Suspected fuel fault advice needed !!!!

[Tasmindevil]

The 400 aka 500 has a hotwire system, every now and again it seems to drop a bank, ECU has been checked, new fuel pump, ne bullet filter, new relays, wiring looks good and all connections OK. Sometimes at high speed sometimes at low speed, strong smell of fuel and really stumped. Oh also new coil/leads etc etc
Thinking Lambda's !!! any ideas
Cheers
Hamish

[mrzigazaga]

Hi mate..I had a strong smell of fresh fuel in the cabin of my 280..Infact its back again and the culprit is/was the 2" fuel hose from filler neck to tank..Im considering cutting my filler neck down..zig

[grahamw48]

Has it got Lambdas ?

Sounds like electrical/earth to me, since it's intermittent.

[dixiebabes]

Earth fault fault, Are they the most frightening 2 words to ever hear when you cant find out whats wrong.

Dix

[Jonny weggie]

Hamish on top of your passengers side front wing there's a small resistor unit where the wires from the ecu go into it and out to the fuel inj plugs, disconnect the unit and clean insides finely and crimp together the earth connector carefully, that caused my left bank to cut out.
best of luck john.

[TVRleigh_BBWR]

Jonny weggie said:

Hamish on top of your passengers side front wing there's a small resistor unit where the wires from the ecu go into it and out to the fuel inj plugs, disconnect the unit and clean insides finely and crimp together the earth connector carefully, that caused my left bank to cut out.
best of luck john.

Only the Flapper Injection has those, the Hotwire uses higher voltage injectors so the resister pack is not needed.

As said it's most probably a earth problem.

[Tasmindevil]

TVRleigh_BBWR said:

Jonny weggie said:

Hamish on top of your passengers side front wing there's a small resistor unit where the wires from the ecu go into it and out to the fuel inj plugs, disconnect the unit and clean insides finely and crimp together the earth connector carefully, that caused my left bank to cut out.
best of luck john.

Only the Flapper Injection has those, the Hotwire uses higher voltage injectors so the resister pack is not needed.

As said it's most probably a earth problem.

Had the car at a great Landy garage, popped it on the diagnostic, list of faults included injector faults bank B, stepper motor (That’s less than 3 months old !!!) Extra air valve (Ditto less than 3 months old) but lambda’s working fine (That saved me £200). He called his mate a RRV8 specialist who happens to have a 500 Griff and he has had the same issue but never got to the bottom of it but he suspects contamination in the fuel rail and/or earth fault.
Anyhow the plan is new earth cable, the chappy gave me a set of injectors so I will test these and change them out, check the fuel rail for junk plus I will carry out a test on all the circuits, just hope Katie has her thermals.
Many thanks all
Cheers
Hamish and probably a very cold and blue Katie later tonight !!

[Jonny weggie]

Sorry forgot it was a hotwire [well didn't think] hope you get things solved and put back together before you head off on the - Beaujolais Run, really sound good, as i said before do us Wedger proud, would hate for these other flash cars to beat you.lol.
Tell Katie we're all asking for her.
cheers john.

[TVRleigh_BBWR]

You may want to change the fuel filter after the pump, they are not expensive, plus will stop any more crap getting into the system, if its letting any in.

[Tasmindevil]

TVRleigh_BBWR said:

You may want to change the fuel filter after the pump, they are not expensive, plus will stop any more crap getting into the system, if its letting any in.

Cheers, new filter element fitted last night, new pump fitted 6 weeks ago and spare pump in the boot, taking a spare filter as well.

[TVRleigh_BBWR]

Tasmindevil said:

TVRleigh_BBWR said:

You may want to change the fuel filter after the pump, they are not expensive, plus will stop any more crap getting into the system, if its letting any in.

Cheers, new filter element fitted last night, new pump fitted 6 weeks ago and spare pump in the boot, taking a spare filter as well.

What pre-filter you using, as you may want to fit a better one, so the main filter has less work to do.

[Tasmindevil]

TVRleigh_BBWR said:

Tasmindevil said:

TVRleigh_BBWR said:

You may want to change the fuel filter after the pump, they are not expensive, plus will stop any more crap getting into the system, if its letting any in.

Cheers, new filter element fitted last night, new pump fitted 6 weeks ago and spare pump in the boot, taking a spare filter as well.

What pre-filter you using, as you may want to fit a better one, so the main filter has less work to do.

Upgraded to a bullet for the pre filter a few weeks ago, but not really used the car much over the last few weeks, around town was fine but took it to Dunfermline yesterday and the issue surfaced again. Filter I took out was not too bad but popped a new one in to be sure.

[TVRleigh_BBWR]

Should be ok, they filters do a very good cleaning job.
Maybe worth back flushing the old filter though to see if there was much crap in it.

[Tasmindevil]

TVRleigh_BBWR said:

Should be ok, they filters do a very good cleaning job.
Maybe worth back flushing the old filter though to see if there was much crap in it.

Good idea but will probably pop another one on.
Anyhow took the injectors out last night and cleaned the fuel rail, fortunately not rusted as the mechanic suggested but a few particles in there. Did a continuity test on the injector cables, good earths and no stray earthing on the positive side, replaced the injectors with the new ones, rebuilt and started. Doah one injector down, popped on one the the old ones on the problem injector lead while running and checked it was OK. Dismatled, reassembled rail and tested, it leaked so went to bed, up at 6 to finish off, new day new start and within 1 1/2 car up and running. Drove it into work today, so good so far !!!
New earth cable tonight and a new TPS should arrive todays so fingers crossed.
Cheers

[Jonny weggie]

Glad to see your getting there but your cutting it very very fine bud.

john.

[Tasmindevil]

Jonny weggie said:

Glad to see your getting there but your cutting it very very fine bud.

john.

Cheers Jonny, life on the edge !!!

[TVRleigh_BBWR]

You should never ever get anything but 100% clean fuel in the rail, only takes the smallest of particles to block and injector, so you must have had a problem somewhere hope it was just the filter and not the metal hoses from filter to engine bay.

[honestjohntoo]

Interesting situation, just re-reading your thread, in the space of just 3 days you've had the following:

diagnosis/suggestions what is wrong

Fuel tank filler hose
Electrical Fault
Earth fault
Resistor unit - Not fitted
Bank B injector faults
Stepper motor
Extra air valve
contaminated fuel rail
change fuel filter
fit a better pre filter
back flush the old fuel filter

and reported you've replaced and/or tested

Checked ECU (how?)
new fuel pump,
new bullet filter,
new relays,
wiring looks good and all connections OK (is that - seems OK - I wonder?)
new coil
new leads etc?
new earth cable
change injectors
new fuel filter
new pre filter
cleaned fuel rail
new injectors - again?
new throt pot arriving soon

One's gorra say, it seems most unlikely that ALL those replaced parts could possibly have been faulty, indeed probably none, which sorta confirms that the only result in using the scattergun approach to component replacement (as opposed to testing for functionality) is to empty the wallet - big time.

On top of all that, seemingly, none of the actions taken made any difference except the last one

Tasmindevil said:

Dismantled, reassembled rail and tested, it leaked so went to bed, up at 6 to finish off, new day new start and within 1 1/2 car up and running. Drove it into work today, so good so far

On these old Efi systems is has been shown over the years that 80%, plus, of all faults are caused either by air leaks and connector/wiring/earth problems, and more recently that pattern has been joined by an increasing occurance of fuel flow problems caused primarily by crud in the fuel tank(s).

Sadly then, I fear you have only temporarily solved the problem which will return shortly.

Thus, your corrective actions should be

• completely purge the fuel system of crud from tank to injectors - AGAIN -

• for good measure attend to all potential efi connector/wiring problems because although you said
  Tasmindevil said:

  wiring looks good, and all connections OK

your testing voracity has seemed somewhat sketchy.

• Make and break all the connectors, visibly inspect the contacts and dress as needed, then apply some contact lube or vaseline for future protection.

• In particulay pay close attention to the ECU connector, as this can be the root cause of the system dropping one bank intermittently.

• And as far as earths are concerned dont overlook the engine earth connector(s) on studs, behind and below the LH rocker cover.

• Finally, because its deffo worthwhile, dynamically check the whole system for rogue air leaks. A process that requires a thorough, methodical approach similar to that fully detailed in the PDF linked from here

Edited by honestjohntoo on Thursday 11th November 21:43