3.7 cranks and tries to fire, but wont start, no obd Codes

[jeepykj]

I had a 3.7 KJ trucked to me today from a car auction i won for £550. v clean looking 2003 extreme sport model with 112K on clock and 8mths MOT.

this jeep was listed in auction as having a bit of a misfire and it was driving about the auction yard, just a bit misfiring, so i thought it could be crank sensor or something or a duff coil pack to fix, so I bit the bullet and threw in a bid.

it had no fuel in it when it arrived ( but was a bit suspicious there was no gas in it when it arrived. maybe the auction house syphoned off the gas, or they had let it run out. )
so I put two cans total 10L of gas worth in the tank, yet it just cranks over, can hear the exhaust chugging, it almost tries to start feels like its going to take, turns over alright nice and healthy like my 2.4L , but ultimately it will just continue crank over try to take but not and not start up. I have later tried cycling turning the key to ignition on a few times to prime the pump, hear a little bit of a motor werr sound for about 3 seconds when first click the key, so presume that is the fuel pump.


I plugged in an OBD2 wifi and connected to software, but was not showing any trouble codes. I have a 2.4L KJ so I have verified the OBD kit works as my 2.4 KJ is throwing 02 sensor code..

does this whole scenario smell dodgy to anyone ) ?? or any ideas of basics for me to look at before anything else.

many thanks in advance
J

 

[renegade 04]

Sounds like a fuel pump problem. I would start with a new fuel pump relay.

 

[teeje]

Don't throw parts at it! Test first! Turn the key. Does the fuel pump prime?


2002 Jeep Liberty 3.7L with brand new engine
Sent from my iPhone using Tapatalk

 

[Birdman330]

Don't throw parts at it! Test first! Turn the key. Does the fuel pump prime?


2002 Jeep Liberty 3.7L with brand new engine
Sent from my iPhone using Tapatalk

Test number one, have somebody turn the key to on and put your ear by the fuel tank door. Best way to do it.

 

[Billwill]

Pretty old model....you may have to drain and clean out the fuel tank and replace fuel filters. The 2003 model should have the access panel to the top of the fuel tank in the Cargo Bay...drill out the Pop Rivets at the rear base of the Cargo Bay that holds two plastic hooks in place and lift up the carpet.

Try swap over the Fuel Pump Relay with an identical Relay near it in the box under the hood, likewise swap over the ASD Relay with an identical one.

If the battery is marginal in the current that it can supply under starting action then the PCM may not function properly!

If this model has the SKIS anti-theft installed....early models show an amber KEY icon when turning ignition ON..then there may be a problem there stopping it from firing. Later models use a Red LED on the left of the cluster.

The Key symbol should light for a few seconds when ignition is turned ON and then should go out.

If the symbol flashes at you then the correct key has not been recognized by the PCM....engine should start and run for a few seconds then cut out.

If the amber light remains solidly ON then the PCM has not recognized that the ASD relay has been energized as instructed by the PCM after the key code was picked up....engine turns over but will not fire.

 

[jeepykj]

Pretty old model....you may have to drain and clean out the fuel tank and replace fuel filters. The 2003 model should have the access panel to the top of the fuel tank in the Cargo Bay...drill out the Pop Rivets at the rear base of the Cargo Bay that holds two plastic hooks in place and lift up the carpet.

Try swap over the Fuel Pump Relay with an identical Relay near it in the box under the hood, likewise swap over the ASD Relay with an identical one.

If the battery is marginal in the current that it can supply under starting action then the PCM may not function properly!

If this model has the SKIS anti-theft installed....early models show an amber KEY icon when turning ignition ON..then there may be a problem there stopping it from firing. Later models use a Red LED on the left of the cluster.

The Key symbol should light for a few seconds when ignition is turned ON and then should go out.

If the symbol flashes at you then the correct key has not been recognized by the PCM....engine should start and run for a few seconds then cut out.

If the amber light remains solidly ON then the PCM has not recognized that the ASD relay has been energized as instructed by the PCM after the key code was picked up....engine turns over but will not fire.

thanks for this info, am waiting for the weekend so I can get to look at it in the day and do the basic inventory on it. but will check out the immobilizer situation. I have a good battery charger so ensure the battery is fully topped up, but it seems the battery is strong it cranks over really enthusiastic and tries to start some moments of combustion but not catching on. . I have just got an pc 4 ch oscilloscope so I will figure this out and probe some of the sensors see what is going on. but not before testing fuel pressure, swapping the relay over etc like you say. not going to spend a dime on it before knowing what it is. just waiting for the weekend to have a look at it.

 

[JasonJ]

Old model? geez.. they only came out one year earlier than this. Even a 2006 or 07 is nearly 10 years old. They're ALL old.. by most people's standards.

Jeepy.. before you go oscilloscoping around, keep it simple to start. Does it run if you spray starting fluid/ether into the intake and then try to start it? Are the plugs getting GOOD spark?

Have you put a compression testing gauge on the engine? If so, what are the numbers?

 

[Billwill]

thanks for this info, am waiting for the weekend so I can get to look at it in the day and do the basic inventory on it. but will check out the immobilizer situation. I have a good battery charger so ensure the battery is fully topped up, but it seems the battery is strong it cranks over really enthusiastic and tries to start some moments of combustion but not catching on. . I have just got an pc 4 ch oscilloscope so I will figure this out and probe some of the sensors see what is going on. but not before testing fuel pressure, swapping the relay over etc like you say. not going to spend a dime on it before knowing what it is. just waiting for the weekend to have a look at it.

Nice to have an Oscilloscope....you can check that the camshaft sensor and the crankshaft sensor are putting out some nice pulses:icon_lol:

 

[tjkj2002]

Old model? geez.. they only came out one year earlier than this. Even a 2006 or 07 is nearly 10 years old. They're ALL old.. by most people's standards.

Jeepy.. before you go oscilloscoping around, keep it simple to start. Does it run if you spray starting fluid/ether into the intake and then try to start it? Are the plugs getting GOOD spark?

Have you put a compression testing gauge on the engine? If so, what are the numbers?

DO NOT USE STARTING FLUID OR ETHER ON A GAS ENGINE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Unless you want to buy a new engine.

 

[JasonJ]

DO NOT USE STARTING FLUID OR ETHER ON A GAS ENGINE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Unless you want to buy a new engine.

Lots of people have been doing this for decades... it might just be me, but I've never seen nor heard of it causing any damage (aside from maybe a blown off intake tube).

Now it is especially not recommended on Diesel engines.. for those, silicone spray works. Also not recommended to use standard starting fluid on 2-strokes.

If anyone has some evidence that is not anecdotal on why NOT to use it, I'd love to see it. Not that I don't think it exists, as I said, I just have not experienced negative effects first or secondhand. If there is a better way, by all means, I'd love to learn about it.

 

[tjkj2002]

Lots of people have been doing this for decades... it might just be me, but I've never seen nor heard of it causing any damage (aside from maybe a blown off intake tube).

Now it is especially not recommended on Diesel engines.. for those, silicone spray works. Also not recommended to use standard starting fluid on 2-strokes.

If anyone has some evidence that is not anecdotal on why NOT to use it, I'd love to see it. Not that I don't think it exists, as I said, I just have not experienced negative effects first or secondhand. If there is a better way, by all means, I'd love to learn about it.

Starting fluid and ether is for diesels and can and will damage gas engines.

Ether is perfectly okay for 2 stroke diesels.

 

[jeepykj]

Old model? geez.. they only came out one year earlier than this. Even a 2006 or 07 is nearly 10 years old. They're ALL old.. by most people's standards.

Jeepy.. before you go oscilloscoping around, keep it simple to start. Does it run if you spray starting fluid/ether into the intake and then try to start it? Are the plugs getting GOOD spark?

Have you put a compression testing gauge on the engine? If so, what are the numbers?

Not got scope out yet. I had a loot at the KJ today before the light dropped. Checked fuel seems to be plenty of fuel spray out when I depress the schrader valve on the fuel supply rail, plenty of spray off.

while I was fiddling about I took off the throttle body and cleaned it all up anyway while I took all the air box off to try check for loose connections anywhere. a couple of the COPs were had a little bit of movement so tightened down the nut a bit to shore then up. all connections seemed ok.

essentially it still cranks over , a few occasions of a bit of a attempt to fire but nothing catching on (same with a little spray of a bit of carb cleaner in the inbox to oomph up the vapours. but no go, cant be fueling. ,

I also swapped over the ASD relay and retried starting but still the same. Also noticed the overhead console (trip computer display) , does not turn on with the ignition. neither do the interior lights work. does that ring any bells to anyone?

 

[ltd02]

I also swapped over the ASD relay and retried starting but still the same. Also noticed the overhead console (trip computer display) , does not turn on with the ignition. neither do the interior lights work. does that ring any bells to anyone?

Did you swap in a new relay for the ASD or a working one from another location? Still could be fuel (all injectors not injecting) or spark. So seems like an ASD type issue but I think a bad ASD would inactivate the fuel pump too. You don't have any security system issues/lights on?

Could the lack of interior and overhead console lights be the adjuster on the light switch stalk shut off?

 

[jeepykj]

Nice to have an Oscilloscope....you can check that the camshaft sensor and the crankshaft sensor are putting out some nice pulses:icon_lol:

I used to do a bit of hobby electronics. I have recently got myself a USB 8ch oscilloscope that was only £59 to have a play with , will be fine for automotive. I do need to order myself a current clamp, but I can get by for now. I will have to get it set up tomorrow and do some testing. I need to find myself a sturdy 12v 20A rated push switch to rig up a push button starter for under the hood starting, as I dont have anyone to help me to sit in and turn key for starter.

Im very dubious about the overhead trip computer module is not coming on , neither do the interior lights work. so there must be something out for this. get these working first I might find some other hidden problems.

 

[Birdman330]

DO NOT USE STARTING FLUID OR ETHER ON A GAS ENGINE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Unless you want to buy a new engine.

What about Hair Spray?

 

[Conundrum2006]

One other thing I found on a similar model is when I held the throttle open it would not fire, so maybe a throttle position sensor or whatever controls this feature.
But first I'd make sure the fuel pump is working and getting fuel to the rail.

The computer isn't going to find any codes unless it runs. Or attempts to. Strange they drained the tank and either disconnected the battery or cleared the codes from the computer.

 

[Conundrum2006]

Not got scope out yet. I had a loot at the KJ today before the light dropped. Checked fuel seems to be plenty of fuel spray out when I depress the schrader valve on the fuel supply rail, plenty of spray off.

while I was fiddling about I took off the throttle body and cleaned it all up anyway while I took all the air box off to try check for loose connections anywhere. a couple of the COPs were had a little bit of movement so tightened down the nut a bit to shore then up. all connections seemed ok.

essentially it still cranks over , a few occasions of a bit of a attempt to fire but nothing catching on (same with a little spray of a bit of carb cleaner in the inbox to oomph up the vapours. but no go, cant be fueling. ,

I also swapped over the ASD relay and retried starting but still the same. Also noticed the overhead console (trip computer display) , does not turn on with the ignition. neither do the interior lights work. does that ring any bells to anyone?

Sorry I missed the second page to this thread.
Does the check engine light come on?
Did the fuel gauge move when you add fuel?

PCM problem or an immobilizer possibly?

I've been trying to help someone with a 4.0 Cherokee with a similar no start they've tested things like battery fully charged, changing fuel pump, trying start with the throttle wide open in case it was a TPS. Down to trying to swap PCM after checking CPS and Cam sensors.

 

[Billwill]

Lots of people have been doing this for decades... it might just be me, but I've never seen nor heard of it causing any damage (aside from maybe a blown off intake tube).

Now it is especially not recommended on Diesel engines.. for those, silicone spray works. Also not recommended to use standard starting fluid on 2-strokes.

If anyone has some evidence that is not anecdotal on why NOT to use it, I'd love to see it. Not that I don't think it exists, as I said, I just have not experienced negative effects first or secondhand. If there is a better way, by all means, I'd love to learn about it.

I agree with you here...never to be done on a diesel engine but I have done this plenty of times in my youth with gas engines with no damage caused.:shrug:

 

[tjkj2002]

I agree with you here...never to be done on a diesel engine but I have done this plenty of times in my youth with gas engines with no damage caused.:shrug:

20 years ago ether was the "cold start" kits on many commercial diesels and older diesels in many military's still use ether as there cold start aids.

 

[JasonJ]

20 years ago ether was the "cold start" kits on many commercial diesels and older diesels in many military's still use ether as there cold start aids.

That's actually interesting (to me). When I worked at the VW dealer, the technicians there had told me that on the diesels, you use silicone spray for this on those engines... not normal "starting fluid". The starting fluid was too explosive and could damage the engines.. much like what has been stated here. But that the silicone spray, while still combustible, was more compatible with the high compression and necessary lubricating properties that diesel engines require to burn as fuel.