Help needed - fuel/running issue

Hi all,

I'm off on a trip to the Alps in just over 3 weeks but my GTA turbo is plagued by what I think is a fuel issue

Symptoms

• Starts from cold fine, idles well, drives well too, with good on-boost acceleration
• After driving for 10-15 mins, the rear fuel pump gets progressively louder/rattlier
• Randomly 20-30 mins after driving, she loses all power, barely holds idle and then promptly cuts out completely. Sometimes it just loses power, and then on application of heavy right foot it seems to 'blow itself clear' and she picks up again - but this only works for a little while, eventually she stalls no matter what I do
• Once cut-out, she usually starts straight away, but it splutters, can't hold idle and typically dies after 30-45 secs. Pumping the throttle seems to hold it at a very low idle, but any more than 25% throttle and it dies. When you turn the key to IGN and the pumps prime, the rear one sounds like it's being strangled (i.e. not like it normally sounds when the car is running fine)
• Very randomly (after trying to start repeatedly, after leaving it for 2 hours, or a day or two) it suddenly bursts into life, perfect idle, perfect acceleration, and the rear fuel pump is back to normal levels of noise - because of this fact, I don't think the pump is the problem?

Work done so far...

• Rear pump off. Cleaned electrical connections, tested pump with 12v, shoots a nice jet of petrol right across my lawn, promptly killing grass , refitted. Didn't bother testing the wiring circuit, as it's obvious the pump is running (noisy)
• Rear filter off, totally clear, no gunk etc, refitted
• Fuel tank is clean as a whistle, not one iota of gunk/dust/sand, nothing (I removed the fuel tank level sensor for good access/visibility)
• Front pump off. Tested pump with 12v, shoots small jet of petrol across garage floor , refitted, tested circuit with ignition on 12v good
• Front fiter is basically brand new, again clear and clean

I've stopped at this point as I've run out of ideas/things to check.

1. Am I right in thinking that when the rear pump goes noisy it's likely that it's not receiving enough fuel from the front?
2. Is it possible that this is an electrical problem somewhere (other than the pump looms)?

If anyone can provide some hints/tips I'd really appreciate it! I'm getting to the point (due to time crunch) where it may have to go to a garage... any one recommend somewhere near Salisbury please? Or any GTA experts nearby willing to help out? I've only got 3 weekends left to get this problem sorted!!

[BIG_MVS]

I had exactly this problem with my first GTA Turbo.

http://www.renaultalpineownersclub.com/ ... 75&start=0

Turned out to be the front fuel pump. Can you hear the front fuel pump running all the time as it should do to feed the swirl pot just in front of the rear pump?

If your front pump is working correctly there are a few other things in the thread above you could also try

The front pump is fed by a relay which may be giving you some trouble. It is situated between the rear seats, or, as Martin suggests, the pump its self. I go along with your view that if the rear pump gets noisy when the fault occurs, it could well be due to the lack of fuel getting to it as they are lubricated by the fuel.
It might be worth disconnecting the ECU`s connector and giving the pins a clean as that is where the control signal comes from to operate the relay.

PS

Front pump off. Tested pump with 12v, shoots small jet of petrol across garage floor , refitted, tested circuit with ignition on 12v good

It might be worth checking if 12v are being supplied to the front pump when the rear pump is in its noisy state.

I seem to recall that David Gentleman mentioned noisy pump = fuel starvation. Surely it can only be either the fuel pipe that feeds the front pump being restricted - i.e some crap in the pipe that is moving around. Hence it works some of the time but not all the time. May be worth (if you havent already) removing pipe and cleaning it thoroughly (DG detailed this in a earlier thread). Or it's dodgy electrics. In which case can you 'piggyback' the 12v feed to a meter in the car and check the voltage when you experience the fault.

As for someone near Salisbury, Paul Eddy (Ren Tek) in Weymouth is a GTA expert - but you'd need to get the car down to him (dont believe he does mobile works). Alternatively another chap Steve Cronk has been recommended to me - he is mobile and has had experience of working on GTAs. I can PM Steve's contact details if you wish.

Rgds
Paul

Thanks for the advice so far guys, much appreciated... I'm taking the GTA out for a run this morning, with a multimeter connected to the front pump so I can see the voltage. I'll also check/clean the ECU and relay contacts. I really hope I get a 'hard' fault to actually diagnose/fix as chasing a mystery fault is driving me potty.

I noticed that ART sells the Facet Posi-Flo as a replacement for the OEM front pump... is this model recommended? (although I will order it elsewhere as I found it for £30 as opposed to the £60 ART is charging).

Paul: thanks for the reccomendations on local experts... depending on how it goes this morning, I may just need them.

Hi guys, the high pressure pumps make a row when they' re having to suck hard because as the fuel gets warmer it will evaporate in the lines and cause cavitation in the pump. DeLorean owners are also familiar with the symptoms you describe - the original pickup hose in the fuel tank has a habit of collapsing when the fuel gets warm if the pickup filter is even slightly clogged.

Update: went out for a run, same thing... after 10 mins the rear pump started making noise, and every now and then she'd lose power. Voltmeter on the front pump was reading 13.1 to 13.6 volts fairly consistently, except at idle it would drop to 12.4ish. Pulled into home, car cut-out completely, volteter was still reading above 13v.

Hi guys, the high pressure pumps make a row when they' re having to suck hard because as the fuel gets warmer it will evaporate in the lines and cause cavitation in the pump. DeLorean owners are also familiar with the symptoms you describe - the original pickup hose in the fuel tank has a habit of collapsing when the fuel gets warm if the pickup filter is even slightly clogged.

Apologies for the dumb question: how can the fuel in the tank get warm? is it from the unused return? And anyone got a photo/diagram of the tank pickup and it's location... I had a look when I was under there yesterday doing the pump/filter and it just seems to feed onto a plastic extrusion on the tank (i.e. no mechanism as such), or is inside that?

Maybe the pump is getting voltage okay, but is simply worn out and not pushing enough fuel? I think I'll change it, but don't want to waste money/time if possible.

[BIG_MVS]

Yes change the front pump, don't be tempted to go 2nd hand as I went through 3 before "striking lucky". Can you hear yours running when idle? It should be running all the time....Yes you might be getting voltage to it but is it actually running?

Apologies for the dumb question: how can the fuel in the tank get warm?

The tank is immediately behind the radiator, the fuel pipes run parallel to the coolant pipes and the fuel is constantly running through the injector rails with most of it running straight back to the tank most of the time.

Apologies for confusing things talking about the DeLorean tank pickup hose - just an example of a different setup causing a similar problem.

I am a little puzzled guys, I have been doing a bit more reading as I do not know the D501 as well as the D500, but in the 501`s fuel systems spec, the front pump is refered to as the "Priming Pump" with a flow rate of 15 L/h at say, 0.5 bar, whereas the rear "Feed pump" is rated at 130 L/h at 3 bar. So, to me, the front pump does not do too much work after it has primed the system. The rear pump, however is triggered from the ECU, and, I suspect, only can operate when the engine is running, or is being cranked, which would be the same as the 500, as this is a safety feature in the event of a crash when the fuel pump would stop the moment the engine cuts out reducing the risk of fire. Any explaniation would be appreciated.

On the A610, there is only one high pressure pump at the front of the car, same as the DeLorean. These pumps aren't much good at sucking - that is to say they easily evacuate the intake side of there's a blockage, and this causes the fuel to vapourise and the pump to make a dreadful row. Low pressure rotary pumps are more like a windscreen washer pump - just a paddlewheel in a housing which can cheerfully carry on spinning even if there's no flow.

Is the front pump the same on both the 500 and 501? The twin pump system in the 501 is probably a legacy of this setup designed for a carburetored engine.

Is the front pump the same on both the 500 and 501?

No,..... both Renault and Simon Autos show different part numbers for them, and the D500 one is listed as having a delivery of 100 L/h.

The front pump on the GTA turbo feeds a ' swirlpot ' for want of a better word ,that then feeds the high pressure side for injection .As Stunned says probably just a legacy from the carbs .
I'd clean out the system especially the feed from tank to front filter /pump .

I agree with Lee, if the voltage is still around 13V then it must be failing to pull and pump fuel. Probably find a small piece of crud in the pipe that feeds the fuel pump.
This is one (of the many) jobs I mean to get round to doing. Remove pipe and give it a damn good clean. Mine front pump has always been a bit on the noisy side and I'm sure it's down to the extra load in trying to pull and pump fuel through.

I think the above comments are all valid (and most likely the cause) but just to add, I had running problems years ago with mine (hesitation, poor idle when hot etc) AND noisy fuel pump.

It turned out to be the total opposite not fuel starvation but overfuelling - it was the fuel pressure regulator which had perforated and was allowing too much fuel to get to to the injectors. Hence fine at wide open throttle.

It took a few visits to Paul Sage to try to diagnose (changing fuel filters etc) before the regulator finally popped totally and flooded the bores, hydraulically locking the engine.

All cleaned out ok and new regulator it was right as rain. Seems unlikely, but it did make the fuel pump noisy and symptoms were very similar to starvation. PRV is a funny beast and the tuning boys will tell you it doesn't like a rich mixture either!