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Car loses power and chokes out after going 80 MPH


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I was on the freeway to work today, and after exceeding about 80 mph, I started to lose power from my engine. If I gave it more gas, it almost seemed as if it was losing more power. I pulled off and into a parking lot where it died. I restarted it and it was fine until I hit about 80 again, I which case I started to lose power once more. I pulled over and restarted it and managed to get to my destination fine, but something good is awry here! I did notice that it seems to be idling a little higher. Any similar experience, ideas, or maybe even solutions? Thank you everyone! ::thumb::

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Starving for fuel / bad fuel pump or relate is my guess.

 

Paul

73 Grande

351C 2v

Now 4v Carb/Cam/headers/T5

 

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Alcohol is for drinking.

Nitomethane is for racing!

 

 

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additional:

are you running points or electronic ignition?

size carb?

if you have a tach what were the engine rpms over 80.

rear end ratio?

check you didn't jump engine timing.

 

history:

 

did you drive the car over 80 before and this never happened?

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additional:

are you running points or electronic ignition?

size carb?

if you have a tach what were the engine rpms over 80.

rear end ratio?

 

It's an electric ignition and an autolite 2100.

I do not have a tach, and as far as the rear ration, I do not know. It's a base 351c 2V with a c4, if that helps :thankyouyellow:

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IIRC you recently had a fuel line issue. I would start by looking at the section you replaced to make sure there is no restriction or kink. If you used a lower grade of fuel line or an improper material it may be collapsing.

 

I would also check for any vacuum leaks at the carb base and around the intake manifold. Just a shot of carb cleaner in these areas while the engine is running will cause the rpm to climb suddenly.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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additional:

are you running points or electronic ignition?

size carb?

if you have a tach what were the engine rpms over 80.

rear end ratio?

 

It's an electric ignition and an autolite 2100.

I do not have a tach, and as far as the rear ration, I do not know. It's a base 351c 2V with a c4, if that helps :thankyouyellow:

 

Smart A** answer................ don't drive it over 80mph, isn't that speeding anyway??

Geoff.

 I learn something new every day!

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Probably 3.00:1 rear end gears (that was pretty standard with the H-Code).

 

Start simple: Check your timing as Dan suggested... if the timing's not where it needs to be at lower rpms, it would have effects with higher rpms. If it returns to normal after shutting down, idling, and goes bad again at speed, that's going to be a tough timing issue to nail down. Maybe something mechanical sticking inside of the distributor or something.

 

Also check your fuel filter - if it's been awhile since a new filter (or if you had lots of problems with the rest of the upstream fuel lines since replacing it), you might have some gunk built-up inside it moving around that reached the magic point of restriction at the sustained rpms at 80 mph. If the blockage moved into a position to restrict the flow through the filter and into the fuel bowls, your carb would've starved until the bowl was refilled as the blockage fell away at the lower rpms (just a theory - seen it happen before, and fuel filters are cheap).

 

Consequently, if the carb's feeding too much fuel in at higher sustained rpms (flooding), that could be a problem that would need lower rpms to clear out as well. The float could be just that much too high, or maybe the needle valve is getting sticky when open or something to that effect. You would more than likely smell a LOT of gas at lower rpms if you were having a flooding condition, though.

 

I'd check the fuel filter before digging into the carb... and checking the things Jeff suggested as well before taking anything else apart. Like I said, always start simple. ;)

Eric

mach1sig2.gif

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additional:

are you running points or electronic ignition?

size carb?

if you have a tach what were the engine rpms over 80.

rear end ratio?

 

It's an electric ignition and an autolite 2100.

I do not have a tach, and as far as the rear ration, I do not know. It's a base 351c 2V with a c4, if that helps :thankyouyellow:

 

Smart A** answer................ don't drive it over 80mph, isn't that speeding anyway??

Woah, I wasn't saying that in a smart a** manner, I just legitimately do not known my ratio! But we have free ways here that are 75 mph. Nonetheless, I don't like leaving a problem on the table.

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Smart A** answer................ don't drive it over 80mph, isn't that speeding anyway??

 

We actually have stretches of interstates in Texas with speed limits at 80 mph - I-10 from Kerrville all the way to El Paso for one. :P

Eric

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Probably 3.00:1 rear end gears (that was pretty standard with the H-Code).

 

Start simple: Check your timing as Dan suggested... if the timing's not where it needs to be at lower rpms, it would have effects with higher rpms. If it returns to normal after shutting down, idling, and goes bad again at speed, that's going to be a tough timing issue to nail down. Maybe something mechanical sticking inside of the distributor or something.

 

Also check your fuel filter - if it's been awhile since a new filter (or if you had lots of problems with the rest of the upstream fuel lines since replacing it), you might have some gunk built-up inside it moving around that reached the magic point of restriction at the sustained rpms at 80 mph. If the blockage moved into a position to restrict the flow through the filter and into the fuel bowls, your carb would've starved until the bowl was refilled as the blockage fell away at the lower rpms (just a theory - seen it happen before, and fuel filters are cheap).

 

Consequently, if the carb's feeding too much fuel in at higher sustained rpms (flooding), that could be a problem that would need lower rpms to clear out as well. The float could be just that much too high, or maybe the needle valve is getting sticky when open or something to that effect. You would more than likely smell a LOT of gas at lower rpms if you were having a flooding condition, though.

 

I'd check the fuel filter before digging into the carb... and checking the things Jeff suggested as well before taking anything else apart. Like I said, always start simple. ;)

 

I had the same exact theory on the fuel filter. I replaced them not all that long ago, but it was a garage buy from an elderly friend of my grandfather. When I drained fuel for the sender, there was crud in it. That will be my first thing to check. I appreciate your timing knowledge, because that was concern #1 :)

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Most likely fuel starvation. At idle and low speeds the carburetor bowl fills up, but at higher speeds it draws the fuel out faster than its being replenished.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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It's an electric ignition and an autolite 2100.

I do not have a tach, and as far as the rear ration, I do not know. It's a base 351c 2V with a c4, if that helps :thankyouyellow:

 

Smart A** answer................ don't drive it over 80mph, isn't that speeding anyway??

Woah, I wasn't saying that in a smart a** manner, I just legitimately do not known my ratio! But we have free ways here that are 75 mph. Nonetheless, I don't like leaving a problem on the table.

 

I was just having a bit of fun with you, didn't mean to offend. Finding out what you have in your car is what this forum is all about, so I hope you sort out your problem. These things can be frustrating to say the least.

Actually, you guys are all fortunate NOT to have the pedestrian speed limits we have here in Ontario where our limit on the 400 series highways is just 61.2 MPH or 100 kmh. More than 50K over (30mph) and you risk loosing your car for a week under that stupid "stunt driving" law we have. Actually most, but not all cops will turn a blind eye up to 30K over meaning we usually can get away with running 75mph, but no more. SUCKS guys, No sense in building a high HP car, we can't use it except on the drag strip.

I'm sooo jealous !!

Geoff.

 I learn something new every day!

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if you have a fuel filter, replace it make sure it is installed the right way with the Arrow pointing to the carb if a directional filter is installed backwards you have fuel starvation at high rpms.

 

i would check the timing, it is possible the engine jumped timing you noticed the idle changed after all this so you want to look into it.. the original nylon timing chain sprocket can jump timing.

 

and go through everything else to make sure.

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i would check the timing, it is possible the engine jumped timing you noticed the idle changed after all this so you want to look into it.. the original nylon timing chain sprocket can jump timing.

 

VERY good point. Mine was so brittle when I was taking my engine apart, it literally shattered and fell apart when I touched it. Not one of Ford's "Better Ideas." ;)

Eric

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I was on the freeway to work today, and after exceeding about 80 mph, I started to lose power from my engine. If I gave it more gas, it almost seemed as if it was losing more power. I pulled off and into a parking lot where it died. I restarted it and it was fine until I hit about 80 again, I which case I started to lose power once more. I pulled over and restarted it and managed to get to my destination fine, but something good is awry here! I did notice that it seems to be idling a little higher. Any similar experience, ideas, or maybe even solutions? Thank you everyone! ::thumb::

 

check the points.

 

your distributor may need to be curved for optimum performance.

 

if the dist vacuum is connected to manifold vacuum, plug it into ported vacuum.

 

you could have rust in your tank that is getting sucked up around the tank filter filter.

 

try 2 sizes bigger on the main jets.

 

if you have a holley or quick fuel carb, make sure the gas level in bowls is just below the inspection holes immediately after you turn the engine off . if it has clear inspection covers, set it so it is near the bottom of the window.

 

post a photo of the front spark plug on both sides of the engine

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If I remember, you've been having fuel system issues, right? Check the filter, I bet it is full of junk again. I would guess that your tank is full of crap as well. Did you replace the pickup/ sending unit recently? There's a strainer on the end and it can exhibit the symptom you describe. For example, running at pretty good rpm's the pump pulls a pretty good vacuum at the strainer, drawing crud up to it restricting the amount of fuel getting in. As the engine starves for fuel and eventually dies, the vacuum goes away allowing he crud to flow away from the strainer.

 

When you restarted the car did you have to crank it like there was no fuel in the carb? If so I would go with the above or another fuel starvation issue. If it started right up I would suspect ignition, like an overheating cool or condenser...

Matt

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hi i had the same problem the fuel line had junk in it so i replaced the fuel line from gas tank to fuel pump , they sell the fuel line at cj pony bends and all its a 2 pcs fuel line i believe good luck.ron

DRIVE IT LIKE YOU STOLE IT*****KEEP YOUR FOOT ON THE PEDAL

 

Ron

 

1972 mustang convertible

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1999 mustang convertible white (sold)

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If it does it again get out and take your gas cap off and if it sucks air in big time something in the vapor system is clogged not allowing the pressure to equalize inside the tank. The caps are not vented that little blue can under the R.H. tower brace is part of the venting of the tank. Something might be clogged.

David

When a man is in the woods and talks and no women are there is he still wrong??:P

David

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After changing out fuel filters, I thought that I had the problem solved. That is, until I took it for a half hour highway drive. After it started choking, I pulled over and shut it off. I popped the hood and immediately noticed a bubbling sound from my carb. and bubbling in my glass fuel filter (sits against the valve covers). I've never overlooked something so much before. Fuel percolation? I bet, especially given the hard starts after my car has set for about 15 minutes or so.

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Sounds like you found the problem. If you want to confirm I would suggest you go drive it with 1/4 tank full of gas until the problem starts. Then drive into the nearest gas station and fill the tank up. Take it out and see if the problem goes away. The very cool fuel from the underground storage should 'fix' it for a while.

 

Are you running your fuel lines in the stock locations? Have you replaced any of the metal line with rubber? How much ethanol is in your fuel (it has a lower boiling temp).

'Mike'

73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

 

Pics of modifications included in: [button=http://www.7173mustangs.com/thread-1973-convertible--3335]My Garage[/button]

 

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Sounds like you found the problem. If you want to confirm I would suggest you go drive it with 1/4 tank full of gas until the problem starts. Then drive into the nearest gas station and fill the tank up. Take it out and see if the problem goes away. The very cool fuel from the underground storage should 'fix' it for a while.

 

Are you running your fuel lines in the stock locations? Have you replaced any of the metal line with rubber? How much ethanol is in your fuel (it has a lower boiling temp).

 

Well, the theory was nice. I did that test last night, and it starved all the way home (about a mile away from the station). When I went to take it to work this very cold morning, and it started to give me issues after a couple minutes. Hesitation and stumble at take off now, and starts to totally lose power right around where it shift into third.

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if it is vapor lock (fuel boiling) then i would suggest a carb spacer, you want a thermal break between the carb and the intake manifold to reduce heat and fuel boiling in the bowls.

 

move the fuel lines away from the engine. you may need to fabricate a heat shield to protect the fuel from boiling inside the fuel lines

 

"glass fuel filter" take the filter off the car and put it in garbage, glass fuel filters are a fire hazard and banned from pretty much everywhere.

 

you can install a metal housing filter down by the fuel pump this allows you to restore original fuel line position and maybe keep the lines cooler and away from the engine heat.

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There are a few possibilities that come to mind-

 

Often high RPM break down and inability to pull at higher speeds is an ignition problem. Check the cap for cracks, the rotor and contacts for being in good condition, the coil for possible failure, the condition of the wires etc. If your car is popping and backfiring under load, I would start here

 

your fuel could be boiling in the float bowls. Often a heat shield under the carb will eliminate this. A simple cheap way to test for this is to wad up aluminum foil and tuck it under the float bowls. If this works, you know a heat shield is going to help.

 

The other is fuel starvation. You may want to check the pressure developed by your fuel pump and it would not be a bad idea to remove the sending unit and check it's condition. The fuel filter/sock on the end of it could be clogged. If the pick up line is cracked inside the tank it will suck air. when you are below a 1/4 tank you can jack the driver side of the car up as high as possible, put it on jack stands and remove the sender without draining the rest of the fuel.

 

Also your car should have a vent line from the top of the tank, up to the firewall. Often the charcoal canister is removed. Some people plug the line which doesn't allow the tank to vent. If this line coming off the firewall and pointing to the passenger side is plugged, unplug it, open the gas tank and try and blow air through it.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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