1990 xj long crank time and hard starting
Thread Starter
Member
Joined: Oct 2011
Posts: 112
Likes: 0
From: California
Year: 1990
Model: Cherokee
Engine: 4.0
1990 xj long crank time and hard starting
im banging my head on this one... sometimes it starts up fine other days not so much and hot or cold makes no difference changed the IAC TPS and CPS sensors started better for a while but now it has seemed to get worse.. also just replaced the alternator and cleaned battery posts, terminals and ground running out of idea's. could it be fuel check valve?
CF Veteran
Joined: Nov 2010
Posts: 5,840
Likes: 117
From: In the middle of Minnesota!
Year: 1999
Model: Cherokee
Engine: 4.0
You have a Renix XJ (87-90) By design, the engine is not going to fire until the computer (ECU) gets a signal from the crankshaft position sensor and measures that signal to indicate that 300 rpms while cranking has been met/exceeded.
Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.
You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.
Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.
Other than that, performing basic tune-ups on a regular basis is important, (plugs, wires, cap, rotor, fuel filter)
The above suggestions are things that will help optimize start times on a Renix engine.
Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.
You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.
Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.
Other than that, performing basic tune-ups on a regular basis is important, (plugs, wires, cap, rotor, fuel filter)
The above suggestions are things that will help optimize start times on a Renix engine.
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Joined: Aug 2011
Posts: 43,971
Likes: 1,578
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Mr. Walker offers excellent advice.
Your CPS can be a bit weak, too. Unplug it and probe the two wires with your meter set on AC volts. You should get .5 as a reading. Anything down around .35 will cause long crank times and possible intermittent no-starts.
Did you adjust your new TPS? If you need instructions on how to do this, I'll bet Mr. Walker would post them in this thread for you.
A good throttle body cleaning is never a bad idea and shold be done before adjusting your TPS.
As stated, ground refreshing at the dipstick tube stud is super important. Don't ASSume anything. Remove, clean, scrape, polish til shiny all contact points there. Do the same with the braided strap where it attaches to the firewall. I recommend ADDING a battery cable from the firewall attaching point to the rearmost bolt of the fuel injection rail.
Your CPS can be a bit weak, too. Unplug it and probe the two wires with your meter set on AC volts. You should get .5 as a reading. Anything down around .35 will cause long crank times and possible intermittent no-starts.
Did you adjust your new TPS? If you need instructions on how to do this, I'll bet Mr. Walker would post them in this thread for you.
A good throttle body cleaning is never a bad idea and shold be done before adjusting your TPS.
As stated, ground refreshing at the dipstick tube stud is super important. Don't ASSume anything. Remove, clean, scrape, polish til shiny all contact points there. Do the same with the braided strap where it attaches to the firewall. I recommend ADDING a battery cable from the firewall attaching point to the rearmost bolt of the fuel injection rail.
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Seasoned Member
Joined: Jan 2011
Posts: 437
Likes: 0
From: Central Jersey
Year: 91
Model: Cherokee
Engine: 4.0 I6 H.O.
My 91 did the same thing, camshaft position sensor under the rotor in the distributor cap. Clean the rust off the metal cup too, that will make more sense when you take it apart.
CF Veteran
Joined: Aug 2011
Posts: 10,489
Likes: 24
From: Nor-Cal Coast
Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Great advise /\.. My fuel check valve is bad/toast. If you turn Ign on you hear the pump run for the count of three. Turn off, then on again, it runs again. Third time it runs a second. THEN the pressure is up and my Jeep will start in a three count instead of double that or a little more. Easy enough to check.
(I learned how to do this from slick761 last month)
(I learned how to do this from slick761 last month)
Last edited by DFlintstone; Oct 5, 2011 at 01:53 PM.
Thread Starter
Member
Joined: Oct 2011
Posts: 112
Likes: 0
From: California
Year: 1990
Model: Cherokee
Engine: 4.0
Mr. Walker offers excellent advice.
Your CPS can be a bit weak, too. Unplug it and probe the two wires with your meter set on AC volts. You should get .5 as a reading. Anything down around .35 will cause long crank times and possible intermittent no-starts.
Did you adjust your new TPS? If you need instructions on how to do this, I'll bet Mr. Walker would post them in this thread for you.
A good throttle body cleaning is never a bad idea and shold be done before adjusting your TPS.
As stated, ground refreshing at the dipstick tube stud is super important. Don't ASSume anything. Remove, clean, scrape, polish til shiny all contact points there. Do the same with the braided strap where it attaches to the firewall. I recommend ADDING a battery cable from the firewall attaching point to the rearmost bolt of the fuel injection rail.
Your CPS can be a bit weak, too. Unplug it and probe the two wires with your meter set on AC volts. You should get .5 as a reading. Anything down around .35 will cause long crank times and possible intermittent no-starts.
Did you adjust your new TPS? If you need instructions on how to do this, I'll bet Mr. Walker would post them in this thread for you.
A good throttle body cleaning is never a bad idea and shold be done before adjusting your TPS.
As stated, ground refreshing at the dipstick tube stud is super important. Don't ASSume anything. Remove, clean, scrape, polish til shiny all contact points there. Do the same with the braided strap where it attaches to the firewall. I recommend ADDING a battery cable from the firewall attaching point to the rearmost bolt of the fuel injection rail.
cps sensor is new and seems to be working properly also cleaned the ground at the dipstick and fire wall
You have a Renix XJ (87-90) By design, the engine is not going to fire until the computer (ECU) gets a signal from the crankshaft position sensor and measures that signal to indicate that 300 rpms while cranking has been met/exceeded.
Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.
You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.
Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.
Other than that, performing basic tune-ups on a regular basis is important, (plugs, wires, cap, rotor, fuel filter)
The above suggestions are things that will help optimize start times on a Renix engine.
Somewhat extended crank times should be considered a “characteristic” of your engine, rather than a problem.
You can upgrade the battery and battery cables--at least 4 ga., 2 ga. better--and buy a high-torque starter.
Be sure that all grounds are good. Remove them and freshen them. You cannot tell if the grounds are electrically good by looking at them! Renix vehicles are very sensitive to ground issues.
Other than that, performing basic tune-ups on a regular basis is important, (plugs, wires, cap, rotor, fuel filter)
The above suggestions are things that will help optimize start times on a Renix engine.
cruiser54 said you might have a right up for adjusting the tps that would be much appreciated
Thread Starter
Member
Joined: Oct 2011
Posts: 112
Likes: 0
From: California
Year: 1990
Model: Cherokee
Engine: 4.0
also have been doing the key cycling seemed to help but figures when i want it to give me the issue it wont do it for me......gonna try this for the nxt couple of days
also would there be any benefit to changing the cam position sensor even if it doesnt have an issue with the starting?
also would there be any benefit to changing the cam position sensor even if it doesnt have an issue with the starting?
Last edited by 1990xj2d; Oct 5, 2011 at 02:18 PM.