Vacuum Question

[robhamster]

1984 3.2 Cab. Whenever I lift the oil cap to check the level with the engine running, it dies. Is this normal. I am starting to get some sort of intermittent vacuum leak and the car tries to die, then goes again.

Is there an easy way to diagose the problems here?

[AFJuvat]

keep the cap on, and get yourself some carb cleaner. with the engine idling, spray carb cleaner around vacuum hoses and fittings. When the idle changes, you have found a vacuum leak. Repeat until you find them all.

Common leaks are at the back of the throttle body, when a vacuum hose gets disconnected.

AFJ

[robhamster]

I have been unable to find the leak and have had the problem happen very intermittently. Last nite I drove the car about 80 miles on the highway and after about 40 miles of running just fine, the car began to sputter and act like it does when the oil cap is off. I smelled unburned fuel in the exhaust. I was able to rev the car up and the problem would go away for a while and then come back. For the next forty miles back home, the car intermittently acted up. Should I be looking for a vacuum leak here or is it something else. Do fuel pumps just fail or can they act up occasionally like this?

[jstobo]

You should have a restrictor (flame trap) in the oil breather line for the oil tank. This line goes to the airbox from the tank. Without the restrictor the engine will die with the oil cap off. I would guess the restrictor is missing in your car.