94 YJ hard starting problem.

camarocal

New member
I have a 95 yj with a 4.0 and a friend of mine has a 94 with a 4.0. When you start mine it will fire off almost instantly. On my buddy's his has to crank over for 4-6 seconds before it will start. We put a gauge on the fuel rail and it has 38 psi but it bleeds down to under 30 in about 3-4 minutes. Any suggestions on where to look for his slow starting problem?
 

Seems the fuel pressure is the issue; it could be either the Fuel Pressure Regulator or the Fuel Pump that is leaking...
 
Replaced fuel pressure regulator. No help. Replaced fuel pump with Bosch from O'Reilleys still no help. Does anyone know what brand pumps Chrysler puts on from the factory?
 
The is typical of some 4.0's. I don't know what the real issue is, but if you think it is the fuel pressure then turn the switch to "on" listen for the fuel pump to come on and build pressure. When it hits pressure it shuts off, as soon as it does, try to crank it. If it still takes the same 4-6 seconds to start then it's not the fuel pressure.
I would start with changing the plugs and giving it a tune up.
 

My 2.5L does the same thing and the long cranktime is common. I'm also looking for an answer for this.
 
pressure leaking by the o rings on fuel injectors...common in wj's, too. it should hold pressure for 30 mins or so, i think chrysler says.
 
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