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Old 05-03-2015, 08:22 AM
v8volvo v8volvo is offline
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Location: Montana, USA
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Quote:
Originally Posted by rado561 View Post
Thanks for the advice i tried that today but it still works badly.
OK, so you went through each one of those things, step by step? Used an external fuel can, electric fuel pump, new fuel filter, bled the fuel lines, and everything else, and it still ran exactly the same?

If you feel 110% certain that you have ruled out the possibility of fuel supply problems, and the injection pump is getting nothing but perfectly clean, high-quality fuel under positive pressure with no contamination or air in it, then you should go ahead and investigate other possibilities.

It sounds like what you really want to do is throw a set of injectors at it. That's OK as something to try; the only problem is that it's a very expensive test (in other words, if you haven't fully checked out other possibilities, there's a solid chance that new injectors will make no difference in the engine's problem). As long as you are prepared for the possibility of spending hundreds of dollars and potentially not fixing the problem, you may as well go ahead. If new injectors do fix it, then that's great, and if they don't, then new injectors are never a bad thing anyway -- yours likely have many miles on them and would benefit from a refresh.

The alternative is to continue working through diagnostic steps before spending money on new parts. If you have a hunch that it has a stuck injector, you can try to identify that injector by opening injector connections one by one with the engine running (in your case you might need need a helper to keep their foot on the accelerator and keep the engine running long enough to do this). Stay back from the high-pressure spray, but as you crack open each injector connection with your 17mm wrench, you should hear/feel that cylinder quit firing and see a nice squirt of fuel out of the loosened connection. If there is an injector stuck open, then when you get to that one, what you'll see instead is a bunch of foam coming out and no effect on the engine's operation with the injector disabled.

If you do that test and find one or more injectors that show signs of malfunction, then you've located your issue. But if not, then the likelihood of getting good results from buying a set of new injectors is very low.

FWIW: the only times I've ever seen an injector stick were in situations where an engine had sat for many, many years or where injectors had just been installed and a piece of contamination had gotten into an open union. Very unusual for them to just suddenly stick during regular operation, with no provocation.
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k
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