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

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

 
internetjunk4631 internetjunk4631
New User | 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  

waynep712 waynep712
Enthusiast | 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...  

wieder wieder
User | 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  

55Guy 55Guy
Guru | 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.  

Sleeper357 Sleeper357
New User | 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.  

cruzv64 cruzv64
New User | 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.  

HOFMAYER HOFMAYER
New User | 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).  

HOFMAYER HOFMAYER
New User | 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.