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Question on Small Block.. Weird Problem..

Posted By: Boosted

Question on Small Block.. Weird Problem.. - 10/21/14 10:17 PM

Car is a 70 Challenger with a 360 4V. Has new tank all new lines new filter new holley 600. You can crank it cold and it runs great until it warms up. Once it gets to operating temp it acts like it runs out of gas and shuts off.

I can buy another fuel pump for it but I am wondering why it works fine cold and at temp it quits? Or is it something else? I am wondering what to look at next. I thought taking the non vented cap off would help but it doesn't.
Posted By: Alaskan_TA

Re: Question on Small Block.. Weird Problem.. - 10/21/14 10:24 PM

Vapor lock?

Do any of your fuel lines run close to the exhaust?
Posted By: colt340

Re: Question on Small Block.. Weird Problem.. - 10/21/14 10:38 PM

Does it have electronic ignition? If it does it could be a dead pickup. I had that problem on a big block and that's what it was. Took me about 2 weeks to find it.


Quote:

Car is a 70 Challenger with a 360 4V. Has new tank all new lines new filter new holley 600. You can crank it cold and it runs great until it warms up. Once it gets to operating temp it acts like it runs out of gas and shuts off.

I can buy another fuel pump for it but I am wondering why it works fine cold and at temp it quits? Or is it something else? I am wondering what to look at next. I thought taking the non vented cap off would help but it doesn't.

Posted By: RapidRobert

Re: Question on Small Block.. Weird Problem.. - 10/21/14 11:32 PM

I'd idle it in your driveway in drive with ebrake on (watch the temp) till it stalls & with a helper to crank it: IMMEDIATELY (1) see if the coil wire has spark and (2) if the AP still has a stream of gas. Holler back
Posted By: dogdays

Re: Question on Small Block.. Weird Problem.. - 10/21/14 11:51 PM

Sounds very much like a bad coil. I've seen it happen three times now where the coil would go open circuit when the engine hit operating temperature.

Easy to do to swap a coil with a known working coil and see if it repeats.

That's the easiest thing to do.

R.
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/22/14 12:22 AM

I went out today and cranked it up. 79 degrees here. Let it sit in the driveway for about 3 minutes and started idling down until it shut off.

Tried to crank it and it acted like it wanted to and nope it would not. I let it sit for about 30 minutes and it fired right back up and ran fine again.But I only ran it long enough to get it back in the shop.

Here is a photo of the motor...

Attached picture 8307770-WP_20141021_003.jpg
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/22/14 12:26 AM

Quote:

Vapor lock?

Do any of your fuel lines run close to the exhaust?



Yes the fuel line on the passenger side is close to the t/a exhaust. I have wrapped it with heat wrap to see if that would help and no it didn't.
Posted By: skicker

Re: Question on Small Block.. Weird Problem.. - 10/22/14 12:41 AM

There was something posted a while back about mounting the coil and that some coils were not designed to be mounted certain ways. I see yours is standing up, I'm not positive but I'm thinking some were maybe designed to not be mounted laying down.
Regardless I think I would repeat the cycle with starting it and letting it warm up till it shuts off. If it doesn't re-fire swap the coil out and try it asap. Its something small and stupid, your just going to have to swap parts out till you find it.
Being that its a Holley double check the float levels to make sure its not dribbling fuel out of the squirters after idling for a period of time.
Posted By: Supercuda

Re: Question on Small Block.. Weird Problem.. - 10/22/14 01:13 AM

When it stalls pop the gas cap and see if it's got vacuum.

Use an IR gun to see what the coil temps are. Same with fuel line temps.

http://www.harborfreight.com/infrared-thermometer-93984.html
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/22/14 01:46 AM

I am running it without the gas cap on and it is doing it. How hot is to hot for the coil and fuel lines? I have a temp gun..
Posted By: Supercuda

Re: Question on Small Block.. Weird Problem.. - 10/22/14 04:57 AM

Gas starts to boil around 180 degrees F. Less than that for both, much less if you can swing it.
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/22/14 02:07 PM

I am going to swap the coil out today for a new one. I know it is getting gas as after it sit for a 30 minutes it took just a a pump of the pedal to crank it back up. Fired right up.. So it did not run out of fuel from the pump and it has a 1/2 tank.
Posted By: scratchnfotraction

Re: Question on Small Block.. Weird Problem.. - 10/22/14 02:34 PM

that looks like an old accel coil..make sure it is for elect Ign systems not the points systems.

I have a points style that would not work very good with a weak spark on the elect Ign sytems.

stalled a lot, lots of spinning to start it..ect.

worth checking the part # on it.
Posted By: Challenger 1

Re: Question on Small Block.. Weird Problem.. - 10/22/14 02:52 PM

Hopefully you don't have the filter between the gas tank and the mechanical fuel pump?
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/23/14 01:54 AM

Coil fixed it tonight. Ran for a long time and never shut off. And yes it was an accel coil.. A very old one.lol
Posted By: scratchnfotraction

Re: Question on Small Block.. Weird Problem.. - 10/23/14 02:15 PM

Quote:

Coil fixed it tonight. Ran for a long time and never shut off. And yes it was an accel coil.. A very old one.lol



gald it fixed it. was it a points coil?

so now you got a antique coil for the
Posted By: Boosted

Re: Question on Small Block.. Weird Problem.. - 10/24/14 03:07 AM

I have not looked it up yet.. I am going to get the car out and drive it some this weekend.. It is finally getting driving weather down here..
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