no power to injector

daverangerover · Post by **daverangerover** » Sun May 03, 2009 6:59 pm

hi all,need to now how to fix this little problem,1988 3.5 efi,no power to one injector,in the wiring diagram [haynes] there is only 3-4 wires that power the 8 injectors,any one any ideas,

ChrisJC · Post by **ChrisJC** » Mon May 04, 2009 10:37 am

Do you know if it has the Flapper type EFi system or the Hotwire type.

If it's the flapper type, the setup is this:
Each injector is fed with +12V. The other side of the injector goes to the resistor pack which contains 8 resistors. The non injector side of the resistors are commoned in groups of four. This gives two connections which go to the ECU. The ECU grounds the connection when it wants the injectors to open.
So, the ECU fires the injectors in groups of four.

If you have four injectors being faulty, it is most likely the ECU or the resistor pack (or wiring inbetween)

If it's just one, it could well be the +12V feed, or the wire between Injector & resistor pack, or the resistor pack itself.

Some multimetering would probably give you the answer.

Chris.

daverangerover · Post by **daverangerover** » Mon May 04, 2009 10:54 am

ive a spare resistor pack will try that later,its the flapper and just one injector not getting any power,

daverangerover · Post by **daverangerover** » Mon May 04, 2009 8:26 pm

thanks mate, i think its the resistor pack bad connection,im thinking of putting carbs on it,as its gas converted and just had a new airflow meter,i think the carbs are a bit more reliable and robust,what do you think,

bodger · Post by **bodger** » Mon May 04, 2009 10:20 pm

LPG is easier with EFI , in my opinion ... it certainly makes it easier to switch over , but don't forget to add a backfire protector or others loosen the jubilee clips on the air pipe
you will also find it better to use copper core HT leads if you run on LPG a lot , only a fiver if you make them yourself .. and it's easy , well i did it so it must be ..

daverangerover · Post by **daverangerover** » Tue May 05, 2009 6:04 am

where do you get the copper wire from,whats it called,look like,

ChrisJC · Post by **ChrisJC** » Tue May 05, 2009 7:07 am

Carbs are definitely simpler than EFi if you're not too good with electronics.

However as Bodger says, switching between fuels is more of a pain with carbs as you have to empty the float bowls before switching over to gas.

Chris.

daverangerover · Post by **daverangerover** » Tue May 05, 2009 7:10 am

does it back fire as much on the carbs,

ChrisJC · Post by **ChrisJC** » Tue May 05, 2009 8:22 am

It shouldn't backfire at all. My Landie on carbs has never backfired. My van on EFi has backfired twice, both times when I had a serious problem with lean mixtures.

Chris.

bodger · Post by **bodger** » Tue May 05, 2009 9:05 am

mine has only backfired once but then it only takes once to destroy the AFM and a back fire protector is well worth the £7.50 they cost on ebay
http://cgi.ebay.co.uk/70mm-ANTI-BACKFIR ... 7C294%3A50

ChrisJC · Post by **ChrisJC** » Tue May 05, 2009 9:26 am

Or just leave some hose clips loose.

On my EFi, I have a flap opener so when on gas the flap is wide open and should in theory not get broken by a backfire......

Chris.

daverangerover · Post by **daverangerover** » Tue May 05, 2009 3:34 pm

i had the safety blowback valve on my last v8 and it did not do anything,blew the bottom off my afm,luckly i had a afm off an old bmw,they are the same apart from the internals,

bodger · Post by **bodger** » Tue May 05, 2009 9:47 pm

they are quite easy to repair , i did mine with silicone and pop rivets ..
my backfire thingy worked fine tonight ..my rotor arm lost it's metal part and it did the most almighty bang and pop , made me jump let alone the que at the bus stop ...lol

daverangerover · Post by **daverangerover** » Tue May 05, 2009 10:00 pm

is the any websites giving info on changing from efi to carbs,

ChrisJC · Post by **ChrisJC** » Wed May 06, 2009 7:00 am

It's pretty straightforward. You just need to swap the inlet manifold and everything that's attached to it. Then get a low-pressure fuel supply (the EFi supply will flood the carbs) and sort out the breathers.

The ignition system is independent of the fuel system, so you don't need to change that at all.

Job done!

Chris.