4.5L in 99 xj wont start

[austin_troudt]

I just rebuilt my jeep 4.0 and stroked it to a 4.5L. checked timing and dropped distributor in @ TDC compression stroke #1. Jeep ran when it was parked late october. Has a new battery, new cap, rotor, plugs, plug wires. pulled plug out of head and has fuel on it. coil has good spark. plugs have very dim spark. Jeep is a 99 cherokee sport fuel injected 4.5L I6. Checked compression its around 125psi. checked spark and its good, have fuel, pressure is around 60 psi. moved distributor and it fired very roughly misfires shakes shudders. tried moving dist one tooth forward and back, once again will not start and hasnt since. after it ran for about 25 min, brand new plugs were black and fresh pistons were black, i have the stock injectors off a 99 and stock fuel pressure regulator. I was thinking it was due to lack of fuel but i guess 97 up 4.0 injectors are around 23 lbs per hour at 49 psi so i dont think its lack of fuel. anyone heard of changing the map voltage and if so how to any ideas????? oh and i have checked tdc compression vs distributor about 200 times now and firing order. maybe off a tooth on the cam or maybe the tone ring on the flex plate is off?


Please help

[rradford9]

Heres a write-up to making your own adjustable Map sensor http://www.go.jeep-xj.info/HowtoMAPsensor.htm

Sorry I can't help with anything else...

[austin_troudt]

thank you!

[SilverXJ]

Isn't 60 psi a bit high for fuel pressure? Also, even with the stock injectors any stroker will at least start. You say the spark is dim? I would start with the ignition system then. Coil, distributor, etc.

[austin_troudt]

re did timing on cam and crank gears, will now start run like crap, however if dist is retarded about 10 degreeswill start and run at about 1100 rpm 3/4 throttle. but no idle and no top rpm could be off a tooth on cam timing gear?????? also rechecked fuel pessure about 45psi

[1bolt]

(Moved over to basics)

Austin lots of people have issues with indexing the distributor/Cam sensor, so that's what I would suspect right away. There's lots of posts about this (refer to the "tooth pick method" and indexing the distributor). Reinstall your timing set and make 100% sure it's straight up, use the link counting method, and not just those indexing dots. Then re-index the dizzy/Cam sensor, using the tooth pick method. Hope I've steered you in the right direction.