runs terrible at high rpm's

[SoonerBob]

my 88 K5 with the 350 TBI runs fine at low rpms for street driving, but it runs absolutely terrible at high rpm's when i have to hammer it down. it cuts out and bogs down and I have almost zero accelerating power. what is going on and how do I fix it??

 

[1985_K5_Silverado]

Could be a fuel delivery problem. Is the ECM tossing out any trouble codes?

 

[Wishbone]

Wonder if the spark plugs are getting enough spark at higher rpm's? Have you changed your plug wires in a while?

 

[Leper]

Many problems like yours are related to fuel delivery and/or spark. Possible causes: clogged fuel filter, sticking injectors, fuel pump going out, fouled plugs, bad wires, coil break down, worn cap, worn rotor, and I have even seen a dist come apart on the inside.

 

[loafer]

My old 88 TBI used to do this quite often; It was always a partially plugged fuel filter. For some reason I used to get a lot of dirt in my tank

Sometimes the strainer on the fuel pickup in the tank gets plugged as well.

my 88 K5 with the 350 TBI runs fine at low rpms for street driving, but it runs absolutely terrible at high rpm's when i have to hammer it down. it cuts out and bogs down and I have almost zero accelerating power. what is going on and how do I fix it??

 

[SoonerBob]

Many problems like yours are related to fuel delivery and/or spark. Possible causes: clogged fuel filter, sticking injectors, fuel pump going out, fouled plugs, bad wires, coil break down, worn cap, worn rotor, and I have even seen a dist come apart on the inside.

the cap, rotor, wires and plugs were all replaced less than 2 years ago. the fuel filter was replaced a year ago but I guess I could double check these things. If none of that tells me what I need then I guess I can assume it's an injector or fuel pump problem. That doesn't make me too happy.

 

[loafer]

I used to have to replace my fuel filter every 6-8months. When you pull the fuel filter dump it out and see if you get any rust.

What about the fuel pump?

the cap, rotor, wires and plugs were all replaced less than 2 years ago. the fuel filter was replaced a year ago but I guess I could double check these things. If none of that tells me what I need then I guess I can assume it's an injector or fuel pump problem. That doesn't make me too happy.

 

[SoonerBob]

well i hate to admit it but i'm not all too familiar with where the fuel filter would be located

 

[steve_kibbe]

How about vacume advance?

 

[88Silverado]

My 88 was doing the same thing last year. Ran fine at low speed but couldnt pass anything cuz it would just croak. It was the Fuel Filter. It didnt set any codes but when the filter gets plugged, it cant deliver the fuel it needs.

The filter is located on the passenger side frame rail about mid-way back. Simple changeout.

 

[JEBSR]

I agree with the fuel filter opinions, however something that I have ran into is a clogged exhaust system causing the same symptoms. I would have the fuel pressure checked and if it is good have the exhaust back pressure checked.

 

[smokkey1]

how would one go about doing that???

 

[Propayne]

for my own knowledge, why would back pressure be problem enough to cause this?

 

[diesel4me]

It cant breathe!!...

A restricted exhaust might not be noticeable at low speeds,but will limit how much air gets IN the motor at higher speeds and loads..if it cant get enough air/fuel mixture IN,it will run poorly,if at all...the exhaust "backs up" into the cylinder,and prevents fresh fuel and air from getting in if the exhaust is restricted..a restriction in the intake ,like a clogged air filter,will do much the same thing,only it makes it run too rich from lack of air...fuel cant ignite without air!..

I'm hoping he doesn't have a cam lobe going flat..but that would likely cause backfiring thru the intake or exhaust at high revs....weak valve springs can cause missing at high speeds too..the valves "float" and cause missing...hopefully its just a clogged fuel filter or weak pump causing his woes..

 

[68MUDSTUD]

my guess is that it would be the vaccuum advance because the springs in your Distributor (if its an HEI) will wear out and you will have to replace them... also it could be the arm or may just need to be tightened.

 

[JEBSR]

As far as the exhaust backpressure you take out your 02 sensor and install an exhaust pressure gauge (most exhaust shops have one) and start the truck up and get your answer.

I would check the fuel pressure first though.