View Full Version : how do i test a fuel injector?

Right Touch
08-25-2009, 12:08 PM
my f450 is losing power and I was told by someone who heard the truck that it was a fuel injector gone bad because he heard a puttering sound. I originally thought it may have been an exhaust leak but he said no its def a fuel injector. I saw an article in Popular Mechanics that said I can use a Noid Light to test. Is this easy to do? I think my f150 has the same problem too because its puttering slightly and theres also a weird high pitched sound coming from under the hood mostly audible when I am idling that sounds like its coming from an injector?

08-25-2009, 05:07 PM
simplist way to do it in my opinion is to stick a long screwdriver on the injectors one by one and put your ear on the handle part to use the screwdriver like a stethoscope. Be careful not to get eaten by your engine as this test can only be done with the engine running. If you hear the injectors clicking then they are working electrically however they could still need cleaning. This is a test for a gasoline engine I do not know if it is the same for diesel. You didn't specify your trucks engine.

08-25-2009, 07:08 PM
When my boss had trouble with the shop Fords he bought a tester similar to this;


I was able to test/look at the spray pattern (which should spray like a umbrella) and test pop-off pressures.....

Right Touch
08-25-2009, 07:54 PM
any idea what that is or where to get it?

the 150 is gas and 450 diesel

08-25-2009, 09:57 PM
That is a diesel fuel injector tester. The injector is fed diesel fuel under increasing pressure until something either breaks or the injector opens. If and when it opens, the pressure and spray pattern are noted and compared with the specs.

That appears to be a manual machine, requiring the operator to pump the lever, kind of like a jack handle. In fact, it looks just like a modified jack.

I have no idea where you can get one, but I bet Google does.

ALLPro Landscaping
08-25-2009, 10:11 PM
what year is your truck.

ALLPro Landscaping
08-25-2009, 10:12 PM
also is it diesel or gas, if its a diesel, you usually see blue smoke coming out the exhaust

08-25-2009, 10:15 PM
On second thought, EBay (http://cgi.ebay.com/ebaymotors/Diesel-Injector-Tester-Mercedes-190D-240D-300D-300SD_W0QQitemZ380148562932QQcmdZViewItem)

However, doesn't your F450 have a common rail injection system? I don't think an injection tester of this variety will work with common rail injectors.

08-26-2009, 04:04 AM
Plug a working one in and see if it fixes the problem.

Right Touch
08-26-2009, 10:18 AM
to be honest i dont know too much about injection systems so i dont know if it is a common rail system. I just know that the 450 has lost power and has a putter sound coming off a stop and someone who knows a bit about engines told me it was a fuel injector. But there is no blue smoke coming out. Thats why I thought it was an exhaust leak.

08-26-2009, 09:08 PM
Can you isolate that injector from the others or is there a fuel rail?