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Running rough seems to be starving for fuel?

3K views 40 replies 8 participants last post by  montecarlo33 
#1 ·
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!
 
#5 ·
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?
 
#7 ·
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.
 
#10 ·
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.
 
#12 ·
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.
 
#15 ·
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!
 
#17 ·
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.
 
#23 ·
Fwiw, there should be two coolant temp sensors. One is for the gauge and one is for the computer. You changed the one for the computer, located on the intake. This one is listed as a coolant temp sensor at parts stores. The other is located on the head on the driver's side. This one controls the gauge and is called a coolant temp SENDER. Just thought I'd let you know in case you wanted to get your gauge working too. This is also assuming 92's are set up the same as my 91. Hopefully it helps, sorry for babbling if it doesn't.
 
#24 ·
I found that out, I got the coolant temp sensor and thought it was the one in the head but it was different, went to three different parts stores and they were all the same and thought wtf why is mine different?? Then I found out I was looking at the wrong one! Haha oh well it's running at least.
 
#25 ·
Glad to hear it's running. I had the same problem with mine when I bought it. The PO never installed the coolant temp sensor when he swapped a new engine in, and it ran like crap. You can check the codes with a paper clip if you want. Go to ck5.com and search it. There is a good article there with a diagram and a list of code definitions that will help you. It only takes about 1 minute to read a code.
 
#26 ·
Well I may have to read the codes. I thought it was running better but this morning on the way to work it started running bad again. When I'm sitting at a light idling it will be fine, I go to step on the gas and it sputters and almost stalls out. Actually did stall one time but fired back up. This is starting to get really old! No check engine light is on right now.
 
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