Search the Community

I was wondering if there is someone that can help me with this truck. It has a rebuilt s&j engine (5.7l 4 bolt main) that I have been fighting to get running well. It has had all new sensors put on it except one thing to note is I received a bad engine with a cracked block installed the first go around and it was ran for a day to work and then next day back to the mechanic so it may have affected the new o2 sensor put on the good engine but I'm not sure. Well this 2nd engine runs really rough when its cold out and the colder it is, the rougher it runs. It takes like 5 to 8 revolutions before it starts and it runs good for about 2 seconds then it just hits the floor, back firing and missing like crazy. Another thing it does is once in a while the volts will drop from 14 down to 10 like the alternator stops working for 1 second then it jumps right back up. I've tried 3 different alternators and nothing seems to change it. It's like something gets turned on for 1 second thats shorted to ground and then shuts right back off but I'm not sure what it could be or if it has anything to do with the other issue. I've put new plugs and wires, rebuilt throttle body with injectors, map sensor, distributor, spark control module, knock sensor with pigtail, ignition coil, fuel pump, both coolant sensors, egr valve and solenoid, iac valve with pigtail, ecm and 3 different alternators. It really lacks power when it is warmed up and its getting bad gas mileage compared to the original engine. I used a red devil river aldl cable and tuner pro rt to pull some data off of it but I need help figuring out why the blm is so low. Is it because of my o2 sensor or what could it be? What could be causing my voltage to drop off like that? I can't get it to drop voltage with the tuner pro connected either. Any help would be greatly appreciated as I am new to this tuner pro data stuff. Thanks! truck2.xdl

I have a 1999 K2500 regular cab with the 5.7 and 4L80E transmission, 285s for tires. I got 14mpg bringing it home, which was about 250 miles. I've been driving it around and I'm getting about 9-10mpg. I have read that an exhaust, cold air intake, and new 02 sensors. I plan on replacing all of the 02 sensors so I was wandering how many upstream and downstream sensors there? And is there any other ways to improve my fuel economy? Thanks

I have an issue with my door locks. The switch on the door quit working. However the key fob still works. I bought a new switch didn't resolve issue. I checked the circuit breakers and they are fine however my cigarette lighter fuse blows the second I put a new fuse in. Any advise on where or what to check would be appreciated.

Is it possible to fit a rear flip kit from a 94 Sierra c1500 onto a 94 k2500 Sierra? If not can someone tell me if ways I can lower my k2500!

I have a 2000 k2500 classic, when I shut it off last night the wipers were vertical and I didn't think about that when starting it today with 6 inches of wet snow on it. Now the wipers won't park, they simply stop wherever they are when I shut the switch off, and they will only work on high. My switch was replaced less than 2 years ago and all of it's other functions still work. And my pulse board is also less than 2 years old so I'm not sure which it would be. Help?

I just got my first GMC truck. It's this beautiful 1981 K2500 Sierra Grande. We bought it and picked it up for the buyer. I carefully drove it up on the trailer but my spotter didn't notice my aluminum transfer case didn't clear the trailer by about a half inch. Soon I heard a thud and my heart sunk. I backed up to discover a puddle of transmission fluid. We used a come along and got it loaded and the hole covered. Got it unloaded and pushed halfway into my driveway. I cleaned it up pretty good with brake wash and it looks like only the housing is damaged. The trucks heavy. I need to push it another 50 yards to it's new resting place all semi steep uphill. Can I drive it that 50 yards? What would happen? Please elaborate! Thanks!

2007 suburban k2500. 6.0/4l80e. I have a click when cranked situation no start. Also, power locks cycle every time it’s cranked. If you hold the key in the crank position it’ll click every few seconds. With the key in the on position I’ve had multiple windows roll themselves down, locks cycle, all kinds of dash lights. So far I have replaced the battery, the starter, main power wire from fuse block to battery, starter power wire to battery, I’ve cut the end off the alternator power to battery cable and terminated all these wires with a different style battery clamp. I am bypassing the 175 amp megafuse. All 2 gauge wire. To my knowledge the oem battery cables are shit so I opted to make my own. On the ground side I’ve replaced the chassis ground to battery wire, the engine to battery ground wire, and I’ve added an engine to body ground wire to rule out the. Braided ground strap on the back of the drivers side cylinder head. No blown fuses, I’ve switched the starter relay with another of the same size, and nothing has changed this trucks condition. I’ve tried tilting the steering wheel to see if that would let the truck start and it didn’t. I’m waiting on an ignition switch to come to oreillys this evening. I’m completely lost. I removed the under hood fuse block and inspected it and didn’t see any corrosion on any connectors. I’ve heard there’s some intergrated relay in the fuse block that could be the issue but I have no idea. I just bought this truck knowing it needed a battery and brakes, drove it off a trailer and parked it and went to move it 3 days ago and got this by surprise.

Hello, I have a 2000 K3500, or what I believe they called a "classic" at the time. This is essentially the same as the 1998 or 1999. GM switched platforms in 2000 but offered the 3500 that year in the old body style (OBS). Mine has the 7.4L and automatic transmission. It currently has 130k miles and I bought it with 75k from the original owner in 2011. I'm wondering if there are some known issues or parts that tend to break that I could do some preventive maintenance on? Any specific areas I should look at beyond regularly scheduled Maintence? Anybody have a good maintenance schedule checklist to reference? Thanks!!

I've got a stock set of steel wheels on my truck, beginning to rust, shown in the attachment. Powder coated gray. I've painted the truck in Upol Raptor paint, black. Now I'd like to have wheels to match but very confused about sizing. Currently have LT 245/75/R16s all around. Wouldn't mind a little larger and more aggressive thread without a lift. Black steel would look good. Any ideas? Thanks, Marc

Hey all, I drive a 97 k2500 p/u w/ 5.7L. I'm trying to diagnose all the problems listed above, but don't have a lot of experience (or money for that matter). As far as the no start problem, it will sit and crank forever, but the only way I can get it to start is by applying the gas pedal and even then it still struggles. In addition to all that, it struggles and stutters and just generally has no balls. I thought it might be the fuel pressure regulator so I got a fuel pressure gauge and attached it to the schrader valve. When I turned it to accessory and let the fuel pump run, it shot up to 60 psi and then down to between 15 and 20 psi after a couple of seconds. When cranking it, it's at 60 psi as well. Does anybody have any advice or idea what it could be or where I should look next? I'm kind of new to troubleshooting vehicles so any help would be great.

My truck has the 5.7l engine in it and I've had this issue only a handful of times. I was wondering if anyone else has had the same issue or has ideas on what to test. The problem: every blue moon when I start the truck for the first time that day and am driving it feels like its choked out one way or another. I have extremely poor acceleration and seems like it simply doesnt wanna go. It only does this for about a mile or two then goes back to normal and drives fine the rest of the day. It seems to only happen on super humid days, after it rained overnight, or once after a car wash. I haven't really checked anything out yet since it hardley ever happens. My air filter is brand new, and the truck has 106k mi on it.

I have a 1999 K2500 Suburban. While driving home from a fire call, I came across a deer in the middle of the highway. "NAILED IT". It had the single sealed beam on each side (Which I had upgraded to HID, but still the same size housing) Is it possible to easily change this to the newer 2 beam on each side set up that most 1999 models and newer had? I have to buy a new grill, and a new light, but the rest of the stuff is un damaged. No sheet metal or any other damage. That is why I won't get a newer vehicle! My 2007 Chevy truck would be hurting bad after hitting such a large deer.

Hello all, Long time reader, first time poster here (haha). I decided to post this because I couldn't find any answers to my questions prior to going through the process. It was very frustrating, my back hurts, and I spent a lot of money in gas, so I am posting this to hopefully make things easier for you than it was for me. Unless you work on vehicles full time with access to a shop, go ahead and plan on taking your truck to a spring shop. Try this if you want to save a few bucks though. My ride: 1994 Z71 Chevrolet (half ton/heavy half/4x4) without a torsion lift, though my truck seems to sit relatively high. I currently have 265R16 tires on mine. What I did: Changed my leaf springs to a set with two additional leafs from a 3/4 ton (yes they fit half tons), purchased everything separately, changed my shocks, tried out some larger tires so I know what to buy next. The newer springs with more leafs/leaves changed the ride height to a perfect level. Why I did it: My truck was sagging, not a lot, but enough to where I noticed it. It was also sagging ever so slightly to one side, not much but enough to where I thought I was losing my mind. The ride was also rough even when I wasn't hauling anything. I noticed it when my buddy's truck had a much easier ride. I also noticed that my front suspension seemed to react "harder" than other trucks to bumps in the road. Later I found that one of my main leafs was broken at the eyelet, the other side was broken at the U-bolts and I couldn't see it. I had probably been driving like that for maybe one year. New parts and what I spent: Used leaf springs from a junk yard (I opted for six-leaf springs from a 3/4 ton) : $200 for both (The junk yard will probably saw them off and hand them to you.) New shackles x2 : $55 New U-bolts x 4: $35 (from a 2000's model, they fit as long as you measure them) New things that the U-bolts attach to: $45 (again, from a newer model, the shop said they've worked in the past) New bushings x2 : $40 (get the stock ones, trust me, all the others are a headache) New shocks x4, replaced a few months earlier : $250ish (don't waste your money if you haul, get the good ones) Had a shop handle the rest, yes it is much easier : $330 taxes and all Used newer model rims with bald 305's from Craigslist : $75 *This is probably the cheapest route to follow give or take pricing on a few items. *Ebay was used for Ubolts and shackles, use Ebay for the bushings too though. Needed tools IF you remove the old bushings on your own: Circular bit (1 5/8" I think, measure yours first) : $20 Power Drill and Sawsall: I already had one. 24" breaker bar : $15 on sale at Harbor Freight *Don't bother with electric or battery impacts, they won't work. *I'd just let the shop press them out when they put the old ones in and save a few bucks. The best path if you aren't a full time mechanic: Note first: I found that my ride stiffness didn't change much from the old springs (broken four leafs to the new six leafs). It is actually a bit better. My buddy also confirmed this thought when he did his, though he said his was a bit more stiff. How many leafs is your choice though. 1. Find a spring shop and get an idea of what they will charge to swap the new ones on (I was quoted $270). I explained that I already had everything and intended to do it myself but gave up, it wasn't the first time they had heard that. You could check what they would charge for shocks too, but those aren't hard to change. I'd have probably paid up to $65 for them to change the shocks to save an afternoon, up to you though. 2. Purchase/order everything needed first so it is on its way. Discuss what shocks to use with someone who is an expert, not just the guy behind the counter. The pricier ones are usually better though. If in doubt about something fitting, buy it from a store so it can be returned. 3. Purchase used six-leaf springs, make sure they aren't broken or cracked. Saw away the crap if needed so the old bushings can be easily pressed out by the spring shop. You could use the circular bit to drill down around the old bushing. Work it back and forth with the breaker bar until free. Turn it one direction with pressure on the other side until it twists out (it takes a while). OR just saw each side of the bolt off and let the shop press them out. 4. Don't waste time trying to have the bushings pressed in or out, it will likely be included in the price if the shop is putting them on. 5. Take the truck in, explain that you want to make sure it won't be sitting ass-up like a jackass, and them them do it. This will save you a back ache, lots of gas money, and many curse words. I kid you not, messing with old rusty bolts and bushings is a major pain in the butt, let them do it! 6. Change your shocks afterward to avoid wearing them out prior to the spring swap (if you didn't want the shop to). Aftermath: My truck looks like it got a little bit of lift compared to the way it used to sit. The six-leafs fit perfectly without the truck sitting too high in the back. The stiffness didn't change all that much for me and the ride is a bit better. I recommend changing your shocks if your truck is old as sin like mine. I found that I could play my old shocks like an accordion. Hey, I inherited it so leave me alone! Keep in mind that changing your springs doesn't change the ability of the axles, so don't risk breaking them by overloading the truck. I found that I could fit 305's on my truck stock, but since I haul and do some minor off-roading, I won't be going over 285's next time. I also read another post where a guy had six leafs installed in order to haul his camper. He changed his tires to 10-ply tires, which I will probably do eventually. I took this path to avoid the markups on parts at the shop, and I honestly thought I could do it myself. Mistake. Skip the machine shops, get what you need, and have a spring shop do it. It will save you a few headaches, lots of sweat, time, back pains, and gas money. Pictures are added below of the end result, still with 265R16 tires. The only concern I have moving forward is the dependability of my newer springs, but brand new ones were crazy expensive so I risked using used ones. Honestly, I'll probably miss replies but plan to check back periodically when I can remember to answer questions. I wish I'd have known all of this going into the project, hopefully it helps you! Other considerations for longevity: If you have an old truck like mine, consider getting a tune up and new distributor cap. You might also change the O2 sensors, I found mine went bad without giving me an engine light. It killed my power and drove me crazy. There is also an inlet at the top of the engine toward the back that will be brittle and break soon, leaking coolant on the ground. Have a shop handle it when it happens, trust me. Also, you might check the circuit board for the windshield wipers if they ever go intermittent or quit.

I'm new to this forum and I just acquired a 1997 GMC Suburban K2500 7.4L for towing and the A/C isn't working. When I push the A/C button I get no light on the A/C button and nothing from the compressor/clutch. Same in defrost mode with full cold temp setting, nothing from the compressor/clutch. The other control head knobs & buttons seem to work properly. All A/C fuses are ok. Any pointers from folks knowledgeable with these A/C systems very much appreciated. Marty

I have a 1989 k2500 5.7 tbi with 171,xxx miles on it. I've had no issues with it until a month ago when the engine is under load it cuts out, as soon as I let off it back fires and everything is normal. I've replaced cap and rotor, plugs and wires, coil, egr valve and solenoid, map sensor, tps and fuel filter trying to track down the culprit. Ran the codes, it came back with code 34 map sensor. Unsure why, cleared the codes and it throws it again. The truck idles just fine just won't drive well. I should probably also include that the truck has no cat anymore and is 3" straight pipped back to a flowmaster. Unsure if that will make any difference with help as it had had this set up for over a year prior to any issues. Please help, I'm not used to these tbi systems but more familiar with old school engines that only need suck, blow, bang to run correct.