1991 Isuzu Truck engine compression / oil pression

JOE1953

MEMBER
1991 ISUZU TRUCK
154,000 MILES

How much the engine compression suppose be on each cylinder, I want to check the compression to see what the numbers is it is a 1991 isuzu four cylinder truck I don't know the size of engine but it is a four cylinder the two cylinder from the front have no engine change when pull spark plug wires off, the wires and spark plugs are good but the fire are yellow looking.

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JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Okay, before we check compression, tell me if the spark plugs from those two cylinders are wet after running the engine. Also, you are correct about the spark. It should be a blue snapping spark.

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Tuesday, July 16th, 2013 AT 6:48 PM

JOE1953

MEMBER
634 POSTS

No I didn't see any wetness on the spark plugs after running the engine.

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Tuesday, July 16th, 2013 AT 7:57 PM

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

If they are dry, that tells me that they aren't getting fuel. If there isn't a spark that can cause combustion, the fuel should build up in the cylinder and get the plug wet with gas. Are you sure the fuel pressure is within spec and that all injectors are getting power and actually working?

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Wednesday, July 17th, 2013 AT 6:16 PM