Problem... Carb or fuel pump?

[mountainexplorer]

This motor ran flawlessly smooth before. Now that I have it advertised for sale, I went and fired it up and it runs smooth and fine, then all of a sudden it misses and acts like it's starving for fuel.

I can keep it running if I keep pumping the throttle (if I just hold it down though it sounds like its sucking air and just dies), so I have to keep on and off the pedal to keep it running. Then when it decides to, it runs and idles fine again.

I'm thinking it's not a spark issue, but more of a fuel issue. It ran out of gas a week ago in the driveway, and maybe it sucked some sediment/particles from the tank into the carb. It's sat for about a week since it last ran fine.

 

[Bhintz]

pump, check the filter

 

[k5freak44]

It ran out of gas a week ago in the driveway, and maybe it sucked some sediment/particles from the tank into the carb. It's sat for about a week since it last ran fine.

Yea it woulda sucked it all into the filter before the carb. Sometimes filters get cloged like that and restrict the amount of fule going to the engine, wich would allow it to start but run like hell when more fule is needed.

I would check that before i do anything

 

[POWERMAD]

Fuel flow problem.
Filter...
While the line is out disconnect the coil and crank it over and check fuel flow.

 

[mountainexplorer]

Only thing is half the time it idles fine, and opens up fine. I can be at a light, stomp on it, and it will run normal without hesitation. Then the next light, it will be all I can do to keep it running and get moving. It doesn't seem to be related to RPMs or when more fuel is demanded. It also doesn't backfire. It seems to be at random... like it runs just fine at idle and all driving speeds, then it will run badly at idle and all driving speeds.

I took it about 10 miles up the highway tonight at 60mph. At that speed, it ran fine, and I didn't even notice much of any miss, but I did barely feel a slight change in the tone of the motor that would come and go at random. At lower speeds though, it's very pronounced.

I'll just have to check filters tomorrow and see what they're like.

 

[diesel4me]

It might need some alcohol (I know I do!)

I'd bet on the filter too,it might have gotten a dose of water from the bottom of the tank too--that wont show up on the filter but it will not pass thru the paper element ,causing fuel starvation(not to mention water doesnt burn very well!)--I find water in every tank I pull out to change sending units or fuel pumps--I'm amazed some of the vehicles ran at all with the amount of water they had in the tank--one truck had several gallons at the bottom of the tank,but it ran pretty good,no real problems with drivability,the fuel pump just croaked suddeny--I'm wondering if its the water thats killing the pumps -----..

Time for my all around cure--isopropanol gry-gas!!(and a new filter?)..

 

[mountainexplorer]

I thought about that too. I almost bought some of that fuel stabilizer/dryer stuff yesterday. But I just ended up filling up with premium.

 

[mountainexplorer]

Checked it out today. Major amounts of water in the fuel. The filter was clogged, so I changed it, but it ran exactly the same. Fine sometimes, and will just die and sputter other times.

I noticed water drops in the filter when I pulled it out. I went ahead and put a clear inline filter in, and discovered after having it running a while the whole bottom half of the filter was visibly water, and atop that was fuel.

How that much water got into it I don't know. It's not just condensation, and I'm hoping someone didnt dump water in while it was sitting. I threw in 2 bottles of that Heet fuel dryer.

Someone told me to pour in a bottle of rubbing alcohol. Would that help or hurt?

 

[diesel4me]

rubbing alcohol is for rubbing--not cars!

No-I wouldnt use rubbing alcohol,it is 70% water if you buy it at the supermarket--isopropanol dry gas will cost less in the long run,its 100% alcohol--youd be adding more water with rubbing alcohol!!..you can use denatured alcohol too,or methanol,but its more costly and less effective than isopropanol--

We had one truck come in for a tune up,we changed all the plugs,cap,rotor.wires,etc--still ran like crap,same symptoms you listed--ran ok for a while,then backfiring,surging,stumbling--but floor it ant it would go pretty good most of the time--ran worse at lower speeds,very jerky--we changed the gas filter and noticed lots of rusty water in it--I smelled gas while it was on the lift,and noticed the filler neck pipe was rotted so bad it looked like swiss cheese!--the rear tire was spraying a huge amount of water,mud,and leaves into the tank-(the owner said it ran worse on rainy days!)-we pulled the tank and it had at least 3 gallons of water in it,and was rusted badly,so the owner said replace it--when he left the shop,he squealed the tires for 20ft ,he came right back and gave my friend a 50 dollar tip and said it had never ran that strong since he owned it-ever!-and several other shops had screwed him out of lots of cash replacing EGR valves,and other parts that didnt fix it--I bet they charged him for a new filter and he didnt get one too--we took off an AC original looking filter...... since we found this out on that truck,we always check a sample of fuel first on any similar complaints..

Oh--if you drain all the gas into a 5 gallon pail and let it sit overnight,the water will settle to the bottom,and you can siphon it back into your tank,just let the siphon hose stay above the water level,and stop siphoning about an inch before the water level--my friend gets the gas from the junks at the junkyard free,and has spent very little on gas this year doing this--his filter clogged a few times after a couple trips to maine--but filters are cheap compared to gas nowadays!!..If I were him I'd get a water separator filter similar to the one on a diesel with a water drain--I've been tempted to put one on my carbeurated trucks....

And your not the only victim of water poisoning!!--I;m not sure if its the weather,poor fuel refining,or a problem at the gas stations or storage tanks,but we seem to have a lot of water in our gas complaints this year more than past years--personally,I wouldnt doubt if they are selling it to us...