Series IIA not getting fuel

[nathanwind]

So...my '71 IIA tends to sit for long periods while I'm out of town. This last round was about 4 months (inside, semi-heated garage). She generally never fails to start after a shot of starting fluid and a few cranks. Until now.

Wasn't catching, so pulled the plugs and checked for spark - was fine. Pulled the fuel line where it goes into the carb, didn't look like it was getting any so I've been working backwards down the line.

Have checked that the lines are clear/not clogged from the carb back to the fuel pump, fuel pump to filter element, and element to tank - all seems to be fine. It's worth noting that the fuel pump is just about brand new - replaced it at the beginning of the summer and worked fine for months before I left it.

Emptied the sedimenter bowl and likewise checked the lines here - seemed fine.

Pulled the fuel filter element - cleaned and reassembled.

Pulled the fuel line that runs from the element back to the tank - fuel seemed to flow freely from here when I checked the line, indicating that there is no blockage from the tank to the filter element.

Blew the lines out with compressed air from the filter element and was flowing unrestricted all the way up to the carb input line - so no blockage/etc.

However, I went to prime the fuel pump with the lift lever and I was expecting it to fill the sedimenter bowl - but nothing happened. Could my brand new fuel filter have crapped out? It's a mechanical pump so it should be pretty bulletproof (hell, the original one lasted almost 40 years...only reason I replaced it was because the seals were leaking!).

There's no pump in the gas tank is there? I always assumed it was just a pickup tube in the tank and the fuel pump pulled fuel up and pushed it through to the carb.

Let me know if I'm missing something.

[carlosz]

if the prime lever does not pick up, the diaphragm in the fuel pump may have gone bad, if it picks up but does not deliver to the carb bowl (not the filter bowl next to pump) then your float valve may be stuck in the closed position simulating a full carb when in fact it is empty....
if the latter is the case just tap the carb bowl and the valve shall unstick... it due to a direct result of gum residue caused by fuel.

[nathanwind]

Carlos:

I've had the latter issue before, and have tapped it to unstick. But the fact that the prime lever isn't working tells me the former may be the issue.

The other thought I had is that perhaps the pickup tube in the tank crapped out. Going to pull things apart again to check before replacing the pump.

------ Follow up post added December 31st, 2011 08:43 PM ------

In theory, if I pulled the fuel line at the carb and sucked on it...shouldn't I get fuel there even if the pump was bad? I'm getting nothing...makes me wonder if it is in fact the pickup tube in the tank.

[Antichrist]

Are you feeling resistance for the full stroke of the pump when you operate the hand lever? If not then the cam lobe has the internal lever pushed up. Rotate the engine a bit and try again.
If the lever seems normal pull off the supply side and hold your finger over the inlet. You should feel some suction when operating the lever. If not, then your diaphragm is bad.

[nathanwind]

It does feel like a moderate amount of resistance on the lever when I operate it.

Pulled the supply line into the pump, and I am getting some suction when I operate it. But still no fuel in the bowl when I operate it.

Again, I checked the lines and they all appear to be clear. I even blew a short blast of compressed air from the filter element back to the tank to make sure it wasn't clogged - flowed freely, and I even heard some bubbling in the tank (which would lead me to believe the pickup tube was functioning).

Thoughts?

[LRover]

Mine is doing almost the same thing. I replaced the original pump with a new one not to long ago and now when I let it sit for a while it acts like the pump looses prime. If I put vacuum on the fuel line and pull fuel up into the pump then it goes on and works. I think my problem (and possibly yours) is there is a little check valve in the pump and I think it sticks open. Even though the diaphram is good, the pump just moves the fuel back and fourth instead of pulling it up through the line. When I get fuel in the pump it frees up enough to work but still allows the fuel to drain back into the tank over time. Kinda makes me mad because, like yours, the original pump lasted 40+ years and now I'm having problems with the new one.

[carlosz]

the hell with it, if the newer/replacement pump will loose prime due the posibility of a defective non return valve, install an inline electric pump and call it done.
it will give you a minimal of 2 psi and a max of 20... more than enough for a carb where the max you would ever need would be 5 psi.
you have stablished suction, and delivery is there, supply is there but pick up fails.
for testing purposes, fill the pump bowl and see if it goes from there... a stetch but if you have the old pump, reverse the installation just to verify... it will be a pain but then you verify a defective pump and gives you a chance to inspect the new unit on a bench.
another way it may work (sometimes it doesn't) cover the top of the carb with the palm of your hand while cranking so the compression of the engine makes vacuum and since it has nowhere to go is will suck the fuel thru the line.
maybe this way once you have fuel past the pump it will continue to work as designed.
the latter will help verify thefuntionality of the non retun valve

[jaygoss]

I went through a few new "proline" repro fuel pumps and found that the newer style (without the glass bowl) genuine works better. If you are unable to get the new one working (and it's a proline glass bowl), and you want to stick with mechanical style it might be worth trying the newer genuine style.

[EWR]

Out of curiosity, do you still have the factory plastic supply line going to the pump?

[Antichrist]

Really sounds like a defective pump. Not sure if "some suction" means a normal amount or not, but if the lines are clear that really only leaves the pump.

[EWR]

I'm not saying this is HIS problem. However, just had a similar issue with a truck that was sitting for awhile. Even though the line was clear and I had suction at the pump was still not getting fuel. Removed plastic line and replaced with a new rubber one (just as a temp ) and I had fuel. Truck runs fine. I found small cracks in the plastic line and even though it was clear, it wasn't delivering. Like I said, I'm not saying this is the case here.

[nathanwind]

Some of the line is the factory plastic line. I likewise am starting to think it may be an air leak somewhere...even if it's a small one. Out of necessity thinking I may replace it all with proper 5/16" new line. Will probably be tomorrows project.

If that still doesn't work I may swap the pump out as plan B.

[Antichrist]

I'm not saying this is HIS problem. However, just had a similar issue with a truck that was sitting for awhile. Even though the line was clear and I had suction at the pump was still not getting fuel. Removed plastic line and replaced with a new rubber one (just as a temp ) and I had fuel. Truck runs fine. I found small cracks in the plastic line and even though it was clear, it wasn't delivering. Like I said, I'm not saying this is the case here.Actually it could very well be. I was really replying to Nathan, but I wasn't thinking of cracks since I replaced all of mine years ago during other work, so I haven't experienced the hairline cracks. Sounds like a good possibility.

[nathanwind]

Well...it's always the simple thing. Got some new flex fuel hose from Napa, replaced the U-bend from the Filter Element around to the input on the Fuel Pump, and fired right up!

Figured I would just do this one section to find out if it was the culprit. And after getting the old flex hose off definitely had some nice cracks (not enough to leak, but enough to suck some air).

The irony is...from the looks of it this was the only section that had been replaced over the years (by a previous owner). All the rest is the original plastic-type fuel hose...

[EWR]

Nice. I always like the 5 dollar "fixes"

[o2batsea]

If you want to go to the bother, the plastic line is plain old nylon tubing available from your friends at McMaster-Carr. You use a heat gun to soften it slightly so that it slips over the hard lines.

[TeriAnn]

1. Did you actually remove the draw tube on he fuel tank for a visual inspection? There is a screen at the bottom end of the draw tube that might be clogged up. Also make sure there is no pin hole in the draw tube.

2. This sound like a job for MITY - VAC! :sunny

Hook your Mity-Vac to the fuel line going between the pump and tank. You should be able to quickly and easily draw fuel to the Mity-Vac. If the Mity Vac gauge says you are lulling a vacuum, you have a clog downstream. If there is no vacuum and no fuel you are either out of fuel or have an air leak in the line down stream. A Mity-Vac is an excellent tool for quickly checking out fuel lines, distributor advance functionality, bleeding brakes, and checking for the vacuum integrity of a brake booster. Every tool box should have one

3. It doesn't take very long to R&R then disassemble a stock AC type fuel pump and inspect the diaphragm for ruptures and check to see if a one way valve has not fallen out.