Testing injector w/o injector tester

[fishlegs]

While looking over my engine manual, I came to wonder: Is there any harm in testing your fuel injector while it is still connected to the hoses of the bike? Ie. remove injector from head, keep fuel connections to injector intact, position injector in a jar, and turn the engine over with the throttle open. I guess this wouldn't reveal much about pop off pressure, but couldn't you use this approach to learn something about injector leaking, chatter, and spray pattern?

[Stuart]

I've done this before but you have to be careful. The spray can cut into your fingers if you get too near it. Kicking over my Hatz 350 once with the injector dangling outside you get an instant BOOF! and a cloud/mist of fuel thereabouts or should do if you've no blockages.
Be careful doing this


Stuart

[Crazymanneil]

I second what Stuart said. Injection injurys are not funny, amputation tends to be the treatment for something which may not appear that bad initially. Some gruesome info out there on the internet, should we post a link as a reminder stuart?

Stay safe,

N

[Stuart]

Here's one I just found. I bet there are more out there.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2097992/

[fishlegs]

I'm a little sorry I asked. I can't get the image of a poisoned finger out of my head. I like to think that testing the injector in this way can be done safely, but I may be having second thoughts.

Thanks for the insight.

[Stuart]

No worries Given the amount of hands on work we're all doing on our bikes we really should have reminded ppl of the dangers about this earlier. Neil is right and I think that we should put a special header at the top of this page in particular to remind folks that one wrong move could result in serious injury. We are dealing with some extremely high pressures here and fuel blasted from an injector is not something you want to get in the way of.

[andrewaust]

Good to see you posting the warning Stu! Also be careful with air and water under high pressure. The newest form of metal cutting devices have been Laser and "water" cutting.

Many will know this anyway, but for the few who are new to mechanics and tooling, be careful out there.


A

[Snave]

take it from me that testing injectors is not a Mk1 eyeball job, and amputation is a very real possibility. Modern Common Rail injectors typically run at the 1,800 bar level or above - or 2,800 psi if you prefer. A steel cuttter will work at 50,000 psi - and a bike tyre is of course about 32-42 psi and THAT can still explode...

Ugly mess!

[Sphere]

Extrapolating upon the old saying "The safest way to light a BBQ is to have someone else do it" I had Nanko test my Hatz injector Alright, alright, he wanted to regardless of my opinion.

There I was, packed in numerous layers of protective clothing (from the cold) waiting anxiously for walls to come down and Nanko to lose limb after limb. Fearlessly, he turned the flywheel... nothing happened! Not very surprising, because there was plenty of air in the system. However, after a few more turns there it was: a nice little cloud of diesel, evaporating in four(?) directions. A fascinating sight

Not to mock the warning, the PDF is very clear. This is not some water spray, to douse plants. On the other hand, you can test your injector without injuring yourself. It is as easy as pointing the injector away from you and not holding the business end between your finger tips.

[pietenpol2002]

I like the approach taken in the link below in which the injector is secured into the metal lid of a glass jar. One can then safely view the spray pattern while the fuel is captured in the jar.

http://www.peachparts.com/shopforum/sho ... p?t=224334

[Snave]

Viewing the spray pattern is simply not a tenable way of testing the injector. For a start the injector needs to be under back pressure load typical of cylinder head pressures or else the spray pattern is not representative. I could go on, (and on... ) but I won't.

I s'pose if what you want to achieve is "ooh look! Somethings coming out the end!" then it might achieve that objective, but then so does squeezing a toothpaste tube, and that's far more satisfying...

[Sphere]

I guess there's injector testing, and then there's injector testing after modifying an engine to directly control the fuel pump instead of the governor. In the latter case it is very reassuring to (still) see diesel clouds escaping from a nozzle.

[John]

take it from me that testing injectors is not a Mk1 eyeball job, and amputation is a very real possibility. Modern Common Rail injectors typically run at the 1,800 bar level or above - or 2,800 psi if you prefer. A steel cuttter will work at 50,000 psi - and a bike tyre is of course about 32-42 psi and THAT can still explode...

Ugly mess!

Hi Snave. Actually, it's even more dramatic, as 1800 bar is not 2,800 psi, but nearly 26,500 psi. Even our humble Yanmar clones are 200 bar injection pressure, or 3000 psi.