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engine hesitating and stalling


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alex1954
Novice

Nov 12, 2014, 1:38 PM

Post #1 of 7 (1157 views)
engine hesitating and stalling Sign In

I have a 1996 chevy 1/2 ton 4x4 ...over the last two years I have had the engine and transmissions rebuilt, along with the transfer case. Over the last few months the truck has had an issue of hesitsting and lossing power. I pulled a list of codes and have one by one fixed the problems...speed control censor. complete tune up, new catalitic converter, replaced fuel filter. Finally the truck was running good...for about two weeks. now the truck is hesitating again, lossing power or stallimg whenI press the excellerator. It acts as if it is flooding and has gotten worse with the colder weather...Any ideas?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 12, 2014, 1:54 PM

Post #2 of 7 (1145 views)
Re: engine hesitating and stalling Sign In

First thing - change your user name, thread will stay but get an email address off there or risk getting spammed out of control.


What engine is this? An "R" code V8 or Vortec anything? They are very fussy about fuel pressure so get a pressure reading at rail KOEO and how well it holds. Then again while running watch it.


I forget the PSI they begin to act up but it will quit even running by about 55PSI at all and really likes 58-62PSI (I think) for Vortecs.


Easy to confuse flooding with plain lack of power and any of it not running well will waste fuel to exhaust. The colder any engine is more sensitive to specs being off,


T



alex1954
Novice

Nov 12, 2014, 2:03 PM

Post #3 of 7 (1140 views)
Re: engine hesitating and stalling Sign In

thanks for the head up on the user name and form the advice.


alex1954
Novice

Nov 12, 2014, 2:06 PM

Post #4 of 7 (1135 views)
Re: engine hesitating and stalling Sign In

the engine is the 5.7 V8


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 12, 2014, 10:44 PM

Post #5 of 7 (1115 views)
Re: engine hesitating and stalling Sign In

OK - My look up show only a Vortec was available for a 5.7 V8. A lot has been done to this, engine, trans, but now I'm focusing on the tune-up and the fuel pressure.


These (and others) want high pressure fuel at the ready as said over 58PSI but would like to see 60+ or it will fumble to run properly. Why? Fuel pumps somewhat common and less than OE GM units have a high failure rate plus none do but this more so do NOT like running low on fuel as it heats up the pumps and poof - they can't take it. Other is plain wiring connections to them along the way and right at it on tank. (edit in here - specs are for pressure to remain between 60-66PSI)


OK? We need the pressure. Key On run with engine off you should hear it prime up and shut off. The pressure at the rail is what you want and takes a tool to read it. See if rentable or I think you can buy one just for this for under $50 bucks. It must have the right threaded fitting for rail and should look like this........

^^
The other possible "ooops" is messing with distributor as you can't set the timing without more equipment than the average person would have. If you messed with it get that known right. If you didn't mess with it during any tune up work it shouldn't have changed and forget it for now.


Either of those not right this engine will run like crap or not at all.


Have to know that much IMO to proceed with what else is possible if not those,


T


PS: Do yourself a favor on these and similar - get some spray grease for the dang fuel filter on the frame and douse it as those flare nut connections suk and breaking them and lines quite possible and can be avoided with plain grease on the outside and all other similar things while there like parking brake cable too. Keep going and check all brake and fuel lines. Apparently GM thought it would be funny to make them rust while you watch on these!



alex1954
Novice

Nov 12, 2014, 11:40 PM

Post #6 of 7 (1109 views)
Re: engine hesitating and stalling Sign In

Sounds like things are pointing to the fuel pump,,,


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 13, 2014, 12:24 AM

Post #7 of 7 (1101 views)
Re: engine hesitating and stalling Sign In

In my experience YES.
The bad news is the whole unit new from GM is pricey.


The better news is with the tools you can see that the pressure is inadequate then have a high chance of not wasting money on something it really doesn't need.


There's a slight chance of getting fooled by a wiring connection that just isn't making a proper contact inside but just enough for it to run at all so if you find one that isn't clean and tight check that out as well. It was or should have been nicely greased when new but bad luck or exposure can take them out slowly. Dang, it would be better if those things would just fall apart and be obvious but many are not,


T







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