I been helping out at a used car dealer. (The place i got my Heep) Well they got me fixing a 96 Blazer 4.3L Vortech. They said it was running when the fuel pump went out and they had someone replace the fuel pump and it still would not work so they gave up and it sat for 2weeks or more. Well they contacted me and i thought it would be an easy $50 because i know GMs have a fuel pump switch in the oil sending unit so i checked it and its connector was loose so i put it back on and the pump worked. I thought great i am done, Well it still won't start.. If it sits for about 15mins you can try to start it and at first it will stumble like its starting then it will just sit there and spin over and if you keep trying all it will do is spin over but if you let it sit again for 15mins or so and try again it will do the same thing as in stumble like its starting up then just spin over and over.

So i check for spark and its good. Check Fuel PSI at the service port and its right at 55psi and holds. So that leads me to think the CSFI is clogged.. Am i on the right track in that the problem is the Poppet nozzles are clogged? Is there a way i can clean these without taking the whole CSFI apart? as in like high psi air pressure about 100-150PSI from an air hose to the service port and spin the engine over to blow out the Puppet nuzzles? and then run top end cleaner through the service port or put some seafoam in the gas tank?

 

I forgot to add this... this is quoted out the fuel system diagnosis thread. But on this thing when you turn the key on you can hear the pump for 2 seconds then not hear it any more even while cranking it then sometimes when you switch it off you hear it again for 2seconds. So maybe its not the CSFI? whatelse would it be?

 

I could be wrong here, but i don't think 55psi is enough to start the truck. I think it needs something like 62IIRC

 

Now if that is true someone let me know and let me know what i can do about testing to see if that pump just can't do it.

 

It appears i was incorrect. Sorry about that.

Here's a DIY article about the fuel system.
https://blazerforum.com/forum/tech-a...agnosis-23038/

 

i BET with them being a used car dealership they got a cheap pump, ie: airtex etc. Find out! it matters.

it needs MINIMUM 60 psi to run efficiently enough. Change fuel filter,if that doesnt help then check pressure with filter off at the filter fitting. if its less then 60,change pump with a delphi or ac delco. If they dont wanna spend the money,then tell them to expect lots of problems.

 

Only thing they can agree on is if it runs sell it or if it don't run make it run as cheap as you can then sell it. does not matter if its safe or not. Like the drivers door needs to be fixed they repainted it but that don't change the fact that the door lock is broke in half.... I told him he would be looking at a law suit if someone bought it and they didn't say nothing about it and they are driving down the road take a turn alittle to fast and the drivers door opens throwing the driver into the road...