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Fri Jan 22, 2010 5:33 pm

'73 1700 with a progressive carb. When the carb went in an electric fuel pump was installed. Over the last couple of months I've noticed the pump getting noisy. Then last weekend it got real noisy. I crawled under and inspected, and the nut mounting it underneath was loose. I hand tightend a little, still loose, but it seemed a little quieter. Parked it for the week intending to tighten the nut this weekend before using the bus.

This evening I was troubleshooting another issue and the bus was running great. Bhen I backed it out of the garage and it shut off. Started it, it ran for two seconds then shut off again. Now it won't start.

My first guess is that noisy fuel pump. Any way for me to check and see if it is pumping fuel? Without getting soaked with gasoline hopefully.

I checked threads first and didn't see anything. Thanks.

EDIT:

Just went out and tried it again. First try, it fired but didn't run. Second try, same thing. Third try, caught and I got it back into the garage. Throttle response seems kind of off.

Fuel pump?

Fri Jan 22, 2010 5:48 pm

Hate to say it, but you might have to do a fuel pump flow test. But first, do you know the kind of voltage your pump is getting? While it does sound like the pump may be getting old, it may also be some corrosion/resistance in the electrical portion of the pump. Check with a voltmeter to see if you are getting 12v to the pump. If so, and the concern persists, then you should do a pump flow test. You will need to disconnect the pump from the carburetor supply hose and run a different line from it into a marked container. If your pump is one of those screw-type pumps that does 3.5 gallons per hour, then you should see close to 36.83 milliliters or 1.24 fluid ounces in about 10 seconds. This is just spur-of-the-moment math, so don't hold me to those figures. Anyway, if the pump doesn't put out the manufacturer's claimed volume, then you need a new pump. If the pump does put out enough fuel, then think about checking to see if you have crud in you carb supply hose or carburetor itself.

And check/change your fuel filter while your at it. :wink:

Fri Jan 22, 2010 6:28 pm

Good tips. I'll check the voltage first. Filter looks clean. Fuel flow is last in line.

Does the fact that it sounds like a sub-machine gun indicate a possible issue? Shouldn't it be pretty quiet? Maybe running at a nice hum?

Fri Jan 22, 2010 7:10 pm

When you say SMG do you mean the noise your fuel pump is making? If so then the pump is quite suspect. But still, continue with the tests I spoke of. If you don't find anything bad with the fuel system then you should check out your ignition system components. But I digress.....

Have you tried waiting a few seconds before trying to start the vehicle? If it starts good but begins to cut out the fuel bowl may be emptying, indicating a possible fuel supply problem.

Now, is there anything you can tell us about the rest of your fuel and ignition system components, like age and last time you or someone else worked on them? Also, is it a weber progressive? Lastly, what was the other issue you were troubleshooting?

Fri Jan 22, 2010 7:26 pm

Definately excessive noise from the pump. I tightened up the mounting nut and the noise is muffled now, but if you turn on the key and walk 50 feet away you can still hear a very rapid tapping sound. It's dying, but not dead. Used to just hum.

Bus is back to running normal again. Fires right up, idles fine. I drove it around the block, no issues. I've one of those clear fuel filters and there's no trash, but it appears it may have some water in it. If so, that would likely be my problem.

The entire fuel system, hoses, pump, carb (weber), filter are about a year old. Gas tank was pulled, cleaned and sealed, but fuel these days is pretty much guaranteed to be contaminated coming out of the pump.

I'll pick up a replacement pump tomorrow and change the filter. If the new pump is quiet then I think I'll be set. I'll post results.

The other problem was shifting related. Thanks for the guidance.

Fri Jan 22, 2010 11:26 pm

Hey dude, no problem. That's why this forum is here, and I'm happy your bus is running better. If the pump is making that noise I would (as a mechanic and as an owner) replace it. It's a literal death rattle. But as a precaution, as you are down there replacing that pump you might as well check voltage supply. Just think of it as preventative testing.
Also, just wondering, but how do you power your pump, as in relay, direct ignition switch feed, etc.?

Tue Feb 02, 2010 5:21 am

Update: No water in the fuel.

My local FLAPS had the same pump that was already in the bus and failing, so I opted for a rotary instead which showed up last week. I installed it on Sunday (two days ago). Hums nicely, doesn't clack, bus fires right up.

The day before I installed the new pump the bus died on me again. Fortunately in the driveway. It would turn over and fire fine, run for a second then die. I let it sit for half an hour, tried again and it started right up.

Could have been the pump failing. It certainly sounds like a fuel issue, except for the fact that it starts again once things cool off. I guess I'll just keep my fingers crossed and see what happens.

Voltage was fine, by the way. There is no relay in the circuit I'm aware of. I think power pulls directly off the coil.

Mon Feb 22, 2010 11:39 pm

Mine just died on me tonight I think, no longer makes any noise at all. It drove fine today, then my buddy flicked the kill switch on the way home then back on. Got in the car to go to the store tonight, was leaving the store and the motor slowly died going up the hill to home. Starts, runs a second then dies; give it gas, dies; clear fuel filters behind each carb are dry. Could this be anything else, or is my electric fuel pump toast (no relay)? :-k

Tue Feb 23, 2010 7:10 am

I'm assuming this is some sort of non stock setup? Sounds like you're out of gas or the pump has died, checked that the pump is getting power and is grounding properly?