1986 Dodge Ram Van 5.9 V8 on a road trip. For the past few months its been having problems idling, very often i would have to give it gas at stoplights to keep it running, still ran great on the freeway or any time it was moving.
Just this week though its started struggling under load. Several times while on the highway would start to feel the power give out and it would slow down and not be able to go above 35 mph. But if i shifted into Neutral it could rev healthily. I pulled over a few times but couldnt find anything obvious and upon starting it back up it would be back to full power. It gradually degraded and got worse over the course of a few days, happening more frequently. It got to the point where, while driving it would all of a sudden just have power completely drop off and slow way down. But i just kept driving and 5 minutes later i would feel a kick and all the power would come back. I didn't change anything in the way i was driving it seemed very arbitrary and this happened multiple times. Sometimes when its hot it would have problems, sometimes when it was cold. How much gas i gave didnt change anything. I had problems at 0ft elevation and at 7000ft. It doesn't matter what gear im in. I cant find the conditions to recreate the problem, sometimes it works sometimes it doesn't, its been maddening. 2 nights ago i was driving to a campsite it had problems for maybe 5 minutes but again it just kicked and switched "modes" and got full power for the rest of the drive. I drove 4 hours with no problems, on the highway and on dirt roads to get to my campsite. But upon the morning's first start it was just not running the same barely chugging 5 miles mph and would not idle at all. I managed to limp it to the trailhead where i spent that whole day and then subsequently back to the campsite. This morning ive been trying to actually deal with the problem.
Long explanation but now we are where i am now. It will no longer idle at all or drive in gear at more than 5 miles an hour. I cant even hold it an rpm, it starts ok, ill hold it at half throttle and it will go for maybe 10 seconds and then chug out and shut off. I took the house off and ran it with no filter to try see what was goin on and i got some backfire pops out of the carb under load. The key is though when i took off the air filter cover i found a decent amount of oil in the intake and the air filter. I went to look at the pcv valve and im pretty sure its bunk. So what i think happened is the pcv has just been sending oil into the intake and clogged the heck out of the carb and now its just running all wrong.
Here is the carb
So my question is what do i do now? Im stuck in Mammoth Lakes 10 miles into a dirt road and 2000 miles from home. My buddy whose with me in his van took me to town to the only auto parts shop (napa). Getting a new carb would take 2 weeks and cost 600$ and they dont have any kits to even order. So im kinda outta luck there. i ordered the new pcv and itll arrive tomorrow. Im going to take apart the carb tonight and try to just clean everything with carb cleaner, but i dont know much of anything about this quadrajet, so just any information will be helpful
im just looking for ideas and ill update this thread if the cleaning works.
what to do? Anything helps, thanks
I'd put a fuel pump on it. Napa likely has one in stock and mechanical fuel pumps are cheap.
Fouled plugs and E36 M3ty ign box
I dont think its the carb and wouldn't take it apart if I wasnt in a work shop and didn't have a complete grasp on what to do.
The very A-B mode of driving points more to an electrical/ignition issue than a carb issue, especially if it ran fine very recently.
You can see if it runs OK on starting fluid when its about to stall, that will help ID carburation or ignition issue.
I would do the following:
- With the engine running and in a dark-enough area, spray the spark plug wires with water and look for arcing. You should hear and see arcing if the plug wires are degraded.
- Replace the plugs, plug wires, distributor cap, and rotor anyway because it probably needs it and they are cheap.
- Check all the wiring to the distributor and make sure it is clean, connected, and not damaged.
- If that doesnt solve it, replace your ignition control module
- Same story, check all the wiring.
- Take your propane torch, open the gas but do not light the torch. Walk the torch head around all the vacuum lines. If the RPMs increase, inspect that area for a leaking vacuum line and fix it.
- Consider replacing the fuel filter and fuel pump but only if fixing the ignition stuff doesnt solve your issue.
I WOULD NOT disassemble the carburetor unless you know exactly what you are doing, have a clean indoor workplace, have a gasket kit on hand, or have exhausted all other options.
Quadrajets have a little fuel filter in the body of the carb. Get a 5/8 flare nut wrench and a 1" standard wrench. Undo the fuel line into the carb, screw the fitting out of the carb and replace the filter. There is a short one and a long one. You need the long one.
DO NOT twist the fuel line off because the fitting started to screw out of the carb before the double flare fitting broke loose.
DO NOT berkeley the threads up in the carb body by winding the fitting in cross threaded.
I also suspect inadequate ignition. Do you have a regular distributor or Lean Burn?
I'd also go with ignition. What's the saying? 90% of carburetor problems are electrical?
I'll throw out another idea, so you have more to check.
Clogged cat? If you can get it running, see if the cat is glowing red. The fact that it ran fine intermittently says it probably isn't this, but, I've had 80s/90s cars where the cat disintegrated and caused similar problems.
Troubleshooting is as easy as unbolting it.
The idling issue might be carb related, but the rest makes me think either ignition, or poor fuel supply to the carb.
Verify fuel is coming out of the fuel lines, and I would verify the condition of all the spark plugs (very likely fouled) and that they are all receiving spark above idle.
The parts cannon order to me would be as follows once you have established that it is getting some level of fuel and and spark (also make sure it hasn't burned all its own oil):
Plugs if they're all fouled from oil, verify that something isn't clogging the fuel tank pickup by taking the line off there and making sure fuel comes out, fuel filter, clean the contacts in the distributor cap with some steel wool or a brillo pad, new coil, bypass the ballast resistor if it has one. At that point if it still doesn't run it may be worth looking at the distributor more closely or a quick and dirty carb rebuild.
Noddaz
PowerDork
6/15/23 9:16 p.m.
Before you buy anything, check the EGR valve. If it is stuck open it could cause these sorts of problems.
In reply to 93gsxturbo :
I took your advice, didn't take apart the carb. Replaced plugs, plug wires, distributor cap and ignition coil. It definitely needed it, I'm pretty sure they were original.
Buuut the van is still struggling. Although it is more consistent now. No longer chugs to a complete stop. I was able to drive it into town but it was limping. Max speed is 35 mph and uphill like 25. It just has no power, in neutral it will rev kind of but I'm still getting pops out of the carb.
I didn't find any vacuum leaks. And it should be noted that it has a brand new fuel filter, lines, and pump as of 2 months ago. Also I'm at 8000ft elevation so that's something to consider also. Those are the details, I'm now slightly mobile, but still stuck
Any other ideas?
manladypig said:
In reply to 93gsxturbo :
I took your advice, didn't take apart the carb. Replaced plugs, plug wires, distributor cap and ignition coil. It definitely needed it, I'm pretty sure they were original.
Buuut the van is still struggling. Although it is more consistent now. No longer chugs to a complete stop. I was able to drive it into town but it was limping. Max speed is 35 mph and uphill like 25. It just has no power, in neutral it will rev kind of but I'm still getting pops out of the carb.
I didn't find any vacuum leaks. And it should be noted that it has a brand new fuel filter, lines, and pump as of 2 months ago. Also I'm at 8000ft elevation so that's something to consider also. Those are the details, I'm now slightly mobile, but still stuck
Any other ideas?
That checks a lot off my list, ballast resistor (idk if that's a thing on your van) could fail causing low voltage to the coil but I don't think that'd be cause for a backfire. Perhaps it is time for a basic carb rebuild after all.
Put a vacuum gauge on it. You can find a picture of the available causes based on your findings. Normal reading would be above 20" of vacuum and a steady needle.
No Time
UltraDork
6/16/23 8:10 a.m.
A couple easy checks:
Get underneath and bang on the cat to see if it rattles. Also do the same thing with the muffler. A clogged cat can cause the symptoms your seeing.
Check the fuel cap to see if it's not venting and causing a vacuum to form and getting to a point that the fuel pump can't supply enough fuel. You could test drive with the cap off to see if it changes anything.
Does your fuel flow seem sufficient? Is the accelerator pump working?
Are your mechanical advance weights stuck?
Shadeux said:
Are your mechanical advance weights stuck?
Also has the timing been verified to be correct?
Popping out of the carb points to a timing issue to me.
It would be worth validating the distributor has not moved. It could also be possible that the timing chain has worn to the point of jumping time.
Since you made it to town, thats good.
Next steps I would take is to validate that the cam to crank timing and distributor timing is correct.
