'97 V6 135 Merc too much oil in top carbie

[woywoyboy]

Afternoon All, my '97 V6 135 Merc has become hard to start and very smokey when it does. Today I attempted to start it and she coughed a few times and would not fire. I checked the spark and it was OK. Next I looked at the inline fuel filter and it was not full. I pulled the hose and it then sprayed an oil and fuel mix all over the place. I could blow through it both ways. I then atempted to blow into the carb side fuel line and could not do this, Figuring I had some kind of blockage somewhere, I decided to pull the drain plug from the top of the 3 carbs. Out came a very oil rich mix. I let it drain and then drained the other 2 carbs and the mix from them appeared OK. I then cranked here over and while still very smokey, she started first turn of the key. Can anybody please suggest what might be happening here and what I can do to stop it happening?

 

[achris]

Re: '97 V6 135 Merc too much oil in top carbie

When were the fuel pump diaphrams last replaced? They should be done on every annual service.

Chris...........

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Thanks Chris- I've just pulled out the most recent service record dated 27/7/07. It makes no mention of the diaphragms being replaced and nor do the previuos 2 service records however the '07 record states that the oil line check valve was replaced due to leaking.

 

[achris]

Re: '97 V6 135 Merc too much oil in top carbie

I'd start with the diaphrams. They get weak with time and the crappie fuels we're dished up these days. I'd say that the leaking check valve didn't fix the problem. They may have found something that looked like that, but missed the real cause, and now you're looking for it. Good luck and keep us posted. If you post your engine serial number that would be a great help, as I have the drawings on my hard disk and can look at exactly what your set up is. They did quite a few minor changes to the oil injection system over the years and it's nice to know exactly what I'm talking about.....

Cheers,

Chris..............
I reside in Perth, home of Rottnest Island, only place in the world that sees all 3 species of marlin in the same place. I'm currently in Kamchatka, Russia (big cold place somewhere north).

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Thanks again Chris- ser no is 09469384. I'll pick up a diaphragm tomorrow and see how it goes.

 

[achris]

Re: '97 V6 135 Merc too much oil in top carbie

You might want to re-check that serial number, it's probably 0G469384. Anyway, the part number you're after for the fuel pump diaphram kit is 21-42990A10.

Cheers,

Chris.........

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Yep - it is a G. It it an easy task to fit? Also, what should I look for to confirm it has fixed the prob? Or am I just looking for the original prob to go away? Thanks again.

 

[achris]

Re: '97 V6 135 Merc too much oil in top carbie

It's quite an easy job. I just put a clean rag on the bench and disassemble. If you have a digital camera you may want to take a picture of the set up on the engine before you disconnect any hoses. Cut the cable ties off the hoses and put them off the pump, should be 3 from memory. You have 4 bolts on the cover of the pump, 2 of them go all the way through and bolt the pump to the block, remove them and take the pump to the bench.... re-fitting is the reverse.

Look for distortion in any of the diaphrams or maybe a 'curled' valve. Other than that, just look for the problems to have gone away.

Chris..........

 

[hkeiner]

Re: '97 V6 135 Merc too much oil in top carbie

If rebuiling the fuel pump and cleaning the carbs does not solve your smoke problem, you might reconsider the oil injection system as a possible cause. If you do, the below linked thread might be of help to you.


http://forums.iboats.com/showthread.php?t=182406&highlight=much+smoke

 

[j_martin]

Re: '97 V6 135 Merc too much oil in top carbie

I'd guess that the problem is the crankcase check valve in the oil injection system. The valve supplies about 2 psi of pressure on the oil reserve tank, and is supposed to let off to 0 in a couple of minutes on shutdown. If it doesn't, it will slowly force oil into the fuel system, first drop off point is the top carb, so that is where most of it would end up.

Simple check, slowly remove the storage tank cap a few minutes after shutdown. If there's pressure, replace the valve.

hope it helps
John

 

[gss036]

Re: '97 V6 135 Merc too much oil in top carbie

I agree with John on his solutition to the problem.

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Thanks All , had to order the fuel pump kit for the local dealer and it won't be in until Friday so I'll try removing the reservior cap after running and see what happens. The check valve was replaced abt 6 months ago so heres hoping that is not the prob again!

 

[hkeiner]

Re: '97 V6 135 Merc too much oil in top carbie

Please note that there are two check valves on the oil injection system that can possibly cause excess smoke. The crankcase check valve, as discussed above, is the most common culprit.

A second 2-PSI check valve, located on the oil line between the oil pump and the fuel pump, can also cause excess smoke at startup if it is stuck partially open. If stuck open, oil from the reservoir tank can be siphoned into the fuel line when the motor is off, and then oil rich fuel is pumped to the carbs after startup. While this valve is less likely to be defective, I suggest that it is worth replacing along with the crankcase check valve just to be sure. The part is not expensive, it is easy to replace, and it is not very easy or practical to bench test for proper operation. It is labeled as #6 on the diagram linked below.


http://continuouswave.com/whaler/reference/mercuryOilInjection.html

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

If the fuel pump kit does not fix the problem. am I able to disconnect the oil and run premix? Reason for asking the the marlin have just arrived and it will take a few days for the check valves to come in.

 

[j_martin]

Re: '97 V6 135 Merc too much oil in top carbie

If the fuel pump kit does not fix the problem. am I able to disconnect the oil and run premix? Reason for asking the the marlin have just arrived and it will take a few days for the check valves to come in.

That takes parts, too. You can't just take the oil pump off, a loose bushing could get into the engine and wreck havoc. You have to put in an oil pump block off kit.

I suspect the problem is lack of relief on the oil storage tank. If you just reach down and crack the top loose after running, or even disconnect the quick disconnect oil and air hose from it after a run, you're good to go.

It'd be a good check anyhow. If you do that and it still loads up overnight, there's something wrong with the pump itself.

I would bet if you tough it out till the check valves come, and throw them in, you'll be over the hump.

hope it helps
John

 

[rodbolt]

Re: '97 V6 135 Merc too much oil in top carbie

I am with John
while fuel pump maint is a god thing, the squre pumps tend to fail alot it wont have anythig to do with carb oiling overnight.
the usual culprit in this case is the Crankcase check valve, I did see the occasional oil line check valve failure.
the oil line check valve prevents the oil from draining into the fuel system and the fuel pump from pushing fuel back up the system.
in the interim like John syas,simply crack the cap on the remote tank and bleed off the pressure when your done for the day,if this cures it you know for sure its the crankcase check valve.
always make sure the remote tank cap is retightened or no oil transfer will occur.

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Righto- fuel pump kit finally arrived today. The dealer supplied me the kit with part no 21-857005A 1. This differs form the one sugested by achris whom said I needed 21-42990A10. I've searched around the web and I think I may have been supplied the incorrect kit. The engine is a 135HP 1997 V6 Carb serial no 0G469384. Before I open the kit, can anybody please confirm this is the correct or incorrect kit?
Also, after running the engine for a few minutes, when I remove the cap off the main oil bottle, I can hear a release of pressure, like air rushing in. This would probably mean the check valve needs to be replaced yeah? I might as well do the fuel pump while I'm at it.

 

[achris]

Re: '97 V6 135 Merc too much oil in top carbie

The kit you have is the right kit. The number I gave you is the correct number for your engine. It supersedes to that new number. You'll also find a gasket in there that won't be used on your engine. It's a 'one kit fits all' kit.

You'll also find that there is pressure in the oil tank after running, it takes a bit of time to bleed off. The engine pumps that tank up so oil will be pushed to the small oil tank inside the engine covers.

Cheers,

Chris........

 

[woywoyboy]

Re: '97 V6 135 Merc too much oil in top carbie

Thanks again Chris, I guess I can stop cursing my dealer now! I'll fit the kit tomorow when I get home from work and report on how it goes.

 

[hkeiner]

Re: '97 V6 135 Merc too much oil in top carbie

I'll fit the kit tomorow when I get home from work and report on how it goes.

Perhaps I am just restating what has been said in the previous posts and you already understand this, but I thought I would say this in case you were thinking otherwise...

Rebuilding the fuel pump is a good thing to do if the fuel pump was not working up to spec. However, your "too much oil in top carbie" problem will most likely not be affected by a fuel pump rebuild. You most likely need to replace the two check valves in the oil injection system, as a start.