I've got a 86 blazer k5 that started will idle fine for about 5 mins and the stalls out... then won't start again I'm wondering what the possible reasons for this are.
I've heard it could be the fuel pump so where is that located on the blazer?

 

what motor and it has a carburetor right not F.I.

 

v8 with carburetor

*Combining Consecutive Posts*

350 v8

 

350 v8

 

Ok then i`m guessing that the choke on it needs to be tweaked a bit with the weather change. ( cold start issue is what it seems to me)..I have an 84 Elcamino that had a 305 in it and i hadto keep making all kinds of choke adjustments on it, until i put a 454 in it with a manual choke.. Problem solved..

 

and how would I go about tweaking the choke?

 

It sounds as though the choke may not be pulling off properly. This could be due to a faulty thermistor unit (what tells the electronic choke to open) or due to a gummed up choke linkage that is just stuck.

Another thing is that the idle feed jets are not properly adjusted or just dirty.

If it has never been done, I would recommend removing the carb and giving it a thorough cleaning. I did this on my 74 K5 and it was a remarkable difference in idle quality. I have another carb that I am going to rebuild and swap in.

 

well if I try to put it in to gear after its started it dies right away

 

Try cleaning the carb. See where that gets you.