Honda 150 EFI

[journey on]

I’m posting this for both information and comment. Whichever you prefer.

Journey On has a 2005 Honda 150 with 365 hours, and three big summers of travel. By the way, it’s counter-rotating, just to mention that. This/last summer I noticed that the mileage went down form ~3 mpg to 2 mpg, at the same time gas went from $3/gal to $4/gal, which was not a good thing. No change in prop, loading or our usual cruise speed. Luckily our trip to San Francisco wasn’t much on gas, but the problem had to be fixed.

I just got back from Oceanside Marine, the nearest Honda dealer, where a very competent tech, Dwight, ran a computer scan/test on THE motor. He reported that #3 injector wasn’t injecting, the fuel pressure regulator wasn’t regulating, and the MAP sensors weren’t sensing. This all added up to a screwed engine. The cause, he felt, was twofold: The injector and regulator had water contamination from bad gas. The MAP (Manifold Atmospheric Pressure, the intake manifold pressure,) was choked with salt debris from running in salt water; i.e., the salt laden air deposited salt. There are 2 ea MAP sensors. The feeling is that Honda EFI doesn’t like salt water, though Honda doesn’t agree. Does say something for carburetors.

Basically the remedy was to replace the parts, which I can do whilst Journey On is on the trailer. The estimate for the parts cost was ~$300, which works out to about $100/year. Not too bad, but none of the items are covered under warranty, since they’re salt and water related. Dwight felt I could clean the #2 MAP sensor, and the throttle body. Which is good, since that MAP thingey is $77. I did change the fuel filters once per year: the boat filter, the water separator filter and the high pressure pump filter. I did get one batch of bad gas, at the ARCO station just north of the Columbia River on I-5, which I feel was a random incident, but that was >2 years ago. Also we do go to some of the out of the way places, and in Spanish, Ontario, Canada, you buy gas at the only station, or you don’t buy gas. Most of our trips have been in salt water.

The recommendation also was to replace the water pump impeller and KEY every 2 years, if in salt water.

As I said above, this is just for info, since there are a lot of 135/150 EFI Honda engines out there. Also, for those of us that think a 150 is big, it’s referred to as the SMALL engine. That said, please feel free to comment.

Boris

[thataway]

Boris,
Did the mechanic feel that the bad fuel cause the injector problem? Would using 2 mm filters, instead of the 10 mm filters help prevent this?

Thanks

[journey on]

Bob,

The tech thought that the water was from gas. And, since the injector only gets gas, I assume that's reasonable. What impressed me, is that he said that one couldn't clean them, nor run injector cleaner through them. I've had the Toyota cleaned via a strong dose of cleaner, injected at a shop. Apparently marine engines somehow are different. I don't fully believe that and we'll find out. Again there are three filters and two settling bowls ahead of the injector.

Also, in case someone was thinking of getting their own software, using a laptop and buying a data cable, Honda doesn't sell that stuff. They only sell a dedicated readout to their shops. I'm going to look into that further. Cost 1 hr. of shop labor, which in Oceanside is $100. Though the guy was very helpful, and listed the parts when I said "I'll fix that." The software even identified the injector (#3.) and assured that I hadn't overheated the engine nor run out of oil. They must have a megabyte of history in that motor.

Boris

[tpbrady]

Boris,

I would like to be able to get into my Honda also and just see how the motor thinks it is. I have the Honda 90 shop manual which you can buy direct from Honda, but you can't buy the Honda pocket tester or diagnostic software. Even if they sold a read only version, that's all I'm interested in. I can get similar devices from my car or truck. Sometimes I wonder if most marine engines aren't OBDC compliant since they are derived from auto engines.

[journey on]

Tom, you and I are in violent agreement. Watch it.

That engine is just a Civic engine set on end. The oil filters, spark plugs, etc are just the same. The OBD plug is different, reduced to just enough lines for a serial data link. I believe even the serial data link is the same, though I don't know for sure. I can't see why they would change a data logger that works well for cars.

As I mentioned above, Honda seems to limit the readout device and software, and its availability. If anybody know of an aftermarket software package and cabling to connect to a PC, I'd love to hear it. The dealer would love it too, since the factory readout is hard to use. While I appreciate the service I got, I'd like to be able to check it every time I went on a trip, as opposed to driving 40 miles each way and paying $100. I can do it for the Toyota car and Ford truck, why not a Honda? EFI is complicated, but it's still EFI.

Boris

[tpbrady]

Boris,

I think I found enough to experiment. Honda generally uses ISO 9141 as its standard OBDC protocol. You can buy a OBDC device to read the Honda data stream from http://obddiagnostics.com/ for about $80 and download the software. The BR-3 OBD II scan tool has a DB9 serial connector for connection to a computer and standard 16 pin OBD connector. On this connector, Honda normally only uses the following pins:
Pin Function
5 Ground
7 K serial data TX Hi 6 vdc
15 L serial data
16 Power +12 vdc

I looked at the wiring schematic I bought from Honda for my BF90D, and the DLC connector (the same term they use in their automobile documentation) uses four wires: +12 VDC, Ground, and two other wires from the ECM labelled KLN and SCS. Logic would dictate that one of these would be Tx and the other Rx. When you turn on the engine key, the tx pin should go to 6 vdc if I read the documentation correctly.

In other words, it looks like that for about $80 we might be able to do what we want to do. I am only a theorist so not sure I can implement it. Besides its winter and cold outside and I can't run my motor till sprint. What we really need is an experimentalist to prove the concept. I'm willing to invest if any one wants to try.