IROCZ285

Hello all, I am a new member to this site, but have been here often for technical advice that I have been looking for that manuals do not answer. Thanks for taking the time to help me out.

I have read a lot of other posts with similar problems, but the underlying problem in those posts don't seem to be able to address mine. Here's what I can tell you. . . .

I have a 1998 Chevy Silverado C1500, 5.7 V8, automatic with just over 207k miles. I bought it about 3 years ago with 185k on it intending to use it as a back up vehicle/ work truck. It is pretty clean and doesn't appear to have been significantly abused over it's life time. The guy I bought it from claimed the heads had been reworked and trans rebuilt. When I bought it, it had a small acceleration problem. It would accelerate OK under half throttle condition until you got to about 3500 RPM. At that point it would start stumbling all over itself and throwing a fit. You could pettle it to get a bit more out of it if you wanted, but it wasn't worth it. I could easily get to 90 mph without too much trouble.

Now the truck is undriveable as it will not hold over 60-65 mph on flat Kansas highways with the A/C off. I cannot get the RPM's over 2000 under acceleration. It will not start on the first few tries at all. I have to crank it 4 or 5 times and then let it sit for 5 or 10 minutes and try again. Sometimes it will start then, or require a third go at it.

It does not put out any engine codes under "normal" driving conditions, but when I push it, I can get multiple engine misfire. o2 sensor codes, or a TPS-which has been replaced. I had a guy at autozone put one of his OBD readers on it, as mine is a cheaper one, and his indicated a lean fuel mixuture condition. Fuel pump holds pressure at 55 psi and goes up with RPM. I have replace the fuel filter twice. I have traced vacuum lines and searched for a leak smoewhere. Now I've started compression tests on the cylinders, but haven't completed it. Results are positive, with readings between 140-150. I have also done plugs and wires.

I have suspicions of what it is, but would rather not mention them and have someone else look at it with a fresh perspective.

I'm desperate for a fix, as this was a back up vehicle that I was having to drive. My fuel saver lost a timing belt last week and bent some valves. The only thing I have left is a sport bike, and riding on it for an hour each way is no way to enjoy it. HELP!

fyreman

i have a 99 chevy silveraldo and just the other day my insturment cluster stopped working all together and i cnt figure out wat is wrong ive checked fuses and relays and all checked out fine i dnt know wat else to do can any bdy please help me with this problem or call me 9102992266 thanks

shamrock246

the fuel pressure numbers i have are 60-66 psi, lean condition with multible misfires sounds fuel related it could be a bad fuel pump,bad pressure regulator,after having a missfire on mine i replaced the spider assy with the upgraded unit, the missfire was only on one cylinder and was a stuck poppet,how old is the fuel?


Sean

97 4x4 burb

IROCZ285

Fuel isn't old. If I think it will sit for a while I usually don't fill it up, only put in what I need. The last week or so I've had to drive it I've put two tanks through it. This winter I drove it quite a bit as well.
I suspect the spider assembly and/or the fuel pressure regulator, I just hate to drop the $300 or so for nothing. For discussions' sake and to make sure I don't spend money for nothin, what else could it be if it weren't the fuel injection assembly?

Thanks for the help!

1Ton-K1500

I have had one just like this and the problem was plugged muffler..theres an easy one to check--just take exhaust off and drive it. Another one that i have found common with these vortecs are the cap and rotor. i have seen them actually arc down the dist to the cam instead of going to the terminals to the plugs. the factory poppet valves in the "injectors" usually are good for 100k mine have been good for almost 200 but most of them fail at 100 hense the upgrade to actuall injectors GM actually had a TSB for them back in the day. thats my two cents, "wet hands make for a rusty zipper" dont overlook the obvious...also i am suprised your engine even starts with the 55psi. most wont even fire if they are under 60 very picky system

shamrock246

i got my spider for $215 on amazon it was a AC/DELCO unit and summit racing sells AC/DELCO fuel pumps,i didn't see the point in repairing the old unit


Sean

97 4x4 burb

IROCZ285

Thank you all for your input. After exploring all other possible problems listed above, I finally broke down a bought a new spider injectior assembly this evening. Took about 4 hours to change it out, but it runs like a champ now! I can actually burn the back tires off, which I have never been able to do before!!! Only problem is I cracked the thermostat housing when I accidentally left the ground wire under it when I was tighening it down. Oh well, so it goes though. Glad it is fixed. Thanks again all.