Duraspark complete, truck dies after a few minutes

jaredm_k · Sep 29, 2015

Hey guys - I'm hoping that kimcrwbr1 sees my post as I have been reading all his posts about this and I am sure he can help me.

I have a 1985 Bronco II....just completed the duraspark. Removed all the computer wiring, installed the felpro gasket, have #42 jets in my motorcraft 2150, and I am using the stock TFI coil.

The bronco starts up and it runs for a few minutes - it ran long enough that I was able to get the timing set to 10 degrees. It runs/idles smooth while it is running but then after a few minutes it shuts off and is really hard to start. It will roll a couple times and then blow a little smoke out of the top of the carb. I can't keep it running long enough to properly tune the carb. I currently have the idle air at the 1 and a half turns out.

I suspect I have a carb issue - but I am unsure how to proceed in my troubleshooting and would welcome any help I can get! I know I am close, can't wait to have my rig back on the road again.

Thanks for taking the time to read.

Jared in Ohio

kbeers93 · Sep 30, 2015

I have converted many cars the only problem i come across is the white power wire, it changes the dwell time. If you have it hooked up disconnect it. And see if that fixes your problem. My buddy lit his arm on fire because of that wire making his car pop throw the carb.

Sent from my LGL31L using Tapatalk

kimcrwbr1 · Oct 1, 2015

Turn the idle air jets out 3 1/2 turns and see if it will keep running. After the engine is up to temp adjust the needles for the highest possible rpms or vacuum pressure. Is the timing at exactly 10 degrees BTDC with the vacuum disconnected and plugged? There is a vacuum port on the back side of the EGR spacer under the carb Is that port plugged, kinna hard to see it points straight at the firewall.

jaredm_k · Oct 5, 2015

I will try turning the jets idle air jets out further. I have that port on the back of the egr plugged. If I can keep it running by turning the needles out I will double-check that I have it at exactly 10 degrees. (Side note this is my first time using a timing gun, so I just set the gun at 10 degrees and then twisted the distributor until the timing marks were lining up). I will double check my vacuum lines, turn the needles out further, and double check the timing and report back. If I keep it running I do have a vacuum gauge to further dial in the carb. Thanks for taking the time to respond! I greatly appreciate it.

Jared

jaredm_k · Oct 12, 2015

OK - Over the weekend, I checked the timing....and I am right on at 10 degrees. The vacuum port on the back of the EGR that faces the firewall is plugged. I twisted the idle air screws out to 3 1/2 turns and I still got the same result. It may have ran a little longer, but that could be in my head as I didn't have a stopwatch or anything. When I go to start it when it dies...it tries to start. And if I hold the pedal down so the throttle is probably about half open. It will run. As soon as I let off the pedal...it will die. Even if I try pumping it to shoot some more fuel in there. It seems it is getting gas and spark, so the fact that I have to hold the throttle open makes me think it needs more air.

I took the top off the carb and the bowl is full of fuel....so it seems my float position and fuel pressure are fine. Let me know if you guys have any other thoughts and as always....thank you!

kimcrwbr1 · Oct 12, 2015

Is the choke fully closed when you push the pedal half way down? As soon as it starts the choke should pull open about 1/4 inch. If not stick a screwdriver in the choke to hold it slightly open and see if it idles.

kimcrwbr1 · Oct 12, 2015

With the top off of the carb the wet float adjustment is 3/4 inch to the center of the fuel in the bowl. Are you using ported vacuum on the carb or manifold vacuum at the tree for the vacuum advance?

kimcrwbr1 · Oct 13, 2015

Did you block off the egr valve?
http://www.ebay.com/itm/87-93-Ford-Mustang-5-0-302-EGR-Delete-Block-Off-Plate-WITH-Gasket-SS-/321654111719?hash=item4ae4143de7&vxp=mtr
Not sure if it fits but you get the idea.

kimcrwbr1 · Oct 13, 2015

The 302 and the 2.8 use the same egr gasket

jaredm_k · Oct 13, 2015

Thanks for responding! The choke is actually not hooked up yet. I close it manually to start it, but I kick it off basically as soon as it starts running. It idles fine like that for almost 5 minutes. It is not too cold here yet but eventually I am going to put a manual choke on it.

I have the EGR blocked off with a very thin plate that I made myself. I will take it off to make sure it is holding OK, and if it isn't I will buy something like that link you sent me.

The vacuum advance is currently disconnected, because I was timing it. I can hook it back up, but I have been running it to the carb, not to the vacuum tree on the manifold. I believe that is correct?

Are you thinking that it is vacuum related? I wonder if I could do a homemade smoke test to find the leaks....I've seen guys do that before but never have done it myself.

fastpakr · Oct 13, 2015

Are you sure the ignition system is working properly after it warms up?

jaredm_k · Oct 13, 2015

I am not sure that it is working properly once warm. Only thing that makes me think it is a fuel/air issue rather than ignition is that if i hold the pedal halway to the floor it will start and run as if to say that it is getting spark.....

What is the best way to test the ignition system? I'm open to any and all troubleshooting suggestions, I really appreciate everyone's help!

kimcrwbr1 · Oct 14, 2015

You can use a length of vacuum tubing to look for vacuum leaks. Put one end in your ear and search around with the other end. The hissing gets louder the closer you get. Put it in the carb to see what your listening for. You can isolate exhaust leaks that way also. Brake booster, PCV make sure the hoses are tight and still soft all the fittings on the tree are plugged. You can hook the vacuum advance to the tree and see if it stays running until you find the vacuum leak.

jaredm_k · Oct 19, 2015

Sorry it has taken me a while, I did get a few minutes to mess with the bronco tonight. Here is what I discovered. My EGR is completely blocked off, I have a plate on there and it is not leaking. I was in the middle of checking for other vacuum leaks with a piece of hose (that is a great trick by the way) when the thing shut off again. However, I noticed the front drivers side of the carb was wet, like gas was seeping from somewhere. It is parked on a slight hill, with the drivers side further down the hill than the passenger. So now I am thinking that gas is seeping somewhere from the carb and getting into the intake and kind of flooding it. Would that make sense since if I hold the throttle half-way open and allow more air in, it will run? I feel like I am heading down the road of buying a new carburetor. That is the latest and greatest, if you have any thoughts on the seeping fuel, let me know. I appreciate your time!

kimcrwbr1 · Oct 20, 2015

Did you check the wet float setting? On level ground take the top off of the carb and measure from the top of the float bowl to the center of the fuel in the bowl. It must be 3/4 inch. Is fuel dripping from the accelerator pump cover? Another possibility is your power valve. Pull the short hose to the intake manifold the bottom center of the carb, if there is fuel in the hose the power valve or gasket is leaking.

Duraspark complete, truck dies after a few minutes

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