90 psi means very little if they are all within about 10% of each other.

Umm, no.  If the compression is only running around 90 on all cylinders that means the engine will be waaaaay down on power and would be lucky to even run, let alone move the vehicle at any speed at all.
Factory spec is 199 psi for compression.  With 170 psi being the service limit.  There should be no more than 14.2 psi between the high and low cylinder.

the only way i was able to get 90psi was by flooring it while i was cranking it over unless im doing the test wrong.

 what should the psi be at per cylinder? does anyone know?

You are supposed to push the gas pedal all the way to the floor, when you are checking compression.

See my previous post, for compression psi.

it started about a month ago and slowly got worse i though it just needed a tune up. so i put new a cap and roatter, spark plug wires and spark plugs and it ran fine for a while and then it was back the same.

So when you replaced the cap, rotor, plugs and wires it started running fine again?  If so, then it appears like there is something up with the ignition system.  But then again, your compression tests would indicate differently.  Faulty ignition components would not make the compression run low.

 i was wondering if the ECM might be going bad but i dont know how to check it other then buy a new one and compare.

I thought 90psi was way to low for a engine to run also but it starts right up.
 
 I already have the engine out and on the stand.

 Skyhiranger you answered my questions straight to the point and are very helpful Thanks 

I doubt the ECM is bad.  The carbed ECMs rarely go bad.  And if they do, they generally just affect how it runs, it would have no affect on compression.
Maybe your compression gauge is off, or you aren't getting a good seal.

i was wondering if the ECM might be going bad but i dont know how to check it other then buy a new one and compare.

I thought 90psi was way to low for a engine to run also but it starts right up.
 
 I already have the engine out and on the stand.

 Skyhiranger you answered my questions straight to the point and are very helpful Thanks 

ECM's aren't cheap.

Have you had anymore time to diagnose anything?

Quote from: DMzuk on October 05, 2011, 05:34:53 PM

i was wondering if the ECM might be going bad but i dont know how to check it other then buy a new one and compare.

I thought 90psi was way to low for a engine to run also but it starts right up.
 
 I already have the engine out and on the stand.

 Skyhiranger you answered my questions straight to the point and are very helpful Thanks 

ECM's aren't cheap.

You can buy used carb ECMs for like $10 or $20.  EFI ECMs are the ones that are expensive.

Gotcha, i was looking at Hawk's website and they are around $320, that's why i was saying that, they must be the EFI setup.

Gotcha, i was looking at Hawk's website and they are around $320, that's why i was saying that, they must be the EFI setup.

They might be, they might not be.  Hawk's usually isn't the cheapest place to buy parts from.