Author Topic: Engine cuts out when warm  (Read 9684 times)

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67xr7cat

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Re: Engine cuts out when warm
« Reply #30 on: August 25, 2020, 01:03:10 PM »
A bad factory tach can result in no power to the coil. Don't know think they usually just gave up, but easy enough to bypass the tach as a test to see.

BIGBLOCKHEAD

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Re: Engine cuts out when warm
« Reply #31 on: August 25, 2020, 01:41:51 PM »
You might try a plain stock coil,I have had the repro yellow top coils and Pertronix coils fail after they get warm in about 10 minutes.  They cool off and they work again for awhile.  I have always run the Pertronix 1 and a plain stock Ford coil in my 69 Mach 1 tach car with no problems.

wayne

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Re: Engine cuts out when warm
« Reply #32 on: August 25, 2020, 02:33:52 PM »
As many have said gas tank vent my 67 fairlane did it and was the switch got hot and broke down  but you bypassed it.How is your ground to the body that can give you fits. I bought a 65 f100 years ago it mite run 20 mi or 20 ft but would idle all day long the guy i got from had it all over trying to get it fixed. I put a 5 gal can in the bed and it ran fine so i took the tank out and found a red shop rag that fixed it.Some one may have lost the cap and stuck the rag in place of the cap and lost it in the tank

fitter

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Re: Engine cuts out when warm
« Reply #33 on: August 25, 2020, 05:16:39 PM »
Will explore some of the suggestions this weekend . To recap. Tried 4 different coils 2 fuel pumps , 2 rebuilt carbs, 2 different distributors, new plugs, new wires, timing chain has 1000 miles from new. Checked body ground. Pulled fuel sump. Replaced screen. Tank looked clean inside. Oil level is constant. Stock hyd cam, non adjustable rockers. Ross ,when it dies is usually when I’m beating on it.  Just dies. No backfire. Like someone shut gas off. I pull over. After a minute it refires , but is very sluggish getting home. If it would quit altogether it would be easier to find problem. Will put better gauge on fuel . It’s stock x pump. Thx

Heo

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Re: Engine cuts out when warm
« Reply #34 on: August 25, 2020, 07:47:51 PM »
Do you have one of those fuelfilter screwd directly to the carb?
If it is the sintered bronce type it don let water through it
fills up with water and dont let fuel through.
Had that problem on a LTD could run it for a short while
till it cut out just like out of fuel. Thought i was out of gas
so i filled up from a jerrycan and removed the fuelhose
to suck up fuel since i had a bad battery. Fuel sprayed
all over removed the filter and poured out the water
started and run fine for 5-10 minutes same story cut out
and high pressure in the fuel line some how i had got water in the
tank. drained the tank and problem went away



The defenition of a Gentleman, is a man that can play the accordion.But dont do it

fitter

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Re: Engine cuts out when warm
« Reply #35 on: August 25, 2020, 08:09:22 PM »
Thx Heo.  Have original style filter in factory carb.  Plus in upstream of pump.  Both have been replaced.

My427stang

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Re: Engine cuts out when warm
« Reply #36 on: August 25, 2020, 09:11:25 PM »
I wonder if you are overpressuring the bowls and flooding it, maybe a couple gear bangs rocking the engine with high pressure and the floats can't hold back>  Also, if it is indeed at high pressure, sometimes you are jamming the floats down so far they don't behave properly.

If it were me, first thing I would do is verify fuel pressure, then set your float level again if you decide you need a regulator. 

That is of course assuming it's flooding, it could simply be an air leak on the supply side of the pump as well

Also, and kinked rubber lines or something kinking with motor flex? 

---------------------------------
Ross
Bullock's Power Service, LLC
- 70 Fastback Mustang, 489 cid FE, Victor, SEFI, Erson SFT cam, TKO-600 5 speed, 4.11 9 inch.
- 71 F100 shortbed 4x4, 461 cid FE, headers, Victor Pro-flo EFI, Comp Custom HFT cam, 3.50 9 inch

wayne

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Re: Engine cuts out when warm
« Reply #37 on: August 27, 2020, 09:50:22 AM »
This is a super long shot but you say a new timing chain is the fuel pump eccentric loose. It may pump enough until you get on it and never catch back up. You should be able to check it with a bore scope through the fuel pump hole.
« Last Edit: August 27, 2020, 10:00:15 AM by wayne »

sixty9cobra

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Re: Engine cuts out when warm
« Reply #38 on: August 27, 2020, 12:16:31 PM »
long shot but my son had clogged cats and acted the same. I realize it doesn't have cats but is it possible the mufflers are clogged, squirrels, mice love to fill them with nuts and things. Also Im not a fan of Unilites to many bad ones to talk about.
« Last Edit: August 27, 2020, 12:18:30 PM by sixty9cobra »

wayne

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Re: Engine cuts out when warm
« Reply #39 on: August 27, 2020, 01:14:54 PM »
X2 on Unilites  never had any luck with them.You are rite clogged mufflers ect will do that if it still has that cross flow muffler i never liked that set up.

fitter

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Re: Engine cuts out when warm
« Reply #40 on: August 27, 2020, 02:30:59 PM »
I will remove mufflers and have a look. thx

70tp

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Re: Engine cuts out when warm
« Reply #41 on: August 27, 2020, 04:20:33 PM »
I’ve had bad coils, bad condensers, broken wire inside of insulation that goes inside of distributor, bad fuel pumps, but the most aggravating one was a gas powered dump truck that ,when the fuel tank was cleaned, silicone was used on the sender gasket.   It broke off and was inside the fuel lines and would run for 30sec or 30 min.  Unhooked fuel lines and blew the silicone out with compressed air.   Was amazing how much was in it.   At one point, the fuel pump had ingested some of it and made the check valves erratic.  Loose check valve in fuel pump was fun to find also

machoneman

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Re: Engine cuts out when warm
« Reply #42 on: August 28, 2020, 06:10:48 PM »
The OEM mesh 'sock' on the fuel pickup/sender may be getting blocked by junk. Tank checked out o.k.?
Bob Maag

fitter

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Re: Engine cuts out when warm
« Reply #43 on: August 28, 2020, 07:37:49 PM »
Replaced screen on sender recently

Put new gauge on fuel line tonight. . Approximately 6 psi.   Thx

C6AE

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Re: Engine cuts out when warm
« Reply #44 on: August 28, 2020, 07:47:14 PM »
It might be good old fashioned vapor lock. Modern gasoline has a very low boil point compared to gasoline when these vehicles were built. Add the vacuum from the fuel pump and a bit of altitude and it drops even further. Keeping the fuel cool until and including when it is in the carb is a problem today.  A loop circuit can sometimes work.

Try a few gallons of 110 race gas just to see if there is a change. A cheap experiment really.

pump gas boil point is about 140°f
race gas is about 240°f
a huge difference