Crusty Old Dodge Van Won't Start
2000 Dodge Ram 1500 Van
Engine: 5.2 L / 8 cyl / Gas / OHV VIN: 2B6HB11Y0Y
Symptoms: Crank/No Start
Here's the break down of what we've checked and tests performed.
Cranking Vacuum is less than 1 psi with a jumping needle.
Oil Level is VERY high and appears that fuel is in the crankcase.
Compression is low: 100 psi to 140 psi, although there's evidence that the cylinders are fuel washed.
Fuel Pressure KOEO 45 psi. Drops to zero with key off.
CMP Signal is good.
CKP Signal is good.
CMP/CKP Sync is perfect against known good wave pattern.
Distributor Cap and Rotor are brand new.
Ignition Wire Order is good, verified by 2 different techs.
Spark Plugs have been cleaned and gap is good.
Ignition coil produces 45kV of energy with a bright blue spark.
Exhaust flow is preset at the tailpipe, although we removed the rear two spark plugs and tried to start it just to be sure. It still didn't start.
Fuel Injection pulse has been verified with a noid light.
The engine would NOT start on alternative fuel (starting fluid introduced into the throttle body and vacuum port on the RH side of the intake).
Unplugged the MAP sensor and it still wouldn't start.
IAT and CTS have accurate readings KOEO after it has been cold soaked
What am I missing that this gawd-forsaken van won't start?
I'd change the oil, squirt some oil in the cylinders, disconnect the fuel pump relay in case the fuel pressure regulator or the injector are acting up and try to start it with a little starting fluid.
The first thing you have to to is remove the contaminated/overfilled oil. If the oil has fuel in it, and is overfilled, it could be washing the cylinders even worse and causing issues with the start. Then, disconnect the fuel pump relay and watch the fuel pressure as you crank it. If it doesn't go down and you've got all the necessary requirements for the fuel injectors to work, you may have…
Plugs were fuel soaked for sure. We confirmed the injectors are spraying. Mechanical timing was checked with the lab scope. It was good.
If you are talking about checking cam and crank sensor on the scanner, that's not checking the mechanical timing. That just checks the function that there's a signal coming from cam and crank sensor. If the timing chain jumped a tooth, or the distributor is not in time, it will not show that the mechanical timing is correct.
David, It's been a very long time, but I don't think scoping the cam/crank on these engines will actually tell you if your ignition rotor is 360 degrees off crank timing. The crank sensor just reads off the flywheel teeth, doesn't it? Have you verified that the ignition is set correctly to TDC #1 compression?
Hmm.... The known good pattern had me checking number 7 injector firing as the CMP sensor went to five volts. I've attached the known good that I used. My scope matched it perfectly.
Right, but it will still line up when the engine is 360 degrees off from distributor timing, right? Might we be trying to fire the spark on the exhaust stroke instead of the compression stroke?
What I mean is, it's the CMP that triggers injector events. The CKP is basically just a speed sensor used for calculations. There's no way to tell looking at those signals if the distributor were put in when the engine was on the wrong stroke.
Correct. Did someone mess with the distributor?
There's no evidence that the distributor was disturbed. It's pretty crusty and oily. Someone else suggested a relative compression test synced to an ignition event or injector pulse. I guess I could check it that way.
I would just make sure that the ignition rotor is lining up with cylinder #1 on the distributor cap when cylinder #1 is at TDC compression. I love my labscope as much as the next guy, but sometimes you just need to put eyeballs on things. If it's not, then the problem could be partially spun distributor gear, camshaft gear, loose or jumped timing chain, any of those. The point here is that even…
Maybe. But, usually won't fill the oil up with fuel. It will usually pop and backfire if that's whats going on.
I have never worked on one of these vans, or many Chrysler's of this vintage, but shouldn't the fuel pressure hold steady after the key is turned to off? At least for awhile? Your test would indicate fuel leaking down. Maybe past the fuel pump check valve, maybe through the pressure regulator or fuel injector. Just a thought.
Correct. The fuel pressure should stay steady with the key in the off position. That's why when you crank it, the fuel pressure should go down as the injectors open. If they are not opening, then it will stay solid.
It is likely a stuck injector. The pressure regulator is part of the fuel pump assembly. It should hold pressure, but isn't.
Sounds like if you did all that, changed the oil, good fuel pressure, cleaned the plugs, good noid light, flowing exhaust, good spark with a perfect cam/crank sync, it should start. Even with 100 psi and some with 140, it still should at least run. Remove the 2 front O2 sensors and see if it will start.. going off trying to start with a disabled fuel pump so excess fuel is not an issue here…
When you tried an alternative fuel supply did you dis-able the vehicles fuel supply? I'd be checking fuel quality and trying to start it on propane.Definitely change the oil and filter and put a little oil down the cylinders to restore compression.
Yes, I pulled the FP fuse and introduced starting fluid into the intake and the throttle body.
Do some testing on the quality of the fuel. Compare the fuel with known good fuel.
Drain the fuel tank and start over with fresh gas. Likely the whole problem.
Right on, Geoff Any fuel over a year old essentially turns to kerosene. Drain the oil and drain the gas, start from scratch...
I would of said turpentine, but "toe-MAY-toe, toe-MAH-toe" ;-) Once you verify injector pulse and spark, bad gas becomes number-one most likely.
Smells like turpentine, runs like kerosene...
Not trying to be a smartass David but did you check to make sure the distributor is turning? CKP is the trigger for spark.
CKP and CMP signal checked. I also verified spark at the cylinder, so yes the rotor is turning.
one you have indexed the rotor to #1 cylinder i agree with the last comments. Get yourself a good fuel sample check for water , diesel and alcohol content. if i had it at this point i would change oil, add oil to cylinders disable fuel system get some compression back then put in fresh plugs and try starting it on propane or at least see if it tries to start. Contaminated fuel whether from age…
Game plan for today: I'm going to do a relative compression test synced with an ignition event to ensure the vehicle is close to in-time. I'm also going to change the oil. I'll let everyone know the results.
So based on the advice from one of the brightest minds in the industry I investigated my ignition trigger as this is presumed to be a timing issue more than anything else. The ignition coil is firing on the trailing edge of the crank signal, so that is good. However, my timing is off. I don't know how to fix it. According to a known good CMP/CKP Sync wave form, my CMP shoud be right in between…
David, The timing on this engine is affected by everything: crankshaft timing chain sprocket, timing chain, cam timing chain sprocket, camshaft distributor drive gear, distributor gear, and distributor housing position. The best tool to see how far out you are in this case is going to be pretty old school: the humble timing light. As I said before, that CKP signal just isn't going to mean…
I'm with you... I'm trying to limit how much tear down I do on this crusty old van. If my camshaft gear jumped, wouldn't my CMP signal be off? IOW, instead of falling in between the CKP rises, it would be lined up with it or fall on the wrong cylinder, no? I was told to investigate why the ignition appears to be firing on BDC instead of near TDC. Here's my latest scope reading. Yellow…
I saw it was firing on the bottom of the signal, but I didn't know if you were using current or voltage for RC. Current goes up with the compression stroke, voltage goes down. I didn't pursue it because it's kind of irrelevant in making sure the timing is lined up. Allow me to correct something I asked earlier: that CKP does not read flywheel teeth, it reads notches in the flywheel. The…
Whhaaa Theee Ffuuuuuuuuudge?!?!?!? Let me get this straight... Just so we're on the same page... I have a 60A Amp Clamp around the starter wire. The scope is set to VDC (10V, 1 second). Are you saying I should invert the signal?
No, if you're using amp clamp, you're measuring current. Your signal is fine, and yes, the ignition timing is way off. Another method is just to measure battery voltage while cranking. You can get a very similar signal, but upside down compared to current measurement.
Interestingly, it looks like your spark is 45 degrees off from the nearest compression event. We just can't be 100% sure which cylinder's compression event that is!
So, what you're saying (in my Cathy Newman voice)... Although Cyl 6 is firing, that's arbitrary. We have not idea if that's the number 6 trigger. It's just one of 8. Yes, I'm 45 degress off... So, wouldn't I move to checking the flywheel? Couldn't I have broken the fly wheel and it shifted? The ignition is triggered off the trailing edge of the CKP trigger.
I can't see the flywheel shifting 45 degrees. If you're hell bent on using the scope, find a way to temporarily modify the notch on the flywheel that is in line with the TDC mark on the crank damper. That will give your CKP signal the cylinder reference it doesn't otherwise have. Maybe a piece of ferrous shim stock taped inside the lip? Should stay in place at cranking speeds, and if it's…
David, Forgive me for not reading each and every response. Far too many and I don't have the time. Forgive me also If I say that my generation successfully diagnosed older vehicles like this one with nothing but a scan tool, vacuum gauge, fuel pressure gauge, compression gauge, and timing light. Anyway, here's my take: #1 low compression usually = a badly worn timing chain, maybe a tooth…
These flywheels commonly break and have had multiple Chrysler products break around the crank bolts and lock back up in a different position causing timing to be off any number of degrees. Telltale sign is powdery rust on flex plate when inspection shield is removed.