1994 Chevy C1500 5.7 bogs/backfires when I give it gas.

380

Asked by Oct 10, 2013 at 01:26 PM about the 1994 Chevrolet C/K 1500 Silverado Standard Cab Stepside SB 4WD

Question type: Maintenance & Repair

My truck bogs down (and tries to die) when I give it gas to accelerate off of a stop. There
is often a backfire or two when this happens. Pumping the gas does not help. I basically
have to crawl through any intersection until it picks up a bit of speed from idle. The truck
idles smoothly, and it runs fine once it's above about 5-10mph or so. If moving at a
steady speed, and I give the truck gas to accelerate, it hesitates and backfires before
picking up the speed. It may be worth mentioning that this problem doesn't happen if I rev
the engine in park or neutral, unless I really gun it, in which case it's a quick backfire and
back to business.

This is inconsistent; sometimes the truck runs like a champ, but most of the time it's
trying to leave me stranded in busy city intersections. This has been happening for about
3 months (yes, I know I should've fixed it months ago; times are particularly tough)

I've changed the inline fuel filter, changed the plugs/cap/rotor, checked the sparkplug
wires, and run a fuel system cleaner through it. I unfortunately don't have a fuel pressure
gauge.

I doubt it's relevant information, but the truck just passed smog check a couple days ago
with no issue, although I didn't see the kid even glance towards EGR/PCV valves.

Any help is greatly appreciated. I can't afford a mechanic, and I'm just praying it's not the
fuel pump.

34 Answers

380

I failed to mention that the Check Engine light is NOT on.

38 out of 38 people think this is helpful.
180

I had the same issue.. It was particularly a little worse until I canted my Cam Shaft Position sensor located inside the distributor cap, and also changed the connecter wires to the crankshaft position sensor located at the front bottom of the engine by the fan kinda. It still does it a little but not as bad as it did so I would start there to improve it some.

18 out of 18 people think this is helpful.
240

Same thing here. Did you ever find out what was wrong with it? I've changed/ replaced cap, rotor, wires, plugs, crankshaft position sensor, cam position sensor, MAF, IAT, TPS, coil, fuel filter, oil and filter. nothing seems to work. i've checked for vaccum leak, fuel pressure, fuses, shorts, etc.. Im still fighting this battle so if anyone has any tips I'd greatly appreciate it.

20 out of 20 people think this is helpful.
240

Have you found out the problem with your truck I have a 1994 chevy c1500 5.7, it mostly backfires when driving on the highway or interstate but once it starts it continues to do it with in town driving to. A lot of the time I have to shut it off and start it back up to get it to quit to get it to quit but ithe usually only stops it for a few minutes. I would also greatly appreciate any tips.

24 out of 24 people think this is helpful.
270

My 94 Chevy Silverado was also sputtering, backfiring, missing etc... I changed the fuel filter to no avail, tried several things to get it to run smooth but nothing helped' until a friend of mine who used to have his own shop told me about a memo he had received years ago dealing with this identical problem. here's what worked for me! I unplugged the idle air control from the left side of the carb (as you are facing it) took a large wrench and removed the idle air control from the carb, and sprayed it down with carb cleaner. then I sprayed the fitting on the carb where I removed the idle air control unit from and sprayed that throughly also. then I sprayed the carb itself. once this was done i let it dry for a few minutes, re assembled everything and tried to start my truck. starting the truck was not easy because of the carb cleaner. it took a minute to start, but once it did it ran like new!!! it has been running well ever since. I hope this works for you as well as it did for me.

27 out of 27 people think this is helpful.
120

I have a 1994 chevy 1500 , 5.7 . I took off the transmission to work on the rear main seal . Put the transmission back on and the truck wouldn't start . I than checked the battery got a new one . Than the the starter is new the rotor and cap are new the control madule the iac is new fuel filter in line is new plugs.I can get it to start but only stays running for maybe a minute or two

12 out of 12 people think this is helpful.
390

To the fella that had his friend with memo, by God when i tell u we have had nothing but trouble with this 94 Chevy since we bought it last year for 3200 replaced so many things on it, it's doing same thing it did last year when we got it out, they said we had water in gas that went through the injectors, We replaced I'm n plugs n have drop gas tank n cleaned it out, it's backfiring and carb has flames, We sprayed it and that was result but haven't removed the new icv n sprayed it

7 out of 7 people think this is helpful.
10

thrudel controll value

1 out of 1 people think this is helpful.
60

i have a 1997 chevy 1500 and i have replaced the camshaft sensor and the icm it fires up and back fires then just turns over any ideas would be greatly helpful

6 out of 6 people think this is helpful.
50

Ideal air control valve, or throttle position censor or both. Get a paper clip and bend it until u have 2 points next to each other about 1/8 apart. Turn your key to on position (Don't start it) just on position. Stick the paper clip into your obd1 at the top right two inserts then count the number f times your check engine light blinks. You'll have sets of 2. Like 1 blink then pause then 2 blinks Your obd1 is located under your steering column

5 out of 5 people think this is helpful.
30

Hey guys I was having the exact same problem with my 1998 silverado 5.7 liter. I noticed gas some time ago right where the fuel rails go into the intake,and on the right side of the rails there is a cover with wires under it and they were eaten up by the gas.I had the same symptoms as everyone. Used liquid tape to recover exposed wires just to find out the gas is coming from under the wires. Off to the shop we go.I hope this helps.someone

3 out of 3 people think this is helpful.
110

i dont understand what up with my truck either its a 1994 c 1500 and when i start it it acts like it wants to dye and when i reverse it dyes and then when i try to go it trying to dye and back fires and when i hit the gas it tries to dye and wont go. i have replaced the spark plugs and wires and fuel filter and fuel pump and throttey sensor and still have the proble. the worse time is if its cold or been satting for awhile then it acts up. if anyone can help me find the problem please let me know.

10 out of 10 people think this is helpful.

It might that the transmission is going out

110

I replaced the transmission already

Try a timeing light check the timeing

80

Holy carp my 94 cheyenne k 1500 5sod 5.7 is doing the exact same thing everyone described but it just started last week. I replace entire fuel pump sending unit few months ago so its new. But just blew clutch fork out last week n pulled tranny n replaced it now I'm having same problems everyone's describing sometimes stslls when idling and 2nd and 393rd hear around 2500-3000 rpm starts dying out and backfires then picks back up. Don't have the $ to just start replacing everything. Just put cap n rotor n still doing it. Going to replace wires n plugs on payday. Any help would b greatly appreciated and can't afford mechanic so I'm doing it myself and need the truck for work.

8 out of 8 people think this is helpful.
10

have a 87 p3500 stepvan everytime i hit a bump going down the highway it tries to stall then sometimes it will pick back up sometimes it won't but when it ttys to stall it often backfires no plugs and wires checked all electric any idea what this could be?

1 out of 1 people think this is helpful.
165

My 1958 Chevy 283 Power Pack has been backfiring, stalling and hesitating at the wrong times. I have been told to rebuild or replace the giant four barrel carb and that will settle it down. It's never been cleaned.

1 out of 1 people think this is helpful.
10

i was going to try to get a new carb but wasn't for sure that could even be a issue everyone kept saying electrical but i found no loose wires or anything at this point its a gamble sinking too much money into a bunch of things that won't fix the problem almost worth getting a new motor

110

i cant afford a new motor or to a place to have it looked at either. so i guess ill either keep buying parts or just junk it but i need it for work so i don't know what to do. if anyone can help me i would love it but if not ill keep buying parts till i find out whats wrong with it and hope it can take me back and forth to work till i find out whats up.

1 out of 1 people think this is helpful.
60

my truck dose the same but bogs when im driving no at a dead stop and when it bogs it dosnt come back untill my truck is fully turned off for at least 5 min. possible its a fuel filter / pump but not 100 percent

6 out of 6 people think this is helpful.
60

My 1993 5.7L TBI engine would bog down when climbing any small hill and the fuel economy was horrible. I used the symptoms and troubleshooting from the above comments and solved my problem. Thank you very much. Here is my solution. Sorry for the long story, but all is helpful in the long run. I removed my ignition control module and took it up to the orange auto parts store to purchase a new one, but the helpful parts person told me, before I purchase a new one, to go to another orange store and have it tested since they misplaced their instruction manual for their module tester. Instead, I went to the green auto parts store across the street and had the module tested. The two counter persons were not properly trained on how to properly operate their module tester but hooked it up from their instruction manual "without grounding it" and my module repeatedly failed all of the tests. I went back to the orange store to again purchase a new ignition control module but a different counter person found their instruction manual and tested it "while grounding the case." The module repeatedly passes all tests. I then recognized the differences in the grounding and then recognized small burn traces on the back if the module where it had appeared to be arching. I then suspected that the module was not properly grounded in my vehicle since the hold down screws were very rusty and the heat sink grease was gone between the two metal surfaces. I purchases some new heat sink grease at Radio Shack and went home. I uses a small wire brush to clean off the rusted screws and mounting surfaces. Applied new heat sink grease and reinstalled. Wiggle the module back and forth for a minute to properly distribute the heat sink grease. I backed off the screws several times to get the serrated screw washers to make a good grounding bond and put the cap back together. All of my engine bogging issues are gone. I can now rocket up a hill. Lessons learned: 1) Make sure the parts service persons are competent in their job. 2) Radio Shack has heat sink grease when the auto parts stores do not. 3) Make sure the ignition control module mounting screws are free of rust and the module is properly grounded. 4) Wear latex gloves when handling heat sink grease. It is contagious like a disease and gets everywhere you lease expect it.

6 out of 6 people think this is helpful.
40

Hey guys I have been having the same surging issue from dead stop for months.. I just allow for the slow acceleration time as the truck is old and mechanics are expensive.. But the last week I was traveling and the truck just shut off no burp chug or chatter.. Just went to give it has and nothing there.. So after trying to trailer it home unfortunately my winch wasn't strong enough to pull the truck up.. I replaced the ICM on the side of the road and it fired right up.. But I still have the surging/backfire from dead stop. Any other suggestions? I'm purity sure I have a throttle body and 2 injectors.. Would the idle sensor still be present?

4 out of 4 people think this is helpful.
60

I have a 98 1500 4x4 5.7 vortex. Was able to start with a little starting fluid to move around but now no start. It has new fuel pump. When it was starting it would not want to go when I gave it gas, unless I barley press the gas. Never backfired. Please help!! Wrecked my car so now need this as a daily.

6 out of 6 people think this is helpful.
50

I have a 1993 Suburban K2500 with a 454 c.i.d. that has a rough idle, and will bog down on acceleration. When I'm at freeway speeds, it will surge and backfire. I have tried all the fixes above including; TPS, MAP, IAC, O2, fuel filter, cap, rotor, plugs, wires, throttle body base gasket, computer, promand the list goes on and on. I have replaced the distributor about 3 months before this problem reared it's ugly head. I have re- grounded the entire engine with several new ground straps and replaced wiring to the knock sensor, the O2 sensor, and the coolant temp sensor due to age and oil contamination. I have also replaced both positive and negative cables and ran a new ground to the PCM. Any thoughts???

5 out of 5 people think this is helpful.
20

My 96 c2500, 350 tbi, has been spuddering, idling really rough, backfiring, amd plain out dying in town. Sounds like plugs but its not, distributor maybe? Timing? No engine light either So i was just tinkering with the truck, and the wire under the the glove compartment, its brown and black, (you disconnect it before you do set the cap for your timing) i unplugged it and the engine light came on, but the truck instantly started working way better. It dont make much sense to me and i am not sure if its really safe to run that way. It seams like it might be smoking a little maybe? Any thoughts or ideas?

2 out of 2 people think this is helpful.
40

most of the folks here with these problems mention a transmission replacement, you have a constant hot wire that runs down and around the stock exhaust manifold and through a heat shield and back to firewall. I also swapped tranny out of mine, (for another truck) and then back in (to drive this truck again) and forgot to bolt the heat shield back via the bell housing bolts. This allowed the always hot wire to ground out on the exhaust and the truck would sometimes die, always backfire, and it usually happened when I hit a bump. I disconnected the wire, pulled it through, taped the exposed wire, ran it along the inner fenderwell and up by the ac drier and back to it's original location without getting anywhere close to the exhaust. Also, there are other backfiring issues, that sound like this is not the problem... these trucks' have distributor issues, a new distributor will likely fix your problem. A coolant temp sensor will make you run rich, the pigtail wiring harness always gets internally broken on these due to the way the engine rocks under load, try to wiggle yours while running to see if the problem fixes... also the TBI injectors have their wires running through a rubber gromet and that over time can wear out and the wire grounds to the air cleaner assembly. if you gun it and it picks up then immediately loses power and check engine light comes on it's your knock sensor most likely, or the connector is loose. and one very important thing to remember, if anything is not properly grounded, or not getting proper power, it will not work, and when sensors don't work on a computerized engine you will have big problems!

2 out of 2 people think this is helpful.
40

bogey, if it's smoking black it's running rich, you'll foul out your plugs running it like that, the knock sensor and electronic spark control module are responsible for adjusting your timing. the ESC module sits under the air intake side of the air cleaner and you should check the wires running to it, wiggle test, and also check that there are no vacuum leaks there and that the vac line is hooked up. your knock sensor is on the bottom of the block, cut your wheel all the way to the left and look behind the plastic fenderskirt. give the knock sensor a wiggle test too. now assuming these two are working properly, the distributor takes the signal, and adjusts timing accordingly, these trucks are known to have distributor issues after 150k or so autozone has them for around 60-70 stock replacement, you'll then disconnect the wire you mentioned to adjust your timing to get the Base timing for your engine. Also, you didn't mention if it did, but an exhaust manifold leak, or noisy lifters even could trigger the knock sensor to retard timing prematurely. have seen guys use knock sensors from 454 to cure this problem because they have a higher tolerance for noise before retarding

2 out of 2 people think this is helpful.
10

try mass air flow with all your back fireing and sputtering

1 out of 1 people think this is helpful.

i had this problem also and replaced most of my sensors, with further research i found fuel pump has a strainer at its inlets without hesitation i dropped fuel tank and removed pump. i discovered the sock was covered in debris, went to local autozone and purchased one for 4bucks. replaced it and reinstalled tank. the truck would start and idle fine just under loan it would bogg and try to kill its self. after replacing strainer i lightly accelerated and noticed the truck has sensitive acceleration response. after replacing all sensors and finding problem my 1989 Chevy Suburban (350-TBI-5.7) runs like its right off the lot!!!

I have a 1992 Chevy Silverado extended cab 4 wheel drive automaticit'll pick up gas then just bog down cant give no gass or it dies can some tell what it is bec I spent over $1009 allredy

40

I could give you a long list of things to check, but you could get a better answer by listing things you've already done. Air/Fuel/Spark that's all you need for an engine to run. check your air filter for restrictions, check your coil, check your fuel pressure. could be a timing issue, fuel issue, cat converter, etc.. If you could be more specific it'll likely be easier to pinpoint your problem.

10

I rebiuld my pick up chevy s10 to race and its doint that to it bog out and dies i tryed looking for a mecanic but they say its a spark plug but its bran new i tryed to race a corvette with it and the motor. Is so strong that when it bog out and i try to accelarate it dosent accelarate but with that motor the way its acting now i broke to transmission and i beed help finding that problem to but there aint nody out there that know i have a race in like a month from nowto race a camarro but it keep bogging out help me as soon as posible

1 out of 1 people think this is helpful.
20

I've had all these same problems with my 92 Chevy 1500 and replaced fuel pump, filter, egr vaulve, distributer cap and roter, the coil wire and coil itself. Didn't do nothing. Then I found out one of my injectors weren't spraying so I was only running on 4 cylinders. So I rebuilt it and it was running like a champ for a good month and now it's doing it again. But only when my trucks been running for a while. Give it gas it sputters and kinda back fires. But when I get up to speed it runs fine until I accelerate.

2 out of 2 people think this is helpful.

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