Cranks fine but hesitant to start

[Zambeezy]

When starting the truck after it has sat for awhile, the engine wants to turn over but it takes a bit to finally fire up. Everything sounds like it's working as it should (no odd sounds at least) but it's just tough to start. If I crank it for a bit and it doesn't start I can pause for a second and then try to start it again and it'll fire up right away.

 

Any thoughts on what might need attention? Any testing I should do?

[Tex06]

Check your map sensor voltages. I was having issues with mine and when the MAP sensor was disconnected it took a while to catch.

 

When I upgraded my injectors it helped with my starts some, fwiw.

 

I believe there's also a known issue with the fuel pump or regulator tending to let gas go back into the tank when they start to fail but don't quote me on that.

 

Sent from my SM-G930T using Tapatalk

[Zambeezy]

Check your map sensor voltages. I was having issues with mine and when the MAP sensor was disconnected it took a while to catch.

 

When I upgraded my injectors it helped with my starts some, fwiw.

 

I believe there's also a known issue with the fuel pump or regulator tending to let gas go back into the tank when they start to fail but don't quote me on that.

 

Sent from my SM-G930T using Tapatalk

Thanks for the tip. I'll take a look this week and see what it's showing. Guess it wouldn't hurt to test the fuel pressure as well to see how the fuel pump is doing.

 

What injectors did you put in yours?

[HOrnbrod]

Have you done a complete tuneup (new plugs, distributor rotor and cap, and ignition wires) since you purchased this truck? A weak CPS signal can cause hard starting too. Disconnecting the CPS cable at it's round 3-pin connector (drivers side of the engine near the firewall) and cleaning the pins with some contact cleaner usually helps.

[Tex06]

 

Thanks for the tip. I'll take a look this week and see what it's showing. Guess it wouldn't hurt to test the fuel pressure as well to see how the fuel pump is doing.

 

What injectors did you put in yours?

 

 

Something identical to this: http://www.ebay.com/itm/1993-95-Jeep-Grand-Cherokee-Fuel-Injectors-4-0L-Modern-Bosch-Ultimate-Upgrade-/192094886132?hash=item2cb9bf58f4

 

I originally pulled a set from a Dodge Neon in the junk yard....I think I ended up selling those back to the ebay seller for credit.

[Zambeezy]

Have you done a complete tuneup (new plugs, distributor rotor and cap, and ignition wires) since you purchased this truck? A weak CPS signal can cause hard starting too. Disconnecting the CPS cable at it's round 3-pin connector (drivers side of the engine near the firewall) and cleaning the pins with some contact cleaner usually helps.

I have not but I had been compiling a to-do list of things to look into, and these things are now on it!

[HOrnbrod]

I just noticed your signature and agree with your vehicle choices.  :cheers:

 

1991 MJ & 2015 JKU Sahara for our his and hers.  :yes:

[Zambeezy]

I just noticed your signature and agree with your vehicle choices. :cheers:

 

1991 MJ & 2015 JKU Sahara for our his and hers. :yes:

Great minds!

 

Have any personal recommendations for replacing those items on my MJ? I'm a buy-once-cry-once kinda guy

[HOrnbrod]

For ignition stuff (wires, distributor parts) I've been using Accel stuff with brass terminals for years and have had good results. For spark plugs I've used the Champion copper cores for all the 4.0 Jeeps I've had through the years. Recently based on the recommendations from some of our forum members I tried a set of NGK ZFR5N plugs. I have to admit the idle was smoother and starting cranking time was quicker. You can't go wrong with either plug.  

[omega_rugal]

if while cranking you feel no detonation is taking place and a weird smell of gasoline comes out the exhaust check the CPS... if there`s a faint detonation but the engine can`t turn on then the fuel system is not pumping enough gasoline to it, or is pumping too much...

[Zambeezy]

For ignition stuff (wires, distributor parts) I've been using Accel stuff with brass terminals for years and have had good results.

Looking at this distributor cap but can't find an Accel rotor that says it's compatible with a 1992 Comanche 6 cyl. Any help on the part number?

 

Also read really good things about the Taylor ThunderVolt 8.2mm spark plug wires. 40 ohms/foot seems to be pretty good for what I've been seeing listed for the competition. Thoughts?

[Tex06]

I went with a MOPAR tune up kit off ebay. Was about $70 for rotor, cap, and wires.

 

Sent from my SM-G930T using Tapatalk

[HOrnbrod]

Looking at this distributor cap but can't find an Accel rotor that says it's compatible with a 1992 Comanche 6 cyl. Any help on the part number?

 

Also read really good things about the Taylor ThunderVolt 8.2mm spark plug wires. 40 ohms/foot seems to be pretty good for what I've been seeing listed for the competition. Thoughts?

I switched to the 94 and up distributor quite awhile ago in my 91 so I can't help with the older 91-93 distributor parts. The newer distributor is more maintenance friendly.

 

Taylor 8mm wires are excellent, good choice.

[Tex06]

 

Looking at this distributor cap but can't find an Accel rotor that says it's compatible with a 1992 Comanche 6 cyl. Any help on the part number?

 

Also read really good things about the Taylor ThunderVolt 8.2mm spark plug wires. 40 ohms/foot seems to be pretty good for what I've been seeing listed for the competition. Thoughts?

I switched to the 94 and up distributor quite awhile ago in my 91 so I can't help with the older 91-93 distributor parts. The newer distributor is more maintenance friendly.

 

Taylor 8mm wires are excellent, good choice.

Yep did this too.

 

Sent from my SM-G930T using Tapatalk