I just recently picked up a really nice 97 suburban with 179,000 miles for a decent price with the knowledge that the engine needs work.
What the symptoms are is a miss / backfire issue. No matter what RPM the engine is at there is a miss to it, almost like a spark plug wire is switched (they're not, I checked). It also bogs down really bad when you step on the gas, blowing black smoke out with a heavy gas smell in the cab.
Also when starting it cranks really slow for about half a second (like it has a dead battery) and then fires up just fine. I've been told this could be some sort of timing issue, but as these engines are self adjusting, I'm not sure what that issue is...
Error codes say 5 and 7 cylinder misfire.
It's had new wires, new distributor, new dist. cap, new plugs, the seal under the top intake manifold (the one the covers the spider / poppet system) replaced, injector cleaner run through the fuel and fuel filter replaced.
I haven't checked the fuel pressure yet.
Using instructions from this thread
, I've pulled the upper air intake manifold off to reveal a pretty serious fuel leak from the injector fuel hoses running to #5 and 7 cylinders.
My question to you elite GM gods here is if I should replace the injectors as well while I'm under here? I've already ordered a new spider, but I just heard there is a newer system without the poppets that works better. Does anyone know about this system and if it's worth it?
I want this thing running good and reliably, but in these hard economic times need to spend my money wisely!
Any ideas from others who have done this stuff are more than welcomed!