Jeep Enthusiast Forums banner

Crank but won’t start, after 4 attempts runs fine

490 Views 9 Replies 4 Participants Last post by  Brad426
Rather weird scenario. I have a 2007 Jeep Liberty sport and never had any issues with starting. There’s around 132000 miles on it. Went to start it Friday and it would crank over but wouldn’t start. Tried it 4 times and it started and ran fine. Ran it down to the pizza place and after an hour parked it started fine. Took it over to a friends place and it was parked for a couple hours. Started right up and ran fine.

went to start it this morning and it will crank but won’t start. Tried it several times. I can hear the fuel pump come on and come up to pressure and shut off. Checked the shrader on the fuel rail and it’s shooting out fuel.

threw the ob2 reader on it and got 2 codes. P0685 ASD/main control circuit
&
P0688 ASD/main sense circuit

after another attempt it started and ran fine. Tried it a few more times and it started fine.
I let it sit for 6 hours and just tried it and crank with no start. 4 attempts and it started and ran fine.
I pulled the ASD relay and looked at it but doesn’t look corroded or anything. I ordered a new one along with a few other relays from rock auto like ignition starter relay, ignition starter switch ASD relay and a computer control relay.
Just wondering if anyone has come across this intermittent issue before. Like I said I’ll change the relay when it comes in but maybe someone has had a similar issue?
Thanks
Todd
1 - 10 of 10 Posts

· My Reality Check Bounced
Joined
·
20,063 Posts
That sounds like the classic weak fuel pump or worn pump relay, but changing the relay is easy enough and simple. You need to measure the rail pressure to be sure.

Otherwise an intermittent open circuit on the relay coil-connector-harness which, in turn, caused the relay not to energize when expected (throws P0688). Could also be the relay or PCM. If replacing relays don't work out, check for corrosion in the PCM connector.
 

· Registered
Joined
·
219 Posts
if schrader valve on fuel rail is "shooting out fuel" as you mentioned, DO NOT run the engine until you get that valve core replaced! (replacement is specific with viton tapered seal). leaky valve won't allow fuel pressure to build for injectors to start flowing.
leaking raw fuel and exhaust headers don't mix :devilish:
 

· My Reality Check Bounced
Joined
·
20,063 Posts
went to start it this morning and it will crank but won’t start. Tried it several times. I can hear the fuel pump come on and come up to pressure and shut off.
I think the PCM of that vintage shuts off fuel and spark (turns off ASD relay) after about 2-4 seconds of cranking with no start.
 

· Registered
Joined
·
6 Posts
Discussion Starter · #5 ·
if schrader valve on fuel rail is "shooting out fuel" as you mentioned, DO NOT run the engine until you get that valve core replaced! (replacement is specific with viton tapered seal). leaky valve won't allow fuel pressure to build for injectors to start flowing.
leaking raw fuel and exhaust headers don't mix :devilish:
No it doesn’t shoot fuel out. I just depressed it to check to see if there was fuel at the rail. I wish it was something that simple. I wouldn’t be scratching my head the last few days
 

· Registered
Joined
·
6 Posts
Discussion Starter · #7 ·
Crankshaft position sensor?
I’m not entirely sure. So far the last 3 days it hasn’t given me an issue in the morning or the evening starting. I did receive the P0688 code this morning again though but it started just fine. I got some relays in today so I’m just waiting for it to do it again so I can start swapping them out in hopes of narrowing it down.
 

· Registered
Joined
·
6 Posts
Discussion Starter · #8 ·
Crankshaft position sensor?
I did change both the crankshaft sensor and the camshaft sensors today. If anyone attempts this make a special note. It took 2 1/2 hrs to get the crankshaft sensor out. I initially got it loose and twisted it till it would spin freely. No amount of tugging or prying would get the sensor loose. Eventually the end of the sensor project off. I had to resort to a pair of vise grips and slowly twist and pull. Eventually the sensor came out. The sensor is plastic. Due to the contract of oil on the sensor, the end inside the engine swelled and couldn’t be easily removed. I put some anti seize on the new rubber gasket and that installed in seconds. The camshaft sensor was pretty easy with really no issues.
 
1 - 10 of 10 Posts
Top