95 Blazer LT, 4.3, 170k

Hey guys! Longtime lurker, first time poster. I recently acquired a 95 LT with 170k on it for a song...because it didn't run right. The girl I got it from said it ran great before it started dieing at random. According to her, it would run fine for a while, then die. Sometimes it would start right away, sometimes in ten minutes, sometimes ten days. I was not able to get it started when I went to look at it, so she let me have it reeeeeal cheap.
It sounded to me like the ignition switch was bad, so I investigated that once I got it home. The contacts were pretty well smoked, so I replaced that. I also replaced the coil they had slapped on there with the original on a hunch. The beast sputtered to life eventually, but was not running well. Smelled rich, and missed badly. I started removing all of the "new" (cheap) parts they had put on chasing the problem and replacing them with AC Delco. Cap, rotor, wires, plugs...voila! One of the Autolites they had used was bad. The truck ran great!

So I drove it to work today. Ran awesome all the way there, about 15 miles. After work I got in the truck, turned the key, and...crank, crank, crank. No joy.

I was able to get it to roar to life with some starting fluid, so I figured I would try to get it home before diagnosing further. Fate had other plans, however. I made it about 1/4 of the way when it chugged and died. After drifting off the road, I called for rescue. I was able to get it to run on starting fluid enough to set me coasting down a hill and into a parking lot, where it sits now, waiting for me to return tomorrow.



The previous owner let on that they had replaced the fuel pump. While I can hear it running, it is quite loud, and judging from their choice of other parts, I doubt it is OEM. They also replaced the fuel filter...twice. They also said they had the spider either "replaced or repaired", but they couldn't recall. I have not checked the pressures yet, but it is on the list for tomorrow's adventure. I have removed the tuning valve (?) and peered into the plenum, and there is no washing visible on either side. Is it possible for a FPR to go bad and not leak? That is where my suspicions lie, as it will try to kick over for a second, but stumbles and falls flat. It seems like it builds sufficient pressure for a moment, then loses it and can't build enough back up to keep on keeping on. If it matters, I can hear the pump start up to prime, then it starts again as soon as the motor cranks. (Yep, it's that loud!) A shoddy, aftermarket pump could be to blame, as well.

I suspect spark is good, as it runs fine when it runs and starts on ether when it won't otherwise. I have not verified this by any scientific means, however.



So what say you, fellows? Any nuggets of wisdom to bestow upon me before my quest after the mischievous Blazer Gremlin tomorrow morning? Anything I am overlooking? Any similar previous experiences that could lend some inspiration? I am open to your thoughts, questions, and assistance!

Thanks for keeping a great forum here!


Edit: After reading my own post, it occurred to me that this sounds a lot more electrical than pressure related. Isn't there a common problem with an electrical connector for the injector that has been experienced in the past? How does one check such a thing? Is there a repair for such a thing?

 

Sounds like your on the the right track with pressure test as the first thing. Hard to tell about the injectors. I didn't see were you said what motor you have, they had two that year and three comp. setups. Mine is the CPI and they all dump at once.

 

Thanks for the vote of confidence! I have the Vortec "vin w" engine. I went ahead and ordered the regulator, nut kit, and plenum gasket this morning for pick up. I figure even if I don't need them, I will eventually, so figure it as preventative maintenance. I have to go to the parts house to borrow the pressure tester, anyway. May as well throw them a bone. lol!

I will report on my success/failure/findings in the event it will help someone else out. Wish me luck!

 

Well, guess what I found? Check out the pic, and you'll see the proverbial washing from the regulator that almost certainly was spraying fuel like a garden sprinkler!

The $45 pressure test kit from Advance was a decent buy. They wouldn't loan me one, as they said they don't like getting them back full of stinky fuel. I figured for the cost versus benefit, I didn't mind. It will certainly come in handy if I intend to keep this ol' girl running.

The fuel pump checks out fine on the gauge, putting out enough to bring the system up around 66 psi. The problem came when the pump shut off...the needle sank to zero within about 20 seconds! Fortunately, I had already picked up the parts I needed, and made short work of the job.

The hardest part was getting the old nut kit out! Those darn things just didn't want to let go! I ended up breaking the lines off near the end and sliding a socket over them, then using a rather large wrench as a lever to push them out. Worked the trick, but took a few minutes to come up with the plan. Over all, start to finish, it took about 2 1/2 hours. Not too bad at all!

On a related note, the CPI connector is a piece of crap. This one has already been replaced, but it is loose as can be. I hope to come up with some alternate plan to keep things working properly. It loosened up on me once on the way home, causing a stall. The old tug on the wires trick brought it back to life, but what a pain if it happens often. Has anyone developed a workaround? Maybe tighten the connector or enlarge the contacts on the injector?

 

EGR valve could be cause. It's very easy to locate and replace. I cleaned mine and sprayed the plunger with WD-40 and it is better. Valve is located on the front of the intake manifold and is sort of at a 45 degree angle. One of the easiest things to get at on the engine.