sputtering at cruising speeds - Page 3

2000CAYukon · #31 07-21-2005, 12:53 PM

Quote:

Originally Posted by wally91vhevrolet

yea i also wondered about the pressure regulator.. ill check all this out

Unfortunately, the TBI trucks do not have a test port for hooking up a fuel pressure tester. There is a tool that goes where the fuel filter is to give you a test port. Then you need a long hose with a gauge so that you can look at it while you are driving.

Otherwise, the fuel pressure regulator is in the back of the TBI unit.

//2000CAYukon

cycowrencher · #32 07-22-2005, 11:52 AM

I just solved this on mine. Truck had the incorrect EGR valve and the EGR restrictor was not installed. There also was issue with the Throttle body base gasket having a small blow through. So small infact that it took 5 tries to find it and 2 seperate attempts at getting a proper seal. Final gasket used was a felpro that was thicker than both the stock and rebuild gaskets. Gasket had to be sprayed with red gasket tack for proper seal. Disconnected the batt for 30 mins, reset everything and no more studder at part throttle.

wally91vhevrolet · #33 07-22-2005, 11:58 AM

well if its the EGR, would undoing the vacuum line that runs to it stop the miss? cause a while back i did that and it still continued, also tested for leaks around throttle body by spraying carb cleaner around the base and there was no change at idle? so i do not believe there is a leak. i don't want to purchase a new EGR valve unless i know for sure thats it because there $40, and not to far back the EGR valve solenoid was replaced. So is there any way to test and see if its for sure the valve?

wally91vhevrolet · #34 07-22-2005, 01:51 PM

ok i checked my EGR and it opens and closes freely, so its good? does anyone know somewhere i could take my truck where they could test my ignition system and tell me whether its that or a fuel problem?

cycowrencher · #35 07-22-2005, 03:20 PM

Quote:

Originally Posted by wally91vhevrolet

well if its the EGR, would undoing the vacuum line that runs to it stop the miss? cause a while back i did that and it still continued, also tested for leaks around throttle body by spraying carb cleaner around the base and there was no change at idle? so i do not believe there is a leak. i don't want to purchase a new EGR valve unless i know for sure thats it because there $40, and not to far back the EGR valve solenoid was replaced. So is there any way to test and see if its for sure the valve?

Throttle body base gasket having a small blow through. So small infact that it took 5 tries to find it and 2 seperate attempts at getting a proper seal. Final gasket used was a felpro that was thicker than both the stock and rebuild gaskets. Gasket had to be sprayed with red gasket tack for proper seal. Disconnected the batt for 30 mins, reset everything and no more studder at part throttle.

Also, which EGR does your truck have, there are 2 different types. Both require and restrictor to be installed and staked into the valve. Also your valve may be good, and your passages may be clogged.

wally91vhevrolet · #36 07-22-2005, 04:21 PM

hell i dont know what kind it is, its got one vacuum hose connected to it and the haynes manual says all u do is bolt it on n hook up the vacuum? and ive checked every vacuum line n there all good..

cycowrencher · #37 07-25-2005, 07:48 AM

Quote:

Originally Posted by wally91vhevrolet

hell i dont know what kind it is, its got one vacuum hose connected to it and the haynes manual says all u do is bolt it on n hook up the vacuum? and ive checked every vacuum line n there all good..

Does it have a silver top or a gold top? Do you know if was ever replaced? What is the number from the original egr valve? Included with the new EGR valve will be a sheet that has a list of numbers and their corrosponding restrictor sizes listed with instructions on how to properly install it. Haynes is not a good manual if you dont know alot about cars. They assume a certain amount of information is already known. Find a local autoparts store that has a retired mechanic working there, this alone will help out, espcially if you can become freinds with him in an apprenticeship sort of way.

wally91vhevrolet · #38 07-26-2005, 09:59 AM

we had another 4.3 put in a year back because my old one burnt oil bad, its ran for a year fine? so if it was the wrong EGR wouldnt it have does this before? I still have my EGR off my old motor its still attatched to my old intake manifold and it does look different than the one on the motor now, the one on my old manifold is black and is a bit smaller, the one on my motor now is grey and is a bit bulkier than the black one, but like i said its ran for a year no problem? so i dont think this could be it? and if it was, unhooking it would have stopped the miss? atleast temperarily?

wally91vhevrolet · #39 08-03-2005, 01:56 PM

well looks like its going to be either a burnt valve or a head gasket, put in new dist. due to the fact that the old one was rusted n had a small crack, now the miss is real steady, the guy that looked at it said it was prolly more than one problem and puttin in the new dist. helped but still didnt completely fix it, hes gonna do a compression check on it and try to adjust the valves to see what he can get it to do, its not so much of a miss anymore its like the engine compression is off on a few cylinders cause the engine itself runs fairly smooth theres just some vibration and it gets real rough when driving it JUST like before when my head gasket blew, ill keep you informed on my success, also may i add i got a rebiuld kit for my TBI and rebuilt it with new seals ext.. also put in my original injectors, and no injector is dripping now but engine is still running bad and getting worse everyday

wally91vhevrolet · #40 08-04-2005, 08:32 PM

update... fixxed tons of problems but nothing changed the missing prob, it varies so much its hard to figure out sometimes it acts like its fuel other times it acts like a miss on a plug, starter cable was loose, tightened it, compression check was ok and valves seem ok, said it might be a lose wire grounding out somewhere sooo new project tomorow, ima check all my stereo wiring and fog light wiring and also check for lose stock wires that might be grounding out or something to that nature, if not i dunno what its gonna be, thank all of yall for helpin me out i appreciate it

sivadnar · #41 08-05-2005, 04:45 PM

Freaking great. I'm having the exact same problem with my truck - 1998 k1500 5.7L. I'm about to lose it. I took it in to have the codes read - random missing cylinder. However, it is precisely three cylinders - 4, 5, 7. I pulled the plugs from these cylinders to check for cracks, etc. All three are fairly fouled - I installed the plugs less than 1000 miles agos, along with new wires, cap, rotor. Please help if anybody has any input.

Thanks,
sivadnar

wally91vhevrolet · #42 08-05-2005, 07:43 PM

well i pulled half the truck appart checking for loose grounds and wires, found a few loose connections it seemed but miss is still occuring, talked to another friend of mine that was having this problem with his brand new f150 and it ended up bein the fuel pump, i was told the best thing to do would be find some1 with a full diagnostics computer and have them run a complete diagnostics on it to find out the exact problem, and if i didnt want to spend that money just drive it untill whatever it is gives out completely, also asked about checkin fuel pressure but its so hard on my truck cause u gotta buy an adapter to go where the fuel filter is and was also told even if the pump is bad whatever is happening could happen so quick the fuel pressure gauge may not even read a change

wally91vhevrolet · #43 08-07-2005, 02:41 PM

well i drove my truck around some today n ive got the worse gas millage ever, drove maybe 10 miles and it used 1/8 of a tank of gas, no more than 40 MPH too, i plan to take it 2moro for a diagnostics but i got a good feelin its gonna be my fuel pump

sivadnar · #44 08-08-2005, 07:16 PM

Keep 'em coming Wally. I broke down and took my heap into a shop for an official diagnosis. I swear my truck has the exact same symptoms as yours. I'll post the official...

steve3320 · #45 08-08-2005, 11:28 PM

Forget the EGR; once your off-idle and up above 2,000rpm or so, you could have a monster size leak in the EGR and wouldn't do what your truck is doing. It sounds like you have been thru all of the ignition system, assuming the new ditributor had a new pickup, etc. on it. I know this sounds stupid, but have you changed the fuel filter recently. If so, I think you sohuld focus on the fuel pressure regulator,the fuel pump, and the relay. I have been told that the relay can be "weak" and not go out all of the way, but cause driveability issues. All of my experience is with small block v8's, but they are exactly the same as your 4.3. You just have 2 cylinders lopped off the front! Good luck, I really think your problem (if not an internal engine problem) is fuel delivery related.

POST REPLY TO THIS THREAD