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Chevy 350 tbi, loosing power, flooding, no ECU codes. HELP!

 
internetjunk4631
I love my Chevy Chevette!
Posts: 1
Joined: 04/08
Posted: 04/07/08 08:29 PM

recently my 1990 Chevy suburban 350 throttle body injected truck started loosing power.  here's the story: i drove it to school, and it quit on me sitting in traffic.  Started up fine after that, then quit again in the parking lot a few minutes later.  This time it flooded, and i could only get it going again by holding the throttle wide open while turning it over.  After that the truck ran like crap. sounds bogged down, and quits running when stopped unless i feather the gas. has normal oil pressure, and temp readings.  every once in a while it "springs" back to life for a split second, and seems to run like it should. with throttle wide open, it tops out at 55mph in 3rd gear.  when i let off the gas, the tranny would let it shift into overdrive, but there isnt enought power from the engine to maintain or increase speed in that gear.  what could this be?  i dont believe its a vaccume line. could an injector be the problem?  it seems as if it would be dumping gas in uncontrollable, rather than rationing it.  Is that possible with out any ECU codes?  please help me out here! Confused  

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waynep712
I have an SS396 tatoo
Posts: 264
Joined: 01/08
Posted: 04/07/08 09:07 PM

could be the fuel pressure regulator gone bad... this happens...

here is a link to autozones basic repair info... for your truck..

http://www.autozone.com/az/cds/en_us/0900823d/80/08/73/1f/0900823d8008731f/repairInfoPages.htm

they are not hard to change with a few metric hand tools.... and some torx tools...  

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wieder
My first time was in a Chevy
Posts: 214
Joined: 03/08
Posted: 04/07/08 10:50 PM

If you haven't already change your oil,good chance it's comtaminated and has thinned out from fuel.WIEDER  

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55Guy
Big Block power for the win
Posts: 895
Joined: 08/07
Posted: 04/09/08 06:21 AM

Yeah, defintiely sounds like the fuel pressure regulator has gone bad. The other guy's right, definitely change the oil too, that much gas going into the cylinders probably washed past the rings and fubar'd the oil.  

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Sleeper357
I love my Chevy Chevette!
Posts: 4
Joined: 04/08
Posted: 04/10/08 06:59 PM

I just solved a problem similar to this on a 91 Chevy truck with a 350 TBI. The problem was that after the new gasket and o-ring set was install into the TBI unit, One of the injectors was getting all the fuel. I found this by simply turning the key on and saw the fuel escaping by the O-Ring at the base of the injector. Thus there was not enough pressurer for both injectors, so only 4 cyls were gettin fuel. The rebuild kit was new but one of the O-Ring had a chunk missing from it, allowing the fuel to escape directly into the throttle bore. Also check the TPS, it can malfunction due to wear and send false signals to the ECM causing excessive fuel spray.  

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cruzv64
I love my Chevy Chevette!
Posts: 2
Joined: 03/08
Posted: 04/11/08 12:14 AM

Sounds to me like you might have a bad module it controls the spark and injector pulse take it to autozone have checked, if not it also could be the fuel pump depending on the miles on truck sometimes they overheat due to lack of proper fuel level for long periods at a time and they will lose presure or simply stall every time you come to a stop sign.  

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HOFMAYER
I love my Chevy Chevette!
Posts: 12
Joined: 04/08
Posted: 04/11/08 09:05 PM

I WOULD CHECK THE MAP SENSOR,THE HOSE TO IT,AND THE THROTTLE BODY GASKET.THE PLASTIC HOSE BREAKS(CRACKS)ALL THE TIME.IF THE MAP DOESNT SEE ENOUGH VAC THEN IT WILL RUN RICH.IF THE BASE GASKET IS BAD IT WILL HAVE LOW VAC AT THE MAP CREATING THE SAME PROBLEM.DOES THE ENGINE SEEM TO IDLE FASTER THAN IT USED TO?ALSO HAVE SEEN CLOGGED CAT CONVETER DO SAME THING.EVER HEARD THE CAT CONVERTER RATTLE?IF SO PORTION OF CATALYST CAN BREAK LOOSE BLOCKING EXHAUST, CREATES SAME PROBLEMS(RUNS RICH,NO POWER).  

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HOFMAYER
I love my Chevy Chevette!
Posts: 12
Joined: 04/08
Posted: 04/11/08 09:16 PM

FORGOT TO MENTION,IF YOU SUSPECT CAT CONVERTER PICK UP VAC GAUGE FORM THE ZONE,INSTALL ON INTAKE VAC PORT,SHOULD HAVE 15-20" VAC AT IDLE.HOLD THROTTLE OPEN(SLIGHTLY) FOR THIRTY SECONDS,AT FIRST VAC WILL DROP SLIGHTY AND THEN WILL STABILIZE,CONTINUE HOLDING THROTTLE OPEN AND IF VAC CONTINUES TO DROP(IN WORST CASES TO ALMOST 5")AND ENGINE TRIES TO STALL THEN YOU HAVE AN EXHAUST RESTRICTION.  

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