blown engine?? engine compression?

[dubless10]

well the title gives you a hint as of what this includes. basically. i have a 1992 4.3 engine code w cpi. i have been having problems with since i bought it, i was told it needed a tune up soo, first i replaced the fuel filter, distributer cap, rotor, spark plugs and wires. when i bought the truck it ran but for about 10 min maximum so i took apart the gas tank and found the fuel hose from the pump and sending unit been to be damaged and bypassing fuel back into the tank. i replaced the sending unit and pump just to be sure. put it all back togather and it runs, but it runs really rough and when i put it into gear and step on the gas it sputters alot and doesent want to move, like there is low compression, weak spark, or low fuel pressure. i have read every page in my repair manual and nothing has jumped out at me, tomorrow im going to find a compression tester, fuel perssure testing gauge, and spark tester. but until then if anyone has incurred this please help, all suggestions welcome, even smart ass ones to make me laugh.
thanks, phil

[Eric]

did you get a new fuel line?

[Danny_SS]

Check your compression, but unless you happen to have one or more cyl with 0 compression that wont be the problem. Even if they are all really low likw 90psi it should run nice and smooth. I would check the EGR valve since they tend to get stuck in the open position and cause all sort of rough idle and hesitation problems which leads many mechanics to go around changing all sort of stuff.
Make sure you have good fuel pressure.
New cap and rotor is allways good yet cheap.
does this rough condition allways happen?
is it a cyl misfire or is it a random misfire?
are you running very rich or lean? any smoke?

[steve]

Test your vacuum. And check all your lines for leeks. If you have a vacuum leek it can make you motor run like absolute crap. And if you are having miss fires like Danny_ss said you might want to check to make sure you did not mess up spark plug wires. I have seen even seasoned backyard mechanics make that simple mistake. Also check your sensors. I had a problem with my 91 2.8 s10 running like crap and I tracked it down to a sensor. If I remember correctly it was my MAP sensor. Try checking that stuff it might be your problem. Good luck.

[icemancomethe]

Even new caps can have defects in them. If you still have the old one put it back on and see if it runs better.

[dubless10]

well it happens all the time. it seems like one or a few spark plugs arent firing. or im just loosing compression, but i dont know how to check the spark in each cylinder without starting the engine, is there a wire i disconnect, so the engine wont start? i want to check each cylinder if it has a weak spark also. i checked the codes and it isnt throwing one for the egr. im hoping it isnt a blown engine :eek:

[Danny_SS]

no it is not a blown engine
just see what is going wrong.
have you checked compression?
and anything else yet?

[steve]

If you turn off your fuel supply your engine wont start. Just disconnect your fuel line and run it out of gas, then check your spark in each cylinder.

[bonecrushins10]

dont forget the pvc valve, those 3 dollar parts are what gets ya