Did High Fuel Pressure, Or E85, Kill My Rb25det Stock Injectors?

[sonicz]

All 6 of my injectors died a slow death within the space of half a year after fitting an aftermarket ebay 385L/h pump and switching to E85. The car began showing problems after running perfectly for some months by beginning to stutter when idling, then running ok again, then eventually misfires got worse, and would run on 5 cylinders, then 4 then 3 and then eventually would not even start. The cylinders were flooded with fuel. Spark plugs all soaked in fuel and black. Injector removal showed all O rings intact.

The pump was a walbro copy looking pump. In addition to this I also did the fuel voltage "mod" by earthing out the grey wire leading to the fuel pump. This made the pump, pump massive amounts of fuel. I know technically the pump does not create pressure but rather volume, however so much was circulating so fast that I feel it raised the fuel pressure by copious amounts. Anything in the boot is about 50 degrees warm due to heating the fuel tank so much, and when I prime the fuel pump so much comes out I can literally fill a 2L bottle with fuel in about 3 primes.

I'm curious which of the two did it (if not both), E85 or too much pressure killed the stock injectors so I can avoid that this time around with the new injectors that I fitted, again stock replacements due to budget limitations.

Car now runs perfectly again with nothing but replacement injectors. I'm running it on 98 octane for the time being.

[Impulse-NL]

Did you make other changes so that e85 would run right ? other then the fuel pump?

Otherwise im suprised it lasted this long to begin with.

[Sub Boy32]

Have you done a pressure test? If you are using the stock fuel pressure reg the pressure should still be the same at close to 3 bar.

I would say it will be the E85, the factory injectors won't be rated to handle ethanol, and the internal seal would have swelled etc.

[zebra]

What ecu?

My stock RB25 injectors have had E85 sitting in them for a few months and have hardly ran the car, and all is fine.

[fatz]

Get them cleaned

If they work after that it was the e85

[methz]

i killed about 2 sets of high flowed stock rb25 injectors over space of 1-2yrs running e85, mine were all random cyclinders, just kept replacing with more shaved injectors, then went bosch and fixed problem

[sonicz]

No other changes really other than bumping up the fuel flow via pump and FPR to flow more to match the higher boost and e85. It was running perfect for many months. Tons of grunt, no misfire or too lean/rich etc so I'm pretty sure it was dialed in right after the initial "setting" guesswork, but something started to get to the injectors in the Damage over time sense. Yea they could have been clogged, but I didn't bother to get them cleaned and just threw in another set.

Based on what people have said here I believe it was the E85 that did it. Either by damaging the internal components or by stirring up so much gunk that had been collecting for 20 years that it blocked them up. I also saw some slight corrosion/rust inside the stock fuel rail, so E85 probably not good for mostly stock skylines..

Having said that, can anyone tell me what is the maximum pressure the Stock RB25DET injectors can handle? I'm curious if just running a very high fuel pressure even just on 98 unleaded can damage injectors in this way and make them die?

The main reason I ask if I have a second series 2 R33 skyline that I keep mostly all stock and clean. The only changes I have made is fit a new fuel pump because the old one from the previous owner started whining, ironically its the same 385L/ph pump that I fitted to the above test mule car I was running on e85.

I also earthed the grey wire in the boot. After doing this same hot boot and screaming fuel pump symptoms as car 1. No other mods to this car and I actually care about it so I keep it on 98 only. But with the new pump its running a bit rougher and richer than previously. I'm worried if now the fuel pressure is too high on my S2 and if I will do any damage running it like this?

It has the stock FPR and I was told thats what keeps the pressure, but I'm reluctant to believe this with the changes made to it. As soon as I fitted the new pump and voltage mod, the car started idling much higher, until the ECU figured things out, so clearly it does make a difference. Should I buy a walbro 255 pump instead of a 385L/h one, or keep the 385l/h one but unto the voltage mod?

Edited March 1, 2015 by sonicz

[GTSBoy]

I think you misunderstand what happens with different FPRs.

The FPR is a hole. An adjustable hole. If the rail pressure is low, the hole closes up. if the rail pressure is high, the hole opens up. The range of sizes available is between fully closed (ie, all fuel directed to the injectors) and fully open. "Fully open" being defined as "big enough to return ALL the fuel to the tank without the fuel pressure going higher than is desired.

The stock FPR is big enough to return all the fuel supplied by the stock pump. It is also big enough to return all of the fuel supplied by somewhat larger pumps. You can tell this is true by all the thousands of cars out there running big Bosch and Walbro etc pumps with normal fuel pressure.

Aftermarket pressure regs serve 2 purposes. 1) they fit onto aftermarket rails where the stocker doesn't. 2) they generally have higher flow capacity than stockers so if you find yourself oversupplying fuel to the stock reg such that you cannot stop fuel pressure from rising way above the desired setpoint, then they will.

So, if you have an aftermarket reg, it is highly unlikely that you have excessive fuel pressure. If you have that big Walbro and a stock reg, then it is possible, although not real likely, that your fuel pressure is out of control.

Luckily, this is not a question that needs to be resolved over the internet. Hook up a decent pressure gauge to the fuel rail and have a look. Job done,, question answered, problem solved.

[jay-rod]

You injectors are fine
Go get them professionally cleaned

Your injectors got blocked up from shit in the fuel tank from the e85 moving it around.

Same thing happened to me.

I repeat , your injectors are fine!

[sonicz]

I needed a quick fix so I just swapped them out. I'll be selling the old injectors for really cheap ($30) in case anyone is interested in them and thinks they just need a clean which could easily be the case. Here they are.

I'm really curious what the fuel pressure is with that high rated pump blazing at full voltage. I got a Fuel pressure gauge, but I'm not confident fitting it myself.

Anyone with experience in this willing to help out by fitting a fpg, maybe for a 6 pack of beer?

I got one of these

But no fitting or adapters or knowledge how it needs to be fitted.

I'm in sydney, let me know and I can drop by.

Edited March 29, 2015 by sonicz

[GTSBoy]

Fittings/adapters is easy. You need a barbed T piece and some extra high pressure fuel hose. A few suitable hose clamps. And a barbed fitting with the appropriate thread for that gauge as an adapter. Fit it between the filter and the fuel rail (pull the hose off the fuel rail end, it's easier). 10 minutes + time spent shopping at a hydraulic/pneumatic supplier.

[sonicz]

I'll a check if auto parts stores like autobarn and bursons have a t-piece with the right thread, otherwise going to have to google my nearest hydraulic/pneumatic supplier.

I'm guessing I'm looking for something like this

http://www.ebay.com.au/itm/AEROFLOW-INLINE-FUEL-PRESSURE-GAUGE-5-16-BARB-ADAPTER-1-8-PORT-BLUE-AF138-05-/400575627401?pt=LH_DefaultDomain_15&hash=item5d442b0089

Thats expensive for an adapter, more than the gauge.

Do I use teflon tape on the thread, thread sealer like locktight? Something else? Do they make fittings with a rubber on the end so you don't have to use a sealant etc?

I'm uneasy about fitting parts after the filter TBH. I could easily introduce something in the fuel that gets stuck in an injector like a piece of tape of sealant, I cant deal with that at the moment.

Any chance you could fitting it gtsboy? I'm in Sydney West.

[jay-rod]

A normal brass t piece fitting is fine.

[sonicz]

I think you misunderstand what happens with different FPRs.

The FPR is a hole. An adjustable hole. If the rail pressure is low, the hole closes up. if the rail pressure is high, the hole opens up. The range of sizes available is between fully closed (ie, all fuel directed to the injectors) and fully open. "Fully open" being defined as "big enough to return ALL the fuel to the tank without the fuel pressure going higher than is desired.

The stock FPR is big enough to return all the fuel supplied by the stock pump. It is also big enough to return all of the fuel supplied by somewhat larger pumps. You can tell this is true by all the thousands of cars out there running big Bosch and Walbro etc pumps with normal fuel pressure.

Aftermarket pressure regs serve 2 purposes. 1) they fit onto aftermarket rails where the stocker doesn't. 2) they generally have higher flow capacity than stockers so if you find yourself oversupplying fuel to the stock reg such that you cannot stop fuel pressure from rising way above the desired setpoint, then they will.

So, if you have an aftermarket reg, it is highly unlikely that you have excessive fuel pressure. If you have that big Walbro and a stock reg, then it is possible, although not real likely, that your fuel pressure is out of control.

Luckily, this is not a question that needs to be resolved over the internet. Hook up a decent pressure gauge to the fuel rail and have a look. Job done,, question answered, problem solved.

I finally did this on my otherwise stock 1998 R33 GTST I mentioned in one of my posts above (not the one I ran on e85 and the injectors died, but running the same fuel pump), and its exactly as I suspected, way way way too high with an aftermarket pump, the stock fuel reg cannot cope.

The poor car must be running crazy rich. Its almost hitting 65psi of base fuel pressure at idle and thats with no boost. During boost it may hit 75+ psi I don't know because I'm not under the hood to see while driving. Stock ECU, stock injectors, stock everything. Carbon deposits, fouled parts, weird detonation...poor ring-lands?

So now, I either buy a stock R33 GTST fuel pump for it (or direct stock replacement), or buy a adjustable FPR and set the correct fuel pressure?

Looks like you cannot just stick a new fuel pump in there and hope the stock fuel reg keeps things in check cos thats just insanely high.

I know people say its supposed to be 43 PSI base fuel pressure, but I have seen a few skylines running stock fuel pumps showing 25-30psi on an actual gauge and the cars ran great even with minor mods. I'm almost 3x that amount.

Edited April 8, 2015 by sonicz

[GTSBoy]

Yuh, that's no good at all.

[sonicz]

So whats the proper solution?

Story goes.

>Me not know much about Skylines years ago (Lucky didn't blow the welds on the intake by granny shiftin not double clutchin like i shud).

>Me read on SAU most stock fuel pumps on their way out and not safe to up boost even a little due to possible leaning out

>Me worry and want to avoid this.

>Walbro 255 suggested as great replacement for stock pump.

>Me go on ebay looking for gss342 pumps

>Me find one thats similar to a Walbro 255 but better, claims to be direct replacement for stock item, and flows 345-385L/H such as this http://www.ebay.com.au/itm/GSS341-Type-340L-H-Performance-Fuel-Pump-Skyline-GTR-RB20-RB25-RB26-R32-R33-R34-/110983052442?pt=LH_DefaultDomain_15&hash=item19d71afc9a

>Me suspect possible problem of changing from stock to aftermarket and have to dig for info and find but find little info on needing a retune etc, and find mentioned info that these fuel pumps are "direct replacements" and thats its just a plug and play job that no retune necessary as the stock FPR will keep the fuel pressure in check

>Me fit it and drive for 2 years wondering why the car never behaves as good as when I first got it.

>Ironically the stock fuel pump was perfect in perfect working order just like the rest of the car and the supposed playing it safe has been causing damage.

>End up in worse situation that if I did nothing at all.

Will an adjustable FPR be good enough or will that get blown out of spec to what the car expects as well? I.e Maybe it will hold base pressure but the rising rate will not be correct for what the ECU wants?

I'm thinking a stock fuel pump may be the best way to go now but I was made to believe they are so old and crap that I think I even threw it out. Ironically on the day I took it out it was a gleaming gold color and was literally twice the size of the new gss342 I replaced it with.

And now I have danger to manifold and my floor pan will blow off as a result..?

Edited April 8, 2015 by sonicz

[GTSBoy]

You do just need a bigger aftermarket reg. Ask someone like Scotty or Trent for one.

[scotty nm35]

I can definitely supply an aftermarket reg, but considering I have run 460L Walbro's on the stock reg, and Nismo regs, there is something not right I suspect.

That pump is a Chinese copy of a Walbro, it isn't a 255 obviously. I would have left the old one, considering it had already been upgraded by the sounds of it.

[sonicz]

You do just need a bigger aftermarket reg. Ask someone like Scotty or Trent for one.

Any disadvantage of doing that though? For example aren't you making the pump work extra hard pulling extra power, getting hotter etc, all for nothing and then blocking its flow with an FPR, when a stock pump would be more ideal for my application?

I also noticed that when I unplug the vacuum hose to the FPR nothing changes as far as Fuel pressure is concerned. You can see this in the video I posted. Isn't the vacuum meant to lower the fuel pressure with the hose connected and make it rise to the "default" value of 43 psi when disconnected? This could indicated the stock FPR is completely busted?

I can definitely supply an aftermarket reg, but considering I have run 460L Walbro's on the stock reg, and Nismo regs, there is something not right I suspect.

That pump is a Chinese copy of a Walbro, it isn't a 255 obviously. I would have left the old one, considering it had already been upgraded by the sounds of it.

Yea but have you fitted a mechanical Fuel pressure guage and looked at the pressure in those cases where you have a 460L walbro on the stock reg. I would be shocked if it was at 35ish psi it should be.

When you say you can supply an aftermarket reg, I'm a little confused, whats the difference between getting them from you and from ebay or nengun for example?

P.S I already have a Nismo FPR in my other skyline which had the e85 problem. I let rego lapse on it since I didn't want to pay for a car that Im not driving so I can easily pull the Nismo FPR off that I guess.

[GTSBoy]

Any disadvantage of doing that though? For example aren't you making the pump work extra hard pulling extra power, getting hotter etc, all for nothing and then blocking its flow with an FPR, when a stock pump would be more ideal for my application?

I also noticed that when I unplug the vacuum hose to the FPR nothing changes as far as Fuel pressure is concerned. You can see this in the video I posted. Isn't the vacuum meant to lower the fuel pressure with the hose connected and make it rise to the "default" value of 43 psi when disconnected? This could indicated the stock FPR is completely busted?

Yea but have you fitted a mechanical Fuel pressure guage and looked at the pressure in those cases where you have a 460L walbro on the stock reg. I would be shocked if it was at 35ish psi it should be.

When you say you can supply an aftermarket reg, I'm a little confused, whats the difference between getting them from you and from ebay or nengun for example?

P.S I already have a Nismo FPR in my other skyline which had the e85 problem. I let rego lapse on it since I didn't want to pay for a car that Im not driving so I can easily pull the Nismo FPR off that I guess.

With ref to your first question: yes, there's no good reason to be pumping huge amounts of fuel around if you don't need to. It certainly leads to hot fuel in the tank, which doesn't help anything. I just assumed that you had your pump, wanted to keep it and wanted to know how to make the rest of the system work with it.

With ref to pulling the hose off the regulator.....if the reg is fully open and not able to control the pressure against the full flow of the pump at idle with the vacuum hose on, and the pressure does not change when you pull the hose off, then it really just shows how far too small the reg actually is. There's actually two possibilities here though. 1) it is working (not broken) but is simply too small. 2) It is broken and jammed at a certain (small) opening. Hard to tell which, even with the test you've done.

With respect to your question to Scotty about what the difference is between buying from him and buying from some web vendor, the difference is that you talk to an actual person who has a brain and works on these systems all the time and might be able to fault find your problem before you actually buy something (off the net) that proves to not solve the problem because the problem was actually something else. Plus, when it comes to choosing the right reg (assuming that buying one turns out to be the right thing to do) you will get solid advice as to which ones are good and which ones are not. If ou just go buy a Sard or whatever from Nengun, you are somewhat on your own. Whether that is important to you or not is up to you and your experience/knowledge/research levels.