After reading thru many posts I found what I though possible solutions to my problem:

I can drive really really slow and nothing goes wrong but as soon as I give it any sort of gas it starts sputtering. If I am going downhill it's not as bad as going uphill.

I took the advice someone had gottem with a similiar problem in another post and went ahead and changed the fuel pump. This did nothing. I then changed the fuel filter and air filter and still nothing's different.

Any other suggestions?

Also, I changed the spark plugs and wires less then a year ago.

Skylar Johnson

 

Fuel filter is the second part I'm assuming you've changed. I get this strange "edit" from time to time that cuts off some words.

When was the last time you changed your air filter? If it's dirty, it will create a problem like this.

You changed the wires and plugs, but did you also change the distributor cap and rotor?

One more thing to check. This may sound bizarre, but I've seen it so many times on other people's vehicals already, I'll mention it.

Are the spark plugs actually tight?

Remove each of them, and put a small drop of engine oil on the threads. I use an old spark-plug boot, slid over the plug, to thread them in by hand, and then tighten them to 10 ft/lbs of tourque. If you do not have a tourque wrench, finger tight with the oil on the threads, and roughly 1/4 turn from there with a regular socket should be about right.

The reason I mention this, and what I've seen many go through in the past. A loose plug allows the cylinder to blow by because there is no compression seal. This contributes greatly to performance loss. Most people just try to thread a plug in dry, and some have luck, some don't. Plugs are made of steel, where engine blocks are either cast or aluminum. Dis-similar metals tend to bind, and create a false "tourque" long before they are actually tight. Just forcing a bit more on the wrench often leads to a stripped plug or block, thus the oil and finger tightening.

 

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i have a similar prob with an 84 f150...its runs great, and then once in a while i get the prob...great power up or down hill..then out of the blue regardless of driving conditions it does it.....i have tried every thing....timing is perfect plugs are in proper and new, new carb, rotar, cap, wires, fuel pump, two things left to check that i don't want to lol....oil pressure to the lifters(351 would make noise if this was the prob, no noise from valve train at all....good compression...) and the gas tank...some times shistey gas tanks can foul gas pretty bad..???

 

how about a stuck float in the carb? try putting some decent carb cleaner in the tank or tapping on the float bowl with a screw driver handle. you may also try blowing the fule line back into the tank. the pick up screen may be full of rust etc. you should check fuel pressure at the carb. good luck.

 

I'd also change out the spark control bosilver box on the firewall that's hooked to the dist and coil) It may be crapping out under load, and can do so at random. Normally they just give up, but the odd one decides to live on as a ghost of it's former self, and really screws up troubleshooting.

 

there is another area that we all seem to be forgetting... the accelerator pump. If by chance the pump is faulty, your GONNA have off idle acceleration problems. take a look see down the throat of the carb (while the engine is NOT running) and see what the squirt is like. It should be a steady little squirt...any disruption or air would indicate a problem. I hope this helps !!

 

Well since the last post the only thing I've done was make sure any hose going in or around the carb was securely fastened. Something happened. The problem did not go away but now it's definitly better. It's probably 50% better. It may give a couple big sputters but it will rev up and go. Sometimes it's like its perfectly fine even. I don't know what I did but something made it run a little better.

I don't know. I think i'm just going to have to break down and go to a shop to have it looked at. I wish I could fix it myself though.

SJ

ps
Thanks for the help.

 

any ways it is hilarious because of the fact that i can make it back fire like a haueszter

 

The backfire would indicate one or more vacuum leaks. Check all of your vacuum hoses, as well as the intake gasket. Easiest way to do this is to spray WD-40 on all the hose and gasket surfaces. If the engine changes RPM in a noticeable way, you've found your leak. Might be worth at least changing the hoses out(one at a time) and then troubleshoot from there.

 

Hi ,Was this ever resolved? I have a similar issue with my 81 F150. Drives fine under 30 mph, but randomly sputters and loses power above 35-40 mph.

 

in my case it was the pick up tube in the tank that was clogging.

 

tedtedted,
What testing have you done to try and fix this issue?
Being it "randomly sputters and loses power above 35-40 mph" I am guessing it is a gas issue and not a spark issue like the key was turned off.
Thing is not to do too many things at once so you know what helped or hurt in trying to fix it.

What motor and 1 or 2 tanks dose the truck have?
Has the truck sat for a long time before getting it on the road again and if so how long?
Also work done on the fuel system before getting back on the road?
If it has not been sitting and nothing was done to the fuel system did this just start or been on going?
First thing I would do is replace ALL RUBBER HOSE in the system. It may look good on the out side but be bad on the inside.
Lets start with that and see what happens
Dave ----

 

Thanks Dave!
The truck has a 300 I6 engine with two tanks. I just had the fuel line from the 2nd tank replaced because it was all corroded and leaking.
I actually haven't switched to the rear tank to see if the issue still happens then.
The truck sits at times for 2-3 weeks in between uses. This issue is new and only started happening after the new hose on the rear. I've only had the truck for a few months, so don't have any other history on it.
Thanks for your help!

 

Ok so we have 2 tanks, what tank is #1 and #2?
By default the rear tank is the one the truck runs on if the tank switch valve is not working.

If this "2nd tank" line was corroded what shape is the tank & pick up in?
If the tank has rust and the pick up also corroded that could be a cause.
Does it have old gas in it because it could not be used?
Even more reason to look into this tanks for rust & pick up.

BTW the pick up / sending unit has a filter sock on the end that can get plugged or just fall apart and cause issues.
If there is rust in either tank it will make its way past any filters and into the carb and show up as "mud" in the bowl.
Dave ----