cker, we are getting 120 lbs in all 6 cyl, a little low from the 125-130 you said is the spec. We also have noted that the engine compartment has an oily residue in it, something we never saw early when the boat was newer, and some towels we stored in the back of the boat smelled of exhuast. When we look in the openings where the throttle plates are, seems to be sort of black and oily? Could it be we have some bad reed valves that are allowing blow by back out the throttle and into the engine compartment?
Also there seems to be no air filter as the throttles are just exposed to the inside of the engine compartment. This seems odd, but looks like how the engine is designed. We have not tested the TPS yet, still intend to do this. Again thanks for you assistance. It might actually be cheaper to replace the reed valves than the TPS.
We re-checked our compression with a new cker, we are getting 120 lbs in all 6 cyl, a little low from the 125-130 you said is the spec. We also have noted that the engine compartment has an oily residue in it, something we never saw early when the boat was newer, and some towels we stored in the back of the boat smelled of exhuast. When we look in the openings where the throttle plates are, seems to be sort of black and oily? Could it be we have some bad reed valves that are allowing blow by back out the throttle and into the engine compartment?
Also there seems to be no air filter as the throttles are just exposed to the inside of the engine compartment. This seems odd, but looks like how the engine is designed. We have not tested the TPS yet, still intend to do this. Again thanks for you assistance. It might actually be cheaper to replace the reed valves than the TPS.
Dr Honda
Well-Known Member
if it's a balanced 120, it's still ok. (even across all cyl's)
The oily residue, and dirty throttle plates is kind of normal. These boats get used, and abused. The could be from an old spill, or leaky hose. And, the dirty plates are just because the 240 engine doesn't have ANY kind of air filter, or baffle. So, all the dust/dirt will collect, and stick.
The reeds in this engine are fiberglass, and will normally last longer than the engine. Also, if you had a badly damaged reed... it would show up as low compression. So yes... you can have a bad reed... but I'm going to say, that it's probably unlikely.
I would get a gallon bottle of "Super Clean", and spray the engine compartment down with it. Then... hose it out with fresh water. Repeat 2 or 3 times... and it will be sparkly clean. You can even hose down the engine. Just don't aim directly at the throttle plates. This will give you a clean slate, and if there are any oil leaks... they will be easier to find.
Did you change the sparkplugs yet??
The oily residue, and dirty throttle plates is kind of normal. These boats get used, and abused. The could be from an old spill, or leaky hose. And, the dirty plates are just because the 240 engine doesn't have ANY kind of air filter, or baffle. So, all the dust/dirt will collect, and stick.
The reeds in this engine are fiberglass, and will normally last longer than the engine. Also, if you had a badly damaged reed... it would show up as low compression. So yes... you can have a bad reed... but I'm going to say, that it's probably unlikely.
I would get a gallon bottle of "Super Clean", and spray the engine compartment down with it. Then... hose it out with fresh water. Repeat 2 or 3 times... and it will be sparkly clean. You can even hose down the engine. Just don't aim directly at the throttle plates. This will give you a clean slate, and if there are any oil leaks... they will be easier to find.
Did you change the sparkplugs yet??
Dr. Honda, thanks again for hanging in there with us neophytes... attached are two pics, one of the throttle plates and one of the reed valves, seemed easy to remove them to look at them. None are broken, but some do not seem to close all the way. Note how dirty the throttle plates are. Hope you can open these pictures.
We had earlier changed the plugs and ck'd all the spark coils, we think we are getting good spark to each cylinder. We did one other test, we disconnected one cylinder's spark plug wire and ran the engine at idle, no change, we did this for all 6 cyl and could not detect any chg in the idle, perhaps because it was running so rough to begin with. One other point. several years ago the engine blew up on this boat, litteraly threw a connecting rod out the side of the engine, it was under warranty and was replaced, but only the short block, so the throttle assembly and reed valves were from the original engine. Thanks again, this has been a real challenge for my son and I..... we will use you rec on cleaning out the engine compartment. Big Tom
Dr Honda
Well-Known Member
The reeds look ok to me. A new set may help with throttle response... but I don't see any fractures. As far as not touching... that's OK too. When the air is being pushed back... they will seal shut.
That throttle body is crusty. I would take it apart, and clean it with super clean... a stiff nylon brush... and water. But still... it would probably still run OK.
Before you pulled the fuel unit... did you check the TPS?
That throttle body is crusty. I would take it apart, and clean it with super clean... a stiff nylon brush... and water. But still... it would probably still run OK.
Before you pulled the fuel unit... did you check the TPS?
No we did not test it..... but will do that after we re-assemble, we need and now have the test harness to test the TPS. Since its apart we will install a reed kit and new gaskets.
Here is "our" theory, and would ask your opinion, we think the voltage put out? from the TPS at idle is too high. As a result,
the computer thinks the throttle is open and is sending too much fuel and is actually flooding out the engine. The excess fuel is splattering in the intake manifold and throttle plates and that explains the large amount of oily deposits??? We are thinking the only thing left that could cause this is the TPS? Thanks again for all your help, and we do remember early on you said test the TPS.....
Here is "our" theory, and would ask your opinion, we think the voltage put out? from the TPS at idle is too high. As a result,
the computer thinks the throttle is open and is sending too much fuel and is actually flooding out the engine. The excess fuel is splattering in the intake manifold and throttle plates and that explains the large amount of oily deposits??? We are thinking the only thing left that could cause this is the TPS? Thanks again for all your help, and we do remember early on you said test the TPS.....
Dr Honda
Well-Known Member
Yes... that's basically the deal.
If the TPS is misadjusted... or just out of range. (open, or shorted) the computer will add fuel to be safe. When the TPS goes bad... it will smoke, and run poorly. But... at full throttle... it's fine.
The computer uses the MAP sender and the RPM to know what it's up to. The TPS, Air Temp, and Port side temp as fuel trimmers. If any of them are bad... it will add 40% more fuel at idle.
If the TPS is misadjusted... or just out of range. (open, or shorted) the computer will add fuel to be safe. When the TPS goes bad... it will smoke, and run poorly. But... at full throttle... it's fine.
The computer uses the MAP sender and the RPM to know what it's up to. The TPS, Air Temp, and Port side temp as fuel trimmers. If any of them are bad... it will add 40% more fuel at idle.
Dr Honda,
Our Seadoo, 240 EFI Mercury is now fixed and running as it did literally when new! Going back to your excellent early on advice to look at the port side temp sensor and the TPS (big bucks!), sir you were on target. After replacing the port side temp sensor, we tore the motor down to where we could clean the throttle plates and look at the reed valves. Then posted pics of the disassembly. We purchased a reed valve kit even though we thought, and you confirmed they were OK and a new TPS ($480 ouch!). The new Throttle Positioning Sensor (TPS) did the trick. We have not adjusted it yet using the spec voltages, but upon initial installation and a few cranks the 240 EFI fired right up and ran smoothly at idle, drastic improvement. We have the cable that allows us to plug in and adjust the TPS voltage and will do that. So our simptoms were, extremly rough idle even with new plugs, oily deposits in the engine compartment, above normal fuel consumption, extremly dirty throttle plates, and a WOT that seemed to be fine. So seems bad TPS allowed way to much mixed fuel into the engine at idle. Well we learned a lot from you on the forum and although this cost us a bit for parts, we learned much about working on our Seadoo. Hard to say what a marine service place would have charged us. We have about $800 in new parts, the TPS being $480. New reed valve set about $200. So thanks much for all you posts and great technical assistance. We are off enjoying the Seadoo once again. Oh we did also take your advice and clean the engine and engine compartment with Super clean.
Our Seadoo, 240 EFI Mercury is now fixed and running as it did literally when new! Going back to your excellent early on advice to look at the port side temp sensor and the TPS (big bucks!), sir you were on target. After replacing the port side temp sensor, we tore the motor down to where we could clean the throttle plates and look at the reed valves. Then posted pics of the disassembly. We purchased a reed valve kit even though we thought, and you confirmed they were OK and a new TPS ($480 ouch!). The new Throttle Positioning Sensor (TPS) did the trick. We have not adjusted it yet using the spec voltages, but upon initial installation and a few cranks the 240 EFI fired right up and ran smoothly at idle, drastic improvement. We have the cable that allows us to plug in and adjust the TPS voltage and will do that. So our simptoms were, extremly rough idle even with new plugs, oily deposits in the engine compartment, above normal fuel consumption, extremly dirty throttle plates, and a WOT that seemed to be fine. So seems bad TPS allowed way to much mixed fuel into the engine at idle. Well we learned a lot from you on the forum and although this cost us a bit for parts, we learned much about working on our Seadoo. Hard to say what a marine service place would have charged us. We have about $800 in new parts, the TPS being $480. New reed valve set about $200. So thanks much for all you posts and great technical assistance. We are off enjoying the Seadoo once again. Oh we did also take your advice and clean the engine and engine compartment with Super clean.
Dr Honda, we are having a problem again, recall we have a Sea Doo x-20 w 2002 Mercury 240 EFI M2 Jet Drive and have posted before. You provided invaluable technical assistance and we solved our problem.
We now have a new problem. The engine will run fine for an hour or two, and then seems to bog down and smoke due to excessive oil in the gas. Draining the fuel from the low pressure fuel pump (about 2 cups of gas and oil mixture) show oil in the mix. After draining the engine will run fine w/o smoking or missing and achieves top rpm. But then after running for an hour or two the same thing happens, smokes misses and runs poorly.
We think we are getting too much oil mixing w the gas like the oil pump is pushing too much oil into the fuel. Thanks for any assistance.
The TPS was just replaced and appears to be working fine.
To further clarify, the issue appears to be a slow increase in oil to fuel
mixture the longer the engine runs to the extent that it will ultimately get
so rich with oil that it fouls out the plugs. I can drain the high pressure
fuel pump and see that the oil/fuel appear almost black due to the high
concentration of oil. I can then turn the key, let the high pressure fuel
pump refill and then drain it again. The engine will then start up and run
perfect for a few hours. Then the smoking returns as the oil to fuel mixture
rises again. I'm wondering if the oil could be bleeding past the oil pump?
Something is causing the oil ratio to increase.
Thanks very much for responding to my post, hope can help. The TSP was pretty expensive to replace ($480), but it fixed an earlier problem. Its been running fine for about 11 mos. I do have the the test harness to test the TPS if you still think that may have gone south in 11 mos with only limited weekend use
we did get a reply from a recent post on the forum:
Ouch, those TPS are really painful to replace. So I really need to know what the results of the last DDT scan were to point you in the right direction here, anything less on that motor is just an exercise in guessing and or hackery and I don't go in for that it sounds like you've had more issues than usual with it at this stage. Some of that can be done with a multimeter but at this point I think your past that stage.
Has a tech had that hooked up and do you have any results on a work order you can share with me? Something as simple as the darn air intake temp sensor can cause that to happen, any codes should be on a work order if it was scanned and I would really like to know the input and output values on the current TPS now that your having this problem
Thanks for any assistance you may provide.
Big Tom
We now have a new problem. The engine will run fine for an hour or two, and then seems to bog down and smoke due to excessive oil in the gas. Draining the fuel from the low pressure fuel pump (about 2 cups of gas and oil mixture) show oil in the mix. After draining the engine will run fine w/o smoking or missing and achieves top rpm. But then after running for an hour or two the same thing happens, smokes misses and runs poorly.
We think we are getting too much oil mixing w the gas like the oil pump is pushing too much oil into the fuel. Thanks for any assistance.
The TPS was just replaced and appears to be working fine.
To further clarify, the issue appears to be a slow increase in oil to fuel
mixture the longer the engine runs to the extent that it will ultimately get
so rich with oil that it fouls out the plugs. I can drain the high pressure
fuel pump and see that the oil/fuel appear almost black due to the high
concentration of oil. I can then turn the key, let the high pressure fuel
pump refill and then drain it again. The engine will then start up and run
perfect for a few hours. Then the smoking returns as the oil to fuel mixture
rises again. I'm wondering if the oil could be bleeding past the oil pump?
Something is causing the oil ratio to increase.
Thanks very much for responding to my post, hope can help. The TSP was pretty expensive to replace ($480), but it fixed an earlier problem. Its been running fine for about 11 mos. I do have the the test harness to test the TPS if you still think that may have gone south in 11 mos with only limited weekend use
we did get a reply from a recent post on the forum:
Ouch, those TPS are really painful to replace. So I really need to know what the results of the last DDT scan were to point you in the right direction here, anything less on that motor is just an exercise in guessing and or hackery and I don't go in for that it sounds like you've had more issues than usual with it at this stage. Some of that can be done with a multimeter but at this point I think your past that stage.
Has a tech had that hooked up and do you have any results on a work order you can share with me? Something as simple as the darn air intake temp sensor can cause that to happen, any codes should be on a work order if it was scanned and I would really like to know the input and output values on the current TPS now that your having this problem
Thanks for any assistance you may provide.
Big Tom
Tsmitty469
New Member
Dr Honda you seem very knowledgeable on the Mercury 240 efi. I have a 2001 seadoo challenger. the nipple on the block is missing and when you put the boat in the water, water runs into the hull. any idea where I can get the nipple or what its called? Also how is it supposed to be hooked up?
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