ok so i've been having this problem since i got the truck. 96, 6cyl. when it's hot, like if i've been running some errands, it won't start right up, lopes a little like maybe it's misfiring or isn't getting fuel..acts like it's choking out..but only does this when it's hot, never when it first starts in the morning or has been sitting for long enough to cool. sometimes i can get it to run smoothly by holding down the gas pedal and running it till it catches but sometimes it just has to sit and cool. i've read in other threads that the fuel pump can malfunction when hot ...but another symptom of this is that two of my spark plugs will back themselves out! i don't know if this is caused by the engine shaking when it's having a rough start or if the rough start is due to the plugs backing out?? i've cranked them down tightly, and it's always the same two plugs (3 and 4) that loosen up.
any suggestions??

 

also, i just read in another forum about checking the pressure at the fuel rail as it might be a clogged injector..how do i do that? i've run some fuel system cleaner through it a few times with no noticeable results.

 

You need a fuel pressure gauge for fuel injected vehicles. A carbureted fuel pressure gauge won't work, it doesn't go high enough. There is a nipple on the fuel rail that looks like a tire valve stem. You hook the gauge there and start the truck. See what the fuel pressure is and then shut the truck off. See how fast the pressure drops.

 

cool. so i'll look for the schraeder valve on the fuel rail. what should the pressure read if it's running properly?

 

Key on engine off should be around 50-60psi an key on engine running should be 28-45psi. there should be a black cap on that schrader valve just like a tire valve stem as well.

 

One catch about the key on/engine off reading - you might have to cycle it a few times to reach the higher pressures. I finally read that somewhere after having been mightily confused by the initial (false) low reading. The key-on sequence runs the pump a fixed time (two seconds??), not until a specific pressure is reached. You might just turn the key on, wait for the pump to shut off, and repeat a few times before even looking.

Bill