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Is it that darn fuel pump!? Help!
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bdpt109
Posted 2017-03-21 8:00 PM (#536404)
Subject: Is it that darn fuel pump!? Help!



Member

Posts: 14

I'm about to drive my Belvedere off a cliff, but the nearest cliff is more than 2 miles away from my house and I don't think I can get there without it stalling...

But seriously. I had some problems earlier in the fall, where the car would stall repeatedly for absolutely no reason after about 15-20 minutes of leisurely driving. This was very annoying as it tended to happen in traffic prone areas. I've replaced the distributor with an HEI ignition system (thinking bad points/condenser/coil), re-routed some coolant lines (thinking the close proximity of fuel and hot coolant lines may be causing vapor lock), and rebuilt the carburetor (because why not). Well, on a drive around the neighborhood on a nice spring day, the symptoms returned with a vengeance.

Now I'm convinced the problem lies in the fuel system--but after an inspection of the inside of the fuel pump, everything looks okay...after all, the fella I bought the car from said it was brand new! My knowledge of mechanical fuel pumps is limited, but the diaphragm is clean and intact, and there's no evidence of gunk anywhere inside or out. The pump lever is fairly difficult to actuate with one's hand, but I figured that's the proper tension for the diaphragm spring...?

At the height of this problem's occurance, the level of fuel in the filter sight glass is very low. I disconnected the fuel line to the carb and cranked the engine, and the flow of fuel seemed to be kind of jerky.

Does anyone have some "ah ha!" advice? Any tips? I know this problem could be anywhere in the fuel system, but can somebody give me a place to start before I begin ordering every part in the book? Someone? Anyone!? Thanks!
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FourFans
Posted 2017-03-21 8:43 PM (#536406 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Regular

Posts: 62
2525
On old cars, it never hurts to have a spare fuel pump. Fuel pumps are also cheap. I would buy a new one, replace it, and then if the old one makes a normal sucking sound as you cycle the arm I would keep the old as a spare in the trunk. Fuel flow should be jerky, as it cycles when the cam pushes the arm down on the pump. Given that it is pumping, I kind of doubt it is the pump.

When troubleshooting, I love clear fuel filters. I would throw one in. If you don't want to replace/cut the line running to your carb, you can put one on the suction side of your pump, but that isn't ideal as pumps like to push not pull. You can then look for crud and fuel starvation (if it is on the carb side) My car has an in tank fuel "sock" type filter, hopefully yours isn't plugged.

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bdpt109
Posted 2017-03-21 8:52 PM (#536408 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Member

Posts: 14

I figured I'd probably end up getting a spare pump anywho--like you mentioned, it never hurts to have a spare anything! I have a clear glass fuel filter between the pump and the carb. When it stars acting up, the filter is nearly empty: at idle, when the car is fist started, it is full and stays full. I'm scratching my head. Could the floats in the carb be at the wrong level? I was very careful to measure when I rebuilt the thing...
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bdpt109
Posted 2017-03-21 9:08 PM (#536411 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Member

Posts: 14

I think the problem, honestly, is a nasty case of vapor lock. I'm up in the sky at 6600' elevation, and as I mentioned before, this problem starts when things get nice and warm. (Usually). Is there something about the design of this car that makes it more susceptible to vapor lock? Has anyone had this problem as well? Any fixes?
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FourFans
Posted 2017-03-21 9:27 PM (#536414 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Regular

Posts: 62
2525
I don't know your car. I know late 60s Mopars and have a 60 Chrysler. However, I find vapor lock is pretty rare unless the car gets hot as hell. Vapor lock is a term that I always heard for early EFI engines. I have heard and seen fuel boiling in the bowl, however on a hot motor. Usually it isn't an issue when running at speed as there is enough fuel flow to keep things cool enough.

I would change the fuel pump, and see what happens. If it still does the same, I would run the engine out of a gas can (fuel pump inlet length of hose when parked dipped in can) and see if it does the same thing. If it does the same thing, can eliminate your fuel system prior to the pump... if it doesn't do it again, then I would start cleaning fuel lines, fuel tank, etc.
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FourFans
Posted 2017-03-21 9:30 PM (#536415 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Regular

Posts: 62
2525
One additional thought. If your car is like mine, you may have a valve on the pass side exhaust manifold that originally closed to force the exhaust gas across the intake manifold into the other exhaust manifold and then out. The goal is to heat the manifold to make it run better when cold. The valve usually sticks mostly closed, but if it isn't, it could cause some really hot intake and carb temps. However, this scenario is very unlikely, as I assume the car ran well at some point while you've owned it.

I am at 7000 ft as well. Colorado.

Edited by FourFans 2017-03-21 9:35 PM
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60 dart
Posted 2017-03-21 11:58 PM (#536423 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Expert 5K+

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how clean is the fuel line and tank . heat riser is a thought . maybe the wrong gas cap . using a gas can as suggested would be a start---------------------------------------------later
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Richbo
Posted 2017-04-02 10:07 PM (#537236 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!


Veteran

Posts: 203
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I had this same problem - intermittent stalling - and I did all that you tried. Finally I happen to feel the ignition coil and it was screaming hot !!! I replaced it and the car never stalled again !!!
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56D500boy
Posted 2017-04-02 10:56 PM (#537237 - in reply to #537236)
Subject: Re: Is it that darn fuel pump!? Help!



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Richbo - 2017-04-02 10:07 PM
I had this same problem - intermittent stalling - and I did all that you tried. Finally I happen to feel the ignition coil and it was screaming hot !!! I replaced it and the car never stalled again !!!


Based on the little that I have learned since Sept. 15/2017 with my 56 Dodge:

1. Even supposedly new good coils can fail these days, perhaps based on the location of their manufacture. (Not North America).

2. A failed ballast resistor = 12V into the coil which kills a coil designed to run at 8V.

I had installed a new brand name coil on the 56 D500 hemi on Nov. 11th and the car ran not bad with it. When I took it in for proper timing and a carb adjustment, the engine died while idling at the shop and would not restart until they installed a new NAPA brand coil (one that needs a ballast resistor). Then it was fine.


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Beltran
Posted 2017-04-03 5:54 PM (#537293 - in reply to #536404)
Subject: Re: Is it that darn fuel pump!? Help!



Expert

Posts: 1729
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Location: Michigan
I recently had a similiar issue. Be sure that your alternator is properly grounded. Mine wasn't and it was over charging the ignition system. It cooked two coils and a pertronix unit before I figured out that once the engine got hot the ground through the mounting brackets would fail. I should have followed the instructions on the alternator and made a specific ground wire from the back of the alternator to the engine. Coils don't explode if you do that! /facepalm
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Beltran
Posted 2017-04-03 6:04 PM (#537296 - in reply to #536411)
Subject: Re: Is it that darn fuel pump!? Help!



Expert

Posts: 1729
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Location: Michigan
Ok so I did have this issue before. I went through all this same issue you are. I didn't discover the problem until I decided to put in a electronic fuel pump back at the gas tank. I thought that this would eliminate the fuel issues FOR SURE!
Well it did, kinda. Since the fuel pump was at the tank now, it pressurized the entire fuel line to the engine. What I learned was that I had a crack / pin hole in the fuel line at a turning point. Once it was under pressure it became obvious as it dripped a lot. But with the fuel pump at the engine it would suck the fuel from the tank and when the line got warm it would suck air into the line until it would not have enough fuel for the engine.

It never leaked! it was never even wet! that is until I put a rear pump in! Check your fuel line !
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