Diamond Dave

I am the owner of the Keihin injectors BUP is speaking about. I sent them to him since I was doing full engine rebuilds and I wanted to make sure everything was ok since we bought this boat used. Sure glad I did! My engines only had 378 hours on them so If you think yours are ok I would bet money they are not... for anyone new to this and even if you are not rebuilding like me, I would strongly suggest having this service done as part of your routine maintenance. I'm fairly confident that the vast majority of boat owners out there do not even think twice about their fuel injectors either.

As far as my experience goes, I cannot speak HIGHLY ENOUGH about BUP, his work ethic, knowledge, honesty and attention to detail with this transaction (I work in the auto service industry so I really appreciate this). I had planned previous to take my injectors somewhere locally to have this service performed and I'm glad I didn't because I can assure you I would have had a giant mess still on my hands with these particular injectors. Not only was I misinformed by them but NO shop would have taken the amount of time that BUP has taken with me with these to get them right again (if anyone questions this please feel free to PM me). After the many late night conversations, pictures and videos he has sent me during this process, I can assure you anyone that uses his services are in more than capable and trusting hands.

Anyways, I am truly thankful for BUP, his contributions to this forum and in doing his part in helping me and my family get back on the water this season. Had I used the injector shop I was planning on I'm fairly confident I would have melted an engine or two down this season and been none the wiser.

Just my experience and hope it helps someone in the future.

articfriends

iTrader: (1)

John has touched on subject of "deadband" ie injector charteristics which i also mentioned earlier. For the few people interested i will touch more on this subject. By pintle design, coil design, efficiency etc diffrrent injectors have different charteristics even though they might have similar maximum flow ratings. Lets say at 13.5 volts a injector has a dead band of .5 milliseconds, this means it takes .5 ms of injector being powered/triggered before any fuel flow starts and when fuel flow stops. Sp for
5ms basically there is no flow. Lets say you buy a replacement injector w same maximum flow rating BUT dead band is 1 millisecond, twice as much time elapses where there is no fuel flow. A stock mefi tune will have fuel tables, map ie load vs rpms. At wot at 100 map at 5000 rpms the box for 100 map might have a fuel pw number of lets say 10 ms. So every other revolution of motor injector fires for 10 milleseconds, so 2500 times a minute at 5000 rpms. So with a dead band of .5ms the injector has actual fuel flowing for 9.5ms or you could also say 95% of time its triggered. If dead band of new injector is 1ms then fuel would flow for 9 ms, 90% of time its triggered. At this point un-tuned motor would now be running 5% leaner, if old target afr was 12-1, it would now be running at 12.6-1. Not good unless your motor was already pig rich. But now, lets step back and look again.

articfriends

iTrader: (1)

Lets say we go to 3000 rpms at 70 map. Lets say our pw is only 3.0 ms. Our new dead band is still 1ms vs our old .5. Now were cruising at 3000 rpms, our 13.8 target afr from fuel table now changes by 16.5%, that 13.8 turns to 16.0, bad things can happen! Now, a difference of .5 ms in dead band is a EXTREME exsmple, its not usually quite that bad but it gives you a idea.

BUP

iTrader: (9)

Post 31 Diamond Dave aka -- David thanks for the huge good words -. Yes I spent a ton of time on his injectors plus gave out hours worth of tips on top of - one of the reasons I had to spend a ton of time was because I wanted to figure out the inherent problem with this exact style of injector. He had 16 of them.

I have had these injectors in before from actually other dealers / service shops - about 16 to 32 depending but do not get them every year. Anyways I thought in the past that the problem with this style of injector was from the fuel / the over dose of fuel stabilization from owners and or dealers for lay ups being the problem - as the fuel evaporated out from sitting over time, it left behind what was internally in the injector that dried up basically . Yes that is true as well being what takes place.

But there is another problem with these injectors. And very fixable after everything is said and done from testing and deep cleaning. Anyways if anyone has questions because I do know the problems that take place with many marine fuel injector applications and the reasons why they do take place.. One is to prevent that from happening in the future or now and 2 is most marine fuel injectors do need servicing of sort regardless.

Some helpful tips --- You need to lay up all MARINE FUEL SYSTEMS with the soup mix with a portable 3 or 6 gallon fuel tank - run the engine on that --- aka 2 stroke motor oil a quality brand and a quality NON alcohol fuel stabilizer with FRESH GAS - double dose the stabilizer but do not over base. 50 to 1 on the 2 stroke motor - or 60 to 1 or up to 75 to 1. even if you are Florida. The key no matter of location is --- if you are NOT going thru a tank full of gas every 30 days or under. You should maintain your fuel system regardless. Next for storage you need to add 2 stroke motor oil to your gas TANK(S) for lay up like 120 to 1 and double dose the fuel stabilizer in there as well.

Next step is Fuel samples - as I told Diamond Dave YOU NEED to do fuel samples 3 different ways - one from the fuel filter itself poured into a clear jar and 2 fuel sample testings from the gas tank. One sample first from a boat / gas tank just sitting undisturbed and the second fuel sample is to shake up the boat making a washing machine effect while getting that fuel sample in the clear jar. You want to shake up any water and grit so it is off the bottom of the tank mixing with the fuel to be to see if any turns up in your sample. Keep in mind all this water and crap is heavier than fuel so it settles at the bottom and more so in the corners of the fuel tank.

Again You need to do fuel samples. If Diamond Dave could come back up here and describe his fuel samples as I preached to him please take the fuel samples so I can see plus send me the pics and send me the fuel filter for delivery - well his filter was so bad that the mail would not even deliver it to me - I actually still have the letter as why they would not ship his fuel filter. Anyways -- Fuel samples can be another indication if your fuel injectors needs servicing. This is solid info

Next tip is -- Every 5 to 9 years depending how well your fuel quality is and how well you maintain your fuel system - any rubber lines needs to be replaced.

articfriends

iTrader: (1)

Now lets talk sbout injector bias voltage, lets say our injector w .5 ms of dead band changes to .8ms at 11.5 volts, the better ecus like mefi4s have a voltage bias table with modifyers that add fuel to make up for this increased dead band/injector latency
So motors is running at 12 volts, dead band has increased to .8ms, a multiplier table now adds a percentage to our fuel tables to make up for flow effectively dropping. Lets say our 2nd injectors dead band changes from 1 ms to 1.4 ms at ssme voltage drop, now the multiplier that is supposed to increase our fuel is also wrong. Motor is even leaner. With blind speed density efi these things are real important, if boats had tailpipe sensors snd self tuning efi, these things wouldnt be as important but they dont!, thats why if your going to a totally different injector you really need to retune your boat or at least drive it with o2 sensors on it to see where your at.

underpsi68

Very good info being posted.

One of my engines runs an aftermarket ecu. The ecu manufacturer has many popular aftermarket injectors listed in the software at various base fuel pressures. If you wanted to run an injector not listed in the software, you can send him an injector to test and he will send you the correct settings in the software.

The higher flowing the injector, the more critical it becomes.

I run a 220lb injector on my little 352ci engine, and the dead times are right on in the software settings. The A/F is very stable at different voltages when I checked.

You can check the dead times by varying the voltage at different rpms/loads (different ms times). The A/F shouldn't change.

BUP

iTrader: (9)

and last for today if you have GEN III cool fuel you need to check the internals out all the time and change those filters bare min once or twice per year. Dump the baskets fuel in a clear jar to see contents. ie water and metal shavings. very common with this cool fuel. YES METAL SHAVINGS as well.

Here is another reason and SO COMMON and the 496 is included in this MIX like I said ALL GEN III cool fuels.

Watch this vid for an eye opener. Not my vid but nothing I have not seen before and still currently, its been in the 100s - I work on more 496's than anyone I know in the biz. Not bragging but I can say this statement is true.

This internal paint from GEN III kills the fuel injectors - they need serious testing and cleaning. This problem has even brought down the 496 engines because the same exact problem shown in the vid.

https://www.youtube.com/watch?v=0ow4jkR0vR0

mike tkach

iTrader: (3)

i will be the first to say that i am not well versed in fuel injection,that being said i believe oso is lucky to have these two guys who go out of their way to explain how it all works and tell about some of the known problems with efi.their is no doubt in my mind that bup and articfriends are the the guys who know what they are talking about,espically efi related stuff.the best thing about them is they are not here trying to sell to us but simply trying to enlighten us.thanks to both gentlemen for the time they spend helping others.

Ryan00TJ

iTrader: (8)

I agree. I've been following BUP's advice here since I bought the Velocity and guess what? No fuel related problems. I closely monitor the Cool Fuel box for paint separation. If it starts, I am pulling the Merc pump setup and going Aeromotive pump setup.

BUP, What interval should the 496HO 42lb injectors be pulled and tested? Say mine for instance, stock 06 and other than getting layed up correctly and seeing Chevron Techron in the spring fuel are stock.

BUP

iTrader: (9)

thanks -- the 496 can experience corrosion internally in the fuel rails This is common more so for the early model 496's and a bit less for the later 496's but still is huge problem regardless of year.. I see this a lot FYI. , I have a set of 16 - 496 injectors in now that has experienced this very badly corrosion internally of the fuel rails.. This is on all 496's including Volvo, Indmar and so forth. Also Volvo's Carter made cool fuel system paint peels in that as well. The injectors then need help asap before you ruin the engine - lean the hell of it. The same with Gen III Merc. Paint and metal shavings Yes Metal shaving in the gen III cool fuel Its from the manu process that never gets cleaned 100 percent out.

The soup mix needed for 30 day or more lay up helps for internal corrosion of the fuel system = and keeps the internal fuel pumps lube for corrosion and believe or not a tad less start up wear internally of the fuel pump.

Johns 496 (above ^^^^ IMO has experienced this - I even sent back his pulled basket filters and the q tips cleaning out the small metal shaving from his top feed of all 8 injectors) .

Actually 496 injectors are not bad its what happens to them from the fuel system that have the problems. But with that said the 496 marine injectors become contaminated by far the worse. NO BS I see it a lot and again I see so much of the 496. period. 70 percent of them have some form of contamination problem, some are small and some are way too much contaminated internally. .

Also in OEM schools its talked about to have your injectors (marine ) side checked and cleaned every 4 to 7 years regardless. Many factors play a role in this - even before these timeframes to have them checked out - so again FUEL SAMPLES IMPORTANT - No water in the fuel nor chit - even the basket filters dry rot out and break apart in the internal injector top feed . Not uncommon for that these days. . Next is proper lay up of the fuel systems. next is fuel filters and do not get me going on that kick. Someone has very poor quality fuel filters to begin with. This does not help injectors our either.