Hello everyone- I wish my first post could be of something positive, but I have a question surely someone here can help me with...

Recently, I "took over" my dads 76 F100, as he never uses it. In fact, the sticker on the license plate is 2000. He has used it on his property for working, but seldom sees use. He warned me that it would suddenly shut off and just quit running after about 10 minutes or so. Upon arrival, I started it and fought to keep it running. I cleaned the spark plugs; all 8 of them showing a rich condition, dumped some old yellow sweet smelling fuel from the carb, added some fresh fuel with carb cleaner, and now have it starting and idling pretty good. Thinking of vapor-lock, I replaced the fuel line (and filter while I was at it), re-routing it further away from the engine. That idea was shot down when it stalled in the driveway while idling...just as described, after about 10 minutes or so.

I first thought it was an ignition module, but it is new. Bad coil is rare, but possible; it's new. The stator was also replaced, but that apparently didn't fix it. I thought of fuel pump, but the stalling is too predictable, and can seemingly about be set by your watch. The only other thing I can think of is a slightly leaky power valve, but as I await for a rebuild kit, I know that's not the culprit, but just a situation of letting them sit for months at a time.

After it stalled on me in the driveway, I immediately tried to start it again. After pumping the accelerator a few times, it seemd as if it wanted to start, but would not. When I checked it three hours later, it started right up again.

Heres some info...
Engine- 1965 390, C-6 auto, Holley 750, electronic ignition, mechanical fuel pump.

I cannot help but to think of something electrical, but I am out of ideas. Can anyone offer any ideas or suggestions?

Thanks for any help!
Greg

 

I would check out the electroic igntion. This is stumping me I cant figure what it could be. Now that I think of it ill bet theres something up with that carb those darned holleys aee notrious for being hard to adjust and whatnot. How old is the carb?

 

This maybe way out in left field, but if its that consistant the you can set your watch by it? sound to me like its running out of fuel, and is dying when the bowls run dry?

 

Plumb in a viewable fuel filter in place of the stock
filter in front of the carb. It will allow you to
observe the integrity of the fuel delivery. Pull the
air filter and start your engine watching the
operation of the auto choke..or even better get
a holley manual choke carb. Test and inspect your
temperature operated vacuum advance trees. Inspect
clean replace or seal off your egr valve. Clean the
carbon out of your carb riser egr ports. Clean and
shine up your engine ground wire were it attaches to
the block. Hope this helps!

 

I'm leaning towards fuel delivery/carb problems too...

Put in a clear filter and see if it runs dry, or if you can't wait to do that, after it shuts off, splash a little extra fuel in the carb and see if it starts right back up. That should give you an indicator, you may need to up the float level in the carb to compensate for the "dryness". I favor the aluminum or "wood" spacers under my carb, just to insulate it from the heat coming from the manifold and minimize any vapor lock possibilities.

--Mike

 

Replace the pickup in the distributor, the coil, the control unit, in this order.

 

If its running out of fuel maybe you can run a hose off the fuel pump into a 5 gallon gas can to see if it fill syphon out of there.....line to your tank may be restricted.

 

Your problem comes up on this forum every once and
awhile and the folks that lean towards fuel problems
kind of go the not enough fuel route. Since I have had
the same problem after thinking about it I believe
it might be a to much fuel problem..in other words
your fuel delivery system is going to rich and killing
the engine. I t may be that as you start the engine
the carb is pooling raw gas in the manifold. At low temps
enough evaporates to idle O.K. However when
the manifold heats the pooled fuel suddenly goes vapor
and the A/F mix is to rich and engine dies. If an engine
quits from lack of fuel it will kick and buck a little as
the mixture goes lean and detonation occurs. If it
quits because of over rich A/F mix it just dies period.
After several autolight new factory rebuilds I solved
my problem with a Holley manual choke carb...so
I do not know if hypothosis is correct or not.

 

Thanks for the replies. I put a clear fuel filter about 1' from the carb. I just got back inside from messing with it...It smells pig rich from the exhaust, but I took the bowl screw out and no fuel ran out. It's been awhile, so I cannot remember what way to turn the float adjustment screw, so I didn't mess with it.

When I first started it, the fuel filter was about 1/2 full. As the engine ran, the filter slowly completely filled up. A few minutes later, it stalled again. I immediately poured a little fuel into the carb, and it would not start.

Too much fuel makes sense, but again, the bowl is not full enough to seep out the hole. It also does not seem to load up before stalling...no difference in engine RPM's- it just suddenly quits as if I turned the key off.

This thing has me baffled big time. Please keep the ideas coming! As for the age of the carb, I am not sure, but I know it is not new. I will re-read the replies and try to come up with something else.

Thanks,
Greg

 

If you have the electronic ignition module mounted on the fender, try replacing that. I have solved the problem you are describing many times by replacing the module.

 

It very well be Ignition...but I kinda , lean towards fuel...For some reason...you said you did replace the filter in the feed at the carb where the fuel line hooks up? its a screen... And when you set your floats,make sure your on level ground..and if Im not mistaken, whitch happens alot..your ports on the side of your float bowls, the gas should only come up to the bottom of those holes..If I remember right? And if its the Electronic Ignition...as soon as it dies...pull a plug wire with a spare plug sitting around and see if you have a nice blue spark..... Thats all I can think of off hand..it cant be much!! Good Luck, and keep us posted! Russ..

 

Russ...are you saying there is a filter in the carb? I have looked online for an exploded parts diagram, to no avail. Is there a filter in or near the banjo bolt?

For a little more info, the ign. module is new, and my dad tried another new one. The distributor is new as well. He also said he tried several coils. The carb also has a 1" aluminum spacer between the carb and manifold. I also wrongfully staed the power valve is leaking...I meant the accelerator pump- the diaphram looks to be ok, but fuel will slowly drip from where the fulcrum-type arm contacts the pump (under the primary float bowl, drivers side). He also had the fuel pump pressure tested, and was within the 4 to 7 PSI range.

The idea of a clogged tank screen makes sense, and I never thought of the fuel line in the gas can idea. I will try that as well.

My dad is leaving Ohio to go back to Florida on Friday. He is going to send me a brand new Holley 600 to try, that he has on the shelf for a 351W- just to see what happens.

I also found info on adjusting the floats...I just couldnt remember what way to turn the bolt. I will turn it CCW until I can see fuel in the sight window, but the problem seems too drastic for a seemingly "mediocre" adjustment. I mean, I know it is important, but you would think the problem would be aggravated when actually driving it under a load.

The fouled plugs and pig-rich smell does not really jive with no fuel coming out of the sight hole. And what still baffles me is how it just shuts off without warning...no increase or decrease in RPM's, no loading-up, etc.

Would it hurt to remove the "tank" line from the fuel pump and blow about 20 PSI of air from an air nozzle through the line?

One more thing...Today, it idled for 17.5 minutes before stalling. My dad says it will not run that long while driving. At 60 MPH, it quit on him twice, right after traveling 6 miles each time. That would of course be 6 minutes time.

Thanks for the ideas and your time spent helping me. I am baffled, but I will figure it out one way or another. I'd just like to drive it!

Greg

 

Some of the holleys do have a screen filter right at the end of the float bowl..where your fuel line come in...and sence it does run, it cant be anything to major, but I would get on that leak at the accel pump,thats bad news on a hot engine, BOOM, then you wont have to worry about finding the problem,LOL, Good Luck ,Russ

 

With the fact that it quit on your dad while driving
puts my money on ignition module failure. I
know it is supposedly new..that is one failure
time..when getting burnt in. The standard scenerio is
that the engine just quits while driving-you pull
over to the side of the rode and while cussing and
looking the little critter cools off and you can resstart
and drive home. I guess you would call it
an intermittent temperature triggered event.

Another scenario consistant with your failure mode would
be water in the fuel. Put a rubber hose on the
fuel line just before it screws into fuel filter and
get it long enough so sucking end is below level of
gas tank..get the fuel going into glass container
and look for water. Good Luck!

 

I still believe it is in the ignition! Did you gap the stator to pickup using a plastic or brass gage? Is the coil wired properly (i.e. + and -)? Is the coil hot to the touch? Try starting it and shutting it off immediatly, leave the switch on for 10minutes, feel for a hot connection in the wiring at the ignition and switch. Feel the coil, is it hot? Start the engine (bet it won't).