the recommission of our series 2 FB continues well, however a new issue occured whilst running up to warm after all the new hoses/coolant etc had been done.
The fuel pump keeps stopping, it was fine.
I had planned on dropping the fuel tank to check inside but the pump needs looking at.
I assume it is meant to tick all the time unlike other cars.....because the RX7 has a fuel return for constant flow. That is what it has done since we got it.
Now it works occasionally.
What pumps do people use? original or perhaps a facet or similar. It is only low pressure but fairly high volume given the fuel use of these cars
I believe you can still get the OEM pumps from mazda, I've never bought a new one and I believe they're quite expensive, or find a used one. This would be the most straightforward option, and should be fine if your car isn't modified.
The stock fuel pumps are known to barely keep up with a stock 12A, and not keep up even on just a 12A with a free flowing exhaust, if you're on long hills etc, although the big nikki float bowl kind of masks this. hogged out nikkis definitely need upgraded fuel pumps.
If you're going to upgrade the pump, you need to make sure you have enough fuel flow, and supply the right PSI to the carb. Racing beat say
4.5psi (S1/S2 should be 4.5PSI, and I S3 is 3.5 PSI, the pumps are different.) but some people who have changed the fuel pump have set their fuel pressure lower for their stock nikki carb, like 2.5-3psi. Stock there is no regulator, so you need to either find a pump that puts out the right pressure and flow, or get a regulator.
I think 50+GPH is a good idea as a minimum on a rotary, I believe the stock pump is 30GPH which is actually more than a lot of facets and similar. Also if you are using a regulator, you probably have a much lower flow after the regulator, so extra flow from the pump is definitely a good thing with a regulator.
I personally use weber carb, which is a bit different. They have a smaller float bowl and are a higher cfm carb, so you can't get away with a lower flowing pump. I use a holley blue pump and I have a dead head regulator. it is very loud and I don't really recommend it for a street car, but it works very well and wasn't that expensive. Other pumps that are popular are mallory and the carter 4070. My holley blue is 110GPH, carter 4070 is 72GPH and is very popular. I've heard of people using facets have not enough fuel delivery, and often use twin pumps, so I'd go for a higher flowing pump than a facet.
the nikki carb if you are using a regulator, I believe you can cap off the return line from the carb. I have heard of people using the same holley dead head regulator and holley blue pump. A bypass style regulator is kinder on the pump and keeps fuel temperatures lower, reduces chance of vapour lock etc, and is much quieter, my dead head regulator does get annoying gargling in traffic, but works. I will probably be changing mine for a return style. If you're using a return regulator, in theory you can have the regulator in the return line, the advantage is you have fuel flowing straight from pump to carb with no restriction from the regulator. I've not tried it, and haven't seen anyone try it on a nikki. EFI works the same way with the FPR after the injector rail not before, usually.
A couple of other things to consider - your rubber fuel lines probably need replacing and are likely perished, especially with more ethanol in modern fuel, and its actually really hard to buy good quality fuel hose, the market is flooded with sub standard far eastern made hose that doesn't do what it says on the tin!
if you're running a higher psi pump and a regulator, you will need a pressure gauge. Almost all low pressure fuel pressure gauges for the automotive market are terrible and can be several psi off, and liquid filled gauges vary wildly with temperature, you're better off getting an industrial gauge from an industrial hydraulics place than a classic car parts place.
The pump flow in GPH does change depending on fuel pressure! for example my holley is 110gph at 3psi, but 65gph at 14psi, so check what pressure the flow is rated at!
Oh and change your filter whilst you're changing pump!
Hi, thanks to you both, I already have a new filter which was on the list when I drop the fuel tank. I even wondered if it may have blocked with muck coming through from the tank after so long idle. Perhaps that could even cause the pump issue if its hard to suck?
Sometimes it clicks a for a few seconds, others I just here a clunk.
It has been fine since we got it until yesterday and always worked.
Pump off and it is intermittent...give it a tap and off it goes. I have not looked yet, it is still mounted on the plate but It does look like the end cover will remove to potentially clean up the contacts inside like the old SU ones etc. They have solid state conversion sets available even.
The fuel filter is cut open...not nice! tank to come out next. can anybody tell me where the sender unit wires are for the furl gauge? the gauge does not even register.
anybody got a usable fuel gauge sender?? also ideas gratefully received as to how to remove this one!!! usual angle grinder in heads not wis with all those fumes unless I fill the tank with water perhaps.
I'd be amazed if the tank doesn't leak, looking at that photo - that sender is a complete mess too
I must have been very lucky with KIMI 1. Here's a photo of the tank when I was cleaning it up to give it a good protection coat. The sender is on the top of the tank. It was easy to remove, in amazing condition and was still working fine. Having said that, I did find an electrical issue, which meant a small fix when I reinstalled it (with stainless steel bolts!).
Fuel Tank rust prep 2 .JPG (145.73 KiB) Viewed 10776 times
2015-02-04 15.28.07.jpg (129.81 KiB) Viewed 10776 times
KIMI 1 : 1st Gen, "hybrid" 1983 silver S2 running gear in a 1985 S3 shell, SORN'd, long term resto project
KIMI 2 : 1st Gen, 1983 silver S2 - now sold to Ian Mothersole on here.
KIMI 3 : 1st Gen, 1983 red S3
Plus a 2004 Full Bridgeported RX-8
rustyrescue wrote: ↑Fri Apr 16, 2021 6:02 pm
anybody got a usable fuel gauge sender?? also ideas gratefully received as to how to remove this one!!! usual angle grinder in heads not wis with all those fumes unless I fill the tank with water perhaps.
I had the same problem with mine. Had to drill out the screws and re-tap the threads. However, the original threaded holes are only in the upper plate. I had to tap these through into the tank itself. I fitted 16mm long M4 bolts from the inside out ( fiddly ), secured with Loctite. On to these "studs" i could place the new sender with lock-nuts. A new sender is still available at Mazda. Was about 85 Euro.
unless I fill the tank with water perhaps.
