nilknarf007 Posted March 19, 2020 Share Posted March 19, 2020 Hello everyone! Rob here, got this beauty for a steal. A tree fell on it and really damaged the bed, so the 92 year old original owner decided to sell it. 120k original miles, and previous owner says he rebuilt the engine at 110k. Engine runs great, and doesn't use oil. I put a wooden bed on it, and some new rims and tires. But - there always is a but - this truck has a lack of power. Even at highway speeds (2400 rpm) it will lose significant speed on anything more than the slightest grade, and that was before the bigger tires. I'm fairly mechanically competent, but carbs have always been a mystery to me. On this YFA single barrel, I've checked for vacuum leaks, adjusted it as best I could, and even ran some Seafoam through it, and nothing has helped. I know that if I try a carb rebuild it will be disaster (I know my limitations). I've also checked the timing, and I think it's spot on. All of the smog stuff has been taken off, and there are a ton of plugged vacuum lines. I'm not really interested in upgrading the carb, such as going to a 2 or 4 barrel, but does anyone think that a newly rebuilt YFA will be an improvement? Link to comment Share on other sites More sharing options...
grumpin Posted March 19, 2020 Share Posted March 19, 2020 Welcome! I usually check for vacuum leaks first. Link to comment Share on other sites More sharing options...
Sac79 Posted March 19, 2020 Share Posted March 19, 2020 Welcome. I'm not an expert, barely competent in fact, but when I started tinkering with my truck, I was told I had two options, replace all the systems to original spec or delete the computer. From what I understand, the computer requires everything to be just right before giving you full power. So all the PO achieved by removing stuff is reducing power. To remove the EEC unit you can either replace the ignition with a Duraspark system or HEI distributor. I'm sure someone else will chime in with more details... Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 19, 2020 Share Posted March 19, 2020 Welcome. I'm not an expert, barely competent in fact, but when I started tinkering with my truck, I was told I had two options, replace all the systems to original spec or delete the computer. From what I understand, the computer requires everything to be just right before giving you full power. So all the PO achieved by removing stuff is reducing power. To remove the EEC unit you can either replace the ignition with a Duraspark system or HEI distributor. I'm sure someone else will chime in with more details... Yes, welcome! Glad you joined. Where's home? We have a member's map I'd be happy to put you if I had a city and state. On the lack of power, Rob has a good point. If you have a computer it will be controlling the timing. But if the emissions stuff has been removed the computer will have its knickers in a twist and won't advance the timing and you won't have any power. So put your timing light on and see if the timing changes as you rev the engine. It should go up with R's, starting around 1500 to 2000 RPM. If it doesn't then timing is locked by the computer and you'll either need to put everything back, or better yet put a DS-II ignition on it. It'll make a huge difference. Link to comment Share on other sites More sharing options...
1986F150Six Posted March 19, 2020 Share Posted March 19, 2020 Yes, welcome! Glad you joined. Where's home? We have a member's map I'd be happy to put you if I had a city and state. On the lack of power, Rob has a good point. If you have a computer it will be controlling the timing. But if the emissions stuff has been removed the computer will have its knickers in a twist and won't advance the timing and you won't have any power. So put your timing light on and see if the timing changes as you rev the engine. It should go up with R's, starting around 1500 to 2000 RPM. If it doesn't then timing is locked by the computer and you'll either need to put everything back, or better yet put a DS-II ignition on it. It'll make a huge difference. Welcome, Rob! How is the gas mileage? David Link to comment Share on other sites More sharing options...
nilknarf007 Posted March 19, 2020 Author Share Posted March 19, 2020 Welcome, Rob! How is the gas mileage? David I get a solid 11 mpg no matter how I drive it. Link to comment Share on other sites More sharing options...
nilknarf007 Posted March 19, 2020 Author Share Posted March 19, 2020 Yes, welcome! Glad you joined. Where's home? We have a member's map I'd be happy to put you if I had a city and state. On the lack of power, Rob has a good point. If you have a computer it will be controlling the timing. But if the emissions stuff has been removed the computer will have its knickers in a twist and won't advance the timing and you won't have any power. So put your timing light on and see if the timing changes as you rev the engine. It should go up with R's, starting around 1500 to 2000 RPM. If it doesn't then timing is locked by the computer and you'll either need to put everything back, or better yet put a DS-II ignition on it. It'll make a huge difference. I'm in Marietta, GA, and glad to be a part of the forum. I'm going to check the timing within the hour and report back. About the ignition, I have electronic ignition already (no points). Does that mean that the DS-11 is all I need to bypass the computer issues? Link to comment Share on other sites More sharing options...
1986F150Six Posted March 19, 2020 Share Posted March 19, 2020 I'm in Marietta, GA, and glad to be a part of the forum. I'm going to check the timing within the hour and report back. About the ignition, I have electronic ignition already (no points). Does that mean that the DS-11 is all I need to bypass the computer issues? Rob, I used to work in Marietta and lived in Powder Springs. Small world! The carburetion and ignition system for the 4.9L engine was the same from 1984-1986. When I first bought my 1986, it returned 9-11 mpg, the first two tanks. The computer was not receiving its needed input due to faulty sensors and leaking vacuum lines. The engine ran poorly and bucked on deceleration. If I remember correctly, you no longer have to pass emissions testing [greater than 25 years old]. Is that correct? If so, and you have a little time, you might gain some information from my quest to improve performance and fuel efficiency. https://www.ford-trucks.com/forums/1325963-gas-mileage-recipe-4-9l-300-a.html Link to comment Share on other sites More sharing options...
Gary Lewis Posted March 19, 2020 Share Posted March 19, 2020 I'm in Marietta, GA, and glad to be a part of the forum. I'm going to check the timing within the hour and report back. About the ignition, I have electronic ignition already (no points). Does that mean that the DS-11 is all I need to bypass the computer issues? Rob - You are on the map. As for the ignition, all Bullnose trucks had electronic ignition. But some trucks had computer-controlled electronic ignition. And if you did much to the system the computer put the timing into limp-home mode, meaning it locked the timing to the initial advance. I once bought an '82 351W that set on a used car lot for years because someone did something that made the computer mad and the MPG and HP went away. But by swapping out the computer-controlled system with a standalone DS-II ignition system it ran well. David's thread, in his link, chronicles quite a saga of going from what you are getting now in MPG to over 20. I'm pretty sure you can do the same, but before we get too far please post some pics of the distributor. Just want to be sure of what you have. Link to comment Share on other sites More sharing options...
844rd Posted March 19, 2020 Share Posted March 19, 2020 Mine was the same way, flat. Had to accelerate slowly. If you pushed harder on the gas it would not go any faster and would loose speed on a hill. I replaced the 1 barrel Carter that had the "feedback" system with a rebuilt one with no feedback. Replaced the ignition system which was the EECIV computer controlled to the DurasparkII and now runs great. All the power I need and gas mileage 20-21 mpg. Link to comment Share on other sites More sharing options...
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