Hi guys, I'd been lurking for a while, and hoped I wouldn't have to make this my first post anyway, I've been searching the threads and have read some on the starting issues had by others, and now me. I just got a 97 blazer 2 wd a week ago, ran ok, averaging about 18mpg on the 4.3, I figured with mileage and age, it wasn't bad. Well yesterday it died on me while accelerating from a stoplight. Sat about 20 minutes and started up, albeit idling at a high rpm, I'm guessing 2500 rpm, tried to nurse it home, died again, won't re fire. I've checked the IAC and it's within range, I do think I have a tps issue as well as when checking those numbers, it's outside the voltage range at wot. It also has a new maf sensor. I put a fuel guage tester on it, and on initial ign ON, it went to 52lbs, and dropped to approx 48 and stayed there for 10 minutes with very small fluctuations in pressure. I reset the guage and tried again, now it only goes to 10 psi before the relay kicks off(I hear it in the dash) the pressure drops to 0. This is my daily driver, so any and all help is greatly appreciated. I promise to do a proper introduction when I get this thing fixed. Thx

 

Your fuel pressure is way too low. I'm pretty sure that it needs to be between 59-65psi, and hold above 55psi for at least 10 minutes after the key is off. Hopefully Captain Hook will chime in here. He's great with this stuff. Most likely you're going to need to replace your fuel pump, and if that is indeed the case make sure you go with an AC Delco or Delphi model. The cheap brand ones rarely last more than 6 months.

 

I was able to "reset" everything, tried cranking again, almost started and was at 58psi, turned the key off and back on, went to 55psi and after 10 minutes I'm at 42 psi

 

You definitely have a leak somewhere, my money is on the spider injector assembly because thats where 99% of the fuel leaks are on these things. So what you need to do is take off the plastic intake boot attached to the throttle body and open up your throttle plate and look in the intake with a flashlight for patches of gold or anything not black. what happens is fuel leaks out of your spider injectors and washes away the black carbon. If you have access to a small mirror use it because if the fuel pressure regulator is the part of the spider that is leaking then you might not be able to see it because it is in the back of the intake. the other tell tale sign is if you smell raw gas.

Since your pressure didnt get very high on a couple of your tests your injectors must be leaking really bad, or there is a slight possibility that you have a faulty pressure check valve in your pump. more often than not it is the injectors.

Hope this helps, let us know what you find

 

Well during one of the tests, I got it started and it idled great for 20 minutes, I pulled it up in the driveway, and let it idle for a few more minutes. I drove it down to the end of the street and back and it did fine. I shut it off, and it started up again fine. We left for dinner and came back and it started again fine, the. Kinda choked out. I restarted it and it reved high for a couple seconds and idled back down and seem to idle normally. When I had the cover off the tbi, I noticed some gold spots looking down into the throttle body. I can try and snap a pic tomorrow and see what you guys think. I'd rather change the spider injection that a pump... Lol

 

If you have washing inside the plenum and can see gold areas like 97CherryBlazer described, then he's probably right that you need to replace the spider assembly. I believe you can update it to the newer system, which is more reliable and provides better fuel delivery.

 

I let the truck sit overnight and it started this morning, I drove it about 5 miles and it wanted to stall out twice but never did and came right back. It idles fine sitting in the driveway, could the spider injectors intermittently cause the hesitation, or could the pump be going out after it warms up and loses resistance?

 

Yeah, when my spider was bad, my truck only idled kind of funny and was hard to start but it would drive just fine. Depending on how bad its leaking it can cause a multitude of different things to happen. But i suggest you stop driving it before you destroy your catalytic converter from running such a rich mixture.

If you have gold washing then its definitely some part of the spider that is leaking. As far as replacing the spider over pump, its about the same job in every way lol. Same cost and it takes about the same amount of time to do the job if you are by yourself.

So post a picture so we can confirm, but i can already tell you thats what it is. Rockauto.com has the best prices, and definitely do like El_Beautor said and get the MPI upgrade and from AC Delco or Delphi. I dont even think you can get the old style anymore.. while you are on rockauto, pick up an upper intake gasket set because you might as well replace them while you are in there.

 

Also, check pressure at the pump. Attach the tester so that the pump dead heads into it. You should see about 80 psi (give or take, I forget the exact spec. Mine was about 80 when the bypass in the pump opened). If it produces and holds pressure at the pump, then start looking at the regulator/spider.

 

Ok, so I'm going to check the pressure before the filter at the pump and after the filter, and I should expect approx 80psi? And if its good pressure there, I should replace the spider injector assembly? It was a bitch to start this morning, but fired up and stayed running all the way to work, so I'm assuming the pump is prob not the culprit but the spider assembly based on previous tests.