Ducati Monster Forum

As some of you may remember, I was having a mysterious problem with my 2L carby'd 1992 Ford Econovan. Currently, symptoms are as follows:

- Starts fine
- Idles fine
- After a few days without driving, it drives fine
- After about 1km of driving, WHAM, it's like I hit something. Engine loses all power.
- I can rev the engine, but it will get a bit above idle RPM and lose power again. It's like it can't go above idle RPM
- I can't stall it with this method
- If I keep my foot down after it has died, it will backfire (loudly)

To fix it I have tried the following:

- Changed the fuel filter
- Changed a spark plug lead that was burned on the exhaust manifold
- Put petrol drying agent in the tank

None of these things fixed the problem.

The only ideas I have are:

- Fuel blockage obstructing but not stopping the flow of fuel.
- Some other thing


If anyone has any ideas it would be much appreciated.

Thanks!

Blocked vent on the fuel tank?

Try driving it with the gas cap off and see if that solves the problem.

(Although I don't really know how that would explain the backfiring.   ??? )

perfectly.

vacuum in the tank, carbs drained, voila -- lean combustion!

My Focus won't run without the cap in place.

Don't know if they have the same type of 'feature' down under.

Fill eight one-gallon milk jugs with gasoline, put them inside, stuff a rag into one of them and ignite it.  Then push it off of a cliff and go buy a Chevy.  [evil]








Sorry, couldn't help myself.  I actually hate Chevy worse than Ford.

Maybe you need a new Cat.  A blocked cat would cause the issue you listed.  I had the exact same issue with a old Ford Taurus.

Cat as in catalytic converter?

That's the slang for them here.

Do aussie cars even have them?

You got me.

Paging bigiain....

or Brad would know too ;D

**UPDATE**

Took the fuel cap off. There was a whoosh sound. Took it for a drive with the cap off. It got almost twice as far, and just as I was thinking in my head how I would write my thankyou reply on this forum, WHAM, same symptoms.

Bugger.

If the van has rubber fuel line anywhere in the system I'd replace them.

Maybe collapsing and stopping fuel flow.

that and pull the fuel pump and make sure there isn't a blockage on the uptake bag. 

but the fact there was a "whoosh" when you opened the tank makes me really suspicious.

the whoosh is normal, the pump sometimes creates a vacuum and you get a whoosh usually when the tank is not empty.  Also you may have an air problem, check your intake system and make sure the the Mass Air Flow sensor is okay. Also you may want to recheck your vacuum hoses.  those hoses are the tendons in an engine they move and adjust all sorts of shit.

Is it possible that it's an electrical problem? If my coil was on the way out would it have these symptoms? The backfire, when it happens, is LOUD!. Makes me think plenty of fuel is getting in there. I'm beginning to think it's more related to how warm the car gets rather than how far I drive.

a coil is easy enough to replace.  hell, if you have a friendly shop they might let you borrow one (or just buy it and return it if it does the same thing).

i doubt it is the coil tho, they tend to just GO

do check the condenser and distributor tho.  sometimes crap in the distributor can prevent spark.  (rust?)

i still think it might be fuel pump related. 

then again, you should be able to test that just fine by disconnecting the fuel line and putting it in a jar and seeing if it fills it (shop manual should give rate of flow..)

I've seen coils go gradually a couple of times.

But never resulting in anything like what you've described.

Once was in the first Monster I owned.  Coils were on their way out and the weak spark resulted in diminished power and fouled plugs.

The other time was in a Chevy van.  When the engine heated the coil up enough, nothing.  Engine completely died.

But that took quite a while, not just a mile or two.

I would be inclined to agree with tizzy and say that it's a fuel problem of some sort.

That whoosh sounds suspicious.

What about the GMC Jimmy you had with the distributor, coil, ignition module, fuel, electrical, spark plug............. problem?   [laugh]   [bang]

I intentionally left that one out.

That was a computer problem in a vehicle that supposedly had no computer.


 [roll]

So you're saying Howley should check for an abacus problem?

If his problem were as sporadic as mine was, yes.

Now stop jacking his thread.

 :P

I'm trying to help.  You left out some pertinent information.  Plus, he'll see all the new posting in the morning and think someone has really figured something out.  [laugh]

/Threadjack ended, maybe

I had a '93 suburban that did something similar. It had a standard distributer, but there was an electronic advance module under the distributer cap. When it got hot, it would short out, and cause the motor to die, sometimes spectacularly. I chased fueling problems around for a while, then finally took the distributer apart to replace the rotor, and noticed some of the insulation on this part was cracked.

Not going to gaurentee it, but I'd check there.

Justin

Coil windings can intermittently fail (open or short) at a specific temperature.  Carry an ohmmeter with you and when the vehicle stalls, key off, place the leads on + and - on the coil.  This measures primary resistance.  If you have specs to compare, fine.  If not, infinity means bad.  + to the coil tower is secondary resistance.  Infinity is bad.  If you have specs, resistance too low is a short. but this is less likely.  You need to work fast, since cooling off will temporarily "fix" it.

Also a good possibility.  Unless your vehicle has ignition points you have some sort of solid state ignition amplifier, often called an ignition module or igniter.  These often cannot be diagnosed and replacement is in order.  This problem has been going on for a long time.  Perhaps bringing it to a pro is in order?

Ford has always had a rep for junk modules.

If yours mounts to the distributor, called a thin film module, that could very well be the issue.

It's difficult for us in the states to know what they used down under when your van was built.

Quite true.  The earlier big aluminum modules were worse, though.  So bad Cabbies used to mount an extra in near reach of the harness.  Even though they can't be field tested, if the coil checks out and there is no spark the module is quite likely.

It's a distributor with points and a rotor. The problem started maybe a couple of months ago, but it went from so intermittent that I blamed it on my driving to really bad in a pretty short space of time (1 drive home).

Thanks for the ideas guys, Keep em coming.

How old is the van?

It's a '92.

When was it tuned up last?

Points need attention at least every 6K miles...

more frequently if the cam wasn't lubed properly.

Last tune up was I don't even remember how long ago. I put a new set of points in about 3 years ago (I think).

Would a problem with the points cause the symptoms, ie. working fine until it warms up?

I'd start with some simple stuff.

points and condenser is as good a place to start as any.

yeah, don't even need to buy new ones just to check... sand off the connections on the current ones and see if there is corrosion or a bad connector or moisture in there.

Points are not likely to cause your problem, nor is the condenser.  Time to change them anyway.  Now that we know how basic your van is, bring someone with you.  When the problem happens, just pull a plug wire, insert a screwdriver, hold near ground and have your assistant try to start your engine.  Good spark?  Fuel problem.  No spark?  Test coil as I described before.  Or even just go to the store and buy one, conventional coils are cheap.

I've seen condensers do some strange things Howie...

I wouldn't rule it out.

I've also seen points short at the pivot and wires to the points chafe and ground when hot...

of course it's been a long time since I've seen a set of points. ;D

you're welcome..

(http://performanceflatfour.com/images/009%20Points.JPG)

Condensers will indeed do strange things.  Most of the bad condensers I ran across were new out of the box though.  They don't wear  My '79 BMW had the original condenser for over 100K miles.  Finally the pig tale gave out, the condenser itself was just fine.

Ducpainter is correct about the point and condenser wires causing problems, not just from chafing but also constant breaker plate movement.  The wire will fracture inside the insulation.  Insulation warms up and expands, open circuit.

Like I said, change the points and condenser anyway, they are overdue.  Besides erosion, rubbing blocks wear and spring tension can weaken.  While you are at it, check the ground wire from the breaker plate.

 

*UPDATE*

I took the coil to the auto leccy and it checked fine. I opened up the distributor and noticed the posts were badly corroded, so I replaced the cap, rotor and points. I took it for a few laps, and was freaking out as I got to the spots where it crapped out before, but it didn't happen! I ended up doing maybe 10 laps with no problems, so I guess it's fixed! Thanks to all you guys for your help, that's why I love this place.

 [beer] [clap]

i wonder if there was some spot on the advance plate or a bad spring in the distributor -- did it have a vacuum advance or just mechanical?

Not sure, probably mechanical.

Does a vacuum hose go to it? That would sort of narrow it down  [cheeky]

vacuum hose and a drum with an armature going into the dist.

vac is usually supplementary to mechanical tho, usually not just vac.