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Discussion Starter #1
I have a 2005 Elise with the BOE REV300 supercharger kit (stock fuel pump, stock cat, stock exhaust).

I think my stock fuel pump is failing. (Often doesn't operate when I turn the key on (no fuel pump whine when it isn't working, but do hear the relay click), and the engine stalls soon after starting when there is no fuel pump whine at startup. It is now doing it sometimes while driving even though it was working for a little while. There is a chance it is an intermittent fuel pump relay problem, which I will diagnose this weekend).

If I confirm it is the fuel pump, I am considering replacing the stock fuel pump with the Walbro 255 pump. However, I need to know if my current ECU tune for the REV300 will work fine with the Walbro pump, or if I need a new tune. (The higher pressure at high flow rates from the Walbro could make it run too rich at high throttle, unless the ECU can learn to compensate. But, at high throttle, I thought it ran open loop, so no learning.)

Does anyone know if I would need a different ECU tune with the Walbro? (I tried emailing BOE a few times, but didn't get an answer.)
 

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Drone Racing Pilot
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Do you have any way of controlling the fuel pressure? Is your lotus converted to a return style fuel setup?

Installing a walbro 255 over the stock pump will require a retune of the ecu for sure. The stock pump flows about 180lhr vs the 255lhr.~ 34% increase in flow. The ecu will not be able to compensate for this and all of the fuel tables will need adjustment. If you drop the Walbro 190lhr pump in there it may not require a retune but might still run a bit richer than the stock pump.

If you decide to drop the 255 in there, i would recommend converting your fuel system to a return style and add a fuel pressure regulator for control. The stock ECU will need adjustment after this mod to be sure everything is still safe.
 

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Chris, check out our Denso pump/kit: HERE It will easily keep up with your power output and is in stock. It is plug and play and does not have the annoying whine of the Walbro pumps. They are loud.

 

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Discussion Starter #5
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Installing a walbro 255 over the stock pump will require a retune of the ecu for sure. The stock pump flows about 180lhr vs the 255lhr.~ 34% increase in flow. The ecu will not be able to compensate for this and all of the fuel tables will need adjustment. If you drop the Walbro 190lhr pump in there it may not require a retune but might still run a bit richer than the stock pump.
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That is what I thought as well, but I was just trying to get some other opinions in case I misunderstood something. If I change to a non-stock pump, I only want to change to a pump for which BOE already has a tune. I don't want to do custom tuning for just my configuration (this is just a daily driver street car after all - no tracking, no competitive auto cross).

So, if I have to just get a replacement stock pump to preserve my tune, is it just the 2000-2005 Toyota Celica GTS pump? (Current Toyota part number 23221-28280.) I found it as low as $250 from an online Toyota dealer parts department ($770 from Lotus).

If my problem turns out to be a faulty relay, I bought four replacement relays (same relay part that is inside the Lotus Multi-Function Relay Unit) on eBay last year, and I'll just solder in a replacement into the MFRU.
 

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ky13
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Just to note, if your fuel pressure and injectors are the same, your tune would not be affected by changing out to a pump that is more capable. The same amount of fuel will still be injected. I've switched friends cars from 255 to 340 LPH pumps without issue (shameless plug: I tune AEM EMS :p ). Caveat to the aforementioned: it's possible to overrun the stock fpr if you drop in a much larger fuel pump (translation: the new pump pushes too much fuel for the stock regulator to maintain, so you end up with higher than desired pressures). It seems that the OP may still be utilizing the stock fuel system (pump/fpr), in which case, I would recommend upgrading to an aftermarket FPR and pump.
 
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I have a 2005 Elise with the BOE REV300 supercharger kit (stock fuel pump, stock cat, stock exhaust).

I think my stock fuel pump is failing. (Often doesn't operate when I turn the key on (no fuel pump whine when it isn't working, but do hear the relay click), and the engine stalls soon after starting when there is no fuel pump whine at startup. It is now doing it sometimes while driving even though it was working for a little while. There is a chance it is an intermittent fuel pump relay problem, which I will diagnose this weekend).

If I confirm it is the fuel pump, I am considering replacing the stock fuel pump with the Walbro 255 pump. However, I need to know if my current ECU tune for the REV300 will work fine with the Walbro pump, or if I need a new tune. (The higher pressure at high flow rates from the Walbro could make it run too rich at high throttle, unless the ECU can learn to compensate. But, at high throttle, I thought it ran open loop, so no learning.)

Does anyone know if I would need a different ECU tune with the Walbro? (I tried emailing BOE a few times, but didn't get an answer.)
This sounds more like an immobilizer problem or a wiring/connector corrosion problem than a fuel pump problem. First check the wiring and connectors, including the relay. Then make sure your immobilizer is working properly.

The fuel pump may be replaced with no ill effects to the tune or other things.
 

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You might look at doing fuel surge pump from BOE. it fixes two issue are once . more fuel and no fuel starvation
 

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Drone Racing Pilot
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Just to note, if your fuel pressure and injectors are the same, your tune would not be affected by changing out to a pump that is more capable. The same amount of fuel will still be injected. I've switched friends cars from 255 to 340 LPH pumps without issue (shameless plug: I tune AEM EMS :p ). Caveat to the aforementioned: it's possible to overrun the stock fpr if you drop in a much larger fuel pump (translation: the new pump pushes too much fuel for the stock regulator to maintain, so you end up with higher than desired pressures). It seems that the OP may still be utilizing the stock fuel system (pump/fpr), in which case, I would recommend upgrading to an aftermarket FPR and pump.
I don't think this is a correct statement "Same PSI - flow rate should be the same, even with higher output pump". If you look at the chart that @shinoo posted you will see the Flow Rate/Volume output is higher at the same pressure. This is the main reason for upgrading the pump to a higher flow rate for the same PSI. What you can also see on the chart is, if the new pump is pushing closer to 80psi (restriction of the stock line/FPR possibly) the flow rate is approaching the stock pump levels. Trust if you have an aftermarket FPRR controlling the fuel pressure that is not getting over run, you will need to adjust the maps or dial the pressure back to adjust for the extra volume. The stock FPR-returnless will see a pressure and volume drop when the engine is running at full tilt, the aftermarket pump may not fall off like the stock pump and that in it self may require slight adjustment to the maps.

This is the same concept with turbo/super charger flow rates.
15 psi on a GT28 vs 15 psi on a GT30. Same PSI, huge difference in flow rate and efficiency. PSI only tells half the story, flow rate is the key here and what is used to calculate power output.
 

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If this is the same pump as the S260 and it does not have a different fuel system, there would be no reason to think it would need a tune to run.

I am no expert, but unless you are definitely over the regulators ability to regulate a larger pump should act exactly like the stock pump. From the graph, the higher the pressure the closer this pump is to the stock pump. The injectors are the restriction, so at the same pressure, they are going to move exactly the same amount of fuel no matter what the pumps ability to flow is.
So if Lotus uses the same regulator with this pump, it would seem to be a safe bet
 
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