• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.

    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Now what? [fixed!]

sparkydave

Jedi Knight
Country flag
Offline
I think I'm getting close to just seeing if I can buy one of those I.V. bag hangers like they have at hospitals, bolting it to the fender, filling the bag with gas, and let gravity do the work! :madder: The funny thing is, the much-maligned Zenith-Stromberg carburetor is working fine - when it gets fuel.

OK. So the Facet pump wannabe that worked great for about a year gave up the ghost. This was to replace the mechanical pump that had a nasty habit of vapor locking. I know the old pump was vapor locking because I could take the cover off the pump and hear fuel boiling in it after it died.

Moss sent me a new pump as a warranty replacement. Now this pump actually says Facet on it, and came with much more detailed instructions. Seems I didn't mount the old pump the preferred way, which is a 45 degree angle. I mounted mine on the bulkhead (the bottom front of the trunk), but it was horizontal. The old pump had very scarce directions, but it worked and didn't mention a 45 degre angle. The mounting put it about 4 inches above the tank. New instructions say it has to be less than 12 inches. So far so good, but it took probably a minute's worth of clattering before it finally got quiet and started pumping gas. Maybe it just needed some priming first. So I got the engine running, and took it for a test drive. Not even halfway around the block, it's stumbling, losing power, then surging to life, then stumbling. Now this seems all too familiar. Limp back into the garage, and notice the pump is clattering like it's got air in it. Maybe that 45 degree mounting really is needed, to let any air trapped in the pump bubble out. So I take out one bolt, tilt it, and start it. The pump still clatters, and I can't hold the engine at 3000 RPM for more than 30 seconds before it just quits. I also noticed the pump goes from very quiet to loudly clattering at idle. So I finally get curious and unbolt the pump, letting it sit below the tank level. Now it stops clattering at idle, but the engine still can't do over 3000 RPM for any length of time.

Now I'm really perplexed. The gas tank is clean, all the fuel lines were replaced 2 years ago, the little inline fuel filter I put before the carburetor is clean, but it acts like this new pump just can't deliver enough fuel. Not to mention it seems to be getting air pockets. I had cut the original fuel line near the tank fitting, and added a short length of hose to the pump, since the fuel line kit I bought didn't have the tank fitting. That fitting isn't loose, I can vouch for that. I pulled the outlet hose off the pump and found it shoots a healthy stream of fuel out. My next plan was to pull the hose off near the carburetor and see if it makes a healthy stream at that point. Following that, I might get the clear tubing and see if I'm getting bubbles in the tank line. If there are, then I wonder if the tank has an air leak inside of it.

Any other ideas? Is the 45 degree angle critical to running the pump? Oh, and it has about 2/3 of a tank right now if that's any help.
 
Re: Now what? [long]

You going the right way. may I suggest that you go to the hardware and get a peice of clear plastic hose maybe 6 or so feet long and try that between the pump and the carbs.

I am sure you have a restriction between the pump and the carbs. In my mind no question about it if you get a good stream from the pump with the fuel line forward disconnected.
 
Re: Now what? [long]

Thanks Jack, I'll give that a shot - tomorrow. Off for a pint of something cold right now. :thirsty:
 
Re: Now what? [long]

Heres a Thought. I had the same basic setup brand new fuel tank new fuel line up over the axel along the underbody to the bulkhead wall horizontal near the axel softed mounted Facet pump with 2 pieces of 1/4 " long 1/4 dia fuel tube .
With me so far? then ran fuel line in the channel on the drivers side of the car coming up near the piont the header makes it turn to the collector. The car ran like this for a year putting on thousands of miles. Then mytreriously the next spring driving it the pump started making a sound like it was running dry on corners and stop light departures3/4 of a tank of gas. WELL IT WAS RUNNING OUT OF GAS! Some where between the tank bulkhead fitting and in side the tank the pick up tube is either cracked loose pointed sideways or gone. filler up and all is good. 3 gallons was the max draw down. ever time could be the same deal.
 
Re: Now what? [long]

Back to basics.........have you tried a new gas cap? Or tried letting it run without a gas cap on?
 
Re: Now what? [long]

Ohiobugeye said:
Back to basics.........have you tried a new gas cap? Or tried letting it run without a gas cap on?

That's an excellent place to start looking. A non-vented cap and a tank whose built in vent is plugged (or missing) can quickly draw enough vacuum that the pump won't move any gas.

I also liked the suggestion that the pickup tube in the tank may be cracked or have a hole. After all, these are cars near 40 years old. All sorts of weird problems can happen.
 
Re: Now what? [long]

One other suggestion: running the fuel line down the driver's side places it closer to the exhaust pipe. The heat from the pipe could be a factor. I ran my fuel line down the passenger side all the way to the front of the engine bay, across the front, under the radiator and then to the carbs to keep the fuel line in the coolest possible route!
 
Re: Now what? [long]

The last two suggestions are the things which would yield good info. The pump behavior described is indicative of the pump suckin' air or unable to overcome a tank vacuum.
 
Re: Now what? [fixed]

Ahhhh..... I found it. The fuel filter I added wasn't as clean as I thought. I put some clear tubing before the pump, and found out I had to crank down the hose clamp a little harder than I thought, because there were some tiny bubbles still getting in, hence the pump building up an air pocket. OK, took care of that little issue, but it still seemed to have trouble moving much fuel up north. I bought 20 feet of tubing, so I figured I'd run that straight from the pump to the carb, so I pulled the filter I added just before the carb... And found I couldn't blow through it. :shocked: Pulled the filter off the hose, and no trouble blowing into the carb. Shoot, I probably had only 2000 miles on that filter. Although I did put it on before I changed the old fuel lines; maybe those lines were rustier on the inside than I thought. Grumble... When I let the fuel dribble out of the filter inlet it looked suspiciously brown. So, off to Autozone to get another, but on a whim I looked in their application guide to see if I had the "right" filter. Nope, they actually call out a bigger one. Got it home, and sure enough, I can blow through the new one very easily. So I took the opportunity to put it down at the pump inlet, since the pump instructions suggest one to protect the valves in it. Not a bad idea for a 32 year old gas tank. I had some extra fuel hose lying around, and a large hose clamp to clamp the larger filter underneath away from the axle. As soon as I turned the key on, the pump primed itself almost immediately, and the engine fired right up. Test drive went with no trouble, and even while idling the clacking from the pump is gone. Guess it really was just a loose hose clamp seeping some air in, but boy, was that filter plugged. Who'd a thunk it could get so dirty so soon?

Thanks all for the suggestions, I appreciate it! :smile:
 
Re: Now what? [fixed]

Ya still ain't said whether th' Mentor BMC/BL parts house has been 'disappeared' or not.
 
Re: Now what? [fixed]

For what it's worth, on my LBCs I don't use OEM type filters, I use the transparent shell type inline filters commonly used on air cooled VWs. They give you a quick visual of both the filter condition and whether or not fuel is moving.

Like this:
https://www.allzim.com/acatalog/803.201.511.e.jpg
 
Re: Now what? [fixed]

Likewise, the clear plastic filters are fine.
 
Back
Top