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Discussion Starter · #1 ·
Hey folks. I had Dragon running in August to have its windscreen replaced. No problems indicated or hinted, just needed to be jumped. I have family visiting so I'm trying to get a second car on the road, but when I went to get Dragon out of its garage, it has refused to start.

Now I've been here before and this time I've checked I have power - there is battery voltage to all the EFI and ECU fuses, and according to my ignition tester, there is spark, so this isn't the relay issue I had before. The rest of the symptoms are the same - cranks but won't fire, smell of fuel in the exhaust.

I pulled the spark plugs and all 6 were in bad shape. They're Bosch Super 4s, which have 4 electrodes and should in theory be good for 48k miles, but they showed white deposits and the centre electrodes were worn down by about half. They've been in the engine for about 30k miles. There was also some yellow substance on the plugs - sulphur?

In any case, white deposits means the car has been running hot, so that means running lean. However, I've always thought Dragon runs rich - there's a lot of after-firing after letting off the throttle, and the emissions results showed that hydrocarbons were a little higher than permitted on the latest Euro 4 specs (which Dragon doesn't need to adhere to), and since running rich is better than running lean, I've left it. But seeing the state of the plugs, I clearly need to do something.

Whilst I can smell fuel, I can't tell if the fuel pump is running. I bridged the check connector and put my ear to the tank, but I can't hear anything distinct. There's 12V at the pump connector. I'm wondering if the fuel pump could have been failing over time and has finally died. That said, Dragon has been responsive and still very driveable. I know about the MK2 pumps having a dead-spot issue and my dad says it's been replaced with a MK3 pump instead (Dragon has an in-tank pump). I have spare MK2 pumps but I don't know if they work, though I could hook them up to a battery to test. There are a few kilo-ohms of resistance on the pump terminals in the tank, though I know that's not indicative that the motor works.

Dropping the fuel tank is tedious and I'd like to avoid it. Is there anything else I've missed?

Thanks!
 

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Discussion Starter · #3 ·
Rob, I would check the EFI fuse under the hood and the power relay in the footwell reset with a paper clip.

Plugs for me ONLY NGKs or Denso, I run the plugs for a 6M per Tanya.

GL
I checked that fuse as well, there's 12V to it (and all the fuses I checked are sound). I put an ignition tester on cylinder 3 and it was flashing, so I have spark this time (meaning the ECU should be powered). The tester only confirms there's a circuit and that power is getting to the plug, so it doesn't confirm there is a strong spark.

I know people recommend NGK plugs and I did look at getting them, but my local parts store doesn't stock them any more and did have the Super 4s in stock... then they gave me 2x Super 4s and 4x standard Bosch plugs, getting that resolved tomorrow morning...
 

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Discussion Starter · #8 ·
Where is ole dave to show you the fuel tank access hole mod? If you do end up dropping the tank, make sure you cut your floor and install yourself an access hatch for next time. It could be something as silly as low voltage to the pump, but without an easy access hatch you have to drop the tank to find out.

I second the fuel pressure check, it's not hard to do per the TSRM and may save you dropping the tank.
No thanks, I'm not cutting holes in Dragon! I've seen those 'mods' and would prefer not to. I've had the tank out a few times already for repairs so it's not difficult, it's just a lot of faffing about with hoses and straps.

It could be something silly, yes, but if it's a dead pump, I'd rather pull the tank out of the car to replace it.
 

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Discussion Starter · #9 ·
Gargravarr,
I don't have a lot of experience with Mk2 or Mk3 fuel pumps, but from what I've read, the pump resistance should be between 0.1 and 3.0 ohms.
If the resistance across the terminals at the tank are in the kilo-ohms range, I strongly suspect your fuel pump is shot.
If you have other fuel pumps I would measure the resistance on them to compare. If they are under 3 ohms, then I'm pretty comfortable predicting a bad pump.
Dropping a gas tank scares me so I would double check for comparison's sake.

If you are running 14V to the pump and assuming no in-series resistor, the current should be 4.66 Amps which seems reasonable for a fuel pump.
If you are running 14V to the pump and the pump internal resistance is 2 kilo-ohms, the pump will only draw 3 milli-amps.
I'm pretty sure 3 mA isn't going to give much pump pressure.

Again, I would compare what the other fuel pumps measure.

Good luck getting it going

Dale
Great info as always, Dale. I'll check my spare pumps. I have a battery and leads to try running them.

I've read that electric motors don't have constant resistance - you can't infer a motor's power draw from the resistance across the terminals, you can only get its wattage by measuring the amps drawn at peak stall. Looked into this when I was modding an electric skateboard (yep!) and needed to know what to spec the electronics for.
 

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Discussion Starter · #12 ·
Nope. So my dad and I changed all 6 spark plugs, and I gave the fuel tank a few whacks with a rubber hammer while the check connector was bridged. Still no start. Seems to be pretty conclusive that it's the fuel pump.

What do people recommend to replace the pump with? I've seen the Walbro 255 recommended, and on Raptor Racing, there's a Bosh model 044 offered. I tried both my spare fuel pumps and neither of them showed any continuity, so I think I need to look at a new pump.

If so, anyone know a trustworthy supplier in Europe? I'm wary of fakes on Amazon and eBay.
 

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Discussion Starter · #17 ·
Thanks guys, I didn't figure the OEM pump would still be available. I've phoned a couple of Toyota dealers near me but the Parts guys don't seem to be working today. However having the Denso part number is perfect, thanks very much 82TURBOSUPRA. I'll see if I can source it in the UK.

dannoxyz - yeah, I will. I brushed off the plugs the first time I had them out and I didn't get a picture of the mess on the electrodes. I did test the pump at the connector on top of the tank. Not sure if I have a piece of hose to check for fuel flow.
 

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Discussion Starter · #18 ·
As promised, here's a couple of photos of the plugs. They've been in the engine since 2013, nearly 30k miles. The burn marks around the ceramic are particularly concerning. I brushed off the white and yellow deposits, and I didn't get a photo of them, sorry.
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I managed to get through to Toyota and against the odds, I can get both the Aisin and Denso pumps brand new, however they're asking over £300 for either pump. The Denso pump would need 3 days to ship from Europe, but the Aisin one would have to come from Japan.

I've looked elsewhere and I can get the Denso pump as listed by 82TURBOSUPRA from either eBay or Amazon for much cheaper (£85 from Amazon), but both ship from the US, which entails shipping delays and import taxes. Obviously I don't want to spend huge amounts of money on something as small as a fuel pump, but if the OEM from Toyota is the best option, then I guess I'll have to.
 

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Discussion Starter · #21 ·
Plugs look OK after cleaning. Burn marks are normal combustion, nothing to worry about. One thing I don't like about Bosch plugs is centre electrode can fall out, causing engine damage. More likely on turbo engines during tuning and getting some knock. I prefer to stay away from them if possible.

What's import-duties when shipped from U.S.? Is it percentage of total declared value or flat-fee?
Well I hadn't heard that one, you'd think a company as experienced as Bosch could figure out how to make that not happen! Duly noted as and when I get a turbo going.

Import duties are a percentage. It wouldn't be huge (20% or so) but this usually has the effect of delaying the shipment. And with global shipping being completely screwed at the moment... I dunno if Toyota's logistics would be better (you'd hope so, given Toyota's reputation!).

I'd be more concerned about fakes, though between an OEM and a performance part, I'd hope most fakers would choose the latter.
 

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Discussion Starter · #22 ·
You could use a walbro 255. The kit for most older Toyotas is the same.
I could, but you said yourself, noisier and less reliable. What is the reliability like for the Walbros?
 

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Discussion Starter · #26 ·
Watch out for fakes of Walbro 255 and Bosch 044 due to their popularity. These are both +400bhp pumps, so maybe select something slightly smaller and less popular to lessen chances of countrefeits.
Are they all the same size? If I turbocharge Dragon, I'm aiming for <250HP, what would you recommend?
I would just pick up a good name brand pump from the auto parts stores. Amazon and ebay are littered with fake everything these days.
Amen to that conclusion, would a generic pump fit in the same bracket, or am I going to have to get the Dremel?
 

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Discussion Starter · #28 ·
I really like Aeromotive pumps; higher quality than OEM pumps. Used by many racers. Check out their line of Stealth-340 pumps.

Can pick up from many vendors:
RossSport
Amazon.co.uk
Okay, this is confusing me. The Aeromotive pumps you're recommending are 340LPH. The Walbro pump is 255LPH and you're saying that's already overkill, and the Bosch is 300LPH and that needs modification of the fuel system (removal of a restrictor) otherwise it'll damage the pump. I can 'check out' any pump you suggest but I have no idea if it'll work, or even fit - none of the pumps in that range are for the Supra and I don't know which, if any, would mount on the same bracket.

All I want is a pump that'll fit the OEM bracket without modification of any of the fuel components, mostly because I don't trust myself to work on fuel systems. Additionally, if it's capable of delivering the extra fuel requirements of a turbocharged 5M, though the latter is quite optional and I'm open to replacing the pump at the time if it's inadequate.

At this point I'm inclined towards buying the OEM pump from Toyota; as expensive as it is, it's guaranteed to fit and work...
 

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Discussion Starter · #31 ·
Yup, easiest is OEM pump. You're gonna need to upgrade it though if going turbo. So might as well fit larger pump now. Can make custom mounting brackets by brazing thin metal strips together.

My comment about Walbro & Bosch is more geared towards fakes. Actual flow-rate just needs to be more than required. Note that flow-rate is inversely proportional to pressure. So keep in mind pressure and boost you're going to run and make sure pump you select will generate sufficient flow under highest demands.
Ahhhh, I get it now. That graph is some great information! I was under the impression from my turbo-build thread that the stock pump could handle it; indeed, since I'm only aiming for a few PSI of boost (not wanting to blow up the 5M!) it looks like the stock pump can still flow plenty of fuel.

I have no skill at brazing or welding so I'd prefer not to modify the bracket.
 

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Discussion Starter · #32 ·
Easiest jump up in flow rate of pumps is to go to the MkIV turbo Denso pump. That will support mid 400ish rwhp with OEM reliablilty. It's been while, but I remember just needing to use the Mk2 rubber bottom isolator on the pump.
Good idea, especially if it's a drop-in fit. I have the rubber bumper from the original still on the pump. Is that going to need any modification of the fuel system to remove restrictors etc.?
 

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Discussion Starter · #34 ·
Good news folks. I found a working pump in my parts stash - it was in a different box to the others. I tested it by having it bubble through the coolant tank of my other car.

Yesterday, my uncle and I took Dragon to bits. As I'd hoped, the bolts were well exercised and came apart willingly. However, when we started to clean the top of the fuel tank, I dislodged some dirt and revealed a new couple of pinholes in the usual spot behind the rear wheel. Damnit. Fortunately I had kept hold of Dragon's original fuel tank, which had been repaired a few years ago, so we swapped all the components onto this tank and put it back in the car. After priming the fuel system using the check connector, Dragon started on the first crank.

Now looking to get Dragon back on the road for the first time since the pandemic.
 

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Discussion Starter · #36 ·
I don't !"£$%^&*()ing believe it, on Saturday I reassembled Dragon ahead of getting it inspected on Tuesday. Brand new battery, even tested it with a capacity tester, 80% charge as shipped. Tried to start Dragon... just cranked. WTF.

Bridged the check connector - can't hear the fuel pump. You have gotta be kidding me!!!
 

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Discussion Starter · #38 ·
Rob check EFI fuse under the hood...and per circuit breaker in foot well
I checked and there was spark (ignition testers blinking). Didn't have time on Saturday to do much by way of diagnostics, it was getting dark. Planning to go over the car on Tuesday morning.
 

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Discussion Starter · #39 ·
There's battery voltage at the pump connector. The pump itself shows a resistance of 0.1-0.4 megaohms, so it looks like the second pump has failed. Cannot believe how quickly that thing died. And now, I can only get OEM pumps from Japan; previously I could get from Europe with a shorter lead time.

Suffice to say, I don't think I'm getting Dragon running today.
 

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Discussion Starter · #41 ·
Wonder what kills these pumps?
I really hope it's just age. The pump was out of my spares box so was in unknown condition. I did test it but who knows.

There's nothing unusual about Dragon's fuel system - the car started up perfectly last weekend and ran normally, but once the engine stopped, apparently so did the pump, permanently. This time I fitted a brand new battery (Bosch Silver) which was a reasonable 12.5v when I got there. There's a solar charger on it.

Maybe some gunk got past the strainer and caused the impeller to seize? Which is kinda unlikely as the last time I got fuel was in 2019 and UK fuel doesn't noticeably degrade with age.

I can't explain it.
 

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Discussion Starter · #43 ·
Okay, so I did a lot of searching around and noticed that Walbro not only makes a high-capacity pump, but they also make a drop-in kit for the original:


I got a good deal on this so I ordered one. Hopefully it'll arrive tomorrow.

I'll have to drain and clean the fuel tank. Having to discard 10-15 litres of fuel is a painful thought with our fuel prices through the roof, and even worse, all UK regular fuel is now 10% ethanol (up from 5%), which Dragon does not like. Premium fuel remains E5. I'm very annoyed I now have to pay extra for premium fuel just to have the car perform like it would on regular.
 
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