Bugger wont start!
Discussion
Had a bit of a misfire over the last few weeks, tried to start the car today....turns over and thats it.. no cough no hiccup zilch, went through the full series of tests from the EFI manual (brainwave and printed it off the Wedgepages before it went off air) and the only fault I can find is on the resistor pack (2PR) three of the injector prongs give a reading of 12.4ohms and the rest give 6.1ohms. (6 being the correct value)
So am I right to assume that this is why it wont start or even attempt to start?
P.S It's a 350 flapper
So am I right to assume that this is why it wont start or even attempt to start?
P.S It's a 350 flapper
Sounds like you are reading two resistor hence double the resistance.
It had to be a flapper as hotwire does not have the resistor pack.
Are you getting sparks and fuel on every cyclinder.
And fuel presure.
Sounds like what paul had, bad fuel pressure. due to faulty pump and blocked filter.
It had to be a flapper as hotwire does not have the resistor pack.
Are you getting sparks and fuel on every cyclinder.
And fuel presure.
Sounds like what paul had, bad fuel pressure. due to faulty pump and blocked filter.
Yeah sounds similar except mine started and then died.
Try switching ign on, and press flapper in (after removing large pipe between plenum and afm) then go to back rhs of car stick head and arm underneath by rear wheel and see if you can hear / feel pump operating.
You could also disconnect pipe from cold start inj and see if petrol gushes out into a prearranged collection jar
instead of going to back of car.
I have also in past attached a tyre pressure guage to this pipe to see if the system pressurizes up
Report back for next steps
Try switching ign on, and press flapper in (after removing large pipe between plenum and afm) then go to back rhs of car stick head and arm underneath by rear wheel and see if you can hear / feel pump operating.
You could also disconnect pipe from cold start inj and see if petrol gushes out into a prearranged collection jar
instead of going to back of car.I have also in past attached a tyre pressure guage to this pipe to see if the system pressurizes up
Report back for next steps
Hi chaps thanks for the replies, but fuel pump runs, lots of pressure on the fuel rail, sparks on all plugs, cant check if the voltage drops for the injectors as my multi tester wont pick up the 100th of a sec impulse on crank speed. Double checked the resistor pack and definately getting twice the resistance value on three prongs.
Have tried my spare ecu, afm, ignition amp and coil (all known to be good)
Still scratching my head on this one
Have tried my spare ecu, afm, ignition amp and coil (all known to be good)
Still scratching my head on this one
Edited by chedder on Wednesday 12th September 17:43
Aha ha , sounds like my other problem I once had on the Wedge, spent ages tracking it down by swapping bits over, but still would not fire. In the end put a new rotor arm on and it started first time, and yes I still had sparks at the plug with the knackered one on
Worth a try, and noot too expensive, probably be able to take one from your other Wedge to try this out ?
Of course the other likly suspect could be the igntion amoplifier on the side of the dissy, as this could also cause non start
Worth a try, and noot too expensive, probably be able to take one from your other Wedge to try this out ?
Of course the other likly suspect could be the igntion amoplifier on the side of the dissy, as this could also cause non start
Check the resistances at the injectors?
PS. Are you picking up the correct "common" pins at the resistor pack? from memory the top row is the reverse of the bottom row (crap explanation sorry, but hope you get what I mean).
Also I seam to remember Wedg1e saying that if these resistors do fail they only fail open circuit.....or was it closed
)
PS. Are you picking up the correct "common" pins at the resistor pack? from memory the top row is the reverse of the bottom row (crap explanation sorry, but hope you get what I mean).
Also I seam to remember Wedg1e saying that if these resistors do fail they only fail open circuit.....or was it closed
)Edited by dickymint on Wednesday 12th September 18:54
Update, all injectors resistance values check out ok, put a timing strobe light on all the plugleads in turn and all plugs are firing with a nice bright light.
Switched the Nitrous crossfire injector on (just fuel and no nitrous) this sprays a stream of fuel into the induction pipe after the afm and the car is trying to run!
Thus ignition amp, dizzy and rotor arm are all ok.
So from that result I can only deduce that the injectors are definately not receiving a signal to deliver fuel.
Checked the continuity of the trigger wire from the ballast resistor to the ecu and that is fine along with the voltage.
?????? any more clues or help appreciated!
Switched the Nitrous crossfire injector on (just fuel and no nitrous) this sprays a stream of fuel into the induction pipe after the afm and the car is trying to run!
Thus ignition amp, dizzy and rotor arm are all ok.
So from that result I can only deduce that the injectors are definately not receiving a signal to deliver fuel.
Checked the continuity of the trigger wire from the ballast resistor to the ecu and that is fine along with the voltage.
?????? any more clues or help appreciated!
P100 said:
Hi guys,
Have you tried, with ign on, opening throttle butterfly by hand, thus triggering the tps and you should hear the injectors click.
If not suspect the tps.
Cheers roy
Have tried this, injectors dont click, but the tps voltage is spot on and the voltage varies exactly as per manual when the butterfly is opened.Have you tried, with ign on, opening throttle butterfly by hand, thus triggering the tps and you should hear the injectors click.
If not suspect the tps.
Cheers roy
Suspect the problem may lie with the earthing of the injectors...No more playing tonight though as battery is now flat and on charge!
If you wire up a 12V LED in parallel with an injector you can easily see it triggering. They're sold as 'NOID' diagnostic lights but you can make your own quickly and cheaply from a male/female pair of minitimer injectors and a 12v LED. It's a very useful diagnostic tool to have, along with an HT tester.
chedder said:
Have tried this, injectors dont click, but the tps voltage is spot on and the voltage varies exactly as per manual when the butterfly is opened.
Suspect the problem may lie with the earthing of the injectors...No more playing tonight though as battery is now flat and on charge!
The injectors are earthed when the ECU fires them! They get supply voltage as long as the ignition is on, from the resistor module. However to get the injectors to fire the current has to be earthed somewhere and this is performed by two power transistors in the ECU (one for each bank of injectors). The transistors are switched on and off rapidly and the duration of the 'on' time determines how long the fuel is sprayed for.Suspect the problem may lie with the earthing of the injectors...No more playing tonight though as battery is now flat and on charge!
One consequence of this is that if either transistor (or its driver stage) fails, you lose all the injectors of one bank. It's rare for them to fail alone never mind as a pair.
The lack of response when you flick the throttle could be an indication that it is indeed an ECU fault...
Wedg1e said:
chedder said:
Have tried this, injectors dont click, but the tps voltage is spot on and the voltage varies exactly as per manual when the butterfly is opened.
Suspect the problem may lie with the earthing of the injectors...No more playing tonight though as battery is now flat and on charge!
The injectors are earthed when the ECU fires them! They get supply voltage as long as the ignition is on, from the resistor module. However to get the injectors to fire the current has to be earthed somewhere and this is performed by two power transistors in the ECU (one for each bank of injectors). The transistors are switched on and off rapidly and the duration of the 'on' time determines how long the fuel is sprayed for.Suspect the problem may lie with the earthing of the injectors...No more playing tonight though as battery is now flat and on charge!
One consequence of this is that if either transistor (or its driver stage) fails, you lose all the injectors of one bank. It's rare for them to fail alone never mind as a pair.
The lack of response when you flick the throttle could be an indication that it is indeed an ECU fault...
chedder said:
Update, all injectors resistance values check out ok, put a timing strobe light on all the plugleads in turn and all plugs are firing with a nice bright light.
Switched the Nitrous crossfire injector on (just fuel and no nitrous) this sprays a stream of fuel into the induction pipe after the afm and the car is trying to run!
Thus ignition amp, dizzy and rotor arm are all ok.
So from that result I can only deduce that the injectors are definately not receiving a signal to deliver fuel.
Checked the continuity of the trigger wire from the ballast resistor to the ecu and that is fine along with the voltage.
?????? any more clues or help appreciated!
I used a spare fuel rail with injectors once to see if the injectors would fire, so if you have one (and not everyone has Switched the Nitrous crossfire injector on (just fuel and no nitrous) this sprays a stream of fuel into the induction pipe after the afm and the car is trying to run!
Thus ignition amp, dizzy and rotor arm are all ok.
So from that result I can only deduce that the injectors are definately not receiving a signal to deliver fuel.
Checked the continuity of the trigger wire from the ballast resistor to the ecu and that is fine along with the voltage.
?????? any more clues or help appreciated!
) then connect the cold start pipe to it and one of the injector multiplug connector, crank the motor and you should then see if the injector is being opend by the jet of fuel coming out of the injector (spraying ito a suitable container )Or I suppose if you had one spare inj you could connect this to the cold start fuel hose and multiplug from suspect bank of inj to get the same result ?
chedder said:
went through the full series of tests from the EFI manual (brainwave and printed it off the Wedgepages before it went off air)
Chaps, get this while you still can:EFI Manual
Udate time.....definately fuel delivery issue, as can get the engine to run very roughly by using part of the nitrous system as a fuel delivery system.
Spark plugs all checked with a strobe timer and are sparking under compression
ECU
AFM
TPS
temp sensors
ignition amp
Fuel pressure
are all ok and within set parameters
Have a dodgy reading on three prongs on the resistor pack (12ohms instead of 6)even with this it should attempt to fire, so I can only come to the conclusion that it must be a fault with the signaling of the injectors.
Spark plugs all checked with a strobe timer and are sparking under compression
ECU
AFM
TPS
temp sensors
ignition amp
Fuel pressure
are all ok and within set parameters
Have a dodgy reading on three prongs on the resistor pack (12ohms instead of 6)even with this it should attempt to fire, so I can only come to the conclusion that it must be a fault with the signaling of the injectors.
Edited by chedder on Thursday 13th September 15:21
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