71 hd cart model D with aftermarket air filter not getting fuel

[sharky55]

Hello everyone, I have rebuilt the carb on this unit and realised that I didn't get the original air canister filter system with this. I have seen k&n filters on this website that people have put on. Are these good to use instead of hunting and paying for a canister type? Having issues with fuel getting to carb. Assuming that this is the reason. The one that came with it is old and dirty. Also was thinking of putting a check valve on to keep the fuel in the line for faster starts. I have 90lb of compression so that is good from what I have seen on this website. Any help would be appreciated. Thanks in advance.

[73eldo]

A clogged up restrictive air filter would have the opposite effect, you would get too much fuel. The air filter being restricted means as the engine sucks it can't get enough air so it sucks harder which means it pulls in more fuel. Without the air it won't run right but you should get plenty of fuel.

If your OE stuff is missing and you don't get lucky and find replacements real cheap then I think the K&N stuff may be a reasonable option. The last few years parts for these carts seem to have got expensive and harder to find.

90 for compression should be enough that it should run. Did you take a reading forward and reverse? The closer the readings are the better. Further they are apart is a sign of more wear.

Does this have a carb with a float bowl on it or the carb that is more like a stack of discs? Since your air cleaner is missing or wrong perhaps you are dealing with non stock stuff or different vintages mixed. Should be the disc type for a 71. The fuel pump is the first stack of gaskets. It operates off air pulses from the crankcase via a passages in the intake and gaskets. If any of the gaskets are on wrong and blocking the passage you won't get those pulses so the fuel pump won't work. It starts with a small hole in the reed plate and continues all the way to the carb so there are plenty of places to get it blocked especially if you had to make or improvise some of the gaskets and spacers.

[73eldo]

Forgot to talk about the float bowl type of carbs. If that is what it has there should be an external fuel pump. OE was a square unit with 3 hose connections. Fuel in, fuel out, and crankcase. This style the intake had a nipple on it for the hose to the pump so only one gasket had to be correct. These didn't have the internal passage to the carb so they won't work with the tillitson disc carbs.

Some people use electric fuel pumps. You have to be careful how much pressure they generate and how you wire them. The OE style pulse pumps are somewhat universal, similar pumps were used on many small engines including snow mobiles and lawnmowers so they can be found pretty easily and buying a OE harley rebuild kit may not fit what you have. One of mine has a Mikuni pump on it that apparently came off some sort of ATV or dirt bike. I found new ones on ebay cheaper than repair kits.

[backyard]

A K&N filter should be fine to use.

You should already have a check valve in the fuel tank. It's made into the fuel strainer.

Which carb do you have?

[johnny reb]

not on 71. is the metal gas tank rusty on the inside? it may need cleaning if you are getting trash in the fuel strainer inside the carb. there is no need for a check valve in the 74 and under since the tank feeds directly into the carb. a K&N should work fine my next build will have one since i hate oil type air cleaners. btw i would recommend a small second fuel filter for rust and crud.

[sharky55]

Thanks you everyone, I have the carb without the bowl float. I'm going to take apart the carb and double check the stack and make sure everything is as it should be. And also I have black crud built up where the carb attaches to crank,maybe a leak? The fuel pump I was looking at was 3-4 lb, but if i get this thing right I won't need that. I will order that k& n filter, and double up on fuel filter,

[73eldo]

When you check your carb check to see that the areas where the screws thread in are not raised up. I have seen several where someone cranked down so hard it pulled up the threads so the gasket could no longer seal. Some careful work with a file or emery cloth on glass can fix it. At first only the high spots will be cut. You just keep working it till you get contact all the way across the disc.

[sharky55]

Thank you, 73 eldo

[backyard]

Ok, no check valve and a metal tank. I've been working on a 52 chevy with a rusted out gas tank recently. The tank has already been cleaned and coated once and the tank is a rust bucket at this time. The filter has been changed 3 times in the last couple months and the lines are toast. Had to clean the carb out twice. Now ordered a new tank. So rusty gas tanks can cause a complete fuel system breakdown.

If the rust is bad, then you're going to have to inspect/clean/fix everything within the fuel system. If you don't then you're likely to be right back with the same issue soon just like the 52 chevy.

[sharky55]

Ok,I took apart the carb and found I made some errors when.I rebuilt the carb 2 years ago, seems the kit I ordered didn't come with all the right gaskets. Any ways I saved the old parts and put our together according to the diagram in the book. New gas filter and will get the air filter Tuesday or Wednesday this week. Still no gas being pumped in the carb unless I put my hand over the air intake and i can feel a lot of suction and then the carb starts to pull fuel into it then it starts to run. Is this normal?