dorwink

I do hope I am in the right spot

I have 2002 Jeep Grand Cherokee that will not start. It ran fine right up to the time it died. I had it towed to a "jeep guy" and he was not sure what was wrong without digging deep into it, and it would be a while to get to it. My wife decided to replace the car and just roll it into the new car loan BUT dealers would not take it on trade as the jeep came from Canada and we live in Florida. I parked it at a friends house but now have to move it (house sold), so I got to do something with it.

this jeep is all stock

When cranking it almost starts, it tries but not enough to catch. The engine is the 4.7 and it is a 4x4, it turns over with no issues and even tries to start (cough) but will not start. Before this the only other codes was for the o2 sensors.

The shop said not worth the money and he was not able to diagnose the issue, said it has spark and fuel on the rail. The computer did not report anything.

I first thought was it might be the crank senor but I have been told the if it was bad there would be no spark at all (is this true)?
if this is true this it would not try and start. If the sensor does not disable the spark, would the sensor put out a code just trying cranking and trying to start? also If sensor it does not shut the spark down is there a way to test it.

How to check the timing and make sure it has not come off or jump timing? that has also been suggested.

Also if I take the Schrader value out of the fuel rail how much fuel should it pump out in a given time and or at what psi (and how to test this)?

Last but not lest I just found out that my wife had put fuel in the tank (½ full) before it died How do you drain it and test fuel (of course it has sat a few months now)?

I know it is a lot of questions but any and all help would be great and I thank you. I still owe 2k on the car and 10 mouth of payments I need to do something !!!!!

dorwink

video of engine trying to start

ZJMAX

If you spray starting fluid/brake cleaner/carb cleaner/gas in the intake will it start? Aslo when you turn the key on can you hear the fuel pump prime?

Max

dorwink

ok I used starting fluid today and was able to get it to start but it was not easy nor did it run clean very rough. all gauges works fine, fuel pump turns on with the key and primes. I will try and get a fuel sample in the morning.

try 1
try 2

dorwink

fuel pressure came up to 50 lbs just turning the key on. gauge leaked so now way o testing if it could hold it

ZJMAX

well if you can start it with starting fluid then the cylinders are not getting fuel. I would start looking in to the fuel system and components that trigger the fuel injectors.

Max

rangermonroe

That timing sounds way off! it should have been screaming with that ether shot.

dorwink

i completely agree so what am i looking for ?


I replaced the crankshaft position sensor. should I look and cam postion sensors as well?
Or am I even looking at pulling the value covers and look at the chain it self?

dorwink

I did a key code check by Turn the key to on and then off 3 times and the 3rd time leave it at on and if there is any codes it will show at on your odometer. it said "DONE" the fuel and Battery gauges work fine and while cranking the RPM gauge shows that. theoil pressure sais high but i think it has always been off

dorwink

I did see 1 o2 sensor broken off

Things I have tried

• replaced Crankshaft position sensor
• tested fuel pressure on the rail at 50 psi (gauge leak so bad was not able to see it could hold pressure but it did indeed hit 50 every time and sprayed until ignition was on
• key check for codes and used odb2 reader and talked to the computer no codes. It says “done”
• check voltage and fuel gauges worked
• sort of start with ether not smooth at all (worked better on old csp sensor then new on it backfired (burnt my hair)
• tried leaving the battery out for months to see if it would reset (did not work)

Things I have not tried because not sure how

• Fuel itself
• Empty and replace fuel
• Fuel injector spray
• Spark coils and plugs (plug in know how but do not have to tool to get them and coils not sure how)

Cherryokee

You'll probably need a new starter soon and sorry for your hair-loss but, being that generous with the starting fluid spray, you're lucky you didn't blow the whole rig sky high. And that broken o2 sensor is probably not helping you in your mission either. The engine seemed to run in that video but I don't think that it was running on spark energy. It seems it was running more like pre-ignition/compression.

If your Jeep sat for a long time then the fuel may have become contaminated with moisture (add restorer/dry-gas to the fuel), keeping in mind that electrical connections may be compromised by moisture and/or inspect everywhere possible for evidence of rodent damage - they love to chew on the wires.

Swap your ASD relay temporarily with another similar but less-critical relay from within the PDC. Try again after doing those things but crank in shorter bursts (1-2-3-stop) and use less ether (or none). You'll know if it's going to catch. It can't hurt to demate, clean and reseat connectors at the ECU also. I have been pleasantly surprised a couple times following such simple poking around on cars that sat for extended periods...good luck, eh?

dave1123

The 4.7 has a history of breaking timing chain tensioners because they are plastic. I would suspect that's what you've got with this one, especially with that many miles on it. It's a major event to disassemble it to check. That's probably why that mechanic didn't want to get involved.

I saw the result of a 3.7 V6 that jumped a timing chain on one side. All the valves on that head were bent and the pistons were damaged as well. From the sound if it, yours probably hasn't jumped the chains yet, but the cams are running retarded.

dorwink

so I am guessing if a cam sensor does not fix it then I i should start taking the value covers off look them. I saw a video on doing the timing chain and with everything at tdc should the cams v8 symbol at the top. if the guides are bad would I see or feel slack in the chain or only can tell once the front cover is off? I could not find a video of tare down to the chains on after it was opened

dave1123

I honestly couldn't tell you much about it because I've never had one apart, but I've seen a 3.7, which is the same design, after it had been taken apart.

Remember the cams drive at 1/2 crankshaft speed so if you don't see timing marks at TDC, go one more revolution.

Wow! After reading my Haynes manual about the 4.7, my brain hurts!

Kris Howard

2006 jeep grand Cherokee Ltd.
Won't start, turns over.
I didnt go to the fuel pump cause I could hear it.
2 days& sensor & fuse hassles,still nada.
I pulled the pump and the 39 cent bladder check valve on the return line was shot. Hope this saves at least someone headaches..