32valves Posted September 2, 2012 Share Posted September 2, 2012 I've been using an electric fuel pump on the Sprint for a few years now (replacing the standard mechanical pump). It's made by FAI and supplies fuel at 2 - 3 psi, 90 litres per hour. Since changing over to 2" SU's, occasionally under really hard use the car has spluttered a bit leading me to suspect that the pump isn't supplying fuel fast enough. If I assumed my car gets down to about 5 mpg running flat out in top gear, ~120mph, that equates to about 24 gallons per hour which is higher than the pump output (90l/hr = ~19.8gal/hr). The fuel consumption is likely to be similar or higher in the intermediate gears too so it looks like I need a new pump. Does this sound right ?Anyway, I've been looking at other after-market pumps, particularly Facet. There seems to be two types, the 'cube' type and the 'cylindrical' type. Apart from price what are the relative merits of these ? Quote Link to comment Share on other sites More sharing options...
TimW Posted September 2, 2012 Share Posted September 2, 2012 cylindrical type tend to have a much higher supply rate. Quote Link to comment Share on other sites More sharing options...
alan pettit Posted September 2, 2012 Share Posted September 2, 2012 ive had 2 failures with the metal square facet type, no problems so far with the black platic cylinder type Quote Link to comment Share on other sites More sharing options...
paulsprint Posted September 3, 2012 Share Posted September 3, 2012 Carl. Does it happen on a straight road or is it when coming out of a bend. I've had all sorts of problems with what I thought to be fuel starvation issues. Turned out to be mostly flooding problems. If it is on the straight after a long period of full thottle then fuel starvation is likely. The first thing to do is change the needle valve for the hi flow completion type. ( the hole is a lot bigger and therefore can flow more fuel.). If the problem happens after the car has been cornering hard then you may need to change the position of the floats. This is done by moving the float lid round. My car would always have problems on fast hairpin bends or when doing autosolos. I after much messing around traced it to the above float problem. Repositioned the float lids and I've never had a problem sinse. Quote Link to comment Share on other sites More sharing options...
32valves Posted September 5, 2012 Author Share Posted September 5, 2012 Cheers for the replies chaps. Paul, it's definitely when accelerating hard but doesn't do it all the time which is why I'm guessing the pump is marginal. I'm assuming you're talking about the float valves. Where can I get the type you mention ? Interesting point about cornering. It might be worth re-positioning the float as you suggest anyway. Let me know what orientation works best and I'll give it a go. Quote Link to comment Share on other sites More sharing options...
Straight Six Posted September 5, 2012 Share Posted September 5, 2012 If you do end up buying a new pump, my car has a Holley Red Top pump. One of these will be more than sufficient for your Sprint, but if you do go for one be aware that they are very noisy. Apparently the Holley Blue Top is quieter, but would be over kill for your engine. Quote Link to comment Share on other sites More sharing options...
32valves Posted September 5, 2012 Author Share Posted September 5, 2012 Hmm, red top looks interesting but info says not compatible with alcohol fuels. I wonder if this includes the E10 that will be inflicted on us. The Holley billet electric fuel pump is apparently compatible with such fuels but would be way overkill for my car (and would need a pressure regulator). Food for thought although ~£230 is a bit more than I was planning to spend ;D Quote Link to comment Share on other sites More sharing options...
TimW Posted September 5, 2012 Share Posted September 5, 2012 I would always use a good quality fuel regulator with most electric pumps as most produce 4 or 5psi which is too much for SU's Quote Link to comment Share on other sites More sharing options...
paulsprint Posted September 6, 2012 Share Posted September 6, 2012 Carl, the needle valves are from burlen fuels they are either 0.096" or 0.125" bore> the standard ones for hs6 etc are 0.070" as for the float lid positions i turned the front one so the inlet pipe is pointing to the left hand side. ( this is no problem as the mounting holes line up, just need a bit of longer fuel hose) the rear carb is a bit more tricky as the fuel inlet pipe needs to point to the air box. the mounting holes don't line up so i used some washers under the screws to hold it down. Before i changed these round i was having so much trouble when doing track days or autosolos. i thought it was fuel surging so fitted a swirl pot etc all to no avail. it was out of sear desperation that i started messing with float chamber lids. after much testing one Sunday on an industrial estate with plenty of islands i came up with this solution. Quote Link to comment Share on other sites More sharing options...
junkuser Posted September 6, 2012 Share Posted September 6, 2012 Fuel pressure will be more critical with those larger valves. Quote Link to comment Share on other sites More sharing options...
32valves Posted September 7, 2012 Author Share Posted September 7, 2012 Cheers Paul, I've ordered some of the large bore valves and I'll have a look at moving the floats around this weekend. Since the current pump is supplying at more or less the right pressure the change to the larger bore valves may well cure the apparent fuel supply issue. I think a good 2000 mile road test is in order ;) Quote Link to comment Share on other sites More sharing options...
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