Author Topic: Fuel in exhaust and oil (Read 5950 times)

PNTdickson · « **on:** June 13, 2018, 07:26:27 AM »

Hoping you can provide a suggestion. I have a 1985 K100 that has been
> sitting in garage for 4 years, and probably sat long before I purchased.
> I have changed all of the fluids last summer, filling with 20w50 oil.
> Got the bike started with starting fluid. Ran a bit rough, and then
> started to idle more smoothly. Noticed while it was running that fuel
> was running out of the exhaust. It ran well enough to take for a short
> ride - it choked/died a few times, but could start after letting it sit
> for 15-20 mins. Cannot get it started now.
>
> Guessing that a valve is open, forcing fuel into the exhaust and/or
> crankcase. Emptied oil today and found some fuel in the oil. Any idea
> what could be causing this fuel problem in the oil/exhaust?
>
> Would appreciate your thoughts. Thanks.

The Mighty Gryphon · « **Reply #1 on:** June 13, 2018, 08:06:29 AM »

Sounds to me like your engine is running very rich and possibly not firing on all cylinders.

What do the spark plugs look like? Wet and or sooty black confirms extra fuel in the mixture.

Have you checked the engine temperature sensor and it's wiring? When the engine is at operating temperature the resistance of the sensor should be around 200 ohms at the big plug on the Jetronic ECU. These sensors are notorious for failing and making an over rich mixture.

It's possible one or more injectors are stuck open. If the bike has been sitting for a long time with fuel in it, the fuel can turn to varnish and stick the pintles in the injectors. Sometimes they can be freed up by running some Techron fuel system cleaner, but sometimes they need to be sent out to a shop that services injectors to be serviced.

I assume you have cleaned out any crap in the tank and changed the fuel filter as well as checking the hoses for the fuel lines and breather. While it's unlikely they are the cause of your problem, they need to be in good order to have a properly running engine.

PNTdickson · « **Reply #2 on:** June 13, 2018, 08:19:24 AM »

All very good points - thanks. Yes, the injectors were serviced (sent them in), and the entire fuel tank was cleaned out, including fuel pump. Installed new fuel filter too. When I purchased the bike some years ago the gas was actually dark and more like varnish. Cleaned and changed all fluids. The fact that she ran when first started is encouraging, but immediately noticed fuel leaking from the bottom of the exhaust. Am planning to remove the valve cover to verify valve clearance and visual inspection. Will also look at the plugs at the same time. Thanks again - will add to my search.

Laitch · « **Reply #3 on:** June 13, 2018, 08:33:48 AM »

Quote from: PNTdickson on June 13, 2018, 08:19:24 AM

All very good points - thanks. Yes, the injectors were serviced (sent them in), and the entire fuel tank was cleaned out, including fuel pump. Installed new fuel filter too.

I think its important to try to disclose everything that has been done to a bike when you're asking for help so the aging brain cells of some of the respondents here aren't taxed trying to suggest some of the things you've already done.

Have you looked at the plugs to see if they are all wet? Or just a few of them?

You should follow the diagnostic instruction in Vogel's troubleshooting guide to focus on the cause of this problem. Grab your multimeter. I'll be surprised if intake valve clearance has anything to do with this.

PNTdickson · « **Reply #4 on:** June 13, 2018, 08:43:03 AM »

Pulled all of the plugs - 1,2, and 3 are completely dry. #4 seemed to be a little wet but not oil - smelled like gas.

Laitch · « **Reply #5 on:** June 13, 2018, 08:49:53 AM »

Quote from: PNTdickson on June 13, 2018, 08:43:03 AM

Pulled all of the plugs - 1,2, and 3 are completely dry. #4 seemed to be a little wet but not oil - smelled like gas.

Are they firing?

The Mighty Gryphon · « **Reply #6 on:** June 13, 2018, 08:51:49 AM »

Make sure your battery is fully charged. If the mixture is really rich it is easy to flood the engine and wet the plugs to the point it won't fire. Once the plugs are wet the fuel will continue to accumulate and increase the flooded condition.

You can easily clear a flooded engine without tools by unplugging the tank connector temporarily disabling the fuel pump. Crank the engine with the connector unplugged until it tries to fire. This usually takes about ten to fifteen seconds of cranking. Then plug the connector back in and the engine should start. If not, repeat. If three or four cycles of this doesn't start the engine, you probably have a spark problem.

The Mighty Gryphon · « **Reply #7 on:** June 13, 2018, 08:53:31 AM »

Quote from: PNTdickson on June 13, 2018, 08:43:03 AM

Pulled all of the plugs - 1,2, and 3 are completely dry. #4 seemed to be a little wet but not oil - smelled like gas.

How long since the last time you tried to start the engine?

The Mighty Gryphon · « **Reply #8 on:** June 13, 2018, 08:54:53 AM »

What color are the electrodes? Are they sooty?

PNTdickson · « **Reply #9 on:** June 13, 2018, 09:33:49 AM »

The last time I tried to start the engine was 6 months ago. I decided to wait until I could diagnose before moving further.

Yes, they are all firing, and the battery is charged. just bought some good BMW oil, but don't want to foul the oil with gas - trying to isolate without trying to run the engine - yep, makes it harder. Is there any value in taking the valve cover off and checking valve clearance?

Laitch · « **Reply #10 on:** June 13, 2018, 09:53:06 AM »

Quote from: PNTdickson on June 13, 2018, 09:33:49 AM

Is there any value in taking the valve cover off and checking valve clearance?

You'll know if the valve clearances are correct and you'll know if you need to adjust them. Follow Vogel's troubleshooting guide. It is an orderly process. Read all about your bike's various systems. Put some inexpensive oil in your engine. You aren't going to be stretching it to its limits while diagnosing. :giggles

PNTdickson · « **Reply #11 on:** June 13, 2018, 10:00:19 AM »

Will do. Thanks very much for all the guidance and suggestions. More to follow.

The Mighty Gryphon · « **Reply #12 on:** June 13, 2018, 10:31:21 AM »

So it's been 6 months since the last time you tried to start the engine???

What happens if you try today? Some current info would be really cool.

PNTdickson · « **Reply #13 on:** June 13, 2018, 10:53:24 AM »

Understand, was simply looking to see if anyone saw these symptoms before. Installed new gapped plugs, new gas, and tried to start. Initially it tried to fire, but then only turned over. Have gas dripping from the low point of the exhaust again (at the clamps). Seems that gas is somehow getting into the exhaust, possibly through the exhaust valves. More baffling is the presence of fuel in the crankcase.

The Mighty Gryphon · « **Reply #14 on:** June 13, 2018, 11:22:27 AM »

A rich mixture will prevent the plugs from firing. The injectors keep adding more fuel which, believe it or not, will exit the cylinder through the, wait for it, the exhaust valve when the cam opens it. Bottom line is that it is perfectly normal for unburned fuel to get into the exhaust system.

If there is enough fuel in the cylinders, some of it will get past the rings and into the crankcase. Speaking of rings, have you done a compression check to see if they are sealing properly. Lack of good compression may possibly cause some of the symptoms you are seeing.

rbm · « **Reply #15 on:** June 13, 2018, 11:59:13 AM »

When were the injectors serviced? Did you add fuel stabilizer to the fuel and run it through the engine before putting it away? It's possible that the injectors are again clogged with varnished fuel, negating all that money spent on refurbishing them

PNTdickson · « **Reply #16 on:** June 13, 2018, 01:05:07 PM »

When I received them back from service ( I installed them, but never cranked the engine. The valuable takeaway from the numerous posts is that it appears to be a fuel related issue. I am going to take everything back off above the intake and clean/inspect. Will respond back in a couple days when I start the engine. Thanks again to all who provided the valuable feedback.

rbm · « **Reply #17 on:** June 13, 2018, 01:15:27 PM »

Before that, crank the engine and listen to the injectors to see if they sound like they are firing. Use a long flat-bladed screwdriver as if it was a stethoscope, placing the blade against the injector body and the handle right against your ear. If the injector is clicking, it's likely working; if no clicking sound then its probably stuck open accounting for the fuel dumping out the exhaust.

PNTdickson · « **Reply #18 on:** June 13, 2018, 02:34:33 PM »

Thanks again, will do. While the injectors have been serviced, I realize that one or more could be nonfunctional. Great suggestions.

Martin · « **Reply #19 on:** June 13, 2018, 02:44:28 PM »

Pull the vacuum line that goes between no 4 throttle body and the FPR and check for signs of fuel. A perforated diaphragm can allow fuel to be sucked into no 4 cylinder. A major leak here has the potential to cause a hydraulic lock and bend the conrod.
Regards Martin.

PNTdickson · « **Reply #20 on:** June 13, 2018, 03:12:12 PM »

Also a great point, Martin - thanks. Formulating my test plan and will look at the vacuum as well.

PNTdickson · « **Reply #21 on:** June 15, 2018, 06:56:37 AM »

Fantastic input - thanks. Just finished pulling and testing all injectors - all worked properly. Compression on all cylinders were correct. Was again scratching my head. I actually have spare relay and regulator ' easy enough to try both. I feel encouraged that through process of elimination I will solve this. Thanks a million!

Paul

Martin · « **Reply #22 on:** June 15, 2018, 05:16:19 PM »

It's easy to check the FPR without removing it. First check the vacuum line for signs of fuel. Then if you wish to check the FPR "T" in a gauge on the return line. The one that goes from the fuel rail back to the FPR, it should rear 36 PSI give or take a couple of PSI. I made up a device out of bits and pieces I had lying around. The gauge is from a pressure regulator sourced of an old compressor.
Regards Martin.

FPR Test Gauge 1.jpg (56.53 kB . 768x576 - viewed 262 times)

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Author Topic: Fuel in exhaust and oil (Read 5950 times)