The Stovebolt Site Forums The Shop Area Engine Shop ignition problem, will start, run, then dies out both at idle & on the road

My '54 Chevy 3100 truck has new build engine, new fuel pump, cleaned gas tank with vented cap, new fuel filter and is getting gas to the carb. It will start, run, then die out. There is power to the new internal resistor coil, power to the distributor. Condensor is tight. New plug wires and plugs.So I am guessing that the only thing missing is spark. What could cause spark to go away intermittantly? Help. Thanks.

Seems to be a common occurance in the ol' Stovebolt world at the moment !Have a buzz through some of the forums and you will no doubt find a few of these questions at the moment.
A quick guess from this side of the world would be to check your float level and the needle and seat in the carbie.
A classic problem is a sticking needle and seat which will let the engine start, run , idle etc. and then fuel up the engine, foul the plugs and cause it to stall after a short time.
Your bowl might appear to have "plenty of fuel" in it, but is it set at the correct height?
A float level too low will have the same result.
I'm leaning towards this as you say all the ignition system will start and run the engine.........so obviously no problem there!
Give all that a check and see what you find...Good Luck.......Doc Bob.

Hello doc bob -
I pulled off the top of the card and looked at the needle and seat. Looked clean - what would cause them to stick? I set the float level with a gauge - I'll double-check that - but if that's good any other ideas? Thanks.

I had the same problem happen to a Buick motor. When the problem reoccurs, disconnect the condensor wire and try to start the motor. If the condensor is external it should be a snap. If internal and a pain to quickly get at you may want to just replace with a new one for testing. It is an inexpensive test. Good luck.

D.Lee,

In my limited experience, intermittent fuel problems are much more prevalent than a intermittent ignition problem. It's a simple matter of squirting some fuel down the carburetor next time this happens to see if it gets the engine going for a second or two. If there is any question about the fuel supply, a temporary little can of gas attached to the suction side of the fuel pump will eliminate the tank and line from tank to pump.

If you can narrow it down to fuel or ignition, you can proceed with vigor...I vote for fuel.

Stuart

By the condensor wire do you mean the wire that runs from the coil to the outside of the distributor or the wire inside the distributor that is part of the condensor? Thanks.

He means the one that is part of the condenser.

I'am with Stuart. Sounds more like fuel than spark. California gas is famous for being hard on rubber parts in carbs and fuel pumps, you also don't know how old the new fuel pump is. I may have been on the shelf for several years and the rubber could be cracked in the pump.

Thanks I'll try that

The fuel pump is new with the motor rebuild. Has at most 1000 miles
on it. True I don't know it's real age though. Hard to tell anything's real age here in California. It could have had a box lift - the rubber could be old.

A couple of questions D.Lee,
Are we talking about a Sovebolt Six here, or something different?
Stupid question, but has yet to be asked!
New fuel pumps can be an unknown thing with their delivery pressure etc. Especially if you have made the common mistake of running a high volume/pressure mechanical/electric pump on a stock carburettor.
Any pump putting out more than 5-8 psi of delivery will slowly flood a standard carby's float needle and seat shut off pressure.
Also as 41 CHEVY has said, the fine rubber seal of the needle takes very little to fail. Age, New fuels, sitting for periods of time, the smallest amount of junk will all lead to failure.
Do you run a filter between the fuel pump outlet and the carb?????? If not, run out and do it NOW!
Also, don't just look at the needle and seat.Pull it all apart and thoroughly clean the two.Put the unit in your mouth and blow through it while pushing on the needle with your finger.Does it shut of the air that you are blowing through it?
If not.....BINGO.....in the bin and try another.
If all this fails, look into the electrical side.
I have always found that working throught he process of elimination is the easiest way to solve any problem.
You will always find that 99.9% of the time people leap into the high tech side of a problem........then slap themselves silly weeks later when they find out the answer to the problem was a 5 cent,two second lapse of basic thought from the start !!!!!!
Best of luck........Doc Bob.

Did you replace the hard line from tank to fuel pump??? On my 53 that was the problem, totally plugged with crapola. Also you can disconnect the outlet side of fuel pump and crank, see if you have any pressure/flow. These pumps made today seem to be wimpy and do not last long. Or, try another carb. As mentioned if the thing runs with just a bit of gas dribbled in the carb your electrical is fine. I'd also use an inline 'glass' filter with the white screen. I had an old paper filter self distruct, found a teaspoon of that paper in my carb.

Yes, we're talking about a 235 inline Stovebolt six. The carb is stock as is the fuel pump, I think. It's mechanical - has the little glass beehive on top. There is a fuel filter - new as of yesterday between the tank and the pump. New hard lines from the pump to the carb. Also new hard vacuum lines - I'm using the vacuum for the windshield wipers. Guess I'd better move the filter to the other side of the pump.
I did pull out the needle and blow through it. Seems fine.
This truck was running like a top a few weeks ago, then would fail occasionally and now won't idle for even ten minutes. I'll try the next step here. By the way, I've checked the points - seem fine, there's power to the coil, power to the distributor.
Thanks for the info and the encouragement.

The line from the tank to the fuel filter is rubber, not hard line, but it's new.

What you describe seems to be that there's a clog somewhere in your line.

Could be Wrong, but its running for 10 Minutes or so at idle, would that get the engine warm enough, and or the coil warm enough if it had a short in its windings, to over heat and cause the truck to stall? May try a different coil.

Had a similar problem myself but it was in fact fuel related, I replaced the line between the tank, and the fuel pump and it runs fine now. Before I could only make it about halfway around the block before stalling.

What does this engine do on restart, can it be started at all?

Birge

As you say Birge, thought it was the coil, but replace the fuel line and it all ran fine.
That is what I meant about a fuel line vacuum leak.
The pump sucks, but if there is a leak anywhere between the pump and tank, it will suck air and not fuel..........instant shutdown !
As I said before, process of elimination.
Do a thorough check of all fittings and lines. Even solid steel lines are renowned for splitting and develping hairline cracks over time. Just because it is steel, don't presume it is failsafe!
Keep up the search, Doc Bob.

P.S- what do you mean by using the new vacuum lines for the windshield wipers ?
You have'nt disconnected the vacuum line from the carb to distributor advance to run the wipers have you?
As the wipers should run from vacuum ported from the inlet manifold itself.

That one had me confused too. That could be another reason why it's not working goo if that's what he did.

I am sure your correct Doc Bob,

D.Lee Whats the prognosis on your end?

doc bob,

Although I understand your statement, your choice of words could be confusing. As long as D.Lee knows that vacuum "ported" from the intake manifold is not "ported vacuum" things are good.

Stuart

The fuel pump is a "double pump" model has vacuum ports that supposedly boosts the vacuum to the wipers.

A bit of testing this evening. The truck started and then quit after 30 seconds. Bypassed the existing fuel line with rubber hose and have fuel to carb. Readjusted float levels, they were +- 3/32 off. Pulled plugs they were black and sooty (not wet). Pulled the condensor wire. After each of the above processes I tried to start the truck w/out success. Any ideas from here?

The Black and sooty plug is a DEFINITE indication to an over-fuelling problem.
Another side of this is that the plugs will "carbon track", which means that after a period of too much fuel burning around the plug, the ceramic insulator will actually form a hard carbon coating that cannot be cleaned or burnt off.The plug will misfire deep into the plug and cause a poor combustion cycle within each cylinder and continue for every revolution of the engine until it cannot fire the mixture at all.....cough, splutter and stop. Sound familiar???????
My suggestion to you now would be to bin those plugs(I know this is hard to do with a set of new plugs!) and put in a complete new set. Fire the motor straight away and let run for 60 seconds, then stop and pull a plug out.Check for any black soot( there will still be some excess in the combustion chamber),clean the plugs and repeat again for another 60 seconds.If you find it is running fine, get a buddy to follow you and give it a good higher speed long run to burn off any excess and then check plugs again. If all is clean.......hey presto......I don't think you will have this problem again. If you do.....look at the plugs straight away, if they have sooted up enough to stop the engine, the fuel system is the ONLY Fault.(too much fuel, forget the ignition etc.)
Old stale fuel will also cause the plugs to do this.
ONLY run fresh clean fuel.Even a cupfull of old fuel left in a second hand tank can effect the plugs in this way.
Have a go and let us all know how you go.
All the best.Doc Bob.

OOPS FORGOT A BIT!!!!!!
RE: Automarc's comment.
I was trying to clear up the fact, that as you know, the wipers work from direct manifold vacuum.I had the impression that DLEE may have connected the distributor to the original manifold wiper fitting on the inlet manifold....and not as you say to the correct "ported vacuum" from the carby.
Just to clear things up!

We have been told that us "Aussies" do speak a different english to the rest of the world......so if somethings are a bit hazy, please let me know!

Yippee ti yi yay - we got the truck started last night. Bypassed the old hard fuel line and filter from the tank to the pump, tightened some loose (and leaking) connections, adjusted the float level in the carb, gave it some choke and it started! I picked up a new set of plugs today and will follow your advice. If they do soot up again, would the air fuel mixture adjustment be the only answer, do you think?

41Chevy,

Do your really think, California gas is different than the gas from the other 49 states????? Duh!!! They all burn the same, HIGH PRICED gas that we have to buy to drive our vechicles.

Ron,

California gas is different than the formulations in all the other states. I don't know if that makes it any more corrosive to fuel system components, but I do know that it's part of the reason we pay more for it. It has to do with our quest for clean air.

Stuart

Hmmm, a lot of stuff in California is different, isn't it?

In reply to DLEE's question...........
No the air/fuel adjustment is only for fine tuning and will not effect the motor enough to soot up plugs.
Dirty plugs will aways come from severe over fuelling.
High float, sticking needle/seat, too high delivery pressure, wrong jetting in carby etc.
But it sounds like you must have a problem with your fuel lines/filter/tank etc. after reading your post Yippee ti iy ay.
If you bypassed all this and the engine is happy....at least now you know what you need to fix and replace.
As I said at the start of this saga......"Start with the simple things first and use the process of elimination until the problem is found".
"The cause will almost always be the smallest least expensive thing, but can cause the biggest headaches!"
all the best Doc Bob.