Hi everyone, I would imagine anyone reading this is dreading this problem as much as I am.

I was here last year with my truck, Problems were..

All at once it started..

Rough idle
Dies when put in gear
started cold the rpms were way high,(about 3500 rpms)
Once choke opened it would sputter and stall out.

Actions taken..

Rebuilt carb
changed fuel filter
changed fuel pump
new plugs and wires
replaced timing chain, both gears
replaced coil pack


Problems got slightly worse after carb rebuild.

Had enough and sent it to a garage.

They called a few days later saying it was running great and they had examined the carb to find some air and fuel chambers were bord out to far, they said it was likely that heavey dust had got caught in the carb holes and as they worked through made the holes larger causing all the problem,

I said, well ok, bill was 585.00..


went to pick the truck up, paid the man, went to start my truck and the battery was dead (been setting a few months while I was collecting the money). Jumped it, got it started, rough idle for about 20 seconds then it went smooth and idled great. I put it in gear at about 3/4 warm, and it died, started it again, put in gear and it died again.

Guy said to leave it overnight and he would charge the battery overnight and have it ready the next day.....aggravated but went with it.

Came back the next day, started the truck, and rough idle for about 3 seconds and then smooth and clean..Put in gear and it didnt died, still sounds good. Shook the mans hand and thanked him, then left.

Drove thru town and it seemed like when I let off the gas it would slow down way to fast, like the truck was moving about 40 mph and then put into 1st gear. Just a really fast slow down without using breaks, before all the problems this truck would coast really well but now no coasting is present.

Stopped and filled with gas, added some coolant, and was back on the road, once I hit the highway I realized a real problem was at foot.

I could take off from a stop and hear the gears shifting (3 speed) once in 3rd gear I would give it more gas trying to get up to 55mph, the engine does not rev up any, sounds just like a normal steady 45 mph pace, but no matter how much gas I give it, then engine does not pick up at all. Once I noticed this, it began backfiring, when I would let off the gas and then give it gas again, it would backfire from exhaust, sometimes one pop, other times 2 or 3 pops.

So long as I was driving on a flat surface, I could get it up to 55 mph, but not much over(nearly to the floor). As soon I would would come up on a grade to any uphill, it would never rev into a lower gear, stayed the same, engine does not rev at all past 45 mph.

Then, out of no where, the hood fly's up and slams the windshield, no damage to the glass but the hood is now toast.

Did a quick look around and seen no damage in the engine area.

Got it home and called the shop and told them what happened.

They said the plugs may be fouled due to running with the bad carb and then setting for so long.

My question is.....does that sound right?

The plugs are pretty new and I am going to pull each of them and inspect and clean them, but could fouled plugs really cause this power and backfiring issue?

Right now, I can start the truck, it starts fine, idles great, and still sounds great when put into gear. At lower speeds I didn't notice the power problem or backfiring, other than at low speeds it seems to have no coast at all, just let off gas and the engine slows it down quickly.


Any help would be great. Thanks for your time.



Doug Huffman
1985 F150 Bullnose.
302 holley 600
78k miles

 

It's going to be hard to diagnose over the internet, but a few things need to be checked;

Put a timing light on it and see where the timing is, and if it advances when the engine is revved up. Also is there any vacuum on the dist when it's idling.

Then pull the site plugs on the holley and see where the fuel level is located.

Their suggestion of checking the sparkplugs is a good one also.

 

With the 3rd gear and no acceleration problem, is this when the truck is cold aka been running for less than 30 min? Even though mine obviously has a different motor, I had the same problem when cold, my foot was in it and it still wanted not to speed up, however it sounded like it was holding back. After I had my foot in it for 2ish miles it freed up and ran perfect. I fixed it with a carb clean though, not to doubt your work but are you sure the carb was cleaned and rebuilt well?

 

Timing light was used at the garage, guy said it was off a bit, but he had advanced it and said the timing was right on the mark.

The carb is brand new and was installed by the garage, I rebuilt the old carb before I sent it to the garage where they installed the new one.

One thing I have noticed tho,
On the old carb, it had a vacuum ling going from the port just above the air mixture screw on the passenger side of carb to the back of the carb on same side behind the secondary diaphragm housing. The new carb has a plugged port above the mixture screw but no port on the back other than what looks like the pcv power break port.

no vacuum port on the dizzy at all, I think its electronic.

Ohh and the backfiring does not sound so much like a gun shot as a muffled pop, not sure if that info matters, could the exhaust be clogged causing these problems?

 

Aha! That could be a problem.

 

Has anyone pulled the codes?

 

I am looking to buy a new dizzy come income tax time, and a few other things just to upgrade the older parts, but it ran perfect with plenty of power with this same dizzy before.

The vacuum advance above the mixture screw? could that possibly go on the power break port?

 

I dont think the code pigtail is working, I tried to pull the codes a year ago and it was just a dead plug.

 

Tomorrow I plan to pull the plugs and clean them, clean cap and rotor, and inspect the plug wires. I may even crawl under it and maybe smack the catt and muffler a bit to see if that will clear it up any.

 

OK, here is where I am at...


Today, I removed each plug one by one to check them, the front plug on passenger side was white and dry on the end when I removed it,, the other 3 on that side looked brand new.

The 3rd back on the drivers side was almost yellowish on the end, and dry as well, alll the others on the drivers side looked new.

The engine still starts great, idles perfect.

When I put into gear, it feels like something is holding it back, when I put it in reverse, the idle still sounds good, I give it it little gas and the engine tries to die once the truck starts moving, I put it back in park and the engine smooths back out.

Drove it down the road a bit, if I give it gas a to speed up, it kinda stumbles then catches up and does fine until around 40 mph, then I give it more gas and the engine remains the same, it does not rev up at all.

Driving tho, t still feels like its being held back a bit, when I let off the gas to coast a bit, it slows down quickly (no coasting).

Hope this little update helps a bit, any info as always will be greatly appreciated..


1985 F150 302 Holley 600 3 speed.

 

OK, on yet another hunch I decided to check the exhaust, noticed drivers side exhaust sounded softer than passenger side, passenger side sounded crisp and nice, driver side sounds a bit muffled.

I thought maybe the cat was clogged causing the problems so I cut the cat out and just left the pipes as they were to see if I had any power.

Started just fine, no louder than it was before, idled good, just a bit of stumble when I give it gas (small revs).

once it warmed up, I shifted into rev and it still seems like its being held back. I checked the tranny fluid and it shows full.

any idea's?

 

Get your brakes freed up and post an update.

 

Ok, here we go. lol

Raised rear end, checked the wheels, they turn pretty easily and are not catching, I had a friend hit the breaks then release and the wheels in the rear were fine,

Set the rear end down and check the front the same way, they are fine to.

On another hutch, I decided that maybe the cats were clogged, used a grinder and cut both cats off, the problem continues..

Problem refresh..

Had a new holley 600 installed by local garage.

Starts fine, idles a bit high till the choke opens, then kicks down and sounds great, nice smooth idle.

I hold break and put into reverse, the the truck will begin to move backwards as I let off the break, but in moving backwards I mean about 4 inches, then it feels like something stops it/ catches, or something.

I can give it a bit of gas and it will go, but engine is revving higher than it should to get movement, and once on the road it feels like it is being held back.

Going downhill I can let off the gas completely, and can quickly slow down to about 7 mph from 45.

On highway, I can get it up to about 45 mph, and it don't want to go much faster, I can floor it at 45 and the engine does not rev up any more than it did to get to 45, and the speed does not change.

Also at 45 mph, it backfires once in a while and hesitates a bit when giving it gas again. Bucks a little when I let off the gas at 45.

Could this have anything to do with a map sensor?
Could this be a small adjustment on the dizzy?

Also noticed...Using more gas, temp is higher than it was before, normal temp is 190, now its steady at around 210. Oil pressure is normal at 35, now its up to about 48.

anything? Thanks for your time.

1985 F150 302 holley 600

 

This is a wild guess, but your symptoms relate to the torque convertor in the tranny being bad. Before you do anything else, take it to a couple of tranny shops and take them for a test ride and see what they say.

There is a thing called a stator inside the torque converter. You can do a google search on "how a torque converter works" and it will explain what is going on. That stator has a one-way clutch bearing it rides on. If this bearing goes bad and locks up, the stator doesn't work right and at about 40mph it will keep the vehicle from wanting to move any faster.

 

Thanks for the reply

Today my father stopped by (50's and 60's garage owner..

He started it up and let it warm up, then after it warmed up he revved the engine a few times and shut it off, he said the dizzy was out a bit and told me to loosen it and turn it clockwise just a tiny bit,

I did as he said and tightened it back down, he started it up, this time the idle was a bit higher, but when I put it in gear most of my power was back, he said to get a light and it will time up perfect.

So now with the power figured out, I think I am going to buy a light and see if I can get it right, he told me that the garage set it up to specs from the factory, but the engine being old has worn some and the factory specs will no longer work so I would need to re-adjust the advance accordingly.

Without touching the dizzy again, I ran it down the street, and now I do have a lot more power, the backfiring has stopped, but it has a bit of hesitation and coughing when I lay into the pedal.

All the power is not back, but considering I cut off the cats from the exhaust, and the dizzy is not right where it should be, the backfiring stopped and power is present again.

How much power would the cats give when re attached? Right now they are cut completely off.

and when I put a light on it how do I determine which direction the dizzy needs to be turned?