low compression on 8th cyl?

[arian5.0]

hey guys im trying to figure out wth is going on with my car it has 10 pounds of vacuum and compression on the 8th cylinder was dead and i brought it back up to 110. PISTONS AND RINGS ARE GOOD, THIS IS WHAT THE MECHANIC TELLS ME. car is not running how it should.. it has a miss at 1500 rpm 2500 rpm. ive posted a topic about this not too long ago and i havent gotten answers.. this all started happening when i changed the fuel pump which was a walbro 255 i beleive it was outside for sometime, im not sure if the fuel injector are dirty or clogged but ive checked the fuel pressure and its good its around 45. the only thing is that pressure drops when the car is hot but not while im driving. when im at a stop.. the car has been in the shop for about a month and they cant figure out wtf!! is wrong with the car and its already gettign frustation.. sorry for the (wtf) PLEASE ANY ANSWERS WOULD HELP

 

[nunly94gt]

:SNSign:So if Im reading correct it still has low compression? If that is the case there are only so many things that cause your compression to drop off. It has to go somewhere and its not to the spark plug. Possible causes for compression loss....
1. Worn rings on piston
2. Stuck Valve (open just a bit, you will hear it popping back through the intake)
3. Cracked block
4. Damaged head

If its a fuel problem, it could be the injector couldnt keep up with the ammount being thrown at it. They go bad, and dont put out what the should. If you can swap injectors from number 8 with number 7 and see if the problem follows the injector or the cylinder. That will narrow the injector down, as there isnt a flow test on the older cars.
There are alot of things that go along with the issue you have. You said the compression came back???????
I dont really see how you can not have it then have it unless a valve was hanging up. Those guides were known to catch sometimes.

Hope this helps, maybe someone else can chime in too.:SNSign:

 

[arian5.0]

YES, THE COMPRESSION WAS AT 45 WHICH IS DEAD,, AND THE MECHANIC FIXED SOME EXHAUST LEAKS HERE AND THERE AND IT CAME BACK TO 110,, ALSO I HAD A BAD TIMING CHAIN..

 

[arian5.0]

:SNSign:So if Im reading correct it still has low compression? If that is the case there are only so many things that cause your compression to drop off. It has to go somewhere and its not to the spark plug. Possible causes for compression loss....
1. Worn rings on piston
2. Stuck Valve (open just a bit, you will hear it popping back through the intake)
3. Cracked block
4. Damaged head

If its a fuel problem, it could be the injector couldnt keep up with the ammount being thrown at it. They go bad, and dont put out what the should. If you can swap injectors from number 8 with number 7 and see if the problem follows the injector or the cylinder. That will narrow the injector down, as there isnt a flow test on the older cars.
There are alot of things that go along with the issue you have. You said the compression came back???????
I dont really see how you can not have it then have it unless a valve was hanging up. Those guides were known to catch sometimes.

Hope this helps, maybe someone else can chime in too.:SNSign:

well we can rule out the cracked block and worn piston or rings car does not over heat, and pistion were checked already

mechanic put the noid light on all injectors and there not the problem either.. hes telling me it can be electrical