I am having trouble diagnosing what the problem is with my truck. I hope someone can give me some advice and guidance!
I’m having trouble starting the truck, whose name is Buster. He cranks but does not start most times. When it does start, it has a very rough idle, between 1k rpm and as low as 4 or 500 rpm. Eventually, it smooths out and while in neutral it revs great, no hesitation. Then, I put it into gear and it jerks going down the road in my neighborhood until I get up to speed… Which takes a while because of the lack of power and the hesitation. It won’t rev over 2k rpm while in gear and definitely won’t ‘giddy up’ like it used to. Kind of just sounds like a low pitched angry growl while trying to accelerate. Haven’t been able to go faster than 45 mph. It has been doing this for the last three days and I just can’t figure it out. My obd scan is reading gm code 44 lean exhaust detected.
I have a new distributor, distributor cap and rotor, plugs, wires, pcv valve, cgr valve, air filter, and disconnected the catalytic converter so it’s not clogged. In my state we don’t have inspections. I have a semi new fuel pump which engages… only, maybe 20k miles on it. When I first bought Buster, I changed the fuel filter, that was eighty thousand miles ago. The filter still looks like it’s in good shape. Tbi fuel injection good spray cone. My truck has 306k miles on it. 5.0 liter 305. New gas from a top tier provider. Any ideas anyone?
Which engine do you have? I presume it is gasoline version, right? 4.3, 5.0, or 5.7L? In general lean problems on otherwise mechanically healthy engines are usually caused by one or more of the following
unmetered air leaks into the engine, egr, pcv, broken ducting, etc
I haven’t checked for that no, it’s starting to look like my only option at this point. Might be a sloppy/slappy chain after all these years. I think I I need a balancer puller/tool and a gear puller to replace it?
Might be a good idea to check the fuel pressure. On those throttle body injected engines, you can remove the air cleaner assembly and actually see the fuel stream spraying in the throttle body. You might take a look at the spray pattern and be able to actually see a fuel delivery problem, if it’s bad enough to be obvious. See if there are two streams of fuel spraying at idle, and see if they look similar.
Thanks everyone for all of the quick replies. I’m sort of new to replacing things on engines, learning something new everyday.
I have updated the specs and info in the original post, the spray cone in the throttle body of my 305 doesn’t appear to have any blockage, strong spray on both injectors.
I will always keep updated with this thread following the ongoing repairs during the next few weeks while I inspect my timing chain in order to log this information on the internet, incase some one else runs into the problem I’ve been having. That way we can avoid reposting.
Cross that bridge if/when you come to it. All that’s necessary at this point is to make sure the valve timing is to spec and no excessive play between the crank pulley and the cam pulley.
