nilknarf007 Posted March 20, 2020 Author Share Posted March 20, 2020 If I'm reading the 1985 EVTM correctly you're looking for wire 324. It is yellow/light green dashed, and Connector 109 is near the computer module, past where the cable sheath is grounded. Someone else with more 4.9l experience may correct me. But I believe 324 is the SPark OUT circuit (at least from the notes an the end of the engine control section) I found the yellow/light green wire, and followed into the cable sheath, then followed that sheath along it's entire length. There's no place for that SPark OUT plug. Can I just disconntect the plug where the yellow/light green wire terminates? Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 20, 2020 Share Posted March 20, 2020 I found the yellow/light green wire, and followed into the cable sheath, then followed that sheath along it's entire length. There's no place for that SPark OUT plug. Can I just disconntect the plug where the yellow/light green wire terminates? I don't know if you disconnect it or ground it. Does someone know? Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 20, 2020 Share Posted March 20, 2020 I don't know if you disconnect it or ground it. Does someone know? Just disconnect it. Early EEC is all PS, and will run on PIP signal. The connector (not plug) should be nearer the computer, not the distributor. This changed to a SPark OUT jumper plug for '86, if the EVTM is to be believed. Link to comment Share on other sites More sharing options...
nilknarf007 Posted March 21, 2020 Author Share Posted March 21, 2020 Just disconnect it. Early EEC is all PS, and will run on PIP signal. The connector (not plug) should be nearer the computer, not the distributor. This changed to a SPark OUT jumper plug for '86, if the EVTM is to be believed. Thanks for all your help guys. To sum up, I fixed all the vacuum leaks, and that made the idle very smooth. I timed it to 10 degrees, and it ran like a new truck. BUT, the idle was too high and it was hard to get the engine to turn over. I backed the timing back down to 4 degrees, it idles a little lower, but now it really lacks power like in the beginning, and since there's no timing advance happening electronically, I made a decision. I have a non-feedback carb and a new ignition with vacuum advance on the way. Hopefully I will give a full follow-up middle of next week. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 21, 2020 Share Posted March 21, 2020 Thanks for all your help guys. To sum up, I fixed all the vacuum leaks, and that made the idle very smooth. I timed it to 10 degrees, and it ran like a new truck. BUT, the idle was too high and it was hard to get the engine to turn over. I backed the timing back down to 4 degrees, it idles a little lower, but now it really lacks power like in the beginning, and since there's no timing advance happening electronically, I made a decision. I have a non-feedback carb and a new ignition with vacuum advance on the way. Hopefully I will give a full follow-up middle of next week. You aren't able to use the curb idle screw to set it at 600rpm, or whatever a 4.9l calls for? Do you still have the vacuum routing/emissions calibration sticker on the radiator support? If so, could you post a picture? Link to comment Share on other sites More sharing options...
nilknarf007 Posted March 23, 2020 Author Share Posted March 23, 2020 You aren't able to use the curb idle screw to set it at 600rpm, or whatever a 4.9l calls for? Do you still have the vacuum routing/emissions calibration sticker on the radiator support? If so, could you post a picture? I got the new YF carb in today. I was able to get the idle down to 700 rpm. Only took about 30 minutes to change them out. So, my next question will hopefully not cause me too much trouble. On the product description of the carb, it said that the oil channels will be blocked and I need to clean them out before installation. I did a cursory search on the internet and found nothing on the subject. In my inpatience, I installed it anyway. I have a consistant miss up to about 2700 rpm, where it begins to fire on all six. But since I rarely get it up to that rpm with normal driving, I'd like to solve this problem, and my assumption is that it has something to do with the oil channels, although I have no idea what that means. I still had the vacuum sticker, and here's the picture of it. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 23, 2020 Share Posted March 23, 2020 I got the new YF carb in today. I was able to get the idle down to 700 rpm. Only took about 30 minutes to change them out. So, my next question will hopefully not cause me too much trouble. On the product description of the carb, it said that the oil channels will be blocked and I need to clean them out before installation. I did a cursory search on the internet and found nothing on the subject. In my inpatience, I installed it anyway. I have a consistant miss up to about 2700 rpm, where it begins to fire on all six. But since I rarely get it up to that rpm with normal driving, I'd like to solve this problem, and my assumption is that it has something to do with the oil channels, although I have no idea what that means. I still had the vacuum sticker, and here's the picture of it. I can't imagine any oil channels in a YF carb, or the 300-6 intake manifold. There was no other explanation? I have seen Chinese carbs come with a float bowl full of oil that needs rinsed out. Better than corrosion, I guess. Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 23, 2020 Share Posted March 23, 2020 I can't imagine any oil channels in a YF carb, or the 300-6 intake manifold. There was no other explanation? I have seen Chinese carbs come with a float bowl full of oil that needs rinsed out. Better than corrosion, I guess. I agree. Pretty sure no oil channels in a YF. But if there's oil in the bowl that will take some time to wash out. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted March 23, 2020 Share Posted March 23, 2020 I got the new YF carb in today. I was able to get the idle down to 700 rpm. Only took about 30 minutes to change them out. So, my next question will hopefully not cause me too much trouble. On the product description of the carb, it said that the oil channels will be blocked and I need to clean them out before installation. I did a cursory search on the internet and found nothing on the subject. In my inpatience, I installed it anyway. I have a consistant miss up to about 2700 rpm, where it begins to fire on all six. But since I rarely get it up to that rpm with normal driving, I'd like to solve this problem, and my assumption is that it has something to do with the oil channels, although I have no idea what that means. I still had the vacuum sticker, and here's the picture of it. If you can't stall the engine with the idle stop I'm thinking you might/must have a intake leak. It seems unreasonable that a 300 won't chug right along, but as I said I'm not the 300 expert. That would be down to Dave & David Link to comment Share on other sites More sharing options...
1986F150Six Posted March 23, 2020 Share Posted March 23, 2020 If you can't stall the engine with the idle stop I'm thinking you might/must have a intake leak. It seems unreasonable that a 300 won't chug right along, but as I said I'm not the 300 expert. That would be down to Dave & David The continued high idle does indicate a vacuum leak. Try the smoke test, again. 10 degrees BTDC should not cause hard starting. Mine is @ 16-17 degrees BTDC with no starting difficulty. The harmonic balancer ring may have shifted. Using a vacuum gauge, see what is indicated @ idle speed. It should be approaching 20" Hg. And, if you do have a miss, it likely will be seen as a twitch/jerk in the needle of the vacuum gauge. Going to 4 degrees BTDC will definitely cause sluggish performance, especially since with the original distributor, there is no advancing of the timing at higher RPMs. Link to comment Share on other sites More sharing options...
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