Dando Posted November 7, 2014 Share Posted November 7, 2014 So last night after running for about an hour my truck started running rough and felt like it was lacking power and at about 3500rpm it would feel almost like it was finally kicking back in. This morning after sitting all night it ran the same way. Has relatively new spark plugs, wires, distributor cap, vacuum lines, fuel pressure regulator, fuel filter, recently cleaned throttle body, tps is set correctly, improved grounds as per cruisers tips, only thing not done has been the distributor indexing. Fuel pressure while at idle reads 22 psi and doesn't change when disconnecting vacuum to the pressure regulator, but the trucks idle improves and feels better driving if I leave the vacuum line disconnected. What do I do, where should I start? Any ideas of what this might be, I'm struggling with this and want it fixed as right now I don't trust the truck and it's my only vehicle. Thanks in advance Link to comment Share on other sites More sharing options...
Dando Posted November 7, 2014 Author Share Posted November 7, 2014 Screwing around with things here in the work parking lot before I start my workday and I just noticed that when I remove the electrical connector from the first fuel injector it does not change the idle or anything, remove any of the others and it almost dies. Bad fuel injector? Would that cause all of the above problems? How can I test the injector wiring to make sure it is getting a signal? Link to comment Share on other sites More sharing options...
cruiser54 Posted November 7, 2014 Share Posted November 7, 2014 Possibly a bad injector. Pull all the plugs and see what they look like. Even with a leaky injector, you should see higher fuel pressure though. Stock injectors? If so, get some 0 280 155 746 Volvo injectors. Programbo on Cherokee Forum sells them. Link to comment Share on other sites More sharing options...
Dando Posted November 7, 2014 Author Share Posted November 7, 2014 Number one plug is very wet Link to comment Share on other sites More sharing options...
cruiser54 Posted November 7, 2014 Share Posted November 7, 2014 Number one plug is very wet That's leaning toward injector for sure. Link to comment Share on other sites More sharing options...
Dando Posted November 7, 2014 Author Share Posted November 7, 2014 Well I assume the fuel pump is bad as well, when doing a leak down test as soon as the engine is shut down the fuel pressure instantly goes to zero. Is there any way to easily diagnose the injector for sure? Link to comment Share on other sites More sharing options...
cruiser54 Posted November 8, 2014 Share Posted November 8, 2014 Well I assume the fuel pump is bad as well, when doing a leak down test as soon as the engine is shut down the fuel pressure instantly goes to zero. Is there any way to easily diagnose the injector for sure? Make sure it's not a mis-firing spark plug. Put a new one in on the offending cylinder and see what happens, or do the old spark plug test by grounding it to the block. Link to comment Share on other sites More sharing options...
Dando Posted November 10, 2014 Author Share Posted November 10, 2014 Ok so I haven't had a lot of time to work on the truck this weekend but here is what I found out. Spark plugs have been replaced with known good plugs from my parts storage. Doing that changed nothing. While under the hood I heard a almost unaudible hiss coming from near the first injector, I played with that injector spinning it in place and the noise went away and the idle went back to normal and driving seems normal now too. There is a noticeable difference when I have that injector plugged in or unplugged. Seems like the injector is working again. Leak at the injector caused by orings? Going to clean up a set of known good injectors from my cherokee today and install new orings on them, hopefully install those once I am ready to do the fuel pump. The injector issue doesn't seem to have done anything for my fuel pressure, it has improved but not by much, it sits right around 24psi both with vacuum and without vacuum. And goes to zero immediately when the truck is shut down will not hold any fuel pressure, also when the fuel pump primes before starting the gauge reads absolutely zero until the truck is started. Definetly the fuel pump? Link to comment Share on other sites More sharing options...
cruiser54 Posted November 10, 2014 Share Posted November 10, 2014 You could have 2 problems on your hands. Link to comment Share on other sites More sharing options...
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