Fuel Injector Help Please!!!

[h2osk8er00]

Trying to diagnose a fuel injector issue and maybe help someone out that has been having the same issue...

I have been experiencing an acceleration issue since the end of last year but didn't pay much mind to it until this year.. Basically had difficulty getting on a plane and getting up to speed.. felt like the boat weighed an extra 1000 lbs.. I was also noticing a lot faster fuel consumption and a strong smell of gasoline would permeate throughout the boat until you got going fast enough to dodge the smell...

So I did a complete tune-up (and then some)... Spark Plugs, Cap and Rotor, Plug Wires, Serpentine Belt, TPS, IAC valve, Injector cleaner...One thing I noticed when I pulled the plugs was that one of the plugs (When staring at the engine from inside the boat- 2nd to last plug on the right side) was a lot more dirty compared to the other plugs.. it was really dark and looked as if it was really burnt up or wet maybe... So when I went out after the tune up I didn't check the plug again becuase I guess I figured it was just bad from time.. (I dunno) Anyway.. I decided that my problem was the prop... and I bought an Acme Prop. I noticed a slight gain in my hole shot but not as significant as I thought it would be..

Now, I just got back from vactaion and was making sure all was in order before I launched and noticed that the injector above the plug that had been really dirty before was hanging on by a thread.. I moved it slightly and it broke off... I checked the plug which I had just replaced and it looked the just as bad as the plug last time (I only had about 5 hours on this plug).. basically all blackened up and kinda wet looking.. I'm guessing that I have been just flooding the $hit out of my one cylinder but was wondering since this may have been going on for quite sometime do I need to check anything else. Going through all the injectors and plugs and all of them look fine. After I replace this one I am going to run some Lucas through, again...

Thanks for reading and I hope I can help somebody out...

FYI- Part number for the fuel injector was 861260T... I could not find this at any autoparts store. I had to order it through a marine store online for like 120-130 bucks I think...

Your fellow Tige boater/learn the hard way guy,

Mike

[chpthril]

A couple things here that throw up a red flag for me. Injectors are electrically opened and closed by spring tension. A leaking injector pintle (opening where the fuel exits) will cause a rich cylinder and show as a wet or dark coated plug tip. But, the physical attachment of the injector to the fuel rail will not have any bearing on the operation of the injector internally, but could result in an external fuel leak, which would lead to the fuel smell and high fuel consumption. This can also lead to a vacuum leak, which could cause a wet plug or a very dry, white ashy looking plug.

Low compression and weak ignition will also be causes of a wet plug or one with a black flakey coating.

[h2osk8er00]

A couple things here that throw up a red flag for me. Injectors are electrically opened and closed by spring tension. A leaking injector pintle (opening where the fuel exits) will cause a rich cylinder and show as a wet or dark coated plug tip. But, the physical attachment of the injector to the fuel rail will not have any bearing on the operation of the injector internally, but could result in an external fuel leak, which would lead to the fuel smell and high fuel consumption. This can also lead to a vacuum leak, which could cause a wet plug or a very dry, white ashy looking plug.

Low compression and weak ignition will also be causes of a wet plug or one with a black flakey coating.

There was definitely nothing white or ashy looking on the plug.. I will try to put on some pics later.. I'm just trying to understand why one injector would go bad in the first place and I guess just understand the whole mechanics of it.. I'm guessing that this should solve my acceleration issue (or hoping). So the red flag that you see is the possibility of the fuel coming out the fuel rail where that injector sits? So do those wires that were connected to the injector only communicate to the computer and really don't tell the engine how much to feed it? Anyway.. I'm pretty positive the injector was bad but is there anyway that I can test it? Thanks for the quick response Mike!

[chpthril]

There was definitely nothing white or ashy looking on the plug.. I will try to put on some pics later.. I'm just trying to understand why one injector would go bad in the first place and I guess just understand the whole mechanics of it.. I'm guessing that this should solve my acceleration issue (or hoping). So the red flag that you see is the possibility of the fuel coming out the fuel rail where that injector sits? So do those wires that were connected to the injector only communicate to the computer and really don't tell the engine how much to feed it? Anyway.. I'm pretty positive the injector was bad but is there anyway that I can test it? Thanks for the quick response Mike!

There are a handful of things that can go wrong with an injector. They are nothing more then an electrical solenoid valve used to control the amount of fuel entering the engine. The wires on top are a ground and a swtiched (pulse width modulated) 12V that commands the injector open when 12V is applied and then it closes when 12v is removed.

So, we can have an electrical open or short in the injector windings or we can have a mechanical issue with the fuel portion of the injector. An open would found with an Ohm check and would result in a dead injector = closed, no fuel. a short would probably result in the same. A mechanical failure could result in an injector that is stuck open, flowing fuel all the time, or stuck closed and passing no fuel.

A leaking injector, which you may have, is easy to find by keying up the fuel pump with the injector mounted to the rail, but pulled from the intake manifold. If fuel drips or sprays, its toast. In most cases, injector cleaner will not fix a bad injector.

[h2osk8er00]

There are a handful of things that can go wrong with an injector. They are nothing more then an electrical solenoid valve used to control the amount of fuel entering the engine. The wires on top are a ground and a swtiched (pulse width modulated) 12V that commands the injector open when 12V is applied and then it closes when 12v is removed.

So, we can have an electrical open or short in the injector windings or we can have a mechanical issue with the fuel portion of the injector. An open would found with an Ohm check and would result in a dead injector = closed, no fuel. a short would probably result in the same. A mechanical failure could result in an injector that is stuck open, flowing fuel all the time, or stuck closed and passing no fuel.

A leaking injector, which you may have, is easy to find by keying up the fuel pump with the injector mounted to the rail, but pulled from the intake manifold. If fuel drips or sprays, its toast. In most cases, injector cleaner will not fix a bad injector.

Awesome info..this is the type of thread I have been looking for.. I'm going to guess that my injector was okay.. but it had just been in a open or closed position constantly.. the connector was so bad that I think it was only connected on one side. so it was def not getting the fuel to that cylinder... I'm just curios why my boat wouldnt misfire.. even under load.. my boat guy came out with me and we test ran the boat.. he hooked up his timing gun and said everything was good. Would he have th of connected it to a computer to see somthing like this? God I hope this makes the world of difference.. another thing I noticed in the past since this issue is that I would loose speed when I had the throttle set... depending upon how much weight I had in the boat and who I was pulling.. Thanks again!

[AnthonyRyan]

A couple things here that throw up a red flag for me. Injectors are electrically opened and closed by spring tension. A leaking injector pintle (opening where the fuel exits) will cause a rich cylinder and show as a wet or dark coated plug tip. But, the physical attachment of the injector to the fuel rail will not have any bearing on the operation of the injector internally, but could result in an external fuel leak, which would lead to the fuel smell and high fuel consumption. This can also lead to a vacuum leak, which could cause a wet plug or a very dry, white ashy looking plug.

Low compression and weak ignition will also be causes of a wet plug or one with a black flakey coating.

i agree with you. But i think low compression is the main reason behind black flakey coating.Hope the link below isd useful to you.
http://auto.howstuffworks.com/fuel-injection.htm



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[h2osk8er00]

Thanks.. The more infor the better. I am supposed to get the new fuel injector today.. hopefully I will have her ready for the weekend so that I can come back to work on Monday and blog about how happy I am with the overall performance now!

[OldeBoy]

Hope you get it sorted out in time to enjoy the weekend on the water.

[bigdaddy_houseboater]

I can read the plugs if you post a pic... hard to do from a description. Flakey black sounds like two things. Either fat (rich) or wet (oil in cylinder). Before I would diagnose a compression issue, I would run a compression test. Borrow a compression tester or get a cheapo one at Harbor Freight.

If you have compression issues, then you likely have big problems.

[h2osk8er00]

Well I replaced the injector and let me tell you.. boat is purrrrrrrrrring like never before. She has the power to pull again and drops down on a plane quicker than I ever remember. I think I must have been running 7 cylinders for a while.. I hope no substantial damage was incurred. Thanks for all the knowledge everyone!