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hct5 · 07-13-2022, **(Subject: cm871 injector )**

having an issue with an injector. engine was running rough and dumping white smoke. did a cylinder cut out test number 6 was dead. also did a cylinder performance test cylinder 6 failed. everything in the overhead looked good and was in adjustment. pulled the injector and pressure tested the coolant system the injector cup is good and not leaking. changed the injector adjusted the overhead and still have the same problem running rough, white smoke and on the two tests stated above i get the same results. any ideas of what it could be? i double checked the overhead to just be safe.

tree98 · 07-13-2022, **(Subject: cm871 injector )**

You losing coolant?

Signature620 · 07-13-2022, **(Subject: cm871 injector )**

Might have dropped or chipped a valve. Remove the wire from the fuel shut-off solenoid and crank it. If it has a quick spot on every revolution then it's got no compression in 1 cylinder. (Not a 100% conclusive test but a very good indicator).

You can also pressurise the intake system and rotate the engine to see if it's leaking out the exhaust both when the intake is closed and/or when the exhaust is closed.

Rawze · 07-13-2022, **(Subject: cm871 injector )**

A leaky injector on the older engines will make it seem an injector is bad, or smo0ke a bit, run rough,. etc.. because it aerates the fuel supply, and leads to someone chasing the wrong set of problems, or replacing the wrong injector.

You should have done a proper injector leak test before replacing injectors blindly like that...
ref: http://rawze.com/forums/showthread.php?t...8#pid67948

Your post implies that a leak test was not done .. so it sounds like you still need to also do that test and replace whatever injector(s) that might be leaky before continuing on.

As well, what was mentioned above for checking weak compression, etc. while you are at it.

trucklogger2 · 07-14-2022, **(Subject: cm871 injector )**

You can remove the EGR pipe at the intake to inspect for leaking cooler also (for white smoke)
if it is not blocked off.

hct5 · 07-19-2022, **(Subject: cm871 injector )**

I ordered the injector leak tool , did the test and have an injector leaking on the front bank. I have barred the engine over a full rotation 9 times but I'm not getting the air line to move in the cup filled with water. when cranking the engine i get around 3 bubbles in 20 seconds .

Grounded Pilot · 07-19-2022, **(Subject: cm871 injector )**

(07-19-2022 )hct5 Wrote: I ordered the injector leak tool , did the test and have an injector leaking on the front bank. I have barred the engine over a full rotation 9 times but I'm not getting the air line to move in the cup filled with water. when cranking the engine i get around 3 bubbles in 20 seconds .

I had one injector on the 871 I drive that was just barely leaking like your last post says. I had to put the bottle of water on a cooler and set my phone up to video the water and it would just barely move when hand cranked. Also, I was calling out my crank locations as I was hand cranking it so I could tell on the video. Maybe you're already trying something similar but just my 2 cents.

Rawze · 07-19-2022, **(Subject: cm871 injector )**

(07-19-2022 )hct5 Wrote: I ordered the injector leak tool , did the test and have an injector leaking on the front bank. I have barred the engine over a full rotation 9 times but I'm not getting the air line to move in the cup filled with water. when cranking the engine i get around 3 bubbles in 20 seconds .

Sometimes it can be tricky to find it if the leaky injector it is not severe enough yet.
ref: http://rawze.com/forums/showthread.php?t...0#pid66690

When they do this.. crank it long enough to get it bubbling real good and the fuel pressure built up an extra bit ... then jump out quickly and bar the engine right away. ... like right away ... (safely of course). Do not give it time to let the fuel pressure bleed back off or sit too long. - The thing will bubble at the right moment and you can find what injector it is.

Mr Hagg · 07-20-2022, **(Subject: cm871 injector )**

I always pressure up cylinder when I have one skipping like that... Fuel smoke means unburt fuel... 2 things cause that. one over fueling or low compression.... Once injector out make sure that cylinder is on compression stroke where both valves are loose and blow down into cylinder to see if you have a valve leaking....These engine are sometimes prone to valve seat issues.