(12-15-2023 )Canadian Trucker Wrote:  I also have a cm2350 Cummins ISX15 that fails that injector leak down test horribly, I timed it for a minute and it dropped from 29,200~ to about 4,000 psi. I guess my main question is what are the consequences of running it like this? I don’t have any check engine light or rough idle or bad fuel mileage or any of the other symptoms i have heard other people having with way less of a drop than mine has. My demandate tune is Rawze approved, and also I replaced that check valve at the end of the rail already, and fuel pump was changed with OEM rebuilt about 200,000km ago. I change oil and sample at 500 engine hours and my fuel dilution is always less than 0.1%. I have ordered 3 of the cummins fuel rail plugs and do plan to test the injectors eventually, just not getting the whole picture of the severity of the excessive fuel pressure drop I guess. If someone can explain it to me would be great! Thanks.

(12-15-2023 )Rawze Wrote:  

(12-15-2023 )Canadian Trucker Wrote:  I also have a cm2350 Cummins ISX15 that fails that injector leak down test horribly, I timed it for a minute and it dropped from 29,200~ to about 4,000 psi. I guess my main question is what are the consequences of running it like this? I don’t have any check engine light or rough idle or bad fuel mileage or any of the other symptoms i have heard other people having with way less of a drop than mine has. My demandate tune is Rawze approved, and also I replaced that check valve at the end of the rail already, and fuel pump was changed with OEM rebuilt about 200,000km ago. I change oil and sample at 500 engine hours and my fuel dilution is always less than 0.1%. I have ordered 3 of the cummins fuel rail plugs and do plan to test the injectors eventually, just not getting the whole picture of the severity of the excessive fuel pressure drop I guess. If someone can explain it to me would be great! Thanks.

The consequences if it is an injector leaking into a cylinder, is fuel impingement (dried fuel crud) buildup, and it will take out the cylinder. In fact, it don't take much at all to wipe out a cylinder or eat the valve train up.

I just saw one a few weeks ago that this happened to in fact ... it was over at Mr. Hags shop being inframed,.. and the piston in that cylinder was covered in crud.. it ate the valve seats up and eventually blew the head gasket. Engine had low miles on it. I was told that what's even worse is that the truck owner refused to have the issue fixed, ran it several months after finding about it, knowing it was an issue.

I should have taken pictures of the cylinder.. it looked pretty bad and it was obvious that a leaky injector took it out.

He learned the hard way that it voided his warranty and now the engine needed an inframe to fix a problem he could have completely avoided.

Also, it over-works the crap out of the fuel pump, causes the fuel to run hotter usually, and this wears out the pump and accelerates wear in the fuel system, pushes other injectors towards failures.

I.E.> It is nothing at all to take for granted just because someone 'feels' like its running ok.

You also loose fuel mileage because the pump is working its arsse off all the time too.

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Trying to save a dollar in trucking on proper repairs and maintenance of especially that engine .. ALWAYS ALWAYS costs thousands (sometimes tens of thousands) of unnecessary $$$$$ down the road, and a whole lot of regrets.