Hey Guys hope everyone is well and had a good Mothers day weekend.

I spent my day trying to figure out why my engine keeps dying out but sometimes runs fine and then dies out again over and over. I have a Carter Comp Carb which For the Guru's here I'm going to try and go through step by step what I experienced and what I did to "shade tree mechanic" trouble shoot it so I can get the best possible answers on what it may be.

Okay, it started doing this last Friday. I started it up at work, let it idle for a while to warm up as usual. Got on the highway entrance and up to speed and all of of a sudden I have no pedal and this whining sucking sound. Pull over ( on a friggin overpass no less during rush hour ). Start it up agaiin and get off at the next exit ( about 200 yds. ) and it dies as it's going down the ramp. Needless to say, it did this about 7 times on the way home.

When I got it home I went and bought a new filter ( in line, clear ) installed it and started it up. seemed fine but the filter was barely filling up. I take it for a test drive and all is fine until I get it on the high way. It starts hitching and again what happened before. Pull over, pump the pedal a few times and start it up, let it idle for a while. Back on the highway to next exit, get it home and it starts diesling and dies in the driveway. I look at the filter. It has about a tablespoon ( by the looks of it ) of gas in it. I figure this isn't right so my next suspect is the fuel pump.

Replace the fuel pump on Saturday. Take it out for a test. All is fine driving around town for about ten minutes. Take it out on the highway and it starts hitching, bucking and again no power and it dies with dieseling. I get it home and hook up the timing light. Timing is off a bit so I reset. Go down and get a can of carb cleaner. Follow directions. Try again same results but it is running a bit better. Home again I take my adjustment screws out and clean them off and squirt cleaner into the needle valve holes and every friggin orifice, pump, and once again into the venturi's following the directions.

Take it out again and it is running okay no dying. Take it out on the highway and it gives me one hitch/buck, let off the gas and pump back up on the pedal and she runs fine down to the next exit and back home. I drove it around for the day running errands and it seemed fine but everytime I shut her down she diesels. I put premium in her and octane booster as well.

This morning decide to take her to work. Start her up and she idles for about 30 seconds and dies. Start again with half choke and she idles fine. Let her warm up and take off for the highway. Get about a mile from the house and she dies at the light. Won't start. I check the filter and it looks dry as a bone. Pump the hell out of her after a few minutes and she starts up. Get her back to the house and she dies as I pull into the drive way.

I have had issues with this carb since I got the truck last June. She has always bogged down when I got into the secondaries from a low speed. This was even more pronounced when this new problem started.

So, unless the new fule pump is bad I am open to suggestions as to what is causing this.

Accelerater pump?
Something clogging the line ( new filter looks clean )?
fuel floats bad?
Distributor issues? ( Advance issue? )
Something to do with the carb/transmission linkage? Not likely IMO.

I would rebuild this carb but I have no idea what model Carter Comp Carb I have, what the CFM is, and when I last researched it the information was scant.

Also, I noticed that when I manually went through the gears it responded better ( didn't bog down as bad ).

I am temppted to just put a new carb on her but that is kind of an expensive trouble shooting step and if that doesn't solve the problem .

Thanks guys I hope my explanation of events helps.

It has electronic ignition

 

I've had problems with something getting jammed into the fuel inlet in the tank.
It was just as you describe, ran great and than died after a lil while when presumably the obstruction got sucked onto the fuel pickup.

to test, get a pressure gauge and a vaccum gauge. Mount them inline, before and after the pump where you can see them. Go for a ride, or at least run the engine.

It'll be pretty obvious if thats the problem.

Good luck!
Drew

 

I really have no idea, but I did have a problem with similiar symptoms once. It turned out the carb was icing up (and it wasn't winter either). The cause was the carb was loose. Tightened the carb, and it was fine after that.

You might also have a bit of water in the gas tank. Cheap to add a bit of alcohol (gas line anti-freeze) to see if it helps.

On the fuel filter appearing to be mostly empty; that caused me to troubleshoot in the wrong direction before. I can't explain it, but it's normal in my car.

Mind you rusty gas tanks can plug the fuel pick-up, but doesn't explain the air.

 

Check the fuel pick up and if you have any rubber hoses between the gas tank and fuel pump replace it. Old hose can become porous and suck air without leaking fuel. That has happened to me. The hose from the tank to the fuel line was sucking air.

 

So hook up the pressure gauge before the pump and the vacuum gauge after? Then what should I be looking for?


Low/no pressure and high vacuum?

 

What type of electronic ignition? These symptoms are typical for a failing DuraSpark ignition module.

 

Hey ND thanks for chiming in. I'm not sure. I have the paper work at home so I'll check. Even if it isn't a dura spark module I have a funny feeling the ignition system is one of the variables at issue.


Way back in in 92 when I had my F100 with the 390 I converted it to electronic ignition after I rebuilt the engine. I don't remember the brand of the system I used but it was one where all I needed to complete it was to go down to the junk yard and pull a module off of a later model Ford to use with the distributor. The module mounted to the fire wall. The mechanic I bought the engine off of told me how to set it up and I never had a problem with it.

This one in the 428 doesn't appear to have an external module. It is all inside the distributor as far as I know.

If it is a Dura spark. What do you recommend?

 

If the pressure drops off and the vac goes sky high there is a restriction.
If the pressure drops off and the vac stays normal, you have an air leak in the suction or the pump is bad.

common sense really.
For all I know it could be ignition related as ND mentions, I'm just saying to check the free stuff before you go buying parts.

Drew

 

Thanks Drew. Good advice. I just wanted to make sure what you were getting at. Like I said, I'm a " shade tree " mechanic so sometimes procedures need to be explained to me. Thanks Bud, Todd.

 

The DuraSpark module is usually located on the left fender inner apron. Inside the dizzy is a stator aka magnetic pickup coil.

Most of the modules used in the 1970's were crap. Were so prone to failing, that Ford techs referred to them as NeverSpark!

The three step scenario of a failing DuraSpark ignition module:

1) Module overheats, engine dies. Module cools down, engine restarts almost at once.

2) Module overheats, engine dies. Module cools down, engine restarts in an hour...or so.

3) Sooner or later, usually sooner, the module overheats, BURNS OUT. Now the engine will not restart.

Engine heat, especially on V8's that radiates from the red hot left exhaust manifold is the mortal enemy of these modules.

If replacing the little charmer, use some washers to space it further away from where it's mounted, cuz the more airflow it gets, the better chance it has of surviving.

And...since the modules usually fail when they overheat, taking them to autoparts stores to be tested, usually test OK...unless the little charmers have burnt out.

Look at the module, it should have an ID number marked on it, post what it is. I'll give you the applications.

 

Thanks ND. Sounds like the system I had on my 65 F100.

The system on my 428 is a Mallory Unilite with a MSD Blaster 2 coil.

So, last night I go down to my local Hot Rod shop ( good old timers work there ) to find out about getting a rebuild kit for my carb. I told the guy what symptoms I was experiencing and he told me to test/ replace the coil as it sounded like the coil might be failing. So I go down to Auto Zone and pick up a new MSD Blaster coil. Now here is where I know I effed up (big time probably ).

1. I didn't disconnect the battery (the real pain is I know better )

2. I didn't note the polarity on the coil with regards to which ones the respective wires were hooked up to. ( Haste makes waste )

So, I take out the old coil and put in the new one guessing on the wire hook up regarding the poles.

1. I try firing her up. Nothing. I have wife come out to crank engine while I check for spark using a screw drivier on number one plug wire. No spark.

2. I disconnect battery ( day late/ dollar short ) and place old coil in and hook up with same polarity set up as I did with new one. Connect battery. Have wife crank engine while checking for spark. Nada.

3. Disconnect battery and switch wires to opposite poles on coil. connect battery. Wife cranks, no spark.

4. Disconnect battery and put in new coil with wires connected like last step. Connect battery. Wife cranks, no spark.

So now I have tried both coils with the wires hooked up both ways. I know I fried something but is it just the coils or did I fry the Mallory unilite ignition, or both Ugghhh!!!

I drew a diagram of the wiring and I will try to explain it clearly here so maybe you can help me.

Components: Dizzy with Unilite system, MSD Blaster 2 Coil, five wires: two red, one green, and two brown/red?, and something which appears to be a resistor block.

Wiring: two harnesses.

1. Dizzy Harness: This one has one red, one brown/red and the green one.
2. Harness from firewall: One Brown/red wire. Igniton right?

3. The other Red wire runs from the resistor block?

Hook Ups:

The green wire hooks up to one pole on the coil. Pos. or Neg.?

The two red wires ( one from dizzy ) and the one from the resistor block? pole TOGETHER hook up to the other pole on the coil. POS. or Neg.?

The Brown/red wire from the dizzy is bolted to the coil mounting bracket.

The other Brown/Red wire runs from Firewall harness to the resistor block? Ignition Right?

So, the big SO is, WTF did I do? And, what do I do from here?

I have a Unilite test procedure sheet. I'm going to see if I can find it on the net and I would like to send it to you if you are willing to help, or anyone else that is reading this!

Thanks, Todd.

 

Sounds fuel related. If it didn't backfire out the exhaust, you have spark, I'd think.

Usually, when ignition is going bad, and it starts to buck like that, the next time it fires, it lights off the unburned gas in the exhaust and boy do you hear it

But then, I could be wrong ...

 

Thanks, and actually it has done that a few times and yes it is quite noticeable.

 

Well. It isn't the coil, or maybe it is since I may have damaged the new one ( see my last post ) Idid some research on the Mallory Unilie ignition system and it appears when the module fails it usually doesn't just die but it give you a kind of warning like the symptoms I have been experiencing with the frequency becoming more pronounced as time goes on.

Anyway, after spending most of my day at work yesterday researching this ( I feel so guilty ) I need to do more because they said one of the causes is spiking voltage from the alternator can fry the module so the last thing I want to do is put in a new module only to have it fried again.

If I bring the alternator down to a parts store that can test them does anyone have any idea if they can test for voltage spikes?

Also, Mallory suggests getting a Mallory Circuit Guard part#MAL29371 but of course they state that it will only help with small spikes.

They also recommend having a spare module and that the E-Spark module is even better!

I am not sure how old this modual is but it is integral with the dizzy so I'm wondering how to disconnect it since the plug connector won't fit through the hole the wires go through in the dizzy body

Pardon me for using Dizzy to describe the distributor. Just shorter and I am long winded. lol!

ANYWAY, anyone with advice please chime in.

 

Testing for voltage spikes is easy.

Do your lights flicker when driving at night?

And "dizzy" is perfectly acceptable... I learned that term here at FTE