i have a 97 4.3 blazer and its slowly been harder and harder to start a few months ago it would take longer cranking no big deal to me no CEL ever and really only used it to pull a boat. nov/dec i replaced the lower intake gasket set and a cap and rotor. but i remember this problem before then, it eventually got to be that it wouldnt start at all no matter how long it cranks, UNLESS you only try to start it as though your just bumping the starter. im talking like half second tries maybe 2 revs of the crank at a time and it will come to life. while running theres no misfire and all the power in the world. and this doesnt seem to be a problem when warmed up. i pulled the left front plug in hopes of seeing it worn down to nubs but its just barely beyond the gap the new one i bought were, i cant check actual gap but they are delco plugs. i used the oreilly fuel pressure test kit and its got the pressure. it wasent a long drive to get there but when i tried to start it to check running pressure it wouldnt start untill i did my little trick to it. pressure was there, i remember seeing about 50-60 while it would crank for maybe 4 seconds.
again i cant say im a long time reader first time poster because ive never had such a strange problem and im hoping someone knows what im talking about thanks in advance for your help.

 

Maybe your spider (INJECTORS)

 

seems like that was cause a consistant misfire while running but i havent had that happen, no problems at WOT only if i crank it for 3 seconds or more it seems

 

I'd check the plug gap, thousandths is hard to eyeball measure.

 

Don't bother with running pressure, the leak-down test is what it needs. Key on engine off 65-60 then no lower then 55 in ten minuets.
You did not say how many miles but could be ready for a pump.

 

Mileage s about 205k and I'm sure it's had a pump sometime since there's coat hanger wire running through the tank strap where a bolt had been. I did check the keyonengineoff pressure an I wanna say it was in spec. I can understand the plug gap requirement part too but the part I don't understand is why it starts after Only bump starting it? With no symptoms of misfire or anything ones it's running?

 

I have had that bump start thing. I think it gives a failing pump a second to recover initial pressure. That's just my theory. Ive read the symptom alot and like I say had it myself.
Never have gotten a good explanation of the physics of the thing.
I kind of shotgunned mine with a fuel reg and pump. Not the most cost effective method for sure but had symptoms pointing in both directions.
Runs good know.

 

well thats exactly what i did and didnt want to hear, its hard to explain that situation like "its hard to start but only when you try to start it" well ill dig into the fuel system a bit harder now. i almost hope its not the fpr cause i coulda thrown that in 2 months ago. will remember to post an update later. i greatly appreciate the help

 

Spittybays is right about fuel pressure, and the symptoms you're describing are classic for a failing fuel pump.

Proper fuel delivery is critical on this engine. When you initially turn the ignition to the RUN position, the pump will be activated for ~2 seconds and then shut off. Pressure must be checked during the 2 second time frame. Key ON, engine OFF, fuel pump running: Pressure must be 60psi to 66psi. When the pump shuts off, pressure will drop slightly but it must remain above 55psi for at least 10 minutes. The results of these tests will determine where to look next. Post your results.

Also, the ignition switch used on 1997 is unique to that year. It is known to have "issues" that might cause what you're describing with "bump starting". This link explains: https://blazerforum.com/forum/articl...-switch-33465/

 

Well today I took the VW to Oriellys to get the tester. Hooked it all up the same way turn the key, 0psi cycle it again 2psi again 5,10,17,2?,bam 55. So needless to say ill be putting in a fuel pump. I am very surprised about how picky this motor is 55psi is not a grey area it's either gonna run at 55 or nothing at all at 54psi.