Any idea on what to do next?

[Bear0007]

Hey all, I have a 1989 W150 with the 5.2. Sorry for the long post but here’s the whole story:
Bought the truck from a “dealer”, ran fine for a couple months (driving into town a couple times, that’s all). It didn’t have much power so I figured I’d change the plugs, wires, and do an oil change. After this I drove it into town and then wouldn’t start after I came out of the store. Had it towed home, let it sit for a couple days, fired it up and ran fine, drove it around a little, shut it off at the store again, and wouldn’t start again when I came out so had it towed home.
Since those incidents it has barely ran at all, very rough idle and very rich, almost straight gas smell from exhaust.
I’ve replaced almost every sensor in the engine bay, IAT, MAP, throttle position sensor, O2 sensor, catalytic converter, as well as fuel pump, fuel filter, and injectors (I’m sure there’s more but can’t think of it at the moment)
The truck will idle much “better” when I have the intake off, once I put it on it won’t start at all.
CEL codes basically say the battery was disconnected and something about the torque converter.
Any ideas? It has been driving me absolutely nuts

 

[crazykid1994]

Could be a vacuum leak? Doesn’t sound right to me but with the intake off that would theoretically reduce the actual vacuum pressure in the intake manifold but that’s a long shot. I would be taking a noid light to make sure the fuel injectors aren’t being told to stay open as well as double check your firing order. Did you change the cap and rotor? Is your ignition coil getting a constant 12v and not losing power. Guessing that the starter is turning when you try to start. But fuel and spark are your go to for not starting. Also double check your spark plug gap. To far open and you’ll have some rough running issues.

 

[fireflymedic]

Sounds like something not working when heated up. What kind of electronic ignition does it have. If it's one with the old computer box on fire wall finder I would replace it. I would have a spare plug check spark cold and than again when it's hot/won't start. See if spark goes from blue to yellow or not at all.

 

[Bear0007]

I’ve tried to look for a vacuum leak with no luck. There is this one odd rubber hose that’s connected to the throttle body that I have no idea where it goes to. All the other hoses have spots to plug into except one.

I can definitely check the injectors, haven’t thought about that.

I have replaced the cap, rotor, and ignition coil (sorry forgot to mention) and triple checked that the firing order is correct.

I can also double check the ignition coil power and plug gap

 

[Bear0007]

Sounds like something not working when heated up. What kind of electronic ignition does it have. If it's one with the old computer box on fire wall funder I would replace it. I would have a spare plug check spark cold and than again when it's hot/won't start. See if spark goes from blue to yellow or not at all.

It definitely does idle much worse when it sits for a couple minutes, then wants to die out unless I’m on the throttle but even then it barely idles.
Will also add checking spark warm and cold to the list! Haha

 

[Always Late]

Check the fuel pressure regulator for a ruptured diaphragm. Easy way to check the regulator is after running truck for a few minutes, shut engine off and pull vacuum hose off regulator. If vacuum hose is wet with fuel, the diaphragm is ruptured allowing fuel to be pulled by vacuum into the intake, enriching fuel mixture. I don’t know if this is the issue but, is very common issue on the old fuel injection systems. Hope this helps.

 

[Bear0007]

Check the fuel pressure regulator for a ruptured diaphragm. Easy way to check the regulator is after running truck for a few minutes, shut engine off and pull vacuum hose off regulator. If vacuum hose is wet with fuel, the diaphragm is ruptured allowing fuel to be pulled by vacuum into the intake, enriching fuel mixture. I don’t know if this is the issue but, is very common issue on the old fuel injection systems. Hope this helps.

Hmm, that definitely sounds reasonable. If I can get it to run for a few minutes I’ll try that. I do notice that it “backfires” through the throttle body when it stalls

 

[Dinky]

Timing is off or you need a new cap and rotor. Distributor could be bad. When those parts heat up causes issues like that.

 

[Dodge trucker]

nothing in distributor to go bad. other than distributor pick up plate. otherwise just a bare distributor body and shaft that holds the rotor. these had the worst EFI ever used by Chrysler, the TBI system. best thing I ever did for my son's truck (89 Ramcharger) was to retrofit to a 4 barrel carburetor and the regular Mopar electronic ignition. I fought with it on my old 88. same "5.2" (I'll still die calling them what they are, 318 CUBIC INCHES.) also fought it on my son's other truck with this setup (90 W250, 360 CID gas) and a few in my years of turning wrenches. and yes I have had bad caps and rotors bite me in the *** before. most recently on my wife's 01 Durango with the 360 Magnum and my 99 Dakota with the 3.9, both were NAPA Echlin caps and rotors/ and neither lasted 5000 miles before I had to re replace them. I hate redo's.

 

[Bear0007]

nothing in distributor to go bad. other than distributor pick up plate. otherwise just a bare distributor body and shaft that holds the rotor. these had the worst EFI ever used by Chrysler, the TBI system. best thing I ever did for my son's truck (89 Ramcharger) was to retrofit to a 4 barrel carburetor and the regular Mopar electronic ignition. I fought with it on my old 88. same "5.2" (I'll still die calling them what they are, 318 CUBIC INCHES.) also fought it on my son's other truck with this setup (90 W250, 360 CID gas) and a few in my years of turning wrenches. and yes I have had bad caps and rotors bite me in the *** before. most recently on my wife's 01 Durango with the 360 Magnum and my 99 Dakota with the 3.9, both were NAPA Echlin caps and rotors/ and neither lasted 5000 miles before I had to re replace them. I hate redo's.

I was previously debating on switching to a carb but wasn’t sure how involved it would be…

 

[reek]

I was previously debating on switching to a carb but wasn’t sure how involved it would be…

throw a bit more money at it and you could go to a 2 bbl TBI injector Fitech or Holley Sn!per. throwing even more at it, a ready to run distributor would allow you delete all of your oem ignition bits, as long as you don't have smog inspection laws.

 

[jawzs2]

How many miles on it? It's been awhile since i've seen one of these, but weren't they known for the plenum gasket leaking? It also wouldn't hurt to check the timing chain. Take the distributor cap off, turn the crank till the timing mark is on TDC, then turn in the opposite direction while watching the dist rotor, see how far the the crank moves in relation to when the rotor starts to move.

 

[Bear0007]

throw a bit more money at it and you could go to a 2 bbl TBI injector Fitech or Holley Sn!per. throwing even more at it, a ready to run distributor would allow you delete all of your oem ignition bits, as long as you don't have smog inspection laws.

I would love to just throw money at it but unfortunately a lot is Gonna need to go to the body work. Fortunately no emissions inspection where I live so I could get away with that if I did go that route.

How many miles on it? It's been awhile since i've seen one of these, but weren't they known for the plenum gasket leaking? It also wouldn't hurt to check the timing chain. Take the distributor cap off, turn the crank till the timing mark is on TDC, then turn in the opposite direction while watching the dist rotor, see how far the the crank moves in relation to when the rotor starts to move.

Has about 150k miles on it, I spoke with a guy that my neighbor knows who used to work on these all the time, he suggested the plenum gasket too and gave me a quick test for it (can’t remember what it was now) but it ended up actually not being that (at least according to the test). I can check the timing though as well

 

[hoohah52]

Timing is off or you need a new cap and rotor. Distributor could be bad. When those parts heat up causes issues like that.

This^^. The Hall Effect Pick-Up assembly in the distributor gets hot and causes stalling, drivability/ignition timing issues. 15-20 mins after stalling, it'll start right up and run smooth like nothing happened until it stalls or runs rough again. It was a common problem with the late 80's, early 90's EFI motors. Chrysler was already replacing those Hall Effect pick-ups on two and three year old Rams and Ramchargers. I think there was a TSB on this. I would replace it first. Use a distributor cap with brass contacts and brass rotor tip for reliability. I've been using them for years in all my Mopars with zero problems.

Sounds like you already replaced the frame mounted in-line fuel filter. I also recommend inspection or replacement of the fuel strainer/screen mounted on the bottom of the in-tank fuel pump. This gets gunked up over time and will cause drivability issues.

Vacuum leaks. It's a pain in the butt however, a re-inspection of the vacuum lines, specifically the emissions lines and tubes, may help. Those tiny black plastic emission lines, 1/8 - 3/16th's diameter, become brittle from the heat and crack and split. Care required when disconnecting/reconnecting them. I've seen some of the tubes cracked where they are undetectable to the naked eye, hidden inside the connection elbows and ends.

Timing chain. The single roller "quiet" nylon tooth cam sprockets that came factory in most all Chrysler V6-V8's is generally fine until those teeth wear down and ignition timing becomes inconsistent, especially on higher mileage motors. Replace with a double roller 340 timing chain. Set the timing and forget about it! (provided the rest of the ignition system is healthy)

 

[etbrown4]

You are the most recent owner of a 23 year old truck and can't possibly know the history. I'd start with the most basic questions. Have you got a sound engine? Have you checked the compression?

 

[Dusty]

How many miles on it? It's been awhile since i've seen one of these, but weren't they known for the plenum gasket leaking? It also wouldn't hurt to check the timing chain. Take the distributor cap off, turn the crank till the timing mark is on TDC, then turn in the opposite direction while watching the dist rotor, see how far the the crank moves in relation to when the rotor starts to move.

Yes. They developed air leaks at the rear of the intake manifold. He should be able to see this using a vacuum gauge.

Your other comment is right on, too (Timing chain), especially at that mileage. The plastic on the silent cam gear would start to come off.

Regards,
Dusty
2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Build date: 03 June 2018. Now at: 065595 miles.

 

[1970Pelle]

Start with your basic trouble shooting test first. The truck drove into where it stopped running. So really nothing changed that has to be unbolted and moved.
You need Spark, Fuel, and Compression to run correct? So I would check to see if you have those three things before ever spending a dime.
Get your DVOM or TEST light(which I hate) but turn the Key to on/run position. Check for Battery voltage at battery. Then Battery voltage at Coil + post. With test light or DVOM hooked up to coil + post. Have someone turn Key to start position and see if there is Battery voltage at the + post on the coil and does it flash when engine is cranking??
Voltage ? Flashing ?

If no Voltage there find out way most likely your No start issue.

Next Test for Fuel pressure. Just crank engine over and see if injector sprays any fuel. Does it? If so Check Fuel Pressue with a gauge. What is the pressure?

And you should be able to tell if an engine does or doesn't have compression. If not check compression on a couple of holes on each side. Has tp be over 80 psi to fire a cylinder. So anything lower than 80 fails. Anything under a hundred is suspect.

So stay with basic's before going to far. Alot of times you will move or hide your No start condition by swaping parts. Plus parts changing is no fixing anything.
Mechanic's are not parts changer's. Learn to fix your Dodge. Its not hard and its very rewarding when your done.

Ken

 

[Dodge trucker]

89 did not yet have plenum gasket. This was on the Magnum series of these engines/ which in 89, was still 3 years from hitting the market.