FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: fitter on August 23, 2020, 05:27:23 PM
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Have a stock 69 mustang 428 cj 4 spd. Runs fine cold. After about 10 minutes of operating temp engine dies out under load . Will stop running. After a minute or 2 will usually start and limp home. So far i have changed fuel pump. Carb 735 holley. Distributor, fuel filters. ,pulled sump from tank replaced screen. Blew gas line out , changed coil , kind of at loss now. Anyone have suggestions? Thx
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Points ignition? Change the condenser.
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Sounds electrical like the ignition components. Check if anything like the condenser has a small crack and goes intermittent or open with heat and vibration. Any potential leaks in the vacuum advance? etc... that lean it out and bring about vapor lock?
Does it pop when it dies?
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Stock dist with pertronix. Pulled dist out today and swapped another stock unit with Mallory unililite module. Same symptoms. After about 10minutes if you get on it by end of of second gear just falls flat.
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What's your exhaust setup? Any chance your muffler collapsed? If fuel supply is good you've got me stumped.
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Sounds like is running out of fuel. When it stalls out, leave the engine off, take the filter off the carb. and open the throttle fast while looking down the venturi. You are looking to see if the accelerator pump squirts fuel. If the carb is empty it will be little to none. A non vented or bad fuel cap will cause this. You build up a vacuum in the tank and lines.
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The air filter hasn’t been on in months as I’ve been chasing the problem. When I move throttle it pumps gas , just seems to run out of gas When accelerating , One thing I noticed is wet black moisture out tail pipes when idling.
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Exhaust is 2.5 inch mandrel bent.
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My guess is that you are boiling the fuel in the float bowls, and it is spitting out of the float bowls and flooding the engine when it warms up. Seen this a few times before. Boiling point on today's gasoline is really low. For a test, you can empty the tank and put in 5 gallons of race gas, which is leaded and will have a much higher boiling point. If that solves the problem, you need to start thinking about a return style fuel system, and insulating the carb from heat, and the fuel lines from heat.
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Fuel/gasoline cap vented? Vent line pinched/stopped up? Rubber swells with the current fuel, and some fuel lines close off. Change all the short pieces of fuel line in the system with alcohol resistant hose. Joe-JDC
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My guess is that you are boiling the fuel in the float bowls, and it is spitting out of the float bowls and flooding the engine when it warms up. Seen this a few times before. Boiling point on today's gasoline is really low. For a test, you can empty the tank and put in 5 gallons of race gas, which is leaded and will have a much higher boiling point. If that solves the problem, you need to start thinking about a return style fuel system, and insulating the carb from heat, and the fuel lines from heat.
X2. Had same issue years ago.
Spot on ..
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Have you tried a different coil?
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Have you tried a different coil?
That was my first thought. I've had this happen a couple of times, with the exact same symptoms. Also, the Pertronix could be acting up under heat, but you mentioned trying a different distributor?
If that's not it, and you have to start looking at a fuel boiling issue, I'd ask if your exhaust crossover is blocked? If not, that would be a good place to start to help control the heat. What are your local daytime temperatures like? A quicker test may be to just try driving the car at night (assuming cooler temps). That could help narrow down if it's a heat problem.
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First question I have is, did it ever run well for you or is this a new build/new car?
If it just started doing it, what changed recently, gas station? new gas cap? hot weather? just broken in started driving hard?
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Valve lash too tight?
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If it was electrical, the engine would not refire. Of it it did it would not stay running. Should be obviously misfiring at hot restart idle.
With carb overflow it would restart by just opening the throttle plates and cranking engine.
I’ve never had the boiling fuel issue kill a running engine.
Maybe the Minnesota gas is weird.
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thx for replies . To answer a few questions. Car ran great for 20 years. No changes to set up. One hot day last summer cruising highway speed it just died. Towed it home and it restarted. Has never been reliable since. I have tried 3 different coils. ( btw Greg) its now got the tko 600 in it i got from you in columbus. Im pretty sure i tried it in cooler weather and had similar results. it is warm here now. Will try it on cooler day . Pulled gas line at fuel pump and gas runs freely from tank. Balance of fuel lines are new. Will pull and check again. I put fuel pres gauge on line to carb always reads about 8 pounds . Planning to plumb it where its visible when driving to see if there is a pres drop when it dies. thx
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thx for replies . To answer a few questions. Car ran great for 20 years. No changes to set up. One hot day last summer cruising highway speed it just died. Towed it home and it restarted. Has never been reliable since. I have tried 3 different coils. ( btw Greg) its now got the tko 600 in it i got from you in columbus. Im pretty sure i tried it in cooler weather and had similar results. it is warm here now. Will try it on cooler day . Pulled gas line at fuel pump and gas runs freely from tank. Balance of fuel lines are new. Will pull and check again. I put fuel pres gauge on line to carb always reads about 8 pounds . Planning to plumb it where its visible when driving to see if there is a pres drop when it dies. thx
That's a ton of fuel pressure.
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That's a ton of fuel pressure.
Agreed. I hooked a vacuum / pressure gauge on mine when I had the fuel line disconnected, just to check, and it was a steady 4 lbs (mechanical pump).
Pat
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This sounds like the famous "pink resistor wire" problem to me. We had the coil on our '67 run through that wire and the spark would break up at RPM. We chased a fuel delivery issue for a year before we figured this out.
https://www.fordmuscleforums.com/threads/pertronix-and-the-pink-resistor-wire.519562/
Make sure this isn't your issue. I'm assuming that a '69 has a similar wiring harness. I'm wondering if that resistor wire isn't getting hot and causing problems once warm?
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Does your Mustang have the factory tach? The coil positive wire runs thru the tach to a resistor wire to deliver reduced voltage to the coil. Petronics needs full 12 volts to operate correctly. Full 12 volts to a stock coil will overheat and possibly ruin the coil.
Make up a jumper with alligator clips and go for a ride. When it acts up, pop the hood and connect your jumper from battery
to coil positive side. This will bypass fuse panel, key switch, tach, connectors, or any Warshawsky items that may have been hooked to the
key switch circuit over the years.
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Car has factory tach. 12 volts to coil ,when engine shut off. 10.5 when running , about 6 volts on negative side when running. This is pertronics 1 and ive read that they didnt need full 12 volt like later models . i have made a jumper. Will take it on next road trip to test that . I have a pertronics flame thrower coil I can try as well thx
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Hey glad to see you put the TKO to good use. I had seller's remorse and was fortunate to pick up another one that I plan to put in my 69.
Sounds like you have a good plan in place to eliminate one potential issue.
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If it only takes 10 minutes of run time for the problem to show up, just jumper the coil + to battery + which will bypass all the factory wiring and eliminate the pink wire problem. The Unilite should run fine on 12v, the Pertonix 1 there are 2 different versions and I think on some they want reduced voltage. Clearly too much voltage isn't the problem since you've swapped the distributors, but in my experience Unilites are very voltage sensitive and a clean steady 13.5-14.2v when running is what they want. Below about 11 volts and they become unstable.
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Thx Rusty Crankshaft. Unilite was just installed yesterday. No difference. As far as fuel pres its a cheap gauge and could be out of calibration. Will install better one on weekend. Ive received some good advice from members and will follow up with suggestions when I get home on weekend. Thx
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I have had coils come & go with heat but generally takes a ton more heat soak than 10 minutes. Have you checked spark when it stalls?
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After reading through your statements again, the fuel pump may be the culprit. Is the oil level changed any? Smell like fuel? Joe-JDC
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Jumping bat + to coil + is a good and easy plan, I need to read back through the symptoms because I am unsure now of exactly how it acts. So correct me if I am wrong.
You run it till it gets hot, it dies. Does it sputter and die or just shut off like you hit the key?
Does it fire right back up or does it have to cool down a bit ?
This didnt start happening till it got good and hot once and now it’s a regular issue ?
I don’t know that I can offer any advice that’s any more help than has already been mentioned.
But couple odd ball things to check,
No particular order.
1, gas cap vent, easy enough to check, just loosen it up or talks it off.
2, only applies to solid cam, valve adjustment? Seems counter intuitive but I have seen very similar behavior ( engine dies when hot, runs perfect when cool ) .
3, double, then tripple check ground strap to block from battery and to the chassis, then run an extra just because, same line of logic as shorting the coil positive to the battery positive. Make sure the current getting to the coil can get back to ground. Do not connect the coil negative to ground! Rather jumper somewhere near the distributor to ground.
4, double and tripple check that it’s not vapor lock, it sure sounds like it to me, but if fuel squirts out the accell pump immediately after it dies then it’s probly not that, but it could be as some have suggested, fuel boiling over in the bowls.
5, snug up the intake manifold bolts, because grasping at straws.....
If I read correctly, you have had at least 3 coils and 2 different distributors in it? Kinda makes it hard to point the finger at spark being the issue. Assuming the coil wire to the distributor has been replaced also?
Fuel pump acting up? I recall one old car I chased my tail for who knows how long on a somewhat similar problem, acted all kinds of weird when it was warm, intermittent though, would run good for days, then would act up all the time, then fine. It was the check valve in the fuel pump, had come loose .
Totally spit balling here on all this obviously, so take it all with a grain of salt.
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I'm still thinking valve train. seat recession, chain, cam. Maybe pull the covers and have a look. Seems you covered all the other stuff.
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We need more info, Joey going the right way
- What does it do when it dies, key off behavior, or craps out slowly and blubbers and dies?
- Does it restart cold, and when it does, do you have to floor it to clear it out, or start it, or does it just go back to normal?
- If it died, could you hold it to the floor and get it started again?
- Can you verify that 8 lbs of fuel pressure? Fixed or not, too much for it.
- Did you look in tank? I had a rag in my F100 in the 80s, no idea who did it or how, but it took a 35 minute drive to float in front of the pickup, then floated away when it got home on the hook
- Next time it does it, IMMEDIATELY run to the gas cap and pop it and listen
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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.
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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.
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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
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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
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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
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Thx Heo. Have original style filter in factory carb. Plus in upstream of pump. Both have been replaced.
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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?
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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.
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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.
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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.
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I will remove mufflers and have a look. thx
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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
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The OEM mesh 'sock' on the fuel pickup/sender may be getting blocked by junk. Tank checked out o.k.?
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Replaced screen on sender recently
Put new gauge on fuel line tonight. . Approximately 6 psi. Thx
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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
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Jay suggested same. Will try that as well thx
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Tried a few suggestions this morning since temps are cooler. As usual when accelerating hard it fell flat. Fuel pres remained at 6 psi. Got out and popped gas cap, no vacuum . Hooked 12 volt jumper to coil, no change. After initial falter as soon as I would try to accelerate it would just die. Limped it home surging at low rpm.
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Very interesting timing, Engine Masters just did a show on ignition...
Plug wires,plugs ,then coil. they swapped in an MSD and ran it with a Chrysler Box, it was failing and would not repeat, then full MSD.
But you have swapped in new plus hot wired it to bypass ignition switch.
I think JDC mentioned fuel breaking down the hoses,I had a problem when I put a RobbMc fuel pump on ,the fuel would foam. The fuel line from the tank to hard line had broken down and it would suck air.
If you get fuel injection rated hose it should be ethanol safe.
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Changed the hoses already. Gonna change filter again thx
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did all this happen after the timing chain change out?
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No timing chain was replaced 10 years a go when stock cam was replaced. Only about 1000 miles on it.
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Sure sounds like foaming fuel/vapor lock to me
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I agree, sure “sounds” like fuel starvation.
Any way you can monitor the fire pressure while your driving?
Pressure could be just fine when idling but drop off under load.
Sounds like you’ve been through the fuel system a few times, so it’s perplexing.
Had a fuel
Line on my f250 that had gotten soft and squishy, probably from the modern gas we get.
It didn’t cause any issues till I took it out on the highway and hit 70mph for a bit. Then the truck started surging. It was the line going into the pump. It linked enough to starve the engine at sustained loads. Normal round town driving it was fine.
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maybe your jets in your secondary's are way too small+ may have powervalve blocked in rear too. it happened to me .i bought a 950 off a guy,threw it on my 428 and it sounded great idling.when i took off down the road it fell flat.it had 60s size jets in front and rear with power valve blocked.after jetting up about 20 sizes it ran great.
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I have observed (more than once) the inner lining of the fuel hose from tank to pump collapse and suck flat under vacuum, impossible to see it in operation.
Fuel injection rated hose is rated for pressure, not vacuum.
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Not saying this is your problem, but this is what a squirrel can do. Didn't know till I fired it.
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Update. Tried numerous suggestions. None seemed to help. Pulled second rebuilt 735 off and installed a ebock 600 off another engine. Other than a hesitation when I jump on throttle it ran fine for a good hour today. Took home and pulled unilite I installed last weekend and put pertronix conversion dist back in. It started acting up again. Not sure I had pertronix timed properly. May reinstall it again next weekend to confirm that its an issue. Thx
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Update. Tried numerous suggestions. None seemed to help. Pulled second rebuilt 735 off and installed a ebock 600 off another engine. Other than a hesitation when I jump on throttle it ran fine for a good hour today. Took home and pulled unilite I installed last weekend and put pertronix conversion dist back in. It started acting up again. Not sure I had pertronix timed properly. May reinstall it again next weekend to confirm that its an issue. Thx
It's incredibly tough without being there, but assuming the Pertronix/Unilite swaps are repeatable, then there you go. However, get a timing light on it each time to rule out variables
(Assuming the distributor wasn't the issue) Is there any way you could put a little pusher electric fuel pump, even if just temporarily wired? The difference between the 600 and Holleys is total fuel volume in the bowls, the Holley and slosh in the rear bowl, and overall fuel required when using all the CFM. Something to think about after you make a decision on the distributors
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Thx Ross. Im getting good a t swapping distributors. I will try pertronix again. What should i set timing at. Stock cj 87 octane Thx
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Thx Ross. Im getting good a t swapping distributors. I will try pertronix again. What should i set timing at. Stock cj 87 octane Thx
12 initial, vacuum disconnected, is a good enough WAG to rule out a problem.
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Thx Ross. Im getting good a t swapping distributors. I will try pertronix again. What should i set timing at. Stock cj 87 octane Thx
im sorry but i would not run 87 in any fe no matter what i at least run 90-93.if your running 87 with 10% ethanol i would bet your vaporlocking and boiling the gas right out of your carb even while running it can boil.i watched mine boil through the glass sight windows with 93 + 10% ethanol.i know 87 will do it.
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i just filled up my 428 comet with 5 gallons of 110+10 gallons of 93 no ethanol.good street mix for performance.
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ok Thx Will up the octane
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I think the stockers did fine on pump gas, but I would lean toward 91, 87 is pretty low.
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Update..Looks like Jay and a couple others may have identified the problem..It appears the gas in bowls was overheating. I upped octane. Made a heat shield and installed under carb. Insulated fuel line. Reinstalled distributor with pertronix. Reinstalled factory 735 Holley. Set timing at 12 degree. Running fine now. Thx to all who offered advice.
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Check this out...
http://www.haneperformance.com/techtips5.html
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Update..Looks like Jay and a couple others may have identified the problem..It appears the gas in bowls was overheating. I upped octane. Made a heat shield and installed under carb. Insulated fuel line. Reinstalled distributor with pertronix. Reinstalled factory 735 Holley. Set timing at 12 degree. Running fine now. Thx to all who offered advice.
Great! Kudos to you for the follow-up message as some don't fill us in after the fact.
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I had a 67 fairlane that had a red shop rag in the fuel tank it would idle forever but when you drove it the rag got sucked up and it would quit.Second time i took the tank out i found it