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 1955 Belvedere mechanical fuel pump still not working!Jump to page : 1 Now viewing page 1 [50 messages per page] | View previous thread :: View next thread |
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Drakeule |
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| This is a new thread to my previous one; I rebuilt the 4280 pump and car started, but died soon afterwards. Hooked up electronic pump and started right up again. Does my Elec. pump (it's most probably the APDTY one available on amazon) need to be bypassed for the mechanical one to do its job? (I haven't checked the PSI without the electronic hooked up.)  | |||
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| 58coupe |
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Expert Posts: 1739     Location: Alaska | |||
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| Drakeule |
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| 58coupe- thanks for the response: Just bypassed the elec. pump, and get 0 PSI when cranking from mech. pump. When you say the cam is worn, do you mean the actuating lever on the pump, or the engine internal cam? If you mean the internal device, I too have had the latter above happen with one of my old Alfas; a high end repair shop friend said that when this happened with the old Ferraris, he just installed a elec. pump as the fix. So, my previous owner (deceased) of the '55 may have known something I didn't...  Thoughts? | |||
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| 56D500boy |
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Expert 5K+ Posts: 9893   Location: Lower Mainland BC | Drakeule - 2021-04-08 10:03 AM When you say the cam is worn, do you mean the actuating lever on the pump, or the engine internal cam? The fuel pump on these old V8s was driven by an eccentric cam mounted externally to the engine, behind the timing cover. (See photo below to see the fuel pump drive cam behind that big nut). I think that you should probably remove the existing mechanical pump and arrange it somehow that you can man-handle the lever arm (move it up and down). You should hear a sucking pop each time you move the lever arm. If not, the diaphragm inside the pump might have a hole in it. That being the case you will need a new pump or a rebuild (there are kits out there if you are game for that). https://innovationdiscoveries.space/diagnosing-and-replacing-a-mecha...  Edited by 56D500boy 2021-04-08 2:16 PM (TimingChainOilTrough_1.jpg) Attachments ----------------  TimingChainOilTrough_1.jpg (189KB - 169 downloads) | ||
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| ronbo97 |
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Expert Posts: 4036 Location: Connecticut | |||
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| Drakeule |
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| The pump seemed to spritz just fine on the bench. I felt vacuum on the "in" side. However, when installed ,I got zero PSI. Could that rocker arm on the pump be so worn that it can't be "excited" by the cam? It appears that the cam and eccentric under the timing chain cover would not be the problem (?) However, I did disturb the exit pipe on the gas tank (looks as if someone did a "quasi donkey" brazing repair in the past on it), and now it's leaking fuel. So I now have a bigger problem. If I can't seal it, expect a new thread discussing options for a new vs rebuilt fuel tank.....  | |||
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| 56D500boy |
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Expert 5K+ Posts: 9893 Location: Lower Mainland BC | . You might have blockage of some sort in the fuel line from the tank to the mechanical fuel pump. I would use a hand-held MitiVac on the fuel line to the fuel pump at the pump and use the MitiVac to pull some fuel from the tank. No fuel or difficult flow = line blockage. There has to be a reason. You just need to find it.  | ||
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| samstrader |
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Extreme Veteran Posts: 443 Location: Beaumont TX | |||
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| 58coupe |
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Expert Posts: 1739 Location: Alaska | |||
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| ronbo97 |
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Expert Posts: 4036 Location: Connecticut | |||
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