Hard to start and low on horsepower
 

Hello,


I own a 1997 s-series blazer 4.3, 4dr, 4wd and recently developed a hard to start/hesitation off the line/low on horsepower power problem. The plugs, wires, air filter (paper filter), and fuel filter are relatively new. MAF sensor looks clean. The CEL is not on and I haven't seen it come on for a long time but it does work. I checked the fuel pressure KOEO at the service port under the hood and got a reading of ~59psi, turned the key off and it held 59psi then took 20 minutes to drop down to 55psi. I then jerry rigged my fuel pressure gauge to the fuel filter outlet and with the KOEO the gauge shot up to 80+psi and then a weak connection sprung a leak.


Do I really need to do a leak down test at the filter if it passed at the service port? Any ideas for what I should check next?


Thanks

maybe your cat is pluged

I went to Home Depot to buy some fittings so I could get more accurate pressure reading at the filter. Here are the new results...

Service port under hood;
Primed - 59psi
After 10 mins - 58psi
After 20 mins - 55psi
After 35 mins - 54psi

Gauge connected to fuel filter;
Primed 25psi first time I turned the key after having the fuel line disconnected.
Second turn of the key fuel pressure shot up to 80psi and when I turned the ignition off it drop down to 78-79psi.
After 10 min - 62psi
After 20 min - 59psi
After 30 min - 58psi

What do you guys think?

Thanks for the reply. I did knock on it when I was under the truck and its sounds solid, however I didn't really think it was or is the problem at this point. I will keep it in mind though.

A clogged cat won't rattle like you think it will and will cause all the problems you are having.

The trucks symptoms feel like a bad tune to me. When I start the truck hot or cold it comes to life weak and I also don't get that cold start high idle, it just idles at 500rpm. It use to start fast, like on the first turn but now turns over a few times before firing and some times I need to give it some gas pedal just to start it and keep it running. If I try and take off from a stop quickly (about half pedal or so) the truck will jump, fall on its face for a second and then go but still a little underpowered. When accelerating from a roll it feels okay unless I floor it. If I floor it from a roll it feels like I'm loaded or pulling a trailer. Fuel consumption seems normal to me. The engine free revs like a banshee in park or neutral. Exhaust smells and sounds the same and I have good pressure at the tailpipe.

I guess I will have to test/inspect the cat.

Any other ideas/suggestions?

Thanks,

My cat tested fine as I suspected. It's defiantly something else causing this problem.

Take a look at your distributor cap and rotor and also the coil. If it is a sensor, you might have to take it to a shop so they can run diagnostics on the engine to pin point what the problem is.