carb icing

[superc_1]

I'm at work and my truck wouldn't start? I think it maybe carb icing? Its about 32 here. Does anybody know of quick fixes so I can get her home this afternoon. It ran fine coming to work except when I got here here it was missing really bad about the last mile. I drive @ 12 miles to work. Any suggestion?:confused:

[datsunaholic]

Shouldn't happen at that temp- if the engine temp is warm enough to melt the frost off the hood the carb won't be iced up. The first clue when real icing happens is the throttle plates stick. I'd be more suspect that your choke is stuck or you have water in the fuel lines that froze in the filter.

[superc_1]

can you check the filter without spilling gas every where?

[Phlebmaster]

Depends on where your filter is located. If you have access to a pan or something you can catch the gas with you will be fine. If your filter is positioned upright then take the top hose off first then carefully tip it over into a cup or something. Try Isoheat...cheap to buy and works great for drying out your gas, if water in the gas is the problem that will fix it.

[datsunaholic]

Why? Is it stuck in the EPA parking lot? It won't lose more than a few tablespoons when you pull the lines, but you'll end up blowing fuel out of the filter if it isn't plugged. If it's a big worry get a soda can or bottle and cut the top off to use as a catchcan.

 

Unless your filter is down under the tank... it's supposed to be on the fender above the starter. What I do with the ones down by the tank (and I've seen a couple added, especially with electric pumps) I just use 2 pairs of vice grips and pinch off the hoses before removal.

[superc_1]

I have a 77 kc deluxe and the elec. fuel pump is down by the gas tank. I didn't want to get fuel all over me til I got home.

[V8Dat]

You need to make sure you are getting fuel to the carb before you worry about icing. And yes you can Ice up at 32 degrees. But it should still start. After it starts is when the icing is going to occur. The high velocity of air getting condensed as it mixes with fuel while going through the Venturi is where icing occurs. The ice build up inside the carb is now changing the shape of the Venturi and now will not run right.

 

The best way to avoid icing is to let the car warm up at a low idle then shut the car off for a few minutes and let the engine warmth heat-sink the carb. Start it back up and it should be good to go.

 

Sounds like you have other issues though.

[superc_1]

Question again! I took the inlet hose off and I had some gas come out. I emptied the fuel filter and the stuff was red looking. I turned the key on and I couldn't hear the fuel pump running? Can you hear it run when the key is turn on? last but not lest I cann't see any fuel in the fuel bowl. Iguess this morning when it was running so rough it must of be icing. It was missing really bad that last mile in to work. It was @ 24 degrees this morning.

[Phlebmaster]

Have you considered rust in your tank?? The gas should never be red.:)

 

Did you get anything to come out of your fuel filter? I mean flecks or chunks?

[banzai510(hainz)]

Its been near 20deg here in the morning . My 521 still is working

 

just try pouring some gas in the carb and if runs

 

if float bowl is emply then there will be no gas shooting in the carb from the accell pump(look in the main barrel and pump the gas) if nothing then the needle valve is not letting gas in or the fuel pump

.

Or try banging on where you think the needle valve for the float might be(hose goes into the carb) sometimes they can be sticky I KNOW

 

IM not positive on datsun eleltric fuel pumps put once it reaches full(to the carb) the pump might not run. you could point it in a safe direction then turn ithe KEY ON and it should shoot out.

 

ck grounds near the pump

 

i think you kow this already.

If I remember right this was a stock motor and assume the stock air cleaner is on there so it would be even harder to freeze up.(is my thinking right?)

[datzenmike]

Throw the old filter away. They are cheap anyway. Cut the old one open and examine for debris. If you have an electric pump check the internal filter IN the pump too. Your truck should have warm air from the exhaust manifold piped to the air filter, if not make one.

[ggzilla]

Carb Icing happens when the engine is running fast. It can happen at temps about 37 degrees (due to the venturi lowering the temp of air inside the carb). The main symtom is you'll be driving along, and take your foot off the pedal, but the engine stays at the same speed and doesn't idle down. The throttle plate is frozen in the open position. Usually a few minutes of idling will unfreeze it.

 

To prevent it, use the "heated air" intake on the air cleaner.

[lancekilgore]

I had the dreaded fuel problem and it turned out to be the steel ine coming from the tank clogged up. To fix the problem I disconnected the lines and spryed carb cleaner down the line let it sit for 5 hours. then I took a ball bearing from a carb rebiuld kit and pushed it back and forth with compressed air. CAUTION make sure you put a finger or something to catch the ball while it goes back and fourth or it will shoot out into lost land. Never had any problems since then.

 

As to the carb icing it has been below zero here and I have not had any problems (I run a webber) Mine is a daily driver.

Lance

[DanielC]

You might have water in the gas tank. Water can get in gas tanks from condensation, more of a problem where it is humid. You need to get the water out of the tank. Siphon the gas out of the tank, and see if any water settles out of the gas. I use a white one quart cottage cheese tub to catch some gas in, You obviously need to clean the cottage cheese container first. After you put a little gas in the container, look for a bubble of water in the bottom of the container, after it has set for a little while. You can also get an idea of how much dirt is in your gas.

If the gas is dirty, or has water in it, coming out of your tank, you need to clean your tank, by draining it, then removing it, and dumping all the remaining gas, water and crud out of the tank you can. I have heard on one method of removing the fuel level sender, and then dropping a short piece of chain into the tank, and shaking the chain around in the bottom of the tank to knock rust loose. Tie a piece of string to the chain to make it easier to remove the chain.

Rinse the tank out with denatured alcohol, and dump out as much alcohol as you can. The alcohol will dissolve the water, and help get some rust out, also. Rinse the tank out again with a little fresh gas, and recheck it for dirt, and water. Repeat the cleaning steps, if you think it is necessary.

Put the tank back together, and back in the car. Put in a new fuel filter.

That should get all the water out of your tank.

If you can put gas that contains 10% ethanol in your car, after the tank is cleaned out, that will keep water out of your tank. If there is a lot water in your tank when you put the E10 gas in it, it will cause problems. Clean out the tank first, if it is dirty.

[datzenmike]

To prevent condensation in tank, keep it as full as possible all the time. Forget those aftermarket gas antifreeze additives...$$$$$... all they are are methyl hydrate...look on the package. Go to Wall Mart paint section and get a liter (or quart) of Methyl Hydrate $3.60 or less, cheaper by the gallon. Add a cup every time you fill up. Gas and water doesn't mix. Alcohaul (methyl hydrate) will mix with either, so it will prevent the water from freezing and will allow the gas/alcohaul/water mixture to be run through the carb and used up by the engine, preventing any build up.

 

Gas line anti freeze will NOT prevent carb icing, which is caused by high humidity cold air collecting as frost on the venturi. Carb icing can be trevented by repairing, replacing or building a warm air system for your carb using exhaust manifold heat.

[superc_1]

First, thanks for all the suggestion. The truck has been running fine for a long time. I feel the problem is either water or a fuel pump. I put heet in the tank last night and it has set there over night so if its water I'm hopeing this will help the problem. I'm going to check fuel pump at lunch.

[V8Dat]

Keep us posted on what you find. Its always good to hear and learn from other peoples woes.

[superc_1]

I had to take carb off couple weeks ago and I heard something loose for a second then nothing. Week later find a venturi noozle in the drive way:confused:? I held onto it. I got to looking today when I got the truck home and the secondary venturi had fell out when I turned the carb over to get nthe gas out and that is what I heard a couple weeks ago

9in my defense I was dark outside and I couldn't see much). I took carb off today tighten everything plus use alot of blue loctite I've clean plugs and she almost started but I think I will need new plugs. I guess the secondary was flooding and it finnally fouled the plugs. I can't believe that it ran so good for a week or two. I'll keep everbody posted on the progress. Thanks

d

[datzenmike]

Which begs the question... where were the screws for the venturi?