2.0 16V won't start

[Rpmayne 0]

This is a problem with an ACE engine (commonly fitted to Audi 80's etc). Finally got the suspension changed and took it for a run.

 

Everything felt fine until I tried a few brake tests and the fuel pump started to make even more noise than it usually does. Then the car intermittently died. Checked the fuel gauge and it was a rizla off the empty marker so just thought I'd ran out of petrol.

 

Limped home, changed the timing chain which I had planned to do anyway(loose as fcuk, surprised it hadn't jumped) then got some petrol in a can and filled it up the next day.

 

Now it turns over ok and I can hear it try to fire every now and again, but it won't start.

 

Until then it hadn't missed a beat, started on the button, idled well etc.

 

Having read a few posts, is the most likely thing the fuel filter? The pump has always been noisy to me so thinking the filter may have been partially blocked and the crap in the bottom of the tank has finished it off.

 

The fuel pump primes ok when turning on the ignition.

 

Thanks.

[bcstudent 0]

Well, based on that info, it's definitely worth changing the fuel filter first. Does the ACE engine have mechanical injection or digi?

[Phil K 0]

I'd be guessing at blocked fuel lines/injectors if it's been run empty?

[Rpmayne 0]

It's has the mechanical K-Jetronic fuel injection with a distributor. Very similar to the mk2 16v Golf engines except its mounted the wrong way.

 

Abit stupid to have run it out really, just didn't look at the gauge.

[Rpmayne 0]

I'm stuck again. Borrowed a fuel pressure gauge kit and measured the pressure to the fuel distributor. I get 4 bar when it primes then it fluctuates around 6 bar when cranking.

 

I took an injector out and cranked it over and nothing came out. There was fuel vapour coming out of the open hole in the inlet manifold though.

 

Any got any ideas? Fuel pump is making a racket so was pretty convinced it was that, yet the pressures seem ok.

[bcstudent 0]

Can you measure the control pressure from the warm-up regulator?

 

Check for a spray pattern at the injector again but lift the air flow flap in the metering head while the engine is being cranked.

[aide 0]

those priming and cranking pressures seem fine iirc, mine was set at 5bar.

 

the fuel vapour coming out the manifold is probably from the cold start valve, which assuming this is direct fuel feed means you have fuel circulation to the bottom section of the fuel distributor. to confirm it is this cold start fuel vapour simply pull of the blue connector and there should be no vapour when cranking.

 

i'd be inclined to pull all the injectors to confirm none of them are spraying. if so then it's likely you've got no fuel geting to the top half of the fuel distributor.

 

as bcstudent has pointed out give the metering flap a vigurous wiggle (before cranking) to see if this makes a difference, you 'should' feel the fuel being 'pumped' on the up motion if the fuel plunger isn't stuck - of course when cranking you'll need two people, and you'll need the co2 adjustment alan key so you can do it whilst the rubber bend is connected, you risk sucking up loose crap otherwise!

 

my guess is a bit of dirt in the fuel distributor, they're so finely machined it would be easy to foul up one of the tiny holes. i've spent half my rado life with these problems!

 

sounds like you need a new filter though, you'll notice a difference in the sound of your pump with a new filter - easy enough to change too

[Rpmayne 0]

Thanks for that.

 

I've now done the following:

 

1. Changed the fuel filter. Pump still makes a racket though, maybe on its way out but not there yet.

 

2. Have tried taking two injectors out now and neither supply fuel when the engine is cranked. Haven't tried them all yet though.

 

I take it the CO2 adjstment manually moves the metering flap up and down? Just a thought but if I primed the fuel pump, took the injectors out then lifted the flap, would that let fuel go under the built up pressure? Just wondering if I can do it without adjusting the mixture.

[aide 0]

the co2 adjustment screw just really finely moves the metering flap up and down - definetely DON'T turn though as your o2 levels were probably fine to begin with and you'll mess the settings up if you turn!!

 

I always found I could move the flap up and down using an allan key in the adjustment hole, you're best bet is to wiggle the metering flap with the rubber inlet bend removed first!

 

there is an accumulator after the external fuel pump which is like a one way valve, if working correctly this should maintain the fuel pressure whenever the fuel system is shut down. if the diaphragm is ruptured in this device this can cause starting problems as the pump has to do all the work

[Rpmayne 0]

I checked the pressure when the engines not cranking and it stays at about 5 bar so I think the one way valve is ok.

 

I will try tonight, but if no fuel comes out of any injectors when the flap is pushed up while cranking, what's involved in stripping the fuel distributor? Would I need any new seals etc?

[bcstudent 0]

what's involved in stripping the fuel distributor? Would I need any new seals etc?

Not much really as the main body is a sealed unit. All you can do is remove the plunger and check for pitting/score marks before soaking the lot in carb. cleaner. Giving the fuel distributor a good servicing sorted out an occasional high idle problem I'd had for two years.

 

I didn't replace any seals when I did mine (there aren't many) and had no problems. You will have to be very careful with the plunger though as they're matched to the fuel distributor. Damage either and you'll be replacing both!

[Rpmayne 0]

Just been out playing with the Audi and tried lifting the fuel distributor flap while cranking the engine over. A healthy amount of fuel then came out of the injector. This doesn't happen when its just turned over without depressing the accelerator which surprises me.

 

Annoying because I put it all back together again, held the accelerator half down and tried starting. It sounds like its going to start but doesn't.

 

As the timing chain was really loose, is it possible the timing was set to compensate, and now its back to how it should be the distributor (spark plug one) needs adjusting?

[aide 0]

by lifting the metering flap up your allowing the fuel to pass to the injectors, and as such you've eliminated a blockage in the metering head and the injectors.

 

when starting of the key the engine should create sufficient vacuum to 'lift' the metering flap and provide said fuel, the cold start valve kick starts this vacuum by providing an alternative fuel source when the engine is cold.

 

one cause of this symptom is that your control pressure is to high, and this is preventing the metering flap from lifting and providing the fuel - however I can't see how this would have adjusted with the works you did, allthough a blockage in this system could cause problems, but getting into that will blow my brain!

 

when i hadn't started my valver for a few weeks i used to have to crank it continuosly for about a minute or two before it eventually fired, it used to fire of one or two cylinders then die, then chug a bit and eventually rev properly - it would start and idle fine from then on when started regularly - dunno why it was just one o dem thangs.

 

you can try testing the control pressure, it's the pipe that ubends into the top of the metering head, at/ below 50degs should be 16psi. other useful fuel pressure figures for kjet below.

 

Cold Control Pressure 50deg F = 16psi, 75deg F = 24psi, 100deg F = 32psi

System Pressure 68 – 78 psi

Warm Control Pressure 49 – 55 psi

Rest Pressure 35 psi

 

check the cam/ cam, crank and distrib timing visually by removing the rubber half moon things, but the distributor *shouldnt* be that far out that it won't start

 

pm me once you have the car started and i'll let you know how to adjust the pressures further for performance purposes :)

[Rpmayne 0]

Thanks for all that aide, will have another go tomorrow with that info. I gave the fuel pressure tester back to the garage but will hopefully get it back again.

 

I've attached a picture of the fuel distributor, are my label correct? If so the system pressure I measured was about 70psi. I didn't measure the others as the fuel distributors had arrows next to the fittings pointing out so I assumed they were returns.

 

Will also check all the timing again just to make sure.

 

NOTE: PICTURE UPDATED.

[aide 0]

yikes - that's kjet motronic me thinks :) kjet does not have that solenoid, connector or black sender thing!!

 

considering i don't know the motronic.... i believe you've id'd the system pressure correctly, not sure where the cold start comes from....!

 

however, the one that turns a left angle and then goes into the top of the metering head is the control pressure, trace this line back to the warm up regulator and then back to the metering head to determine the feed for the warm up regulator - but saying that i can only see five lines leaving the metering head 1 per cylinder, 1 wur and ???

 

I'll have a check in the book tonight and let you know this evening or tomorrow morning!

[bcstudent 0]

kjet does not have that solenoid

What solenoid?!

 

The connection marked 'system pressure??' is correct. It is the inlet to the fuel distributor from the fuel pump. The black box above that arrow is the ECU-controlled differential pressure regulator valve and is the KE version of the K-Jet warm-up regulator (WUR). The black box on the opposite side is the air-flow plate position potentiometer.

 

The object marked as the 'control pressure regulator??' is the system pressure regulator and is in the return line to the fuel tank from the fuel distributor. The small fuel pipe marked 'control pressure??' feeds the system pressure regulator with the excess fuel to be returned.

 

The 'cold start injector' connection is labelled correctly.

 

 

 

...I think!

[Rpmayne 0]

Sorry, didn't realise it was different to the Kjetronic on the 16v VW's. Would be cool if you can find anymore out.

 

Checked the camshaft / crank timing marks and they are as close in line as they can be (about 1mm out on cam, but next tooth makes it further out). The distributor is attached to the end of the exhaust camshaft but doesn't look like a normal rotor arm / cap type, more like a sealed coil type. Tried advancing and retarding the ignition with no joy. Marked up where it came off so pretty sure it's where it was to start with but tried anyway.

[aide 0]

kjet does not have that solenoid

What solenoid?!

 

considering i don't know the motronic....

[Rpmayne 0]

Cool, just updated the picture with the new labels. So far;

 

Fuel pressure ok

Injectors work if cranked and flap manually pulled

Cam / crank / distributor timing ok (well, not 180deg. out and leads in the right places)

Spark plugs working as occassionally it lazily fires

[bcstudent 0]

kjet does not have that solenoid

What solenoid?!

 

considering i don't know the motronic....

 

Not having a dig chap, I just thought you'd seen something I hadn't. Had there have been a solenoid I'd like to have known it was there. I don't know the KE system that well either having never owned a KE-fuelled car.

[Rpmayne 0]

Thanks for all your help, found the problem at the weekend. Took the cam cover off again to double check the cam-to-cam timing against the cam pulley and crank. Found the inlet cam was a tooth out. Seems that when I lined them up they weren't at the centre points of the cam. Re-aligned it and put it all back together, now runs although abit rough. Going to get the distributor timing / mixture checked this week then hopefully all well. Never sounded like any valve/piston contact was made so hopefully got away with that. We shall see..