Testing for leaking fuel injectors

[kaldek]

Hi folks,

The injectors on my '02 started to leak after they were cleaned. This is not uncommon on high mileage injectors and basically means they were already stuffed. If you ever want to find this out for yourself easily, here is the very simple process to do so:

Lift the tank and remove the airbox cover and air filter. Remove the intake stacks and set aside, then lift the airbox base gently.

Disconnect the IAT sensor, the MAP sensor (electric and vacuum) and flapper valve vacuum hose and electrical plug, then remove the airbox base.

Take a piece of paper towel and cut it into three inch wide strips. Tightly roll each strip into a "stick", and about an inch from the end, fold the stick back on itself into a hook.

Plug all the open vacuum lines and start the bike. Ignoring any FI warnings from disconnecting the MAP sensor and IAT sensor, let the bike warm up to operating temperature and then shut it off. With the bike no longer running, hold the throttle wide open and take a paper towel stick. Put the stick into the throttle body with the hook facing the injector port. Push the stick down until you can tell the hook has moved past the injector port, and then left the paper towel stick gently. It should hook itself into the injector port a little bit.

Now, prime the fuel rail by turning the key to the ON position (WITHOUT STARTING THE BIKE!) and waiting for the fuel pump to stop. Repeat about six times and then remove the paper towel stick by pulling on it gently. Don't rip it, because it will fallt into your motor!

Check the end of the paper towel for signs of leaking. It will be slightly darker spots on the towel, and you may need to unroll the stick to see it.

If your injectors are leaking, it's time to have them replaced. Even if you replace only one, you want all four to have matched flow rates. The easiest way to do this is just buy a set of four, either aftermarket or from Honda. 2006 and newer injectors have the same stated flow rate and are cheaper than 02-05 model injectors. 1998 injectors are apparently the same flow rate as well, however they are a pintle type rather than multi-hole type injector. New model injectors may still work fine on the '98 though, so feel free to do some research!

Lastly, here is a short video on how stuffed my injectors were:

[Misspent Youth]

Thanks for the helpful info and video. Once replaced, please do post to confirm the replacements don't leak (or otherwise!).

[kaldek]

Thanks for the helpful info and video. Once replaced, please do post to confirm the replacements don't leak (or otherwise!).

Confirmed, sir! The replacement 2006 injectors were given to a reputable car performance workshop and cleaned three times, resulting in matched flow rates. After fitting them, all running problems are gone and the bike is back to its magical norm.

[JayWalker]

And this solved your surging issue?

[Guest dendron]

Is the leaking due to internal injector seals that wear out over time, or is the spray pattern partially plugged due to varnish or contaminants? Would an injector cleaner additive such as Techron be at least a partial workaround?

[JayWalker]

The injectors on my '02 started to leak after they were cleaned.

I think the issue started after an additive was used.

[Ranger77]

My '01 injector bottom ends are way different in shape.

Edited November 5, 2010 by Ranger77

[Veefer800Canuck]

My '01 injector bottom ends are way different in shape.

6th gen injectors are WAY different than 5th gen injectors. Not interchangeable.

[Ranger77]

Yea. They look more "vehicle" type.

[Polarbear]

Hey,

Great, very informative post. :fing02: However, some not so mechanically-inclined people like me are still missing some key information If you have time, would you mind answering the following please?

a) what was the problem before you replaced them? Surging?

b) what (other?) problem leaking injectors may cause?

c) did it solve it completely?

d) what was your mileage?

e) how much approximately for the set of 4 injectors?

f) aren't you supposed to open a cold one before, and another one after you're done, shake your head thinking about how much this may have cost you at the dealership, and then smile? :beer:

Many thanks for educating the ignorant ones, such as me. :biggrin:

C

[spud786]

The key part of the vid and you hid the camara , did you pee on your finger, where did the wetness come from?

I just dont understand why you went to all the trouble of the video and not show the where the leakage was coming from.

Its like reading a book and skipping a chapter of key info

[Ranger77]

The key part of the vid and you hid the camara , did you pee on your finger, where did the wetness come from?

I just don't understand why you went to all the trouble of the video and not show the where the leakage was coming from.

Its like reading a book and skipping a chapter of key info

He probably doesn't have a tripod. You can't stick one hand's finger down the tbody with out the other one opening the butterfly and turning the key on.

Edited June 5, 2011 by Ranger77

[Guest kennybobby]

Hi folks,

The injectors on my '02 started to leak after they were cleaned. This is not uncommon on high mileage injectors and basically means they were already stuffed. If you ever want to find this out for yourself easily, here is the very simple process to do so:

...

2006 and newer injectors have the same stated flow rate and are cheaper than 02-05 model injectors. 1998 injectors are apparently the same flow rate as well, however they are a pintle type rather than multi-hole type injector. New model injectors may still work fine on the '98 though, so feel free to do some research!

Thanks for sharing, this is great information. Here is some results of my research done on multi-hole type.

And i have a big red flag warning here about the type of injectors, i.e. the older pintle (bosch) style versus the multi-hole (Nissan) style. Just go read the nissan forums about the nightmares they are having with their injectors. Internal to the injector are some very tiny holes in an orifice plate that is welded to the end of the solenoid--these holes are only 0.008" (0.2 mm) in diameter! If you thought the pilot jets in carbs were tiny...

The varnish and residue from dried ethanol fuel can and will clog these very easily--that's why the nissan guys are so busy swapping them out all the time, and it is a big hassle to pull them on a nissan engine. There is no way to clean them out that i can see and i don't think any sort of snake foam or sea oil mixed with your fuel will do any good once they get plugged.

i think the pintle design is superior but just guessing that there may be some sort of economic factor in not wanting to pay royalties to bosch to use them.

In light of the watered down crap that is sold for fuel these days, going to the tiny orifice plate injectors was not a smart move by honda.

How did your injectors get "cleaned" to begin with?

[kaldek]

How did your injectors get "cleaned" to begin with?

They were cleaned on an ASNU ultrasonic injector cleaner by a mobile guy in a van. Nice fellow, but all the cleaning did was clear out the goop from the rust pits in the injector bore and cause the injector to leak!