Bf200 Fuel Smell

I have a pair of 2003 BF200's and today I noticed a raw fuel smell on both of them when I was near them while they were idling after cruising. I could not locate where the smell was coming from while on the water, I just smelled it. Once I got the boat home and flushed the engines I could still smell it around both midsections. I could not smell it in the exhaust ports or through the prop, but I could smell it at the seam where the side cowlings meet the midsection, especially where the small rear cover is that goes over the bolts where the cowlings meet. I pulled one of the covers off and did not see anything strange, and I did not see or smell any fuel. I did not have a chance to look deeper yet, because we got back late today. I will try and check into it further tomorrow. It seems odd that both engines would have the same raw fuel smell. I feel the economy is not quite what it should be, and am wondering if this may be a contributing factor.
Any ideas what where the fuel smell may be coming from? Is this normal on a BF200?

Just a shot in the dark.....if you had your high pressure filters changed lately, the o ring could have been cut whiile putting everything back together. It will only leak while under pressure....that is when the key switch is turned to on and while it is running.

Yes, it would affect the economy.

Without pulling the cowling, have someone turn the key switch to on for two seconds, off, then back on several times as you look at the cap of the high pressure filter location on the vapor separator. If it is leaking, it will do it then.

Mike

I replaced all the filters when I did the new midsections, but did not see any leaks or notice the fuel smell after that. I will have to check them out. I had all the cowlings off so there was access. I put in new o-rings and was careful when putting them back together, so I don't think they would have been cut, and it would seem strange that the o-rings would have been cut on both engines. I am definitely smelling raw fuel though. The engines seem to smell like they run rich, but not like unburned fuel.

If no leaks at vapor separator, then check the spark plugs. If they are black, you are running rich.

Mike

Any warning sound ? It could be o2 sensor. It may have been Runing rich..
if i were you, i would do compression first..

I can check the plugs, but I did just replace them and the old ones looked good. I have not pulled the O2 sensor yet to see what it looks like. The compression was checked before I bought the boat in November, but I could check it again.

I can check the plugs, but I did just replace them and the old ones looked good. I have not pulled the O2 sensor yet to see what it looks like. No warning lights or buzzers. The compression was checked before I bought the boat in November, but I could check it again.

It is certainly not normal to smell gas coming from these big Hondas. Above and beyond recommendations above, first pull your dipstick(s) and smell the oil. If you smell gas, pull your thermostats and make sure they are not stuck open.

If you are absolutely sure that you are smelling raw fuel independently from each engine, then back up to the fuel distribution system from the tank. and look for problems where the fuel feed splits off to supply each engine. It think it is highly unlikely that both engine would have the same failure at the same time if the problem was internal to the engines, except for the possibility of the thermostats are sticking at the same time, or the changed out HP filters were installed incorrectly.

What else did you do when you changed out the HP filters? If you also changed out the LP filters, check those sealing rings.

I checked the oil and there is no fuel smell there. I changed the thermostats and the zincs in the manifolds within the past few months. I smelled the raw fuel from both engines. The first time was when I was in the water and I could not tell where it was coming from, so I checked the fuel lines and filters, my floscan sensors and anything else I could get to. I pulled one engine cover on the water and smelled all around the engine and did not notice any fuel smell at all. When the cover was on, I would get a whiff but could not tell where it was from. When I got the boat home, I flushed the engines and then walked around them to see if I could locate the smell. I could smell it behind the engines, but not inside the ports in the rear, or at the prop, just right at the 2" wide cover that hides the cowling bolts in the back. I noticed the same raw fuel smell on each of them but did not smell it with the covers off while checking the rear of the engine the following day. I will try to run them or prime and cycle the ignition to build pressure, then look again around all the fuel areas. I did change hp and lp filters, cleaned the bowl and replaces all the seals on anything I opened up.
The hp filters went back in the way the came out, and there was no issued getting the cover to seat without having to force it. Again, it would seem odd that both were damaged, but not impossible I suppose.
There is no fuel smell anywhere else on the boat that I can find. I have a pretty good sense of smell so I would notice that for sure. I smell the vents on the port midship hull in rough seas on occasion, but nothing else. The tank is usually full so the vents have some fumes. They are far from the engines so there is no mistaking them for what I am finding now. I have a tank to each engine with a racor filter before each engine. I have changed them recently as well, but no leaks or smells in the bilges. The boat is a cat, so that is the reason for 2 bilge areas, if you were wondering.
The engines have apprx 925hrs on them. They do seem to run a little rich. I get some black stuff on the cowlings around the ports after running it for an offshore trip. I seem to notice a little missing or slightly erratic idle at times, but they run good under load and have plenty of power. They will turn 5500+ rpm, so no issue there. I think the fuel economy could be better though. These are my first four strokes, so I am not familiar with how they "should be".
When I flush them near my shed, the exhaust smells rich and you don't want to right near the engines. I get not fuel in the water or heavy soot, the plugs burn pretty clean and the oil is not black or smell like fuel. No warning lights on the dash either. Could both O2 sensors be bad? I would think if the engines were dumping fuel, I would see that in the plugs.

O2 sensors are a major issue on those engines. Both being bad would not be that unusual, especially if they are the earlier type that Honda did a recall on. Have your engines had the new sensors fitted and the updated ECU to go with them?

I bought the boat in November and the dealer said they checked everything and there were no missing updates. Of course I called my local dealer much later and gave the serial #'s and was told they were never in for any tsb's or updates that he could see. I ended up finding both midsections were bad and replaced them along with all the filters, thermostats and zincs. I plan to pull the O2 sensors tomorrow and see how dirty they are. Is there anyway to check them other than taking to a dealer?

I went to the engines today and did not smell anything at the rear. I primed the bulbs and then smelled it at the same location as before. I looked all over the engines and checked all the filter locations, but did not see any leaks. I even used a q-tip to rub around everything, then smelled it to see if any fuel smell and there was nothing. I took some of the bolts out of the port engine cowlings so I could spread them apart and look inside. I did not see anything there, but went ahead and cycled the ignitions to run the pumps. I could smell it when the cowls were closed but the smell dissipated quickly when I opened the cowls. I looked all over and cannot see anywhere the fuel smell could come from. I smelled the exhaust ports and prop area again and cannot smell any fuel, only at the cover for the lower rear cowl bolts. The midsections are new,so there are no cracks or anything like that. I did not start the engines, only primed them with the bulbs, and then with the ignition on the port engine. There are no visible leaks around the high pressure filters and the drain tube has no fuel smell whatsoever.

I took a picture of the rear cover, just in case anyone did not understand where I am smelling the fuel. Not sure why the photo is sideways now.

I have only checked them with the Dr Honda sw. From memory the new versions only have 1 or 2 holes in the tip whilst the older verisons had several holes (6??) in the tip. If you are getting the smell without running the engine, they aren't your smell problem though.

Now this is an interesting mystery.

An off-the-wall thought - pull out the clear plastic hoses used to drain the VST and smell them for fuel. It's possible that the set screws that you open up for draining the VST are not fully seated, allowing fuel to come out of the hoses when under pressure. Even if they seem fully seated, open them up anyway as if you are draining the VST and reseat them several times. The little drain passage does often get clogged up.

Given where you are smelling the fuel, then it seems like the problem must be around the VST and HP fuel filter.

Take a look at this diagram: http://www.boats.net/parts/search/H...BF200A3 XA /VAPOR SEPARATOR ASSY./parts.html#
for your 2003. Check the seal at item 40 and 48.

I checked the drain hoses on both engines and there is not even a faint fuel smell, and no sign of any liquid in the drain hoses. I will check out the diagram. I may need to pull the cowling completely off to get a better look at the back of the engine. It puzzles me that I only get the smell in that location. It must not be a lot of fuel if it seems to dissipate quickly when I have the cowls separated a bit.

I looked at the diagram and see that # 40/48 are for the pressure relief. I never took them out before. When I checked that area yesterday there was no sign of fuel or any smell from inside the cowlings around the engine at all. I did not even smell anything when the cowls were opened a little and I could get right inline with the hp filter area. I only smelled it by the 2 small bolt holes for the lower part of the cowls, like in my photo. If it came from the midsection or exhaust, shouldn't I smell it from the exhaust ports, or even the prop? I know the midsection is all open inside and the exhaust ports just stick off the back of it, so they are all open to the same area.

Well okay, it was just a SWAG. I assume you did your smell tests while the key switch was on and the fuel system had pressurized.

I guess at this point I'm lost, too. Hard to do any further diagnosis from afar.

I re-read your posts...
1. You are getting the smell at both engines on each hull of your catamaran
2. You are getting the fuel smell when the engines are not running, but the fuel pressure system is energized.
3. The smell is localized in the rear center of the upper cowling, where the center cowling bolts are located under the cover tab.
4. You've tested for leaks at all fuel line connections, the HP filter cover, the VST cover, the VST drain screw, the VST drain tube, and every other place in that area.
5. You've checked for leaks at the fuel pressure relief bolt and seal.
6. You feel that there is no problem with the newly installed rubber O ring seals on each HP fuel filter
7. You are not getting any smell from the two exhaust ports.

I only see one other (very remote) possibility - something is loose and leaking up around your fuel rail near the injectors. I've never torn into those, so I don't have any advice on checking them out. Besides, it would be unusual to say the least that a problem there occurred with each engine simultaneously.

As someone advised earlier, check your HO2 sensor. Easiest way to do that is to shunt the red service connector as has been described many times on this forum. A single blink on the MIL light indicates a bad HO2 sensor.

I did the tests before priming and there was no smell after the engines sat for a day or more. I pumped the primer bulbs and then I could smell it on each engine. As expected, I could also smell it after energizing the ignition switches, which pressurized the fuel system via the fuel pump. The list you have there seems to sum it all up.
I will look up the test sequence for the O2 sensors and then I will probably pull them to see if they have a lot of holes or just a couple in them. I will probably pull the cowls off to get a better look at the rear of the engine, while having someone turn the ignition on.
I know there is a possibility the o2 sensors may be bad, but they would not allow the fuel smell when the engines are not running. Maybe just another issue. They may contribute to the fuel economy if they are letting the engines run rich. Wouldn't the plugs be getting dirty if the engines were rich? Or would that only happen during extended periods of low rpms? I fish offshore mostly, so I don't do a lot of idling. We run a wake zone, then it is up to cruise speed for about an hour, then engines off until it is time to move or head in.

A faulty HO2 sensor will cause the engines to generally run rich, especially a low speed. So your cruise speed runs off shore may be masking the richer fuel-air mixture.

Let us know what you find when the cowlings are off.

I did not have a chance to pull the cowlings yet to get a closer look at the fuel smell, but I did jump the red plug to see if there were any codes. I jumped the lime green wire to the black one. I did not use the one with the black stripe on it. The stbd engine light blinks one time every few seconds and that is it. No long or short blinks, only the one flash, then out, then back on. The port engine did not flash, the light stayed on steady. What does that mean?

I read that the one flash means the O2 sensor is bad. If both engines seem to run the same and both smell rich when idling, would it be safe to assume both sensors are bad?

The "one" blink indicates a bad HO2 sensor or the connection is bad OR faulty plug firing. Check the connection first. From reading previous posts on this forum, it appears that sometimes a bad HO2 sensor will not always show up from the shunting procedure. So both may be bad. But that is an expensive assumption.

There is a test procedure in the Helm Shop Manual (pages 5-26, 5-27) but it's pretty complex and requires a super accurate digital multimeter.

AutoZone has a test procedure which appears to be the very similar to that described in the Helm manual. See http://www.autozone.com/autozone/re...tsHowTo&pageId=0996b43f80a01215&subtitle=test

Perhaps someone has a better testing procedure.

Is there a difference between the Ho2 sensor for the comparable honda car, as opposed to the BF200? Could you essentially buy a heated O2 sensor at the auto parts store and replace it? I know some of them don't come with connectors on them, but that is not a problem.
My other question is, would a bad O2 sensor cause you to have poor fuel economy at higher rpms, or just at low speed?

To the best of my knowledge, YES, there is a difference and NO, you cannot substitute an auto sensor. A bad HO2 sensor will cause fuel economy problems across all ranges. The ECM meters the fuel/air mixture based on the readings from the HO2 sensor across all rpm ranges.

I read the test procedure and plan to remove them and test them that way. This will allow me to see what condition they are in as well. It makes sense that they are not working correctly, based on the way they smell when running. If you were in a somewhat sheltered area, I think the exhaust would make you tear up.

So I tried the test procedure that AutoZone listed, and I was only seeing about .33 V on the meter. I heated the sensor for a little bit, so I was not sure if I was supposed to continue to heat it or not, but it was pretty hot. When I removed the heat, the voltage stayed the same and was not really dropping. I set it on the ground and came back a couple of minutes later and it was still reading but was dropping as it cooled. There was no instant response. I was checking the gray wire and had the meter grounded to the body of the sensor. There were 2 white wires which appear to be the heater circuit, and then a black wire and a gray wire. My guess is that the O2 sensor is no good. This was the one on the stbd engine. I believe it is the old style.
If the dealer was right and the engines have not been in for any tsb's , then maybe these are the original sensors. The engines have a little over 900hrs on them from what I was told by the dealer. They seem to have lied about most everything else, so who knows for sure. There is no hour meter on the boat.

The one flash without an alarm, just tells you that at some point the O2 sensor was out of range.

The manual says to erase the code and run the engine at a certain rpm to see if it comes back. If it does, then you do have a problem. If not, go boating.

That was my short paraphrase of the manual instructions....

Mike

From what I read, the reset procedure is:

turn the ignition on, then flip the kill switch 5 x and turn off the ignition after hearing a beep or beeps.
If the sensor did not seem to test well, then wouldn't it be a good idea to replace it? The engines do seem to run very rich at idle as well. Do you have a better way to check the sensors?

That reset should work fine.

If the code comes back....and all the other electricals check out....definitely. Running rich can be caused by many things. The O2 sensor, map, IAC, valve clearances, thermostats, temp sensors, etc. all tell the ECM what combination of fuel and air to use. As an example, if the temp sensor is misreading the engine temperature and is telling the ECM that the engine is colder than it really is, it will run rich.

The o2 sensor does seem to have a bad reputation, so it is probably the problem. You just have to minimize or eliminate the other possible problems so that the O2 sensor is your best guess.

Unless you have Dr H or an HDS to watch everything that is happening on the engine, you have limited information to make your best guess.

Since you already have them ordered....change them out and see what happens. Most likely, things will improve, but i do not think anyone will be able to tell you for sure.

I know of no other way, than what the manual says to do for testing the O2 sensor.

I generally just follow the book, make the change and move on. When I need a second opinion, I do call the tech guys at Honda to discuss. Since, as a Dealer, we pay a yearly fee for that help, it saves a lot of time zeroing in on a problem.....most of the time.

I wish I had more time to explore some alternate tests, but being in fresh water, I do not run into O2 problems that much.

Mike

Is the salt what causes the O2 sensors to go bad? I have tried to slow the boat gradually to keep the water from rushing up the back of the engines when stopping. I also trim the engines up when driving up on the trailer, and rev them a couple of times before I shut them down after the boat is secured on the trailer. It seems the exhaust ports are close to the water when the boat is angled up on the trailer and the stern is downhill.

Any kind of water is bad for them. Salt water is probably worse...but that is just a guess.

Mike