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jaybird

jaybird

Yoda
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Okay. This is my first 'dumb' question since the 'black drippy stuff on my toes' post when I first got the B. It's not really dumb, I just don't know, and I'm getting conflicting answers on this. Including my husband. So, once again...I come to the experts.

Have a 74 1/2 MGB. Ya'll know how much I love this car. Far from perfect, but my baby. Well. My baby is a hard-starting wench. She runs perfectly once she starts and warms up, but wow, is it tough to start her.

Have an electronic/electric (?) fuel pump. It ticks. But doesn't stop ticking. Is it supposed to? Two times she started right up, and both times, I turned the key, waited, and the ticking actually 'wound down,' could hear it. Started on the first turn of the key.

Are the pumps supposed to stop or 'wind down?' ((The choke helps - sometimes - but dang, it's hard for me to pull out))

Thanks guys. /ubbthreads/images/graemlins/crazyeyes.gif
 
Hi J,
Some pumps are designed to keep "clicking", others such as the SU are designed to stop clicking once fuel pressure is built up. It sounds like one or both of your carbs are leaking enough to drain the float bowls over time. If you wait for the pump to refill them (when it stops clicking), the bowls are full & the car starts more easily. The pump may not have enough voltage to it, during cranking, for it to continue pumping. Best to wait until the pump stops before trying to start. Even better, would be to fix the carb leaks.

Using the choke would make cold starting easier. Might be a good idea to work on the choke cable also.
D
 
AFAIK, the fuel pump should stop clicking if you turn the ignition on and do not start the car.

I just rebuilt my carb, and my fuel pump behavior has changed a little since I got the car. Before the rebuild, my fuel pump would click rapidly when I switched on the ignition and slow down to an almost stop. After it slowed down, it would click 2 or 3 times every other second.

Now (after the carb rebuild) when I switch on the ignition the fuel pump rarely clicks rapidly, and the only times that it does is when my B has set for more than a day. My pump now only clicks 3 or 4 times when I switch on and then it stops.
 
Nunyas, I was reading your 'adventures in carb-land' thread the other day. That's what made me ask, because you mentioned the pump not stopping.

For what I know (which isn't much, obviously) my pump never stops. Maybe when it's started and I'm driving, but the road noise and radio would drown it out -- so I wouldn't know. /ubbthreads/images/graemlins/wink.gif

Dave, this would be a definite indication of a carb leak? The pumping never stop completely, where I can't hear it at all. So my first course of action would be to fix carb leak(s) somewhere? /ubbthreads/images/graemlins/frown.gif

ARGH! I was just bragging about fixing my heat yesterday. I even mentioned next thing you know I'd be rebuilding a carb. /ubbthreads/images/graemlins/crazyeyes.gif
 
J,
As I said previously, there are a few pump designs such as The Carter rotary pump that never stop running, but not standard British car pumps or other plunger type pumps.

With the ignition on, but the engine not running, SU type pumps should pretty well stop clicking. Maybe a click every three to five seconds or so. When the fuel pressure drops a bit the pump will click again to restore the pressure. It's not uncommon for the pump valves to leak down pressure a little bit. Clicking more often than once about every three seconds, under the above condition, indicates a pressure loss, leak, somewhere.

You could check the fuel pump lines & valves by disconnecting the fuel line, where it first comes to the carb, & holding your thumb over it. The pump "should" stop clicking or maybe click once every three seconds. If it doesn't stop, there is either a leak in the pump valves, or the lines to & from the pump or a pin hole in the pump diaphragm.

The fact that the pump has to run so long when first turning the switch on, & that the engine doesn't start, indicates that the carb fuel bowls need refilling. ie - the fuel in the float bowls has either evaporated or leaked out.
D
 
Thanks Dave for explaining (again) and in words I can understand (for the most part) The pump clicks constantly, and rapidly...several times a second, never ever less than once or twice a second. I've got all day tomorrow. Guess what I'm doing? Hubby is helping son finish his basement, I'm getting greasy! /ubbthreads/images/graemlins/wink.gif

Step 1, turn on key, open bonnet, disconnect fuel line, put thumb over it, listen for ticking to stop. If ticking doesn't stop, move to step 2. Replacing fuel line or finding/fixing leak.

((wouldn't I see some sort of drippage under the car on the garage floor if it were leaking out though?))
 
J,
It might be best to turn the pump on after the line is disconnected. A lot of fuel can be pumped out during the line disconnect process. Some will be pumped out between the time that you turn the key on get back to plug the line. An even better alternative would be to disconnect the line & plug it with something such as a pencil eraser & then turn the key on. This would eliminate the time required to get your thumb over the line end.

If the line between the pump & carb was leaking you probably would see a drip, depending on how fast the gas evaporates. If the leak was between the tank & the pump, it would be a suction leak which would not drip. This leak allows air to be sucked in to the pump. Since air is compressible, the pump would keep trying to pump. If the leak was at the carb base, it would probably evaporate pretty quickly as it contacted hot metal. It could even evaporate as it leaked out & not leave a drip. Likely the float bowl would be mostly emptied before the engine cooled completely. Even a small drip would empty the float bowl over a period of hours.
D
 
You won't necessarily have any 'wet' spots under the car. the fuel could be flowing back through the pump and back into the tank, or it could be leaking out of the carb(s) and into the intake manifold. Not to mention it would not stay on the floor very long since gas evaporates relatively quickly (relative to water or oil).

The other possible cause for the pump to never stop ticking is the float in the carb being set too high, or the grose jet valve being stuck open. In both cases, you would smell gas under the hood if you let the pump run long enough.

When I rebuilt my carb I had the float set too high on my first 2 goes. The first time the pump never slowed or stopped. The second time the pump slowed down to about 1 click per second, but never stopped. In both cases I could see the fuel puddling in the "mouth" of the carb when I took my air filter off. I'm not sure if you'll be able to see it on yours since you have a different setup than I do.

But the fact that your pump slows down after a few seconds indicates that the initial rapid clicking is due to the pump refilling the float bowls on the carbs. Anyways, if the pump does stop clicking when you pinch off the hose then you'll most certianly have a leak of some sort in one or both of the carbs.
 
This has been on hold. Had a bit of drama at my sister's house Saturday (like a big tree falling and landing on house/garage/both cars) and was busy all day Sunday.

Then radio went kaplooey so of course THAT was a priority.

Hubby's gone today and this evening - working up at the son's house - so I am going to dig around myself and see if I can't check out that fuel line.
 
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