Can a coil be breaking down intermttently? I've only had them work or not work. I can get the engine to start but not run. It's FI and I've replaced the double relay and the fuel pump is working so I've ruled that out but with someone else cranking the engine there seems to be no spark at the plugs>
Coil or it's connections can give intermittant probs Barry. Chuck om another to test it, but make sure the connections are good as you go.
When it starts, it doesn't run at all, so just fires on a cylinder or two??? Doesn't sound like ign. but you can check spark as you've said, maybe coil HT lead is a prob???
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
Also maybe check the earth strap from the trans to the chassis.
Have heard of cases where the strap was busted and the engine basically only earthed through the clutch and throttle cables... it'd fire once or twice but that was it.
VWDCQ vice pres & web dude - vwdcqinc.org.au
Join a car club - get car peeps
My toys
'70 Hillclimb Bug 'Jezebel' w/- Haltech EFI -
http://bit.ly/VwTNtQ
'60 KG Coupe - resto kinda started
01 New Beetle - gf's car, but I turn the spanners
I thought it would be the fuel pump circuit as the pump comes on only when the starter motor runs then the double relay keeps the pump running when the starter is no longer needed. The engine starts up then dies as if the pump has stopped, so I checked first that the pump works, it does. I checked that I was getting a spark at the points,I was but when I had someone turn the engine over there was no spark at the plugs. All that happened was one day I drove to work-all fine, the next morning nothing, everything checked out fine, just wouldn't start, like no spark. I replaced the double relay and it started so I used it for work, no problems, drove home. Next morning nothing. I have another new double relay but I may go get another coil as they're not expensive and try that but I'm very tempted to get rid of the FI all together except that when it's running it is super smooth.................for a VW!
Before you buy a coil, go step by step with the coil output. You said the points were sparking but no HT output, where did you test that. While you test the points, the coil should output, so at the same time, hold the coil HT lead near an earth, arc the points, (preferrebly by rocking the engine with the points just opening and closing), test for spark at the dissy end of the coil H/T, etc.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
ancientbugger wrote:Can a coil be breaking down intermttently? I've only had them work or not work. I can get the engine to start but not run. It's FI and I've replaced the double relay and the fuel pump is working so I've ruled that out but with someone else cranking the engine there seems to be no spark at the plugs>
Hi
Yes, coils do break down internally, or the top can crack..
so, something is happening at the points...
so, I presume Your spark is there..?? maybe..
but not getting out of Your dizzy..??
or.. not getting to the dizzy, via the high tension leads...
high tension leads , [not the ultra expensive ones] can break down or short out..
test each lead with a multimeter...
check Your high tension lead is pushed right in at the coil and at the distributor..
PS: I do carry a spare coil... lol
cheers
LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---
yep coil can and do break like that. a few types of failures are:
Primary coil open circuit.
Primary coil short circuit.
Secondary coil open circuit.
Secondary coil short circuit.
Sounds like you have a problem with the secondary as you are lacking output when clearly you have current draw on the primary.
Time for a new coil.
71 notchback,
Past owner of, 70 NB, 73 SB and 72 FB TLE
I've checked all the leads and they're good, the distributor and cap are fine. I haven't checked the HT from the coil to the dist. so I'll pop out and check that now, I'll also change the points while I'm there and see what happens but what keeps on throwing me is it still feels to me like a fuel thing-forget about the lack of spark for a moment but it'll fire up on all cylinders and then die like the circuit in the double relay isn't keeping the pump going.
Are the points burnt a blue colour,it may be a condenser as they will break down intermittently,but grom your description it does sound like fuel supply,on the main fuel rail there is a 7mm bolt in a T remove the screw and fit a fuel pressure gauge over this fitting,this will tell you if the pump is stopping and you can work from there.Cheers Les
That sounds like a good idea Les.
Gday all does the car run a balast resistor it maybe wired incorrectly when you let it return off start and it stops theres a wire unpluged for ign side of resistor this is my thoughts on it starting but not running
Ernie
Ernie it does have a ballast resistor on the coil but that has never been unwired(?). Would it cause any damage to anything if I wired it the other way round. In the past and present with all my cars the coils have never used one but this came with one and I've never had a problem so saw no reason to change it.
is the resistor wire burnt out?
Or put a test light accros the fuel pump terminals, will proove it gets continuous supply.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
AND THE WINNER IS.....................none of you! It was an air leak! Where the intake boot connects to the plenum chamber it had slipped off but not until I had given everything a thorough shake,pull or just a bloody good talking to. I'n no expert with FI but it all seems arse about face with the symptoms, when there's an air leak it runs slower or in this case not at all. In Pauline Hansons famous words "Please explain?" BTW she's running sweet again.
ancientbugger wrote:AND THE WINNER IS.....................none of you! It was an air leak! Where the intake boot connects to the plenum chamber it had slipped off but not until I had given everything a thorough shake,pull or just a bloody good talking to. I'n no expert with FI but it all seems arse about face with the symptoms, when there's an air leak it runs slower or in this case not at all. In Pauline Hansons famous words "Please explain?" BTW she's running sweet again.
thanks pauline...lol
Must have been a BIG leak..??
although Fuel Injection is like rocket science... lol
everything balanced..??
LEE
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---
Gday all glad to hear you have it running nothing worse than not knowing where to start. then finding an unrealated symptom to be the cause have a nice weekend
Ernie
An air leak makes perfect sense. an FI system with a AFM (air flow meter) as opposed to a MAP will stall instantly after start up. Its the central main component for the computer to make judgement on air/fuel ratios based on teh programmed air/fuel curves. Its like ripping a heart out of a human, it doesn't work well lol (don't try that one at home kids!!) 😂
IE: ur afm wouldn't have registered air flow as it would be sucking through the vac leak (near complete bypass if large enough). the start up injection does its job, then it just dies over because it doesn't register any air flow (or very little) and adjusts the fuel mixture to suit the wrong air flow.
And if its next to no air flow in the afm, it'll spit out next to no fuel to suit. (like a fuel cut off at the injector)
(ô_!_/ô) (ô_!_/ô)
69' baja: kombi box, thing spindles, irs, disc front, type 3 rear drums, 2 inch lift kit, 31x10 rears. 👍
New engine in process: 94mm p&bs, 74mm C/w chomol Crank, 35.5x39 SP heads, turbo. Wierd combo, hopeful torque monsta!
Where the elbow fits over the lip of the plenum inlet there's not a great deal of overlap so when the hose clip tightens up it slips up and off. It was only when I actually made the mad dash from switching on then back to the engine I actually heard the hiss before the engine died. All good now😉
bajachris88 wrote:An air leak makes perfect sense. an FI system with a AFM (air flow meter) as opposed to a MAP will stall instantly after start up. Its the central main component for the computer to make judgement on air/fuel ratios based on teh programmed air/fuel curves. Its like ripping a heart out of a human, it doesn't work well lol (don't try that one at home kids!!) 😂
IE: ur afm wouldn't have registered air flow as it would be sucking through the vac leak (near complete bypass if large enough). the start up injection does its job, then it just dies over because it doesn't register any air flow (or very little) and adjusts the fuel mixture to suit the wrong air flow.
And if its next to no air flow in the afm, it'll spit out next to no fuel to suit. (like a fuel cut off at the injector)
They also split the rubber and again run like crap.Glad you have it sorted out.Les
You've have to love this forum, this has just happened again and I couldn't remember what caused it last time but a search and sorted!
