87m6chris

1992 4.0 L

I'm about to do a leakdown test on my "new" Cherokee to get a base line for work that needs to be done, so need to shutoff the fuel so it is not spraying while I'm cranking. Apparently, the ECU bypasses the fuel relay on start up so pulling the relay won't work.
Any ideas?
Thanks,
Chris

SeriousOffroad

Wait....What?


What exactly are you trying to do?

4.0cherokee

I did a leak down last week and I only needed my buddy. My leak down tester, a long skinny screwdriver and a large breakover bar for the main pulley bolt.

PingPong

Are you sure you are not talking about a compresion check? Thats the test you do turning the motor over. That is the test you do to see how healthy your motor is.

Leak dowwn test is when you rotate the crank around and fill each cylinder with air then waiting a period of time to see how much air it loses.

I don't do either one of these test unless I have issue with runnability and lack of power. Then that is after I test spark and fuel systems.


Also you want the cylinders wet when you do either one of these tests.

87m6chris

Sorry, me not being clear. I always do a leakdown test followed by a compression test dry/wet. I'm really talking about the compression test. So I need to shut off the fuel so it isn't spraying while cranking the engine over. There's got to be a way to activate the starter without involing the fuel system.

SeriousOffroad

Unplug the electrical connector at the pump.

UserID6095

For that you need one of these. But what Frank said is a lot easier.

87m6chris

Thats it. Nice and simple,
thanks