R32Gtr, Troubleshoot Cause Of Eng Hyd Lock From Fuel

[GTRsean]

Story goes like this.

Last weekend, one of my mates (Sloane) went along for an SAU event that got cancelled due to bad weather.

I wasn't there when it happened but he filled me in when I got there. Car had to be towed home.

He said that he was driving at 80KM/h just cruising along, when the car had a big backfire then started to splutter. Then the engine stopped and could not be started on the starter motor at all, no rotation.

Car has following upgrades that have been on car since before he bought it:

Sard 720CC injectors

twin entry fuel rail

adjustable fuel reg

fuel pump

Z32 AFMs

Power fc

Apexi turbos

HKS cams

etc. About 420HP at the rears.

Last few months the car seemed to blow more black smoke out the exhaust than usual and throw flames pop etc. Weather was cool and car had been running for around 25minutes when it happened.

Power fc showed no malfunctions.

He had done an oil change that morning.

A week later I decided to have a look at the car to try to find out what had happened. Engine would not rotate at all, so I was thinking cam belt/tensioner, a dropped valve or broken cam. Pulled the cam belt cover and cam covers off and belt and cams looked fine.

Put that back together and moved onto pulling the coilpacks and plugs out. Did notice a fuel smell in the engine bay before and during working on the engine.

First three plugs looked okay, then got to the 4th and that was soaked in fuel. Same with the 5th and 6th plugs but not as bad. Got a spanner and tried to turn the engine over on power steering pump nut. It turned!, but the cylinder was completely full of fuel, and that rised up as the piston went up. Was surprised that the fuel stayed in the cylinder for over a week.

So then I cranked it over on the starter, and heaps of fuel was ejected out of the rear cylinders. Just cranked it till the bores were clear of fuel.

So my question now is,

What could of caused it?

What damage may have been caused?

My idea is that a couple of the injectors failed causing heaps of fuel to fill the cylinders and cause the hydrolock. So older injectors may have started to leak due to some part in the injector being faulty.

Less likely, Engine management could of stuffed up?

At worst there might be a bent rod or 2 due to hyd lock, but due to engine spluttering then stopping at low RPM hope that isn't the case!

Might pull the injectors out and get them tested, but it's up to him when he gets back.

So if anyone has some ideas on why this happened, please enlighten me!

Cheers .

[ronnydotk]

Unlikely that 3 injectors had a mechanical fault all at the same time causing them to pour fuel in. I'd be saying electrical problem of some sort that caused the 3 injectors to earth out and stay open. Unplug fuel pump and check with a noid light if all the injectors are being switched while cranking the car. If there is a short to ground on the earth side of the injectors you could check for continuity to ground in each wire (with ECU unplugged) to check that. From there chase up rubbed wires in looms etc (fun stuff).

as for damage, it is hard to say. You said the engine continued to run until idle, then died. This suggest to me that at higher rpm then engine was able to get rid of enough fuel to stop a hyd. lock up, which is good. Then at idle the engine simply couldn't get rid of the fuel quick enough and so it filled the cylinders up until hyd. lock stalled the engine. I'd be saying probably no damage... but you won't know until it runs again. I've seen pictures of diesel trucks getting a guts full of water and throw rods through blocks/bend rods/crack heads. Hopefully this has been avoided. The fact there was still petrol in the cylinders means the rings aren't smashed down the skirts anyway!!!

[marksuxass]

We get diesel engines in at work that do much the same thing. Hydro lock, pull at the glow plugs and it will be full of fuel. Always replace the injectors. Id say best bet would be to test the injectors cause there probly leaking back, and this would be a much easier solutions then looking into the engine/fuel control side of things?

[JonnoHR31]

first test is to crank it over with the plugs out but injectors plugged in and watch the injector duty on the power fc. if its normal pull the rail out with the injectors still in and hooked up, let the fuel pump prime and check for leaks.

also, long shot but check the vac line for the fuel reg for fuel

[XRATED]

Ha ha, I've had this happen.

I assumed the worst and started to pull the head. Luckily I pulled the plugs before I undid the first head bolt and noticed a cyl was full of fuel!

Ended up just being dirt in the injector, jamming it open.

Luckily, I had a breaker inline in by battery cable- so the starter didn't push to hard before the breaker flicked off.

Cheers

J.

[DVS JEZ]

A mate had this happen 2weeks ago. Failed injector was his cause.

I had

This happen on my old s13, the wiring rubbed through near my ecu on that one.

Scary when it happens

[woodsy900]

good to see that the issue may be small... I'll see if i can get the pictures off my phone later and throw them up for people to see. It's not good to read that a fair few other people have seen or had this happen to them :S

[r31 25t]

I've also had this happen. Mine was a faulty injector o-ring (lower one on a side feed injector).

[GTRsean]

Thanks for the tips guys. I'm leaning towards a faulty injector due to not knowing how old they are too. They don't last forever.

I'll probably do a few checks as well though to make sure there isn't a problem with wiring etc first, as mentioned.

If I check the injectors on an RB26 with fuel pump on and rail removed, I'll have to secure them somehow, otherwise they will just pop out of the rail.

[tm_r33]

make sure you drop the oil too mate. if a jag load of fuel has been in the cylinders then no doubt a small amount must of leaked past the rings and contaminated the oil.

[GTRsean]

Ha ha yeah just told him this arvo to drop the oil. Good call!

[blue_vl_t]

I'll agree with above saying if all three rear cly. were full of fuel it wont be the injectors, most likely electrical short.

Although, what would happen if you were low on fuel and took a big gulp of dirt, blocking/seizing 3 injectors, possible i suppose.........

[MrStabby]

Although, what would happen if you were low on fuel and took a big gulp of dirt, blocking/seizing 3 injectors, possible i suppose.........

That could only happen if the fuel filter material is ripped/torn. They dont bypass when dirty.

OP use a multimeter to find if there's any injector signal wires with zero resistance to ground.

[GTRsean]

Definately was the 4th cyl that was full of fuel. Most of the fuel could only escape towards the back of the engine so it must of gotten into the rear cylinders as I cranked it over. There was quite a lot of fuel to get rid of. I'll crack out the multimeter anyway.

Cheers.

[Rolls]

sounds like electrics caused them to jam open, very unlikely for more than 1 injector to fail that way.

edit use a multi meter, you'll soon see if one is earthed out

Edited March 31, 2011 by Rolls

[GTRsean]

Did a multimeter check, and no grounding shorts.

Plugs were stuffed so they got replaced. Injectors were changed with same part numbers.

Did a warm compression test with throttle open, the cylinders showed average 145-150 PSI. Also put in stock fuel rail and regulator to replace the dodgy leaking setup.

Got the car running but had to pull out .500 fuel just to get it to run at idle, it was running very rough and rich.

If you rev it, it would run lean due to pulling out the fuel, so richen it up it got better... then back off the fuel again at idle or it would want to stall from running so rich.

Drove it up the road and gave it some stick, it would boost up and a massive cloud of fuel smoke would come out the back!

He plans to put in new split fire coil packs, but it's looking like the Z32 AFM's might be the problem we have now, got oil soaked a lot in the past, so they will get replaced. Don't know how old they are either. At least it's not hydro locking anymore!

[DVS JEZ]

Try cleaning them with contact cleaner.

What ecu is it running? Maybe u should get a retune. Especially since u have changed fuel presaure

[Adriano]

My guess is the dodgy adjustable pressure reg has a tear in the diaphram causing fuel pressure to go up the vacuum hose into the manifold-instant flooding

[GTRsean]

Running a power fc. So it will get a tune once AFM's and coil packs are replaced.

Running stock fuel reg now.

There was no evidence of fuel in the fuel reg vac line.

He did an oil and filter change. About an extra litre of oil came out due to fuel in the oil!

[Sloane]

Car is back on the road

With the above things mentioned above done plus a stock air box put back on and Yellow jacket coilpacks.

Running 334.3 AWKW's @ 21Psi

Tuned by Croydon Racing Devolpments