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| Moderated by: Greg Fletcher |
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| Intermittant Fuel Pump Problem | Rating: 
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| Posted: 11-19-2005 06:33 pm |
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1st Post |
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edward_davis Member 
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Yesterday, after driving for only about 20 minutes, my engine spluttered and died. I was able to restart it and get another two blocks, but she wouldn't idle, and eventually she wouldn't run. The fuel pump had been a lot quieter yesterday, so I immediately suspected it. There wasn't any fuel in the fuel filter, and when I pulled off the line below the pump and tested it with the key on, there was no suction. Also, the pump was pretty hot. So I called AAA for the three-block tow back to my apartment. I would have pushed her, except for the hills... After the tow, I switched the key on again, just to see what would happen, and the fuel pump made its normal racket. I guess that cooling off had made it function again. I was able to let it pump for a while and then fire her right up. So here's my question. Was it something I did? Do I need a new fuel pump? It's not the original type, by any means. I've attached a picture. I checked the fuel filter, and it looks clear. Also, the tank is a relatively new aluminum one, so I don't think rust/ dirt in the system is a problem. I had about 1/4 of a tank of fuel when this happened. Attachment: Fuel Pump.JPG (Downloaded 171 times)
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| Posted: 11-20-2005 01:16 am |
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2nd Post |
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Judson Manning Member 
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Ed, In my experience, JH's and fuel pumps just don't get along. While Greg Fletcher has had incredible luck, mine has been extremely poor with the original SU. Even the Holley pump I bought died after a few 1000 miles. The current pump I have came from AutoZone when I was stranded many years ago by my Holley. I walked up to the counter and said I needed a fuel pump for a 1975 MG. I think it cost me $20.00. If you don't know the history of the pump, it's cheap insurance to buy one from our quality sources and to have a little piece of mind. Judson
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| Posted: 11-20-2005 03:17 am |
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3rd Post |
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Gary Martin JH 15371 Member
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Ed, I agree with Judson. They are not that expensive for that "clicker" type you have installed. That type is commonly available at most parts stores. I would replace it and any fuel filters you have. Also you might check how well the pump is grounded. Your photo shows no bolt in one of the mounting holes. Gary Last edited on 11-20-2005 03:18 am by Gary Martin JH 15371 |
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| Posted: 11-20-2005 06:54 am |
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4th Post |
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Mark Rosenbaum Member 
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Ed's fuel pump looks like the typical Facet / Purolator unit sold by Delta and many other sources. The one in my car has been working fine for 4 or 5 years now. It normally rattles fairly loudly but will occasionally become less noisy or even stop clattering entirely, all without any apparent effect on the way the car runs. It's been doing this ever since I installed it, and the fuel pressure has remained a constant 2.5 psi at the carbs, so I feel safe in presuming this to be its normal behavior. Upon reading Ed's report, my first thought was that there was debris in the fuel. A single flake could hold open one of the pump's valves and thus halt fuel flow. The pump relies on this flow to remove much of the heat generated by its operation, and on good contact with the chassis to dispose of the rest. If there were no fuel flow, a pump installed in the manner shown by Ed's photo could easily get fairly hot. Perhaps the pump might even quit working as a result. This hypothetical debris could easily have come with the purchased fuel. A gas station's underground fuel tank(s) will rust, often heavily, and their pumps' fuel delivery hoses tend to rot from the inside out after prolonged exposure to fuel blends containing MTBE (which would have been the case in Ed's location). I would suspect this is why the Facet / Purolator instructions state that the pump should have a filter on its inlet line. In general, electric fuel pumps don't develop much suction, and the lack of suction from Ed's pump may not be significant. Also, the Facet / Purolator pump has both a ground wire and a power wire and therefore does not require a ground through the chassis. (However, as noted above, a good connection to the chassis may be needed to remove excess heat.) I've attached a photo of my car's pump installation. The filter is on the pump's inlet side, and there's another in the engine bay, just before the tee for the carbs. The two 90° elbow fittings were very inexpensive and allow a neat installation. The green tape secures the pump's power wiring. The black painted steel mounting bracket I ginned up for the pump is pretty much hidden, but it's there. What I would do in Ed's position would be (a) install a filter in the pump's inlet line and (b) secure the pump to the chassis via a good mounting bracket. I'd replace the pump only if it were to quit again once this was done. Attachment: facet pump & filter.jpg (Downloaded 88 times) Last edited on 11-20-2005 07:00 am by Mark Rosenbaum |
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| Posted: 11-20-2005 06:23 pm |
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5th Post |
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edward_davis Member
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I do have a fuel filter between the tank and the pump; I should have pointed that out in my original post. It was a relatively hot day on Friday when she quit, and I had her parked in the sun for two hours before I drove home. Could it have been vapor lock? I thought that a rear-mounted pump was supposed to prevent vapor lock, but the symptoms were there: hot pump, no gasoline in the filter, so there was air inside the pump. I should also explain that there is a bypass line that runs from a t-fitting above the pump and back to the tank. I'll put in a picture if there's a question. It looks like it's there to relieve pressure when the float bowls are full. Maybe. I don't think it's at all stock, nor is the tank. Does the stock tank have baffles? Mine does. I took her out yesterday for a drive and had no problems. Thanks for all of the suggestions.
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| Posted: 01-15-2006 01:52 am |
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6th Post |
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edward_davis Member
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After more problems and solutions, I have the fuel pump problem licked, but I now have a carburetor problem. The old fuel pump cut out several more times, so I replaced it with a new Facet Power-Flo. That's the one with the black plastic body that's supposed be longer-lasting than the old brass one. The old pump also caused an excessive flow of fuel from the rear carb, when it was working. I thought that what was happening was that, in failing, the pump was varying between no pressure and too high pressure. Of course, I really had two problems, so now that I have the new carb installed, and I've installed a fuel pressure regulator, I still have fuel leaking from the rear carb. The pressure is held to ~2 psi by the regulator, so that can't be the problem. I pulled the carb and took out the float and float valve. It's the ball-bearing kind, and it holds water under the faucet with only a slight pressure from underneath. The floats are water-tight, so no problem there. I'm going to get my calipers from work and check the float height on Monday. What else could be causing my problem? What could cause the float to get out of adjustment, if that's my problem? The gasket around the float bowl was intact; the leak was not from there. Thanks folks, Edward
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| Posted: 01-15-2006 03:16 am |
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7th Post |
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Mitch Ware Member 
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How about the o-ring on the brass/plastic plug that goes in the bottom of the float bowl? Mitch Ware 1974 Jensen Healey JH5 #111119670 1971 Triumph TR6 #CC66950LO
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| Posted: 01-15-2006 06:39 am |
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8th Post |
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Mark Rosenbaum Member
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"I pulled the carb and took out the float and float valve. It's the ball-bearing kind, and it holds water under the faucet with only a slight pressure from underneath." The valve has to seal tight against a pressure of 2.5 psi, which is equivalent to a 5-foot-high column of water. Just holding it under a faucet may not be an adequate test. "The floats are water-tight, so no problem there." Not necessarily a meaningful test, as gasoline may penetrate even when water won't (due to its higher surface tension). Weigh the float, if possible, or balance it against one from a carb that is known not to leak. IIRC, a good float weighs about 14.0 grams. "I'm going to get my calipers from work and check the float height on Monday. [...] What could cause the float to get out of adjustment, if that's my problem? " I don't know of any mechanism by which the float adjustment would change in service. If it's wrong, assume it was improperly set. "What else could be causing my problem? [...] The gasket around the float bowl was intact; the leak was not from there." Mitch Ware mentioned the o-ring on the brass/plastic plug at the bottom of the float bowl. This is a common place for leaks especially if there's any damage to the bore for the plug. These o-rings are offered by the usual suspects, as well as being a standard size that should be readily available locally. Other possibilities include a cracked rear carburetor body or float bowl, badly damaged threads for the fuel inlet valve, lack of gasket between valve and carb body, loose fit between fuel inlet pipe and carb body, and something wrong with the start enrichment ('choke') circuit in the front carburetor that would dump fuel into the rear carb through the connecting hose. And finally, any one of the hoses attached to the fuel tee could have a pinhole leak or might not be sealing properly.
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