1998 cherokee interrmitent no start

zoom63

Well-Known Member
Joined
Mar 7, 2007
Location
Kannapolis, N.C.
Cherokee will sometimes crank but not start. Have spark at the plugs, fuel at the fuel rail. If I hold throttle body wide open, it will start right up. When I shut off and try and restart just by cranking and not holding open throttle body it will not start. Thanks in advance for any advice.
 
Does it run rough and smoke a touch of black after starting? If so it could be a rich issue. If not it could be a idle air issue.
 
Try and just barely Crack it. If it'll start, look at iac. If it won't get it started and look at oxygen sensor voltage and fuel trims to determine if it's mixture is rich or lean.
 
2 things come to mind:
Check fuel pressure and see if it bleeds down after turning it off. If you have a leaking injector it could cause a long crank requiring more air to start

Check your throttle position sensor voltage with the key on, but engine off. Should be around 0.7 volts IIRC. Then sweep it to wide open and see if it moved fluidly.

Holla back and I'll help out
 
Jody Treadway said:
2 things come to mind:
Check fuel pressure and see if it bleeds down after turning it off. If you have a leaking injector it could cause a long crank requiring more air to start

Check your throttle position sensor voltage with the key on, but engine off. Should be around 0.7 volts IIRC. Then sweep it to wide open and see if it moved fluidly.

Holla back and I'll help out
Click to expand...
Agreed!
 
Hooked up fuel pressure gauge. Turned key on to activate pump. Fuel at 43psi. Cracked open throttle body to start. Fuel at 46 psi running. Turned car off. Fuel psi leaked down 18 psi in 10 minutes. Squeezed rubber fuel line from pump to fuel rail and it still leaked down.
 
If I question an injector, I'll pop the rail out, unplug the injectors (just for safety sake) and watch for a leaking injector. As always make sure if any oring is disturbed it's replaced
 
Unbolt the rail without disconnecting the supply line. Cycle the key to pressurize the rail and see if any of the injectors leak.
If not, the pressure regulator on the fuel pump module may be leaking.
 
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