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putter

96 gmc 1/2 ton ext 5.7 106000miles

10 posts in this topic

well this is kind of a odd one. my dad did intake gaskets on it and thats last time it would start.i checked the timing that seems to be ok,got fuel and presure at the rail [didnt check with gauge] i also checked over harness connections no bent pins or broken wires. i have power at the injector harness

with test light.we dumped fuel down the throttle plate starts and run smooth other than that the truck dont even begain to fire. any suggestions

thank you

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You need to get a fuel pressure gauge. That engine has central port injection which requires a minimum of 55 psi to start. Anything less, 54psi or lower, and it will not start.

I have also had the poppets on the end of the injectors freeze up after leaving the intake upside down during the repair. Typically only one or two will do this and typically the engine will still start/run.

The last thought is to make sure you check the fuses just to make sure you didn't inadvertently pop one.

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i checked all fuses none blown. i will bring my presure tester over test that. i was kind of thinking about the poppets my self

ive had them stick also butt it usally will start up with a mis fire code

thank you for the responce

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62 psi at the rail how long should it hold psi im assuming no mare than few sec considering it wont start

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62 psi at the rail how long should it hold psi im assuming no mare than few sec considering it wont start

It should hold that pressure in theory for days at a time. If its bleeding off right away than there is another issue that may or may not be causing the no start.

Is the snorkel on so that the MAF is reading airflow? are you sure you have all the vacuum lines/hoses hooked back up? Are you sure you have the upper intake sealed so there are no vacuum leaks. It may be worth pulling the fuel lines back out of the CPI unit to see if one of the plastic collars didn't turn sideways on you and essentially plug the fuel rail? Just some thoughts. Keep us updated!!

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had 62 psi tappered down to 58 psi dont remeber if it held at that or not i will double check that. dad pulled the upper intake off and cleaned inj tippes he said it spitts and sputters now.i looked at the vacuum lines sat am didnt see anything disconnected.you wouldnt think that all poppets froze

thank you for your posts airjer

i will keep you updated

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Running pressure and holding pressure will be two different numbers. 62 to 58 drop would be perfectly normal as long as it holds at 58. If it went from 62 to 0 in a minute or so then there is a problem.

I guess the next thing you could do is pull the upper plenum, Remove the poppets from the lower intake, Unplug the coil, plug in the CPI, hook up the fuel rail, and crank it over to see if the poppets are spraying fuel.

I do for some reason remember getting a call from a guy who worked at our hastings location a few years ago. he had the same problem after doing an intake (crank no start) and if I remember correctly he ended up replacing all eight poppet's/injectors. Obviously that is not going to be cheap so I would recommend getting a professional opinion (check data with scan tool and confirm signal to injectors) first.

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i had my dad crank the engine over to see if fuel was spraying out last night no fuel butt i dont know if he plugged it in.

its going on 5yrs since i worked on that engine and living a hour away with 4 kids also working nights has a diesle tech.im trying to walk him through the steps my hand held or the shops wont check gas engine data signal. iwill call him in the am

ask him if he remembers pluging cpi back in. how would i now what direction the plastic collars need to face in cpi idont see it the chevy c/k manual

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The plastic collars in the CPI where the fuel lines go in are there to space the o-rings that seal the fuel lines. It doesn't matter which way they go in.

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parts came in today replaced all 8 injectors fired up first try

talk about bad luck having all eight go out

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