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Old July 29th, 2013, 06:22 PM   #1
camoII
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Default Running rough seems to be starving for fuel?

I have a 92 gmc with a 350 tbi. Been running great but the other day went to start it and it barely started. After it warmed up seemed ok. Thought maybe I got some bad gas because I stopped at a station I usually don't go to. Put water remover in the gas, no difference, changed the fuel filter, no difference, still after starting it runs horrible til it warmed up.

Today I put wires, cap and rotor, still no difference. Now it will idle but as soon as I try to rev it up it wants to die.

I bought a fuel pump hoping maybe mine is on its way out and I'm going to put it in tomorrow, if that doesn't do it does anyone else have any ideas what it could be?? Any other time I've ever had a pump go it just goes bad and that's it so I'm doubting that's my problem. Any help would be appreciated!
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Old July 29th, 2013, 06:35 PM   #2
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The service engine light has been coming on for a while too. Not sure why..
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Old July 29th, 2013, 06:39 PM   #3
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Check the spring in your fuel pressure regulator. Just one idea, but easy to check.
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Old July 29th, 2013, 06:40 PM   #4
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I was just reading about that. Is that where I take the torque screws out of the top of the tbi?
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Old July 29th, 2013, 06:53 PM   #5
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That's it. There is a small slot on the side that you can see through and see if the spring is broken. You can also drill out a hole on the end of the regulator opposite(I think it's the bottom) of the spring to expose the top of a screw. Use a Dremel tool or similar to put a slot in it, then you have an adjustable regulator. I forget what size drill bit... quarter inch maybe?
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Old July 29th, 2013, 06:54 PM   #6
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Diagnose the problem before throwing parts at it. Check fuel press before changing the pump.
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Old July 29th, 2013, 07:20 PM   #7
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Yeah I should have checked the fuel pressure. Just kind of in a pinch vehicle wise and figured I'd do the easy stuff first. I already have the old pump out and ready to drop the new one in tomorrow. My truck is stuck at my work now so I'll see what I can figure out tomorrow. Thanks for the help.
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Old July 29th, 2013, 07:32 PM   #8
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Hope that works for ya
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Old July 29th, 2013, 07:36 PM   #9
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If the pump doesn't do it I'm hoping the fuel pressure regulator does the trick. I'll check the pressure for sure.
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Old July 29th, 2013, 08:09 PM   #10
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The regulator springs tend to get weak and/or break at that age. They factory specs for pressure were 9-12 psi, but realistically they need 12-13 to run "properly". If you pull the regulator, do yourself a favor and take the extra 5 minutes and convert it to adjustable. If you can get your supply to about 13psi it will run smoother and more efficiently. This is obviously after you figure out the stalling issue.
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Old July 29th, 2013, 08:22 PM   #11
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Sounds like the coil needs to be checked. They will run very bad when they are about to totally die
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Old July 30th, 2013, 09:16 AM   #12
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Really it could be a lot of things. Check fuel pressure. If that doesn't work check your grounds. I believe there is one inside the cab, from the ecm that tends to corrode and break. Irc, it's on the passenger side by where the passengers left knee would be. For more ideas check out ck5.com. They have a lot of info on there about these problems.
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Old July 30th, 2013, 09:27 AM   #13
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Is this always, or only when wet (ie after rain or dewy mornings). If when wet, could be rotor and cap (although you already changed these) or could be a cracked coil allowing moisture to get in a foul it out.
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Old July 30th, 2013, 09:31 AM   #14
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Check the coolant temp sensor

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Old July 30th, 2013, 02:34 PM   #15
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Ok, thanks for all the ideas I'm gonna go thru and check all these things. I put a set of used Injectors I had sitting around on it and made no difference, new fuel pump, no difference, I already bought it so figured I'd try it. Tried a used iac sensor I had and it made no difference.

So I'm down to checking grounds and coolant temp sensor. The coolant temp sensor I know is bad bit never thought it would make it run bad. It hasn't worked in some time as far as I know because the gauge has been pegged for a whole but I knew it wasn't overheating. Thanks for the help!
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Old July 30th, 2013, 02:41 PM   #16
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personally I would check why the service engine soon light is coming on, it may just guide you to whats wrong instead of guessing and throwing parts at it. If that gives you nothing you may also want to check to see if your cat is plugged up
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Old July 30th, 2013, 02:46 PM   #17
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I don't have a way to check why the light is coming on. I haven't put to much into parts just yet so I'm not worried about that yet. I just looked and I see I have a ground strap that is broken the goes from the motor to the firewall right under where the coolant hoses come out of the heater core. Maybe that's just it.
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Old July 30th, 2013, 02:48 PM   #18
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Quote:
Originally Posted by camoII View Post
I don't have a way to check why the light is coming on. I haven't put to much into parts just yet so I'm not worried about that yet. I just looked and I see I have a ground strap that is broken the goes from the motor to the firewall right under where the coolant hoses come out of the heater core. Maybe that's just it.
That area is your power distribution center. So yeah that ground strap should be pretty important.
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Old July 30th, 2013, 03:02 PM   #19
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when the coolant sensors go bad it keeps the engine in closed loop and the pcm makes it run rich and it makes them sluggish and they sometimes stall, and that's proly why your check engine light is on.
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Old July 30th, 2013, 03:30 PM   #20
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Ok I fixed the grains straps and no improvement. Next the coolant sensor, and check the coil. This is crazy because it happened just sitting over night, got up to go to work and it barely started and hasn't been the same since!
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