Logo

BF 130, 2000yr: reading spark plugs

stan101

Member
Attached are two photos of plugs that indicate problems, but I don't know enough to diagnose it. Lately the engine has been a problem maintaining cruise at 4800 rpms. Running 18 miles to the sword grounds it works fine, but on the return trip full throttle will get only up to 4400 rpms.

The plugs are NGK ZFR7F with 50 hrs on them.

The first plug (No.1 on the engine) has a black streak on the porcelain under the center electrode.

The second (No. 3 on the engine) seems to have excessive tan deposits on the porcelain under the center electrode.
The other two plugs in the engine look normal.

When examining the plugs I did a compression test, too, with the following psi results: 140, 136, 140, 141.

Any ideas about the wear patterns on the plugs?
 

Attachments

  • STB No. 1 10-6-2011 10-23-53 AM 302x410.JPG
    STB No. 1 10-6-2011 10-23-53 AM 302x410.JPG
    28.4 KB · Views: 57
  • STB No. 3 10-6-2011 10-31-47 AM 352x432.JPG
    STB No. 3 10-6-2011 10-31-47 AM 352x432.JPG
    30.5 KB · Views: 73
It might just be me, but those plugs don't look too bad at all.

It may just be the photo but the electrode on the first plug looks weird. It looks like it has a sort of rounded edge whereas the 2nd plug's electrode has a nice, clearly defined edge. But the plugs were oriented differently when you shot the photo to emphasize the black spot.

The tan color doesn't look excessive and could be an indication that #3 cylinder is operating at a slightly elevated temperature compared the others. Not unusual for an inside cylinder in the lineup to do that. Fuel that has too many additives from over treating with stabilizers and cleaners can leave tan deposits like that as well.

The black spot on #1 might be where the spark isn't taking place dead center of the electrode and is trying to jump to the plug body. This might happen when the plug gap is incorrectly set or if something (like carbon) got caught temporarily between the plug body and the insulator. Make sure the electrode tip is flat and with defined "shoulders" and that the ground strap is centered over the electrode and is not twisted.

Might as well put in new ones since you have those out though.
 
I agree with Jimmy's analysis - they don't look that bad to me. And, it's weird that going out everything is firing fine, and on the return trip it is not. That sure doesn't sound like a plug problem to me. It could be a coil or grounding problem. But, it sounds like you are running out into the Atlantic, trolling for swords, getting bounced around a bit (or quite a bit) then running back in and getting lower RPM's. To me, that suggests a fuel feed problem. If the 130 has a VST tank, as does the bigger Honda's, that is the first place I would look. Pull the VST, clean it, check the float valve, and change out the high pressure filter. Also, the next time that happens, check your pump-up bulb and make sure it is tight, and not partially collapsed. Try opening up your gas filler and see if the problem clears. If so, you have a partially clogged breather on your fuel tank. Also, disconnect your pump-up bulb and blow air back into your tank to clear any possible debris clogging your plick up tube. If your pump=up bulb does not get tight after a couple of squeezes, then the check valve may have failed.
 
Thanks guys,

I was wondering if a partially blocked fuel injector could cause the carbon pattern on the No 1 plug?

The analysis about going out and getting bounced around a lot is right and I've been digging into fuel problems, including draining the VST, changing the hi pressure fuel filter, and switching the fuel lines from STB to PT to see if the problem followed the fuel line or stayed with the engine: it stayed with the engine. So next I'll disassemble the vapor separator: will have to wait a few days for new o-ring parts, though, before reassembly and testing.

The photographs do make the first plug look wierd, but the electrodes have well defined edges.

Thanks for your help. Stan
 
I certainly wouldn't rule out a clogged injector causing that "spot". If the spray pattern is erratic or irregular, it could cause localized leanness and or richness in the combustion chamber that could cause the plug to discolor. But, the "classic" discoloration for a plug in a lean cylinder is a sort of grayish hue.

I think you are on the right path, as chawk_man has suggested, to verify your fuel supply and delivery before getting too focused on anything else. That is a great baseline to be confident about at any time, not just when trying to solve a problem. So, if you're going offshore, it's time well spent along with fresh batteries for the hand held VHF :)

I have seen posts though, from the very guru himself, hondadude, that say that some of these engines are VERY spark plug sensitive. And, there was a guy recently that initially ignored his suggestion to change out his plugs as the cheapest and easiest thing to try first only to end up chasing his tail for a week or so until reporting back that the new plugs solved the case.

I can't remember which motor that was though....just sayin'.
 
This is a real long shot - but do you have a motor extension on your boat, and if so, what type is it? The reason I ask is that last winter coming back into Hatteras channel from fishing in the Gulf Stream, my boat got really sluggish and the motor seemed to be bogging down. I initially wrote it off as just too much weight in the stern from fish, ice, etc. However, on further inspection, I found that the seal on the access hatch to my motor extension had failed, and it was full of water. Pumped it out, re-sealed it, and everything was fine. So, I guess the question is whether or not you are somehow taking on more weight, or re-distributing your weight on the run back in from fishing, either from something like a leaking motor extension, water in the bilge, or a lot of fish.

On other thought. Not sure how the air breather works on a 130, but I would check that, including the air intake valve.
 
Hi, I'm working on getting the vapor separator off to clean it and check the float, etc., but the hang up is a simple electrical connector that will NOT come apart. Has anyone found a tool or technique to get these apart?
 

Attachments

  • El Connector 1 10-9-2011 11-10-31 AM 1129x1572.jpg
    El Connector 1 10-9-2011 11-10-31 AM 1129x1572.jpg
    46.8 KB · Views: 49
You can use a little screwdriver, but a fingernail can work too.

First - you have to get it off the mounting. I think the outer connector goes to the fuel pump. There is a little tab just on the other side of the wires at the top. Just push a tab a little and slide the connector off of the holder.

Then pull the little tab....the one pictured at the bottom where you see the small rectangular slot. Pull the tab toward the slot and pull the connector and plug apart.

I think once you get it off the mount, it will make more sense.

Mike
 
Thanks Mike,
It came apart right away! Getting the top cover off the vapor separator was a bear, but the screws eventually backed out. One lesssion is to NEVER, NEVER use an automotive anti seize (a graphite looking product) in a marine environment. This particular set of screws had anti seize applied to them about 5 yrs ago and were practically welded to the vapor separator body. Anyway it was nice and clean inside and the float and valve seem OK, so I'll get it put back together soon.
 
They make a special anti-seize grease meant for the marine environment, but I don't have any left, and cannot recall its name.
 
Back
Top