Fuel Starvation?

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Ricks70Duster340

Ricks70Duster340

Child of the King
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Have been chasing what I believe to be a fuel issue for some time now. Have a purely street driven Challenger with a 512 stroked 440. Has a fairly new fuel tank & sender with 3/8" line from the tank to the front. Started with a 440 Source mech fuel pump (1/4" inlet/outlet). When cruising, no issues at all but going to WOT the engine acts like I turned off the key. When I let my foot off of the gas the engine comes back within a few seconds.

- All 4 of the tank vent tubes were plugged so I opened the larger one to ensure venting.
- Changed the mech pump to the Edelbrock street pump with 3/8" in/out. No difference.
- Changed fuel filters, no difference.
- Changed carbs (started with Quickfuel 750 and went to AVS2 800), no change.
- I even played with the timing curve and went from 32* down to 27* when the issue occurs, but no change.

I'm open to ideas from the braintrust!
 
Try disconnecting the vac line from the distributer. See if that helps. On rare occasion, I have seen a bad connection in the dist, and when the dist loses vacuum, the advance plate moves, and cuts the ign.
Another question. Have you connected a fuel pressure gauge? What is your FP? Does it change when the engine dies?
 
Charrlie_S said:
Try disconnecting the vac line from the distributer. See if that helps. On rare occasion, I have seen a bad connection in the dist, and when the dist loses vacuum, the advance plate moves, and cuts the ign.
Another question. Have you connected a fuel pressure gauge? What is your FP? Does it change when the engine dies?
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I am running the progression ignition that uses a timing table like an EFI system. I have a FP gauge from Summit but it is very inaccurate so I removed it. I would not be able to see the pressure with the hood closed anyway. Maybe down the line I could install one that would have a gauge under the dash that I could see.
 
halifaxhops said:
Also what ECU you running? What brand, they can act like that at high RPM
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Am running the Progression Ignition with the live timing table I can see on my phone. Edit: I have the rev limiter set to 5500 though I doubt it is getting much above 4500 before the issue occurs. Don't currently have a tach in the car.
 
You really have to see which it is, nothing is usally no spark, Hard to find unless you are reving it parked!

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Ricks70Duster340 said:
I am running the progression ignition that uses a timing table like an EFI system. I have a FP gauge from Summit but it is very inaccurate so I removed it. I would not be able to see the pressure with the hood closed anyway. Maybe down the line I could install one that would have a gauge under the dash that I could see.
Click to expand...
Nah, if it were me, I wouldn't mount a fuel pressure gauge inside of the car. - 2 cents
 
Sounds to me that maybe the plastic sock or debris in the fuel tank is being sucked against the opening of the fuel pick up in the tank restricting flow.
 
Other than the load on the engine and the acceleration.

You should be able to duplicate the circumstances in the driveway.

  1. You need to measure your fuel flow at RPM
  2. Your fuel pressure at RPM
  3. Insure your dist can run to the max rpm, maybe even swap in a stock type ignition system.
A friend was chasing his tail with a holly sniper etc. at higher rpm the engine would run crappy and die, the ECU would loose its programing etc.

He found part of the problem was the coil wire would move during acceleration and got burnt on the manifold and short out.

He fixed that but still had ECU issues.

But it ran fine till the ECU would crap out.

He switched back to stock parts and things were more normal, he sent the ecu to Holly and they sent a repaired/ replaced ECU. He put it all back on and still had the issues.


My guess, ( no hands on time with the car) is electrical noise from the stock type 67 charging system.
 
You didn't mention the hoses connecting the sender and the fuel pump to the fuel lines. Have you inspected them? Remember, they break down from the inside, so the failure may not be immediately noticeable. If you have not, I'd replace them with Gates Barricade EFI hose. There are a couple of different Barricade hoses, it has to have EFI printed on it.
 
RustyRatRod said:
You didn't mention the hoses connecting the sender and the fuel pump to the fuel lines. Have you inspected them? Remember, they break down from the inside, so the failure may not be immediately noticeable. If you have not, I'd replace them with Gates Barricade EFI hose. There are a couple of different Barricade hoses, it has to have EFI printed on it.
Click to expand...
I replaced the hose from the metal line to the fuel pump inlet with EFI hose. The rear hose looks good, and was probably replaced when the tank was but I have not checked it.
 
Ricks70Duster340 said:
I replaced the hose from the metal line to the fuel pump inlet with EFI hose. The rear hose looks good, and was probably replaced when the tank was but I have not checked it.
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I would. That was what was wrong with my Ford truck. It was doing the exact thing you're describing here, but the hose looked fine from the outside. There was one soft spot in it. Once I replaced it, it was fixed. The fuel pump was sucking the hose shut.
 
Ricks70Duster340 said:
I am running the progression ignition that uses a timing table like an EFI system. I have a FP gauge from Summit but it is very inaccurate so I removed it. I would not be able to see the pressure with the hood closed anyway. Maybe down the line I could install one that would have a gauge under the dash that I could see.
Click to expand...
What was the issue with the FP gauge?

You could use a standard fuel pressure tester tool kit that has the gauge on a hose and includes a tee to put near the carb inlet, shim the hood hinge up enough to run the hose out to the windshield, and duct tape the gauge face to the glass. Could also use a $20 usb borescope cable camera plugged into your phone.

I'm thinking tank sender too. I believe they make a high flow version.

Might also loosen the gas cap and reinstall right before a test with to see if it makes a difference. The fuel burn rate at WOT may exceed the one working vent's capacity to let air in.
 
Just throwing this out there, I'm having a high HP 414 built and was told at the power levels we plan on making (550+) a mechanical pump wouldn't be sufficient? We went with the Aeromotive in-tank pump that is supposed to be good up to 750 naturally aspirated.
 
MV8 said:
What was the issue with the FP gauge?

You could use a standard fuel pressure tester tool kit that has the gauge on a hose and includes a tee to put near the carb inlet, shim the hood hinge up enough to run the hose out to the windshield, and duct tape the gauge face to the glass. Could also use a $20 usb borescope cable camera plugged into your phone.

I'm thinking tank sender too. I believe they make a high flow version.

Might also loosen the gas cap and reinstall right before a test with to see if it makes a difference. The fuel burn rate at WOT may exceed the one working vent's capacity to let air in.
Click to expand...
The Summit gauge read 3 PSI right out of the box, and would sometimes go back to zero when the engine was off. Reviews on that gauge said it did not work well when cold but was more accurate hot.
 
BrianT said:
Just throwing this out there, I'm having a high HP 414 built and was told at the power levels we plan on making (550+) a mechanical pump wouldn't be sufficient? We went with the Aeromotive in-tank pump that is supposed to be good up to 750 naturally aspirated.
Click to expand...
If I need to use an electric pump I will, but am very hesitant to do so. Unless the pump is actually in the tank there is very little room back there to mount one that does not interfere with exhaust and other things.
 
Freiburger made 950 hp and ran 8.50s with a mechanical pump. A Holley 190lph if I remember right. You don’t necessarily “need” an electric pump, but you do need to make sure the pump you use is sufficient. You need to do some diagnostic work to figure it out. What goes away when the engine shuts off? It has to be fuel or spark and it’s on you to figure that out. Do a fuel flow test in to a bucket, rig a spark tester you can see while driving, rig a fuel pressure gauge you can see while driving. Those kind of things.
 
Need more info. Going from cruising to WOT & engine dies?
- what rpm does the engine reach before it dies?
- same rpm in each gear?
- how long does the engine take to come back to life?

For reasons known only to Edel, they used pidling little 0.093" n/seats in their carbs. These will be too small for a large cu in engine that gets up to 6000 rpm.
 
Partially clogged fuel filter? Enough fuel flow to start and cruise, but under WOT there could be insufficient fuel flow to fill the carb. Therefore, the engine stops.
 
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