EFI troubles/carb swap

[Ed Townend]

OK two parts to this post:

First, my EFI SOHC has become very unreliable. Sometimes it starts first time, others it cranks but won't attempt to start at all. I've not found a particular pattern to it failing to start but if it won't start that's pretty much it for the next 24 hours or so at which point it will more than likely start first time. When it's running it's fine but if I stop it and try to start it a few hours later it won't go.

There's a good spark and plenty of fuel at the fuel rail, but if I pull a plug after cranking it they're bone dry so it seems the injectors just aren't firing. It seems SOHC pintos don't have a crank position sensor so I'm not actually sure how the computer knows when to inject at all.

The complication is that this engine has a sequential LPG system fitted by a previous owner, which I understand works by intercepting the signal from the EFI computer and if petrol is selected passes it straight on to petrol injectors but if LPG is selected (and the engine is warm enough) modifies the duration and timing before passing it to the LPG injectors. Unfortunately this seems really well joined into the EFI loom so I can't just unplug it to rule it out as a fault.

I've had a mechanic friend come over and he pretty much confirmed the same. Does anyone have any ideas?

Part two is that because I'm so fed up of this fault, as a (semi) temporary solution so I can use my car I'm considering swapping to the standard carb. I've got access to all the parts I could need including a complete carbed pinto engine but in my head all I'd need to do is remove the existing inlet manifold, bundle up the loom but leave it in place, bolt on a carbed manifold, swap to points ignition and set up? Or am I being incredibly naive?

[1xf87h8w80hlh]

what car is it as had  a similiar folt on my grandads Galaxy and it was a relay under n/s seat

[Ed Townend]

It's from a '85-87 Sierra in my Legerra. Should have pointed out the carb idea would just leave the LPG stuff dangling, no point in trying to make that work with it.

[Adrian Southgate]

Ed, have you tried contacting Mike?

Second thought - is the switchover relay for the fuel stuck? (if there is such a thing)

Try phoning a well established ford dealers and speak to the guy in the stores / parts dept. If its a common faulty part they will know about it.

[28ullkq4hau58]

you could try the  ,autogas,, association  i used to be friendly with  tony rushworth, the founder.. he,s getting on a bit now but i believe he,s still very much involved and upto date ..

 

  just a thought ,,,

[Ed Townend]

Think I should probably trace all wires to the LPG computer and disconnect it electrically to rule it out as a fault. Have checked it's not trying to inject LPG rather than petrol but still...

[Ed Townend]

Completely disconnected the LPG system from the Ford ECU today, so back to a standard ford EEC-IV setup. Started very reluctantly once and then refused to start again. Same problem as before, the injectors aren't getting triggered at all. I'm stumped!

[Adrian Southgate]

Have you got a spare ECU you could transplant or can you borrow a known working spare from someone?

Same for the coilpack? (and any other sierra bits?)

What about a ford diagnostic unit and just plug the ECU in, let it tell you whats wrong?

[Adrian Southgate]

If it's any consolation, mine won't start today either and thats a standard carb and points engine.

Turn the key and all the dash lights go out but no solenoid action, not even a flat battery click... I think the fire eat a few wires I haven't found yet..

[Ed Townend]

Yes! It was indeed the ECU relay that had failed. Popped a new one in and away she went. A bit reluctantly but that was more than likely because I'd been cranking for ages so the battery will have been down. I was actually ready to swap to a carb.

Thanks everyone, now off to Keswick I go. Expect to see me on a tow truck shortly.

[Adrian Southgate]

OOOh your'e such a pessimist Ed :-)

You'll be right mate.

[Ed Townend]

Never mind, thought I'd check on her last night and there was no go. Same problem as ever. Was too dark to check if the new relay had failed so now I've got to have a lift in a stupid boring reliable Toyota Aygo. Not bitter at all.