NOT Vapor lock? Options

[mrholland2]

Full story:

About 600 miles ago I replaces my Electric fuel pump (carbed 1.7) because it was silent. Replaced with a low pressure Napa inline pump in the exact same location.

Last week on my way home from work, (98 degrees), drove to the gas station and filled up the tank after being down 2/3. I stopped after 11 miles to get the mail, the car started, drove 10 feet and died (going downhill). . managed to get it to sort of run for the 1 block home eventually. Ran 2 hours later (didn't drive it)..

Drove it the next morning 11 miles to work. . no problems. . drove it a few miles to lunch. . no problems. On the way home (95 degrees) stalled while driving downhill, coasted a while and stopped 10 minutes NOTE-FUEL PUMP WAS VERY HOT). . it started and ran 1 mile, and stalled again driving down hill, coasted and pulled over. . started after 15 minutes and drove it home. Started and ran fine 2 hours later (didn't drive it).

It sat for several days.

This morning (temp 70 degrees) started and ran fine. Drove 2-3 miles and it stalled again, on a slight decline. Pulled over and it started right up. Turned around and headed home. Stalled again after 1.5 miles. . again, a slight decline (not sure that matters). Started right up and drove it home (large UP hill which it did fine). Haven't checked anything after that, but am seeking advice.

Here are the suggestions I've gotten or found:
1. Gas tank not venting.
2. Vapor lock (doubtful from this morning's debacle)
3. Bad new fuel pump
4. Crap in the bottom of the gas tank suddenly causing a problem.
5. Little German gremlins messing with my mind.

Thanks in advance for all your help. You guys are great!

Sean

[mrholland2]

Seriously help!!!!!!

[bigkensteele]

I know that you said it is in the same location as the one you replaced, but is it still in the engine compartment, or had it been moved up front? I know nothing about carbed cars, so I am just asking the question that others will also ask.

Have you replaced any of the fuel lines? I recently replaced all of mine, and I am also experiencing an intermittent fuel starvation problem. I think that one of my soft lines under the tank might be kinking, but I am not sure how to verify this.

[timothy_nd28]

Doesn't sound electrical, but it does sound odd. Your car repeatily fails when it see's a slight decline? Is it possible your drawing fuel from the return port on the gas tank?
To isolate the electrical, vs mechanical,,,wire up a dummy light at your new fuel pump, and run the wire inside the interior. So that you can see the light. Drive around and try to duplicate the failure by finding a steep decline. If the light goes out, you can then concentrate on the electrical side. I personally believe it's more mechanical, either the wrong port used, or maybe a kink in the rubber lines under your tank,,or even a hidden plugged fuel filter under the tank. What year is your car?

[ChrisFoley]

What is the location of your fuel pump?
If nothing wrong with the fuel pump, what is the status of your fuel tank strainer or inline filter?

[Mike Bellis]

Fuel may be vaporizing in the pump due to the overheating. This could be caused by fuel pump pushing on the carbs which are using little fuel. I saw this on a larger scale with a diesel pump pushing on a pressure regulator. Pump got so hot, it vaporized the diesel.

[mrholland2]

Okay, answering the various questions:

The pump is in the engine compartment and is a low pressure pump.
I didn’t replace any fuel lines, but some were replaced 1500 miles ago, but did not cause problems with the old pump.
I’m not sure the slight decline is part of the issue EXCEPT the carb might be drawing less fuel causing the proposed heating of the pump issue which is vaporizing the fuel in the pump????
I don’t know about the tank fuel strainer, but I think it would be odd for it to be fine and then doing this suddenly? (Maybe not?) the filter is new with the pump (few hundred miles)
As I said, I swore it was vapor lock when the temps were in the high 90’s to 100s but then it did it worse in the 70’s.

Sean

[ChrisFoley]

It sounds like either the pump is nfg, or there's a blockage in the supply to the pump.