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Duncan sent me this

Here's one from a pal in the village, my autosparks man Martin Griffin, He used to run Yorkshire Kit Cars, some may have met him at last year's workshop when we all went to his bonfire party.

Originally published in a Kit Car mag a few years back but he still has the copyright


My Engine Won't Start

That cloud of despondency that you hoped was just passing over is turning darker and settling in for the long haul. Some smart arse who was a mate until a few moments ago is asking the usual dumb questions. "Yes I have got fuel and yes I have checked for a spark". You can't help the testy edge in your response. "Always preferred a good old distributor", his knowledge base has dried up, "You know where you are with points". "Bog off" you want to and perhaps even do retort. You checked it out. Fuel in the rail, a good feed to the coil. You know it's all correct but nothing, damn thing isn't even trying, not so much as a cough or spit. It must be something simple but what. Ex mate is going on about condensers now, you are only half listening. Everybody's a bloody expert.

If you haven't been part of this sort of scenario it's only a matter of time, believe me. Take a perfectly functioning engine out of its original home, slip it into your kit and it goes one of two ways. It will either start second turn, (be honest it's never on the first one) or nothing, zilch, the big zero. Older stuff isn't too bad as your mate above knows. Points and carbs, you know where you are, so I am pretty much going to ignore those and do a bit of electronic ignition / fuel injection stuff. Not your plug it into a diagnostic wussy type but real world kit car I can do this myself type.

So you need some kit. You don't need anything expensive and you will use it all again. Most useful is a proper automotive test probe, a clip each to live and negative. Probe earth it goes green, probe power and it goes red. You can do most stuff with one of these and unless you are getting serious. Don't look any further except maybe an injector lead tester, and you can make one of these with an LED and a resistor (see diagram). Where to start, your whiz bang twin dohc 16v zecotchnical has, as a friend of mine puts it, a sheared powerful nut, i.e. It won't go. Your right it probably is something simple so that's where to start.

Fuel

Just because you have fuel in the rail is not enough, it has to be at the correct pressure. Two things affect this. First the pump, a typical modern EFI engine needs a pump giving around 3 bar, pumps designed for carbs will not do. Second the fuel regulator. These are generally very reliable however make sure your regulator is on the return end of the fuel rail. If you are still convinced you are not getting any fuel through then it must be the injectors. Armed with your new test probe switch on the ignition and check an injector connector. One terminal should give you a live. If that checks out make sure its being triggered by the ECU using your LED tester. It will flash if all is well. Still nothing, then it must be the injectors, they may be gummed up or stuck. Even new injectors can stick if they have been lying around for some time. Take one out, connect and see if it gives a squirt under cranking. I have heard of people clearing them with a tap but I have never achieved it myself. Try soaking overnight in injector cleaner.

Electrical

Everyone's favourite this, often perceived as a black art, but the basics are simple logic. Start with the obvious. Are you getting a decent spark? Make sure the plugs aren't tracking have the correct gap and are clean. If they are OK then make sure the leads are in the correct firing order. No spark, then let's check back down the line.

The coil positive, on modern coil packs it's the middle terminal. Check with ignition on and during cranking. You would not be the first to wire up a new system from the accessories, rather than the ignition position on the ignition switch effectively turning everything off during cranking. If you have a good feed at the coil and no spark then it could be the high tension side. Try borrowing a set of HT leads and a coil pack.

Still nothing. Starting to get more serious. Could be bad connections or broken wires, check everything before blaming the ECU. One good one I came across was on a Ford Zetec transplant. It turned out that the engine originally had an auto box fitted and the crank sensor is slightly further inboard than the manual box one so it wasn't picking up the flywheel signal.

Still dead... you did make sure the engine has an earth lead... of course you did. If you made the loom up from one of the DIY type ensure you have the coil negatives, the throttle position and the injection trigger wires are the right way round. Damn, we are getting right down to it now, must be a bad earth. It's always a bad earth. Your ECU does have the correct map doesn't it. If it's a Ford system don't forget they use the same ECU on a range of cars and whilst it may plug in it may not have the correct connection or map.

Speaking of Fords you haven't forgotten that later model Zetecs have a passive anti theft system (PATS). This needs coded signals from various components such as ignition switch transponders otherwise it will close down the ECU and whilst well documented, people still fall foul. Just last week I had a call from a chap who had done an otherwise fine job of installing a Zetec into a Quantum H4 and could not understand why it would not trigger the injectors or coil pack. We solved it with an after market performance ECU, a few more bhp but an unexpected expense.

Finally it could always be something strange. This one took me a while. Ford SOHC injection transplant, an early one and on the face of it, dead easy. The customer wanted a rebuilt engine so the old one was sent off and an exchange from a reputable builder fitted. I did the wiring and all looked fine until start time, just a few coughs and bangs. Went through the lot, nothing at all. Finally with nothing left to check I called the engine builder. "Yea Pinto engine all the same those" say he. "So it was a carb not an EFI engine you sent then" says I. Not all the same, one minor but critical difference. The inlet port on the EFI has a notch at the top to allow for the injector, with the carb type head the injector was blanked off and the guy fitting it didn't (and why should he) know the difference.

Crank it over... spit... and again... cough... catch it... vroom... ha, no such thing as an engine that won't start.

Martin Griffin


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