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Discussion Starter #1
My Omni seems to be acting up lately. It is an 87 with the Holley 6520, yes I know those carburetors suck but I live in CA where emissions are strict so im stuck with it. The issue that seems to be happening is sometimes It will work great then after I drive it later on it will get me down the street and start to die and pushing in the gas pedal will do nothing until it dies. I pull over and crank it and it take a while but starts then dies. Start it again and apply some gas and as soon as I let off it dies. Sometimes instantly. After about a dozen tries it finally runs. I bought a reman Carb last year and since rebuilt it again in case it was something with it. It has a new feedback solenoid, float is adjusted to 1/2 and 1 7/8 like the factory service manual calls for. Im not sure what is causing this but wondered if anyone has any suggestions? The next thing I was going to change is the EGR and the O2 sensor. My future plans might be to run a Weber and swap it with the 6520 when it comes time to smog ever 2 years. But as of now i would like to get this thing running correctly.
 

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Have you verified that the fuel pump is operating correctly?
A new fuel filter is installed?
No leaks in the vacuum system, vacuum hoses ok?
Choke operating correctly?
Yes, check your O2 sensor. Sine the 6520 is a feedback carb the O2 sensor maybe affecting it...
 

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Discussion Starter #3
Have not checked the fuel pump yet, Fuel filter has been changed, No vac leak, all plastic lines have been changed to new vac hose. Choke operates correctly when cold but this seems to happen when its warm and had already been running for a while.
 

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Disconnect the fuel line at the carb, stick it in a glass jar, crank and verify that ample fuel is coming out (no smoking now LOL).
If you are going to change out the O2 sensor then apply some penetrating oil, lightly tap the sensor with a wrench and let it sit overnight. I bet that it's rusted on there good but hopefully not...
 

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All is good advise, however...
Drive the car until it stalls, before trying to restart take a look into the carb and open/close the throttle a few times, do you see any fuel spraying from the accelerator pump port.
If no then you can start looking to see where your lack of fuel issue is coming from.
Remember, the mechanical fuel pump works on vacuum and pressure.
When testing the pump you need to check for vacuum on the inlet side and pressure (3 - 7 PSI) on the outlet side with both fuel lines disconnected.

Be sure that none of your rubber lines are restricted or collapsed.
Be sure you fuel cap is not the issue, had that happen on my 72 Duster at the track and the car slowed down drastically each round, the cap has to allow air into the tank as fuel is used, if it does not it will create a vacuum in the tank and you will lose fuel pressure/volume.
 

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Discussion Starter #6
Thank you both for the ideas.I will try all of this information and see if this helps the problem. I have not run into the issue today while driving, it seems to do it when it wants. All the fuel lines look good and have been changed not to long ago. I will get a new gas cap as it might be the original. Carb was reinspected and float level is to spec and at this point I dont believe it is carb related. I know the 6520's suck but this thing is practically new. Setting the idle on these carbs is a bit annoying using the kicker solenoid.
 

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Have an idea: What was the ambient temperature when it ran fine? What was it when the car would stall/die?
Vapor lock might be a possibility???
 

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Discussion Starter #8
I dove it on Tuesday in the morning when it was in the 60's and stopped at my moms for a bit by the time I left it was maybe close to 70 here in CA. The week before I drove it in the afternoon and it ran fine then went to the casino for dinner and it did this when it was cooler out. How can I check for vapor lock? This idea crossed my mind as well
 

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Usually when it's hot the gas turns into vapor in the fuel lines. At those temps that you mentioned vapor lock shouldn't be an issue.

Check the fuel pump as NAJ recommended. He's the resident expert here and knows best!
 

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Discussion Starter #10
So it happened again today, I plan to test fuel pump pressure and Vac this week and bought the gauge set mentioned by NAJ. John you mentioned if the choke was operating correctly and I dont think it is. The gap is not correct on the choke plate and it seems the only time the coke and fast idle seem to work is when I start it the next day for the first time. Today I went over for a superbowl party and the omni sat for a few hours. Buy the time I left its pretty chilly out and you would think it would Choke and fast idle but it does not. It started and idled around 1000 RPM for 15 secs and fell flat. Started it up again and same thing like I mentioned before that happened the other day.

On earlier start ups today, the car will start and idle high around 1500-1600 RPM and stay like that for a little over a min then Something (ecu or kicker) kicks the idle down to normal and this is after the fast idle is kicked off. If you shut it off and start it again it will idle high again until it kicks down on its own. My omni is a Auto with no AC that uses a Solenoid kicker for idle. Always wondered if the kicker is operating correctly? Is there a part number for a replacement as I cant seem to find one.

Im going to also adjust the fast idle and choke by the procedure in the factory manual because I dont think its working correctly. Also I need to adjust the choke plate to spec. The procedure for the fast idle states to disconnect the feedback test connector located on the left fender shield. Not sure if Im disconnecting the right one but is this the connector that has 5 pins to the carb? of the connector near the coil and vacuum distribution block?
 

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When the car stalled were you able to go underhood before cranking the engine and look in the carb throat while opening/closing the throttle to see if a fuel spray was present?
 

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Discussion Starter #12
No :(
It was dark out this time at 11 pm and I did not have my flashlight with me. Going to have to hope it does it during daylight next time. If it does this again should I pull of the airbox and move the throttle shaft to see if the Accelerator pump is pushing gas through the throat?
 

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Yes, if you can, safety first...
That will tell you if the issue is fuel related, usually a carburated car with a stalling issue due to a lack of fuel will not stall immediately since the fuel bowl has to run dry before the engine will completely stop running and then it will take a few cranks of the engine to fill the bowl again before the engine will restart.
 

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Discussion Starter #14
Ok I will try this if it happens again. Its just frustrating because the car will run great most of the day and it was started maybe 5-6 times with no issue and its a guessing game if its going to do it again. I know it cant be the carb or float level since I have checked it so many times and it all looks correct. It was a reaman and I even rebuilt it again to make sure so I did put a new accel pump on it. But that does not rule out something before the carb. I did buy a new gas cap but this does not seem to make a difference. I also had the concern of the idle kicker, what if it is mis-set and trying to make the car idle high on a cold start trying and stalling it out?

I did have another question for you NAJ, Once I get this running and the issue solved. If I wanted to run a 5220 non feedback carb, would most of the Vac lines match up to it and would I have to run a different spark controller to match the carb? I figure I could smog mine with the 6520 in CA and then swap to the 5220 for 2 years until the next smog. Only takes 10min for me to pull the carb off. Just a thought and a little cheaper than a weber.
 

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Discussion Starter #15
So today I was trying to figure out how to hook up that gauge I bough from harbor freight. I decided to change the fuel pump out with a new one. I also installed a new O2 Sensor as well as a new EGR valve. When it started it ran fine for a bit. I went to check timing and Set the idle per service manual procedure and it began to run bad would not idle correctly sounded bad and was letting out black smoke. After messing with the idle solenoid and even using the stop screw to force a set idle I gave up messing with this thing. I gave it an hour and started it back up. idled ok so I took it down a straight away, when you brake to a stop idle drops to 500 RPM and runs ruff and slowly brings it back to normal idle (see video). I took the fuel line off the carb and had my brother crank it to see how good fuel is flowing from what I can see it looks ok. (see other video).


 

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I feel you on intermittent issues being a PITA, you cannot diagnose the issue unless it is acting up,

When did the Black Smoke start, is that a new symptom?
If so it is possible a piece of dirt got into the carb and is holding the needle open from the seat and allowing the fuel bowl to over fill or there is a problem with the Evap System.
98% of the time a new problem arises after a repair or diagnostics it is related to something that was done during that repair.

After giving it some thought I was going to mention that an intermittent issue with a mechanical fuel pump is unlikely, mechanical items are usually either good or bad.
To connect your vacuum/fuel pressure gauge to your pump you need a brass vacuum fitting that will screw into the pump where the fuel lines enter and exit, you then connect the hose from your gauge to the fitting.
When testing the inlet (that is the suction side) you should have a vacuum reading when cranking the engine, the outlet side will read pressure , 3-5 PSI.
You should be able to get the fitting you need at Lowes or Home Depot.

What I was going to mention was that there could be debris in your fuel tank causing your intermittent issue.
Way back we had a Ford Van doing what your car was/is doing, would just stop running while driving or idling and it turned out to be a dead Bee in the tank, it would get sucked up to sock in the tank, restrict fuel flow, when the engine stopped running all vacuum from the mechanical pump was gone, the debris would fall off until next time.
If that is the case the fuel bowl will be empty when you check.

I remember all types of issues on these cars back in the 80's, one issue with running poorly and people blaming the carb was the wrong PCV Valve.
Chrysler used 4 different PCV Valves on their cars in the 80's, 2.2L Carburated, Low Pressure TBI, High Pressure TBI and 4 Cyl Turbo/Slant 6/V-8.
The 4 PCV Valves were color coded so you knew which was which.
The wrong PCV valve changes air flow under the throttle plate usually resulting in a lower RPM, people then adjust the idle which opens the throttle plate more, exposing the main metering jets to engine vacuum but not enough vacuum so fuel drips from the main metering jets and then they say" Carbs No Good", they replace it and it still does the same thing and they say "these carbs are junk".
Be sure you have the correct PCV Valve and the PCV system is functioning properly.
The Chrysler Part # for the PCV Valve for your vehicle is 4343581.


 

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Discussion Starter #17
Wow NAJ you are a world of help as far as ideas.

My bother mentioned it was blowing black smoke when it was having issues when it wouldn't even idle after I was trying to tweak the carb. The car would idle below 500 rpm and only stay alive if you throttles it and even at that point it was choppy. Thats when I gave up and tried again an hour later. It started and idled but then did what I showed in the video.

As far as the fuel pump I thought that as well and my dad said the same thing, they either work or dont. But I threw a new one on anyway since its not that expensive and hard to change.

So if this happens again where it stops and I go under the hood to look for a fuel squirt and it does not then the bowl could be empty due to a blockage in the tank? I might let the tank empty and drop it and clean it out and replace the sock while im there. wont hurt and ill at least know its been changed.

I did change the PCV valve a few weeks back with one that they had at oreilly's seems to be the same looking one that my dodge neon uses. But like you mentioned there are 4 types which id never guess made any difference. I will look for the correct one with the part number you provided.

I don't think it has to do with the new EGR or O2 sensor I just installed. The valve I got was Standard Motor Products Part # EGV133 and I used the correct spacer for the correct factory part # original. The O2 sensor is a Denso 234-1002. I wanted to get the NTK but that one seems hare to get in stock.
 

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Is this car your daily driver?

It has been 30 years since I have actually worked on a 2.2L carburated car but the knowledge is still in there somewhere and little by little it floats to the surface.

You can try tapping on the fuel bowl with the engine running to see if it will dislodge any dirt/debris that may be present.

Just some stories so you do not think you are alone...
We used to get cars that the customer said would stall and not restart after long drives and we had to duplicate the conditions before we could diagnose, it sounded like a fuel pump issue (fuel injected) so we would connect a fuel pressure gauge, start the car and let it run, we would go out every hour and check the gauge and sometimes it would take 7-8 hours before the car stalled and we saw the loss of fuel pressure.

When I was a diagnostic specialist for Goodyear in the 80's a customer with a Chevy Celebrity complained that on damp mornings the car would not start but as the sun came out the car would start and ran fine with no issues and it did not do it everyday.
I went over the car to check all of the basics, tried to duplicate morning moisture and could not duplicate the problem.
I said " do you want this fixed, then you will have to leave the car with me until it happens, they agreed.
Every morning first thing I went out and started that car, if it started I was done until the next morning.
Finally two weeks later the car would not start, opened the hood and had someone crank the engine and there it was...
The ignition coil (brick style) was arcing to the engine block, the moisture had to be just right for that to be an easier path to ground than through the wires.
Replaced the coil and they lived happily ever after.

The moral of all of this is...
Hang in there, do not get discouraged and do not throw parts at the problem since you may create other problems doing that.
One thing about intermittent problems, they always get worse and that makes the problem easier to find.

Just an FYI that I still remember from training years ago...
On a feedback carburetor the feedback system only has 20% control of the fuel system, the carburetor itself by design has 80% control so your new O2 sensor does not have the ability/authority to make you run black rich.
 

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Discussion Starter #19
I daily drive it in the winter and take it to car shows as it is a no AC car and it gets too hot to drive it in the summer here in CA and I use one of my other cars with AC then lol. Ive owned it for 2 years and it now has 50,500 original miles. I wanted this car as I like the box looking 80s cars and this was Chrysler's first front wheel drive car which then progressed to the Shadow/Sundance then to the Dodge neon which I have been into for years (own a 97 and an 03 RT)

I have heard stories from a tool distributor that I do part time work with, I'm 27 and he is 54. He worked on these things in the 80s and told me they where nightmares to work on. He also told me the same goes for the 86 Fifth Ave my wife drives. He said the feedback carbs were problematic. But I did not want to listen and bought the car. When I first had it I believe the carb had a worn throttle shaft due to a vacuum leack which he mentioned was common with these Holley carbs. So this is the reason I had purchased the reman last year. It ran great for a while but it always had a problem starting. You would crank it and it would take a while to fire, even if you shut it of and tried again right after. So then I figured the float level might not be right. I adjusted it an it seemed to help but then it went back to doing what it was before. I went and bought a brass float then it did the thing where it would start and die and not start until a dozen tries later like I first mentioned. Thought it was the float. went back to the original one. No change. Only other thing I have done to the car is replace all the hard vacuum lines with vacuum hose as most break just looking at them.

I dont want to give up on the car I just want to understand and learn why and what might cause this. Factory service manual troubleshooting does not seem to help, You have learn this from year of working on these things to understand and what to look for like you have. Its a learning curve in the world of fuel injection.

I dont think it will help but I have a Miller C-4805 scanner, Not sure how to actually use it but would there be any codes?
 

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Some more things from the top of my head to check:

Did you check the timing & adjust if necessary?
The carb & isolator are on tight to the intake manifold?
There is no warpage between the top air horn & base of the carb? This occurs from tightening the wingnuts too tight on top of the air filter assembly.
Intake manifold on tight, no issues with gasket?

Hang in there with it. Frustrating but once you figure it out you'll have a wealth of information under your belt!
 
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