FYI FORD MustangSteve's Ford Mustang Forum / 302

**Posted by Chelby-Ann** 11/15/2024 10:24 AM

I'll start here by telling you that I have pulled all of my hair out during the last 6 weeks trying to trouble shoot this problem to no avail. Until about 6 weeks ago she was running fine. Only 13K miles on the engine. I only put 93 octane in the tank. Starts up fine, smooth running. After 15-17 minutes it starts to starve for gas. You can see the fuel in the glass filter start to disappear and then about 3 minutes later its shuts down every time I replaced/chased a thought/suggestion. I have videos of the event that i am unable to upload so if you want to see it, I can email or text it to you. Below is what I have done so far and still no luck. I have included some photos of the engine bay. SME's, please what the heck is going on??
Carb - Holley 650CFM - Rebuilt professionally
Edelbrock Mechanical Fuel pump #1725 - Replaced original with 2 new ones.
Plugs replaced.
Ignition Coil replaced.
Bypassed the fuel tank using a gas can
Replaced all of the fuel lines from the pump to the carb.
Replaced the old aluminum fuel filter with a glass fuel filter.

**Posted by Greg B** 11/15/2024 12:59 PM

Are you saying this exact thing is going on even with using a can of gas for the tank?

Because my first thought is the gas tank is not venting.

**Posted by Chelby-Ann** 11/15/2024 1:28 PM

Greg B wrote:
Are you saying this exact thing is going on even with using a can of gas for the tank?

Because my first thought is the gas tank is not venting.

Yes Sir.

**Posted by BobE** 11/15/2024 2:27 PM

Did you check the ‘stone’ filter(s) at the carb inlet? They might be partially clogged?
Has the car sat w/o running for some extended time?

**Posted by RTM** 11/15/2024 5:12 PM

Maybe the floats in the bowls are not allowing the needle seat to open? Some sticking or hanging up inside there.

**Posted by Chelby-Ann** 11/15/2024 7:01 PM

BobE wrote:
Did you check the ‘stone’ filter(s) at the carb inlet? They might be partially clogged?
Has the car sat w/o running for some extended time?

Filters replaced. Running all spring and summer. Trouble started about 6-7 weeks ago.

**Posted by Raymond_B** 11/15/2024 7:13 PM

Before doing anything major I wonder if it would be a good idea to get a cheap electric fuel pump and try running that way. But it sure does sound like some sort of vapor lock.

**Posted by 50vert** 11/15/2024 7:29 PM

Are the fuel bowls at the right height when it stops?

**Posted by MS** 11/15/2024 7:54 PM

Check with fuel pressure gauge.

**Posted by Rufus68** 11/15/2024 11:04 PM

How long do you have to wait before you can restart the engine after it stops?

**Posted by TKOPerformance** **Online!** 11/16/2024 6:00 AM

My first thought would be either the fuel pump or the needle valve in the carb. You can bypass the fuel pump by hanging the fuel can from the hood (above the height of the carb inlet). You don't really need a fuel pump; its there to fight gravity. Old cars had no fuel pump and they mounted the tank under the seat and the carb down low on the engine. Cheaper alternative than buying anything to see if the fuel pump is the issue.

Worth noting to make sure the temporary gas can is vented too.

I've had issue over the years with needle valves that have a rubber tip. I think the ethanol in the fuel does something to the rubber and causes the valve to stick closed. I just had this issue with my tractor this year. A new needle valve solved the issue. It did the same thing, ran fine, but 2 minutes after throwing a load on the engine by starting the deck it died.

**Posted by rpm** 11/16/2024 11:16 AM

Buy an electric fuel pump and fuel pressure gauge to eliminate or confirm the fuel as the issue at O'Reilly's or Vatozone, as they allow returns without issues.

**Posted by GPatrick** 11/16/2024 3:33 PM

What is your full ignition setup? Some ignition module failures will show similar symptoms. You could try to keep it running using a squeeze bottle and dribbling fuel into the carb. If you have a timing light, trigger it while the engine is running and see if the ignition quits (light stops flashing) before the engine stops. If it runs out of gas it would keep firing until it finally stops.

**Posted by Chelby-Ann** 11/17/2024 8:13 PM

MS wrote:
Check with fuel pressure gauge.

Hooked up a Fuel Pressure gage today. Ran at 6 PSI and over a period of 15 minutes it slowly went down to 4.5 PSI and died the same way.
I tried to start it right away and it would not start.
Waited 1.5 hours, opened the gas cap (flip down) and she started right up.
Ran for 10 minutes and just died. 5 PSI before it died.
Maybe a bad batch of Edelbrock pumps? I'm returning this one too.
Any suggestions on a different mechanical fuel pump?
You can watch the PSI drop.

**Posted by Chelby-Ann** 11/17/2024 8:15 PM

GPatrick wrote:
What is your full ignition setup? Some ignition module failures will show similar symptoms. You could try to keep it running using a squeeze bottle and dribbling fuel into the carb. If you have a timing light, trigger it while the engine is running and see if the ignition quits (light stops flashing) before the engine stops. If it runs out of gas it would keep firing until it finally stops.

New Mallory ignition module, cap ordered. Be here on Tuesday.

**Posted by Chelby-Ann** 11/17/2024 8:17 PM

TKOPerformance wrote:
My first thought would be either the fuel pump or the needle valve in the carb. You can bypass the fuel pump by hanging the fuel can from the hood (above the height of the carb inlet). You don't really need a fuel pump; its there to fight gravity. Old cars had no fuel pump and they mounted the tank under the seat and the carb down low on the engine. Cheaper alternative than buying anything to see if the fuel pump is the issue.

Worth noting to make sure the temporary gas can is vented too.

I've had issue over the years with needle valves that have a rubber tip. I think the ethanol in the fuel does something to the rubber and causes the valve to stick closed. I just had this issue with my tractor this year. A new needle valve solved the issue. It did the same thing, ran fine, but 2 minutes after throwing a load on the engine by starting the deck it died.

New needle valves installed.
What would I use to make a gas can to hang from the hood. This is something to try for sure.

**Posted by Chelby-Ann** 11/17/2024 8:19 PM

Rufus68 wrote:
How long do you have to wait before you can restart the engine after it stops?

Would not start right back up so I waited 1.5 hours (dinner break) started right up.

**Posted by Rufus68** 11/18/2024 4:18 AM

If you are still having the problem, you can eliminate heat in the fuel system by getting a can of starting fluid and squirting some into the throat of the carburetor when it won't start. Just remove the air cleaner and give a shot of starting fluid straight into the carb. Hit the key and see if it fires up. If it does, you will need to correct the heat issue you have with the fuel.

Assuming it does start with the starting fluid, do you have a spacer between the carburetor and the intake manifold? If so, what material is it made of and how thick is it?

**Posted by TKOPerformance** **Online!** 11/18/2024 5:39 AM

Chelby-Ann wrote:
TKOPerformance wrote:
My first thought would be either the fuel pump or the needle valve in the carb. You can bypass the fuel pump by hanging the fuel can from the hood (above the height of the carb inlet). You don't really need a fuel pump; its there to fight gravity. Old cars had no fuel pump and they mounted the tank under the seat and the carb down low on the engine. Cheaper alternative than buying anything to see if the fuel pump is the issue.

Worth noting to make sure the temporary gas can is vented too.

I've had issue over the years with needle valves that have a rubber tip. I think the ethanol in the fuel does something to the rubber and causes the valve to stick closed. I just had this issue with my tractor this year. A new needle valve solved the issue. It did the same thing, ran fine, but 2 minutes after throwing a load on the engine by starting the deck it died.

New needle valves installed.
What would I use to make a gas can to hang from the hood. This is something to try for sure.

There are bulkhead fittings meant for going through thin plastic or metal, creating a seal and allowing you to thread in a fitting. Something like this:

https://www.amazon.com/Joywayus-Connector-Theaded-Bulkhead-Stablizing/dp/B07GPP23K9/ref=sr_1_2_sspa?crid=24KOSD13GXTIF&dib=eyJ2IjoiMSJ9.JcCZzMjKiDKFoRdGsKHMAglQAP9lU7wdDQem3iEU112nJz-NlZ_3HSuuIYBMEkdZdBZ1sSuHsQROqom3hNYSDSqW_hALRmZ9JJ1FzK0cBK8PP6cKstbXSFLnb8LiwzZP2q7Ga62n9mZ3XPpoSGN4hVBX9x037Zf2FVRLvLo2w1kQM0m3FyO76baxbbv9VTz3waDA9iSBaQaKMOnR72fI1VIWKBGS9v8WmSRsiQaNfiA.ZSSmdGnR_uuxs8rv6Q88Sr80d6NLGRmcCCa8cBJoveI&dib_tag=se&keywords=bulkhead%2Bfitting&qid=1731929735&sprefix=bulkhead%2Bfitting%2Caps%2C107&sr=8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

Then just get a cheap 1 gallon gas can or even like a gallon jug of detergent, etc. (good quality plastic) that you washed out thoroughly. Bulkhead fitting in the bottom of the container with a nipple for the the fuel hose size you need (probably 5/16 or 3/8). Rig up something to hang it from and Voila!

**Posted by TKOPerformance** **Online!** 11/18/2024 5:41 AM

Chelby-Ann wrote:
MS wrote:
Check with fuel pressure gauge.
Hooked up a Fuel Pressure gage today. Ran at 6 PSI and over a period of 15 minutes it slowly went down to 4.5 PSI and died the same way.
I tried to start it right away and it would not start.
Waited 1.5 hours, opened the gas cap (flip down) and she started right up.
Ran for 10 minutes and just died. 5 PSI before it died.
Maybe a bad batch of Edelbrock pumps? I'm returning this one too.
Any suggestions on a different mechanical fuel pump?
You can watch the PSI drop.

Okay, here's what you need to do now: run it until it dies, immediately open the gas cap and see if it starts up again. If not, the problem persists and its not a tank venting issue. If it does then its a tank venting issue. Try running it with the gas cap off/open and se if it dies.

**Posted by TKOPerformance** **Online!** 11/18/2024 5:45 AM

Rufus68 wrote:
If you are still having the problem, you can eliminate heat in the fuel system by getting a can of starting fluid and squirting some into the throat of the carburetor when it won't start. Just remove the air cleaner and give a shot of starting fluid straight into the carb. Hit the key and see if it fires up. If it does, you will need to correct the heat issue you have with the fuel.

Assuming it does start with the starting fluid, do you have a spacer between the carburetor and the intake manifold? If so, what material is it made of and how thick is it?

Not necessarily. If it starts off starting fluid it really just means there's a fuel supply issue. It could be vapor lock, or it could be something else. I find it hard to believe he's encountering vapor lock in 10-15 minutes, especially when he said it was running fine through the summer and spring, which is when it could be most prone to vapor lock.

**Posted by Rufus68** 11/18/2024 6:41 AM

TKOPerformance wrote:
Rufus68 wrote:
If you are still having the problem, you can eliminate heat in the fuel system by getting a can of starting fluid and squirting some into the throat of the carburetor when it won't start. Just remove the air cleaner and give a shot of starting fluid straight into the carb. Hit the key and see if it fires up. If it does, you will need to correct the heat issue you have with the fuel.

Assuming it does start with the starting fluid, do you have a spacer between the carburetor and the intake manifold? If so, what material is it made of and how thick is it?

Not necessarily. If it starts off starting fluid it really just means there's a fuel supply issue. It could be vapor lock, or it could be something else. I find it hard to believe he's encountering vapor lock in 10-15 minutes, especially when he said it was running fine through the summer and spring, which is when it could be most prone to vapor lock.

My point to him is to give him a way to eliminate the fuel as the issue. If it is not fuel related, it should not start from the starting fluid when hot. However, if it does start then it is a heat related fuel issue.

**Posted by BobE** 11/18/2024 8:18 AM

I agree w/TKO, try running it with the gas cap open. If it continues to run after several minutes with no issues, (watching the fuel pressure) close the gas cap and see if is stalls out in the time frame as it had been doing.
I believe the 68 model still vents the tank through the gas cap.
Althougn if it has a 'gas evaporator' system, maybe it is clogged.

Last edited by BobE (11/18/2024 8:21 AM)

**Posted by TKOPerformance** **Online!** 11/19/2024 6:08 AM

Rufus68 wrote:
TKOPerformance wrote:
Rufus68 wrote:
If you are still having the problem, you can eliminate heat in the fuel system by getting a can of starting fluid and squirting some into the throat of the carburetor when it won't start. Just remove the air cleaner and give a shot of starting fluid straight into the carb. Hit the key and see if it fires up. If it does, you will need to correct the heat issue you have with the fuel.

Assuming it does start with the starting fluid, do you have a spacer between the carburetor and the intake manifold? If so, what material is it made of and how thick is it?

Not necessarily. If it starts off starting fluid it really just means there's a fuel supply issue. It could be vapor lock, or it could be something else. I find it hard to believe he's encountering vapor lock in 10-15 minutes, especially when he said it was running fine through the summer and spring, which is when it could be most prone to vapor lock.

My point to him is to give him a way to eliminate the fuel as the issue. If it is not fuel related, it should not start from the starting fluid when hot. However, if it does start then it is a heat related fuel issue.

Fair enough, but if you read what you initially wrote you claim that if the car starts off the starting fluid the issue is heat related, which may not be the case, which is why I clarified that it would really only show if the issue was fuel related or not. Not trying to start an argument, just trying to help the OP.

**Posted by 6sally6** 11/19/2024 2:52 PM

Any progress ?!
6s6

302 - ENGINE TROUBLES

Greg B wrote:

BobE wrote:

MS wrote:

GPatrick wrote:

TKOPerformance wrote:

Rufus68 wrote:

Chelby-Ann wrote:

TKOPerformance wrote:

Chelby-Ann wrote:

MS wrote:

Rufus68 wrote:

TKOPerformance wrote:

Rufus68 wrote:

Rufus68 wrote:

TKOPerformance wrote:

Rufus68 wrote: