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Jul 16, 2012 13:21:37 GMT
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The e21 320/6 car I'm working on has an electric fuel pump fitted, even with my finger holding the float shut the pump continues and floods the carb (presumably why the car sometimes randomly stops?). Is there a way to regulate electric pumps some how? Is the original pump likely to still work after a few years of dry pumping? Also can anyone tell me how the vacuum below is meant to work, it looks like the vaccum is meant to keep it shut at idle and then open it at full throttle? Its a solex 4A1 carb.  |
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Last Edit: Jul 16, 2012 13:27:50 GMT by mgbizzle
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Jul 16, 2012 13:34:54 GMT
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The vacuum should keep it shut at idle and open it up as it goes up the revs. Does the car not have a fuel pressure regulator hooked up? it should be restricted to about 3-5psi IIRC filter king fuel regulators are pretty good.
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Last Edit: Jul 16, 2012 13:35:56 GMT by damien4884
1977 datsun 810 180b estate |
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Jul 16, 2012 13:40:06 GMT
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The vacuum should keep it shut at idle and open it up as it goes up the revs. Does the car not have a fuel pressure regulator hooked up? it should be restricted to about 3-5psi IIRC filter king fuel regulators are pretty good. The way the spring arrangement works though keeps it shut, the only way I can see it working is at a higher throttle range the vacuum starts opening the butterfly's. The car does have a regulator, could this be at fault? Also reading further into electronic fuel pumps could the random stopping be caused by the fuel pump being mounted high up near the carb? |
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Last Edit: Jul 16, 2012 13:40:59 GMT by mgbizzle
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Jul 16, 2012 13:53:44 GMT
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Should open up around 3000-4000rpm, my vw van had a similar carb bit smaller and the spring had come off and if you went over 3000rpm the butterfly would start to open catch the air going in shoot open and jam it on full throttle.  Normally you would mount the pump in the boot/ low down near the tank so gravity pushes the fuel towards it rather than it sucking it up and mount the regulator near the carb. Going by the rate it sounds the fuel is coming out I would say its not being regulated properly. If its an adjustable type try turning it down more and see whats happens. Off topic but Su carbs will shut off 3psi reliably and will deal with upto 5psi but no more (as long as the float valve is good) most carbs should be around the same. |
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Last Edit: Jul 16, 2012 13:55:36 GMT by damien4884
1977 datsun 810 180b estate |
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Jul 16, 2012 15:19:10 GMT
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Normally you would mount the pump in the boot/ low down near the tank so gravity pushes the fuel towards it rather than it sucking it up and mount the regulator near the carb. Would it work intermittently if fitted high up? |
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Jul 16, 2012 15:30:55 GMT
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It should be mounted so it pushes fuel not pulls it, if the pipe comes out the top of the tank and you mount the pump in the boot its not far to pull so should be alright, however mounting it at the other end of car up in the air could be causing some problems.
Has the car been running using this set up before? sounds like the mechanical pump hasn't worked for a few years so i'm assuming it has been alright with current set up to now?
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1977 datsun 810 180b estate |
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Jul 16, 2012 15:53:02 GMT
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Has the car been running using this set up before? sounds like the mechanical pump hasn't worked for a few years so i'm assuming it has been alright with current set up to now? Apparently there's nothing wrong with the mechanical pump hence why I'm tempted to try it, it has had issues with randomly cutting out and flooding before on the electric pump. I'm only really going by what people have told me though so its hard to say whats true and whats not. |
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Surely whatever needle valve closes the fuel inlet into the float bowl should shut off tight enough to stop fuel flooding the float bowl and stuffing the fuel mixture?  So either you need to fix/fit the/a regulator so that the pump pressure cannot overcome the sealing of the needle valve, or replace the needle valve?? My only experience with this is from my Mini which obviously runs SU's - the needle used to jam and not shut off properly, flooding the float and so on... Hence, if I'm talking rubbish feel free to ignore me... :-) |
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Mechanical pump could be ok or it could be knackered from "dry pumping", you would have to have a look/test it.
I would inspect the float valve/replace, move the electric pump to near the tank with a filter before it, fit a regulator in the engine bay turn it down to about 3psi then see how it goes.
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1977 datsun 810 180b estate |
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Jul 17, 2012 13:34:15 GMT
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I tried the old pump today and I think its fubered. I think the main problems are the pressure of the electric fuel pump and its location.
Would moving the fuel pump nearer the tank reduce the pressure? Would putting a filter in front of the pump also reduce pressure? Are they relatively waterproof or do they need to be housed in something?
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Last Edit: Jul 17, 2012 13:42:00 GMT by mgbizzle
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ChasR
RR Helper
motivation
Posts: 10,194
Club RR Member Number: 170
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Jul 17, 2012 17:25:51 GMT
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What you have suggested may reduce the pressure but by no significant margin. A regulator will however. Whereabouts in the country are you? If close to Warwick I could check your fuel pressure with a gauge of mine?
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Whereabouts in the country are you? If close to Warwick I could check your fuel pressure with a gauge of mine? The cars in Malaysia, so unless your willing to take a flight out here... ;D Il relocate the fuel pump today and then go from there. |
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