Help needed - fuel/running issue

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?

I could not agree more I always replace with new parts now having tried to do the job on the cheap so many times it just costs you more time, money and very definately FRUSTRATION.

si21

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 .

Lee we want to run the swirl pot in JIL so don't remove it, it's there for fuel surge from the tank to keep the main pump primed. That's the case with even a baffled and foam filled tank... Doctor Doctor

I'm not removing it ya fool !! Was just explaining the function and possible cause ...610 has not got one ....
Need a bigger one in actual fact on JIL I think ......

ya ya... 610 lardy tank not meant to go round corners quick init...

Update 2
Well, really at a loss now...

• I've taken out the feed pipe from tank to front filter (it was a bit rusty on the outside, but clean as a whistle on the inside)
• I've removed the front filter and put a temporary straight connector in, as the filter was a mini-plastic cone paper filter as opposed to the correct wire mesh - just trying to rule out any restriction it may have had
• I've confirmed that fuel is flowing very well upstream of the rear pump (disconnected the hose, applied 12v to everything, lots of fuel).

Went for a run, same thing... after everything warmed up, rear pump noise increases, she starts to mis/backfire, and eventually starts cutting out.

I did notice at one point after she got going, that as soon as the turbo spooled up she starting wheezing again, but if I backed off and kept out of boost it would pootle along okay... does that help point to something else?

Time is getting really, really short now... every garage I've tried locally doesn't seem to want to touch it, or everyone's on holiday (including Sportomotive in Salisbury).
I'm begging for any help, and willing to pay good money for it!

Fuel pressure regulator .
When they go the pressure ramps up and if on boost that is increased relative to manifold pressure .Any evidence of overfueling ? Black smoke ?
Not always that evident but would make the pump noisy .

[BIG_MVS]

Have you changed the front fuel pump yet? Change it!

No black smoke. I had a quick look at the fuel regulator, but looked pretty awkward to get out and didn't see what I could really do with it except replace it? Are they easy to get hold of new?

You can't repair it .It's a simple enough job .Single reg ?

Have you changed the front fuel pump yet? Change it!

Not yet, not certain that this will help, as there is loads of fuel at the rear pump. If you're really certain, then I'll cough up and order one I suppose.

You can't repair it .It's a simple enough job .Single reg ?

"Single reg?" Huh?

Is there a way to diagnose that it is the reg? i.e. run the engine, take the vacumn feed off the reg and expect... what?

Thanks for all the help by the way!

Agree - it has to be pressure or delivery (effectively pressure) related.

I would suggest investing in a fuel pressure gauge and appropriate connections, and then fit and get some data to base further investigation i.e. what is the fuel rail pressure, and is it being held? This should cut your problem areas to investigate in half..

From the sound of it your front pump is running correctly, it is not going noisy, and continues to prime the pressure pump, correct? The front pump is low pressure and should be under little strain.

The main pump works against pressure, and is a "pusher" pump not a lifter, so must be primed to run satisfactorily, but they are working hard and fuel cooled and lubricated. Stall the fuel and it will start getting warm quite quickly - when the regulator demands a higher fuel rail pressure the pump works against a higher pressure, and the rate of fuel delivery falls.

If your regulator is playing up, it will make the high pressure pump work extremely hard, and to the point of stall, and hence go noisy...

When you blip the throttle at idle, you are modulating the pressure on the regulator from vacuum to atmospheric; when the reg signal line sees atmospheric it will enrichen the fuel mixture by virtue of the fuel rail pressure...

So I would get a fuel gauge and probably get a loan regulator to test...

[BIG_MVS]

Have you changed the front fuel pump yet? Change it!

Not yet, not certain that this will help, as there is loads of fuel at the rear pump. If you're really certain, then I'll cough up and order one I suppose.

Can you hear the front fuel pump running ALL THE TIME?

I will try and find one in the shed tomorrow .Let me have an address and I'll post it out sale or return
Early cars just have one ,later have a damper ,twin reg setup .
You could try with the vac pipe but careful as it won't then ramp up with boost and if not the issue could go lean .

Is there a way to diagnose that it is the reg? i.e. run the engine, take the vacuum feed off the reg and expect... what?

I would run the engine at idle with the signal hose off the reg, the engine will run rich (black smoke), and probably be quite rough. If you have a vac pump then great hook it up, pull vac and she should clean up. Conversely if she's running sweet with the hose off, put a foot pump on it, and you should be able to make it real rich... and even cut out from running too rich.

But it appears it plays up after it gets hot..