Disaster?

The car has been running great. I took it out this morning, and disaster? About 5 minutes out, everything fine and smooth, never over 5800 rpm, I hit the throttle a little, and -- hesitation, knock, sputter. Ease off, everything fine. Try it again, same thing, the rev counter doesn't get above 2500, though the engine sounds like it's at 4000+/-. At low revs, everything sounds a-ok, up to about 35-40 mph. Oil pressure fine. Turned around, parked it, restarted, sounded fine.Had to run, so no time to start investigating. Electrics have been acting funky lately.(Last night the turn signals didn't work, and the lights were very dim... seemed better this morning.

 

Well, this is going to be interesting to unravel.

I'll await the input from the crack Dino engine analysis team. I have a couple guesses, but I'm not giving them up as I always end up wrong.

DM

 

Although I had the same problem once on a brit car. Turned out to be distributor related. The rotor was bad, had a crack, and as it revved up it got loose from its mounting shaft, wobbled a bit, and made poor contact with the cap. Idled fine.

DM

 

Maybe Fuel related? filter/pump... wasn;t there a thread about something like this recently.... And just found it... marcjh's thread... symptoms sound similar, and others in the thread identical. Car needs an oil and filter change anyway, so will do it all at once... any firm feelings on what filters to use? I'm sold on Swepco oil.

 

mike - if u get stuck let me know...I can maybe swing by this week...I am up to my armpits in new alternator today. We have the show next Sunday New canaan Motorsports...would love to have u come ...so lets get it fixed!!!

 

Been using Fram HP-1 for years. Easy to find and does the job nicely. Hope the running problem is only fuel. Pump and/or filter can be a problem and you have the symptoms. Your car had not been used for a long time and you are just getting all the juices flowing. Stirs all kinds of things up but usually nothing a good cleaning won't cure.

John

 

The rev counter at 2500 rpm while the engine sounds like 4000 rpm suggests something other than fuel. A sputtering engine without power when load is applied (at higher rpm), by itself, speaks for fuel starvation. This is easy to check by simply disconnecting fuel line at input to carburettor and checking for pressure/strong flow. However, the disparity between tachometer and engine rpm speaks to ignition issues, specifically electronic control box that sends a square wave signal to the tach. If you have the original Dinoplex, or some other system, I would entertain disconnecting it temporarily and going with the basic coil only. If this corrects the problem, then you have identified the culprit. The tach will/may not work during this trial, but the engine should run well. If you need help in doing this, let us know.

Jim S.

 

I had to leave for a couple of days, but had 5 minutes before we split, so I started up the car, let it idle for a couple minutes and then just tried revving the engine in neutral. It ran just fine up right to about 5k rpm, and the tach movement was smooth and looked right for the sound. I thought about it, and the problem started just after a hard left bend-- got the usual fuel starvation, and it never recovered, only running at low revs. Maybe Tuesday/Weds I'll get back to the car and take a short drive and see if it was some kind of transient fuel issue. I don't really see how there could be fuel supply enough for 2500 rpm and not more, though, unless it's some kind of fuel pump issue. The car had sat overnight, put away slightly warm after a 5 minute drive, and the garage heat wasn't on -- so temps dropped from 65/70 to about 50 in there -- condensation in fuel lines-- is that even possible?

 

Mike -

No, condensation within the fuel lines is not an issue. Fuel starvation can lead to hiccups above 2500 RPM. Where the symptoms begin depends on the degree of starvation. A bad fuel pump is far more likely than a clogged filter. As I mentioned in a thread discussing a similar symptom, I have yet to see a clogged fuel filter with modern fuel-delivery infrastructure. If the gas tanks are full of crud, perhaps.

More likely a fuel pump going bad, or as you suggest, a long, long, high speed left hand turn. If not fuel, than remove the capacitive discharge system (electrically, not physically) and see if this improves the symptom.

Check it out when you get home.

Jim S.

 

Hmmm. Car sat for a week. The battery was too low to start it, so I gave it a jump and ran it last night in the garage... sounded fine. It was raining like crazy. I hooked up the charger and it started fine this morning, went out and everything is back to normal. Some kind of fuel or electric problem, I guess, solved either by getting more juice in the battery, or a clog in the line/filter settling back out? Will investigate this week.

Could an alternator problem have caused the rev cut out? It felt more like a fuel problem on the throttle, though. The sketchy electrics lately make me wonder. I know Champ's been in alternator hell for a while, so if that's it, he'll have the solution to that for sure!!

Anyway, it was sure a beautiful morning... best time of year for driving, so glad the car is running again!!
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The car actually runs off of the battery. The job of the alternator is to keep it fully charged at all times. If the alternator is weak or the battery is quite low from storage (especially in combination) you could get some ignition troubles (especially at higher RPM's when the sparks come more frequently).

 

I have no idea how old the battery is. It's an Interstate. I'm going to buy a new one tomorrow!

 

There will be a manufacturing date code stamped on the top of the battery. It's usually a letter to designate the month, A for January, B for February, etc., then one or two numbers to designate the year. For example, F04 or F4 would be June of 2004. It's also possible to run a load test or conductance test to determine the battery's condition. Of course, it's important that the person conducting the test knows what they're doing...

Of course, age isn't everything. Most people don't know that a battery that has been completely discharged (as in leaving your headlights on overnight) has suffered an irreparable injury that will significantly shorten its life. That's why a test is more reliable than simply going by the age, especially in your case where you don't know the battery's history.