Jesse rostotski

hey everyone, im honeslty desperate to find the solution to my problem with my K1500 pickup. Its the 4x4 with the Z71 package, ive had the problem for 15 years.

Fuel pump blew one day and I had it repaired but it still never drove the same after that. The truck runs at about 1/3 power and cannot break loose on gravel. It was an amazing truck but now I use it as a work truck, it takes a long time to accelerate but gets there eventually which is why I still use it.

The truck loses even more power when hitting about 2300 rpm, it almost governs itself out at 80km and when trying to exceed that it will force itself back.

Its a huge problem, I took it to a dealer and they charged me 2600 and they could not find the issue. It would be amazing if someone with the same problem had found a fix and could let me know that would be so amazing.

the engine light is also on and the code reads O2 sensor, im pretty positive something so small is not the problem though.

I'd also like to point out the fact that I've considered a whole new powertrain as i thought it was the only option to fix it. I've tried many things and that could be the only option.

oilcanhenry

Sounds like a fuel issue. Everything from the "new fuel pump" to the poppet valve fuel injectors to me. lots of parts these days are defective out of the box, so new means nothing'
these days and it doesn't matter what brand and make we are speaking about, FoMoCo's are even worse.

Jesse rostotski

So what do you recommend I do, I feel like the dealer "expertise" can't be trusted. I think the truck needs to be driven to really grasp the issue because its very strange. It would be great if I could pin point a problem and go from there but I reslly can't.

Gumby22

What engine is in it, automatic or manual trans, and what is the code? There’s at least 3 O2 sensors and a dozen possible codes. It may seem insignificant but codes don’t set for no reason and if you’ve been dealing with the problem for 15 years then it’s at least a starting point.

oilcanhenry

I'd never tolerate this issue for 15 years. I have pretty much the same pickup, but not a Z-71, but the fuel pump is original, as are all the fuel system parts but the fuel filter. Could be a clogged up catalytic converter, but something is not flowing properly, I am pretty sure of that..

Jesse rostotski

I've only been tolerating it because it is not a daily driver, but when it was my daily driver it was the best so I want it back again. I might look into getting the cats cleaned as they've never been cleaned before. It has 360k km on it too.

Jesse rostotski

it has the 350 in it with the 4 speed automatic.

kevinkpk

That thing would be setting at the dealer till fixed! That is alot of money for them to not find the problem.

Jesse rostotski

Maybe its the air hoses, the engine might be starving for air. Thus why it slows down at higher revs because it needs to chill out.

Gumby22

Air hoses??? There’s more than one? Do you have a custom intake?

I asked for the exact code you got because I (like oilcanhenry) suspect there is a restriction in the exhaust (catalytic converter breaking down). If the code is P0420 or P0430 (converter efficiency) that would at least be reason enough to go straight to testing back pressure in the exhaust. However, I have seen failing torque converters act similarly to restricted converters which is why I was curious if it were an automatic.

Restrictions in the intake or exhaust can usually be ruled in or out using 2 simple tests - first, checking engine vacuum at idle with the engine up to operating temp; second, with a compression test.

Engine vacuum should be 18-22 in-Hg with a steady needle (subtract 1” for every 1000’ above sea level). Depending on mileage and the last time ignition or valve timing was serviced, minor fluctuations of 2” or less could be normal. Large fluctuations of 3” or more are reason to suspect a restriction or other base mechanical problem.

For most engines in passenger vehicles, regardless of mileage, the minimum compression reading is 100 PSI with no more than 10% variation between the highest and lowest reading. For your truck, I’d expect to see at least 130 if not more (again, mileage will affect it).

Results determine the next step:

-Good compression on all cylinders, a restriction is unlikely.

-Low compression on all cylinders, suspect a restriction or problem common to all cylinders (for example, the air filter is so dirty it’s either collapsed or torn, the timing chain jumped causing the valve timing to be off, or a converter shared by both banks is breaking down).

-Low compression on one bank only, suspect a problem that would only affect that bank (converter)

-Low compression on only one or 2 cylinders, something that could only affect those cylinders (head gasket, block, etc).

If you suspect a restriction in the exhaust and want to rule out the converter(s), the next easiest step is to remove the upstream O2 sensor and test for back pressure at idle - anything more than 1-2 PSI is reason enough to suspect a restriction, especially if revving the engine results in higher readings.