Yank poor starting, fixed it!

[danthecapriman]

Right, as I'm sure most of you are aware I'm having a nightmare trying to get to the bottom of a starting/ running issue with my Mercury. I've also suffered seemingly simultaneously with a failed brake master cylinder, causing fluid to leak into the servo. The fluid has definitely been burning off last time I could get the car to run (a puff of white smoke, quickly clearing)

 

Now my theory!

 

Is it possible that the reason the car will no longer start and if it does it runs awfully, the master cylinder is now empty and full of air, no more brake fluid can be sucked in and burned. This air is now being sucked through the servo, down the inlet manifold vacuum pipe and into the engine. This having the effect of weakening the mixture massively preventing the engine running.

I may be clutching at straws as nothing else seems to be causing this issue, but can this even happen? I've never heard of it before but is it possible?

[Mr_Bo11ox]

If you're thinking that, why dont you just disconnect the pipe to the servo and block up the hole on the inlet manifold and see if it makes a difference.

[danthecapriman]

I will try it, but can it happen? I've been thinking about possible causes all day and so far this is all I can come up with!

It just seems a bit too coincidental!

[forddeliveryboy]

Obvious solution - fill the m/c reservoir with super unleaded. Once running, fill with sealant then finally DoT4.

[Timewaster]

Stranger things have happened.

I remember a mate being given an automatic Sierra years ago. Very clean but the old boy who owned it gave it away because it had started smoking and then the auto box began to misbehave.

A diaphragm had split somewhere and the car had been burning the atf until the level got low enough for the box to get upset.

How he diagnosed the fault I'll never know.

[danthecapriman]

Thanks for the input so far!

 

It really is pissing me off! I can not find anything at all wrong with the fuel system (except maybe the fuel itself being old) the ignition system is all seemingly ok, the carb seems fine.

It just seems very coincidental that the master cylinder failed and at about the same time the bad running starts. The brake fluid can be burned when it's sucked in but since that's now run out all that's possibly getting drawn in through the failed seals is air = weak mixture. Would also explain why when I adjusted the carb mixture screws there was no change to running but there should have been.

 

It just seems like an almost unbelievable thing to happen. I mean, why would you think that a failed master cylinder can result in the engine failing to run!

[vulgalour]

As MrB suggests you need to isolate the vacuum/brake from the engine and readjust to get it to run properly, if you can achieve that  then you know the issue is with the brakes.  A failed master cylinder may also mean you've got a failed seal in your servo which is letting the brake fluid contaminate the air supply and thus causing appalling running.

 

It's a problem I've been told about as a real oddity, I didn't expect someone to present with it again and had filed it away at the back of my mind.  Solution was to rebuild the servo that was leaking, get the engine running to burn off the contaminant and everything was then okay, though the mixture took a while to set to correct again as it had been adjusted to compensate.

[oman5]

an air leak on the intake does sound likely from the symptoms, but modern petrol has been said to have a shelf life of only 3 months or so. Have you tried tipping some fresh petrol down the carb, see if it starts up ok that way?

[danthecapriman]

I didn't get chance this afternoon to go get any fresh fuel, but I will get a Gerry can full during the week. But, if I spray a load of easy start down the carb it will very briefly fire up.

I thought of an air leak or lean carb mix but then discounted it as I found nothing, and adjusting the carb richer and leaner made no difference.

But if this is where the problem is coming from then the extra air is leaking into the induction system after the carb.

 

Vulgalour, you could be right about the servo itself also having a defect, or torn diaphragm or something. And your right, the mixture will probably need rechecking aswell. I think you can get new ones still on Rockauto fortunately.

 

I'll take the vacuum hose off, plug it with a bolt and jubilee clamp or something and try starting it, tomorrow hopefully.

[twosmoke300]

It does happen . I had , of all things, a 87 corvette with poor running and hard brakes . The plastic servo body had cracked

[hauserplenty]

It's rare, but certainly possible. Tighten all the carb bolts at its base, then all the screws on the carb to eliminate vacuum leaks. Also check the PCV valve, as a vacuum leak there can certainly cause the problems you describe. I'd also suggest you purge the old fuel, change the fuel filter, then fill 'er up with some fresh dead dinosaur juice.

If all that fails, try turning the mixture screw in all the way, then backing it out 1/4 turn at a time until you can get the engine started. It sounds to me like you're dealing with several problems at once, so it's best to start with the most obvious possible causes. A poorly adjusted choke can also cause this, as well as a plugged or contaminated fuel line/filter. Or a weak fuel pump. A pressure test might be in order, judging by the fact you can run it on ether, but not go-go juice.

In my part of the world, motion lotion turns to varnish in about six months.

You can also use a can of Braakleen or similar to look for your vacuum leak: once you get it running, spray it around the base of the carb. Listen for a change in the idle speed. A failed gasket or ruptured hose will show itself this way. The carb-to-manifold gasket can also cause this; it's cheap enough to just throw one at it.

As for the master cylinder, you might have a failed booster, since the fluid usually can't get drawn into the engine unless it has also failed. Depending on how long the car has been sitting, you may need to replace them both.

[michael1703]

All plausible theories but a healthy engine will run without vacuum hoses connected, I've started many with just the basics connected

[danthecapriman]

Thanks for the help. I'll try plugging the servo vac pipe tonight hopefully.

 

Everything else has been checked, rechecked and/or changed. Pcv valve, seal and hose to carb base are new. I've also tried spraying the bases of the carb etc and various vac pipes. The only one I didn't try was the servo pipe!

[Bren]

Was the car running badly before?

 

Did it misbehave when you applied the brakes?

[alf892]

It will 'run' on ether without a spark or fuel so not much use as a diagnosis tool.

 

You have wet plugs after cranking? You say there is a spark but where.....king lead or actually at plugs?

 

Suck eggs for bit and recheck basics one at a time. You only need compression, fuel and a spark at the right time so focus on those first. Easily overlooked are rotor arm and cap so while you have a spark it may be getting lost of happening wrong time.

[Taff]

I'll agree with Alf & Michael, there is only so much that can go wrong.

Think of it like this, if the motor was on a pallet, how would you go about getting it running? Clean fuel for starters, make sure you have a good, fat spark at the plugs, and try turning it over on the starter with all 8 plugs out, listen for nice, healthy "whoop-whoop-whoop" noise of that lovely compression.

 

 

tapped on the radiator using morse code

[alf892]

Just a thought on compression......if you have hydraulic followers very oil/thick oil can cause them to pump up causing zero compression after a few seconds cranking. You can usually tell though as it cranks faster.

[danthecapriman]

Was the car running badly before?

Did it misbehave when you applied the brakes?

As far as I can remember I started the car probably about mid February, started easily and ran well from cold up to temp. Then moved car up and down the driveway to make sure brakes were all free. No issues.

Then started it again a few weeks later, I didn't touch or alter anything. Just started it up. Ran rough, bad idle, no real throttle response. I switched it off after a few mins as I couldn't be arsed with it.

Then last Friday tried to start it again, same rough idle, no real throttle response. Once it got a bit warmer (after stalling several times) it randomly ran very well again, full normal throttle response. Then ran bad again. That's when I noticed the empty brake fluid reservoir and fluid on the floor.

There was a little bit of white smoke on initial start up which cleared. Possibly brake fluid burning off from master cylinder leaking into the servo.

As I've tried absolutely everything I can think of, I was sat around yesterday evening trying to think of a possible thing I may of missed or overlooked. That's when I remembered about when it ran well then started playing up. The common thing is that it ran perfectly until the master cylinder failed and the fluid was all lost. Coincidence?

 

 

I have spun it over with all plugs removed just to try and blow out any excess fuel. Without the plugs it sounds just as expected. With plugs in the spinning over sounds healthy. All the plugs get wet with petrol.

 

I think the way forward is to try disconnecting and sealing servo vacuum pipe, try starting it. If it still fails then I'll try running only from fresh petrol, if this fails then start from scratch and methodically work through it over again. It can't be anything major as it did run perfectly until recently and intermittently has within the last few days.

[Taff]

keep at it, mate. It ain't a complex set-up you have, it will be something simple, just a case of being methodical & finding it

[danthecapriman]

Thanks.

One things for sure, IF this is the cause I've never seen it happen before!

 

As soon as I have a bit of time I'll try it, next few days hopefully.

[hauserplenty]

Bung a vacuum gauge on it, too. Eliminates the guesswork and tells you exactly where to look next. If I was a bettin' man, my money would be on bad gas + brake fluid, 'cos with the information provided so far, I'd be thinking the same.

Have you checked the EGR circuit? It should be off at idle, and it can dilute the air charge and cause similar problems. Large vacuum leaks show up at idle speed, smaller ones usually show up under load.

[danthecapriman]

Ok, update time.

 

Put all original good spark plugs back in, all cleaned and dry. Everything is as it was before this problem started. Battery has been charged.

Removed servo vac hose, plugged and sealed. Tried to start car - nothing, just cranks over the same as before with no attempt to fire.

 

So, I put the vac hose back onto the servo as it's clearly not the problem.

 

Tried running a new fuel pipe from the pump straight into a Gerry can of new petrol, after cranking for a while it began to try to start but wouldn't catch.

Kept trying and eventually it would fire but not run for more than a few seconds. Kept trying and now it will fire and run but the starting is very hit or miss, sometimes it will sometimes it won't.

Once it starts there is no throttle response, and idle is very rough. It splutters and misses and eventually just stalls. If it's running and the throttle is used, it won't rev and often will instead cause the engine to stall.

 

Had to stop now though as the battery has gone flat again and is back on charge.

So I'm back to square one!

[Asimo]

Carb. needs a strip and clean. Probably. The tank and petrol pipes as well no doubt.

It is only sparks and petrol so you will get there eventually but it does feel desperate sometimes.

A mate and I nearly went round the bend trying to get the simplest car ever (Anglia) going. Eventually found the distributor drive gear had lost a couple of teeth.....

[Inspector Morose]

For the want of sounding stupid, condenser? Had a warty with the very same symptoms and it was just that(well the three of them anyway)

[Sigmund Fraud]

You only need compression, fuel and a spark at the right time so focus on those first.

 

^WHS !

 

I usually check the ignition side first : clean all the contacts, check the timing, check there's 12v at the coil, ground one of the plug leads to make sure there's a nice, fat spark.

 

If all that is OK, I check that fuel is reaching the carb float chamber. The next step is to re-set the carb settings and try to start the car. If that fails, a compression test will ensure that there's nothing really bad going on with the engine.

 

If that's OK, it's usually time to whip the carb off and take it apart on the workbench. A piece of cake with an SU or Solex, I can't see septic carbs being much more complex (with the possible exception of those evil smog-spec ones !).

[Jim Bell]

No idea what carb is on it, so may not be applicable at all, but I had similar with a split diaphram in a carb at some point.

Rebuilt with a new diaphram and it was grand.

[alf892]

Well it's clearly got a spark at about the right time and it must have some compression to do even what it does.

 

Like sorn says get a look in the carb.

 

You could maybe just nip the top off just after it stalls to see if there is any fuel in the float chamber before taking it off and fully cleaning......you might get lucky.

 

That Fiesta I had cut out on the way home from MoT.....so maybe in the first 10 miles after its 18 year kip. On that it turned out to be the tank so rotten that rust was blocking the fuel pipe despite no filter. The first time it happened after 10 miles and quickly went downhill.

[Squire_Dawson]

I'd check the condenser too. Very often they appear to work by giving a visible spark when in fact they're kaput.

[danthecapriman]

For the want of sounding stupid, condenser? Had a warty with the very same symptoms and it was just that(well the three of them anyway)

Definitely not a stupid suggestion. The points look ok but condenser could be shot I suppose. I have bought an electronic ignition kit for the car but I'm avoiding fitting it yet until I can get it running on the points set up, as it should do. Possibly fitting it now there's a chance I could introduce a new problem into the mix.

 

The carb is a bog standard but non original edelbrock unit, no emissions control crap on it other than pcv breather inlet.

Might try taking the lid off, see if there's anything obvious inside.

After cranking it over, if you look directly down the throats theres no obvious or excessive amounts of petrol splashed up the sides etc so it doesn't appear to be trying to run rich.

 

Stupid question time! To prove the condenser isn't at fault could I use any old condenser from any old car? Like say a Ford Capri!?

I don't have a spare set for this but I know the one from my Capri is good so surely a condenser is a condenser?

[alf892]

Agree on condenser as symptom just like fuel.

 

I just buy ones from the local factor that fit the available space. Local factor still has a listing book so you know what you are getting although.

 

Maybe just get a capacitor from Marlins if you know the spec?