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Randall C
Randall C, ASE Master Tech
Category: Chevy
Satisfied Customers: 12803
Experience:  ASE Master, L1, 32 years, Diagnostic / Electrical Specialist
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96 blazer 4.3L v6. hard to start as if starved for fuel. has

Customer Question

'96 blazer 4.3L v6. hard to start as if starved for fuel. has progressively gotten worse over last few months. runs great when started but have to cycle fuel pump off/on a few times or even jump start if that doesn't work. have changed in-line filter and replaced battery with no change.
Submitted: 7 years ago.
Category: Chevy
Expert:  Randall C replied 7 years ago.

Hello, at anytime have you had the check engine light come on? if so do you know what codes were set?

Customer: replied 7 years ago.
check engine light has been on since purchasing 3yrs ago. never checked codes. new plugs, wires, dist and rotary. got plenty of fire. even when jumping have to cycle fuel pump off/on. never a stong odor of fuel when trying to start.
Expert:  Randall C replied 7 years ago.
i think i aknow where the problem may be as it was common for this engine and year. Give me a few minutes to type and send all the information. back shortly. thanks
Expert:  Randall C replied 7 years ago.
I forgot to ask. After to cylce the key and finally get engine to fire, does it run 100% right from the second it starts OR does it run slightly rough till you get the RPM's up a little and then runs 100%
Customer: replied 7 years ago.

it runs rough for a second or two only then runs 100%. usually it will try to start or barely start for a second and then die. sometimes have to cycle fuel pump 5-6 times before trying to turn over the engine in order to start but when it does catch it just sputters for a second and then purrs. does this model have a regulator? or could a weak fuel pump or even the sock in the tank cause this?

Expert:  Randall C replied 7 years ago.
, thanks. I am NOW going to type the info for you as I feel the problem is. Bear with me. I should get with you shortly
Customer: replied 7 years ago.
Expert:  Randall C replied 7 years ago.

This engine uses a special design of "fuel injector assy". We refer to it as the "spider" injector" See below. it is all one piece and the injectors are actually called poppets. mounted on this "spider" is a fuel pressure regulator. You are describing a loss of fuel pressure after sitting. This is caused normally by one of two things. the regulator allowing fuel back to tank OR the "spider " assy where as a poppet is sticking open slighly. the fact you get brief rough run leads me to a bad poppet or "injector assy". these had known problems from injectors (poppets) not seating correctly due to debri caught at the tip of one or more. This will allow fuel to drip into cylinder while sitting, cause brief rough run upon startup and then clear out once the fuel burns off. Usually pretty quick. If you had a bad regulator, fuel would loop back to tank and keep doing that and making starting almost impossible and if it runs, it would barely run at all. I am leaning towards the "spider injector' assy being bad. very common. So much there was a recall for the ones in California for poppets sticking. Now... you have 1 of 2 options. many times you can have a shop do a full fuel injection flush and soemtimes this will get the tips of the poppets clean and you will be just fine. This does not always work. In this case, the fuelmeter assy "spider" will need to be replaced. not too bad of a job but the upper manifold must come off to replace it. A fuel injection flush by shop generally about $75 on the average. This problem will not get better but worse over time. Fuel additives just do not work.



Customer: replied 7 years ago.
so no way it could be a weak fuel pump or clogged sock?
Expert:  Randall C replied 7 years ago.
By all the times we have had to replace the spider assy due to excatly what you describe, chances no. A weak pump will remain weak. Not just be weak after sitting and then run great all day. A weak pump will cause performance issues , bog down etc all the time till it eventiually fails. The sock? same scenario. if it is blocked, its blocked. You would have overall running problems. To confirm anything, a fule pressure test needs to be done. I feel very strongly if you have this done, you will find the pressure drops off. not a lack of