Fuel Starvation / Mechanical Fuel Pump

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Criscobath

Criscobath

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Could sure use some help. Leaving for Power Tour in 2 weeks.

I'm running a mechanical fuel pump on my 360ci/380hp Magnum crate. Just did a few miles in the car and suddenly the car dies while cruising at 40-45 mph. I have a clear fuel filter between the pump and the carb and there is barely any fuel in the filter. Once the car is restarted, I can see an insufficient amount of fuel pumping into the filter.

This is my second mechanical pump I've had in the car. The first was an Edelbrock and the current one is an aftermarket parts store special.

Is a mechanical pump incapable of supplying the amount of needed fuel for this motor? Is it time to switch to an electric pump? Any and all help is appreciated!
 
Should be plenty of fuel when just cruising. Is the fuel tank properly vented.
 
Mechanical fuel pump is fine. You have a restricted line or it's vapor locking.

Could you show pictures of your fuel line routing from carb to frame rail?

Did this problem just start? Sounds like you had this problem before and changed the fuel pump. If so, how long before that, and what changes since start of problem?

Could even be float setting.

Have you ever seen junk and debris in your fuel filter?
 
Just a point to ponder... should be a full fuel system as in full of fuel. If you don't see fuel in liquid form you see air or fuel vapor. Ask yourself where that can come from. If the fuel is boiling in the bowl and making more vapor than can escape through the bowl vent does it build enough back pressure to push vapor back into that filter ?
 
its not your fuel pump,debris in the tank,or fuel line.vapor lock which is my quess.
 
Your Mechanical pump can handle the supply. If this problem only occurs when car is warm you probably have a vapor lock issue. Phenolic Carb spacer and good tank vent helped solve my issues. Fuel lines away from heat sources.
 
Sorry, dinner and kids.

I have DEI cool tube around the 3/8 fuel line between the fuel pump and the firewall. I don't have any cool tube between the fuel pump and the carb. The fuel lines follow the factory path and are pretty close to the header primary tubes in spots. I have no room for a carb spacer with the current hoodscoop (Cougar Eliminator).

The tank was half full when it first happened today and then full when it happened the second and third time.

The tank is vented and I have a vented cap.
 
I'll post a picture of the line between the carb and fuel pump after I put the kids to bed.
 
This same problem has been persistent. However, the car isn't driven much. I had the same issue last Spring/Summer and not so much this past Winter.

As many of you suggested, vapor lock has been my guess too. I just thought the cool tube over the fuel line would fix the problem. It hasn't.

One more thing, the car runs rich. I swapped the plugs out today and there was gas on 4 of the 8 plugs. Not sure if that might be a contributing factor too.
 
I'm pretty sure a vapor lock gives you a lean condition. You may want to install a fuel pressure gauge between pump and carb.
This is starting to sound more like a carb issue. Good luck. I'm gonna follow this thread. I'm sure some of tech guys have some good troubleshooting for this one.
 
The carb is a 750 cfm Holley Vacuum Secondary SMI carb. I had it built for this car.

I've never seen any trash in the fuel filter.

I did notice the hose between the chrome carb fuel inlet line and the fuel filter was pretty hot.

Also noted that fuel filter fills up with fuel once the car cools.
 
Looks like your boiling the fuel just before the pump running that line so close to the header. Does it act up when it's warmer outside? I ran my line up on the inner fender.
 
I wonder if I can get by with adding more heat shielding around the fuel line in that area? I seriously don't have time to reroute the line (the right way).
 
The line from hard line to fuel pump looks ok. It's just the top angle that makes it look close.

It looks like the rubber line leading into the carb solid line is touching or close to the heater hoses.

I like to run hard line from fuel pump to carb. A stock line I think should work with your fuel pump. Even if it's smaller it would be fine. Do you have your old stock line? ...Or run heat shielding over that whole line from fuel pump to filter from filter to hard line. And put the DEI shielding over the splitter double pumper carb hard line. Shoot air into the sleeving to slip it over the tube nuts.

Doesn't all look that bad. Are you running stock fuel line from gas tank to engine compartment. or a repro 3/8" line? Or did you make the line your self?
 
autoxcuda said:
The line from hard line to fuel pump looks ok. It's just the top angle that makes it look close.

It looks like the rubber line leading into the carb solid line is touching or close to the heater hoses.

I like to run hard line from fuel pump to carb. A stock line I think should work with your fuel pump. Even if it's smaller it would be fine. Do you have your old stock line? ...Or run heat shielding over that whole line from fuel pump to filter from filter to hard line. And put the DEI shielding over the splitter double pumper carb hard line. Shoot air into the sleeving to slip it over the tube nuts.

Doesn't all look that bad. Are you running stock fuel line from gas tank to engine compartment. or a repro 3/8" line? Or did you make the line your self?
Click to expand...

I really appreciate the help. The current line is brand new prebent 3/8". The old fuel lines are long gone. I'm going to take your advice and shield the line between the pump and carb. I hope DEI has a frequent shopper program. :D
 
gtsdude said:
Looks like your boiling the fuel just before the pump running that line so close to the header. Does it act up when it's warmer outside? I ran my line up on the inner fender.
Click to expand...

X2 big time.
It's not just that number two header either, as the heat from all the pipes will build up all along that fuel line the way it is.
Header wrap would help, but I hate seeing that stuff all over the place.
Heat shield or insulation is about the only temporary solution to that issue, but rerouting would be the way to really take care of it.

Just an FYI I use 1/2 heater hose split longways around steel lines that get a little close to the headers.
It allows an air gap between the hose and the line and seems to work well.
Maybe that would help your situation until you can reroute.
 
Run the car without a fuel cap, or with it loose. If it is not venting, that could be an issue.
 
Criscobath said:
I really appreciate the help. The current line is brand new prebent 3/8". The old fuel lines are long gone. I'm going to take your advice and shield the line between the pump and carb. I hope DEI has a frequent shopper program. :D
Click to expand...

I went around the alternator (mini one) altogether to get the line away from the heat.
 

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It does sound like vapor lock or fuel is boiling.

Quick test: Get it Hot enough for it to happen again, Locally or in your driveway so your not stuck out on the road somewhere, then either run a garden hose over the fuel pump and lines & check to see if it starts.
Another trick is to take a bag of frozen peas or corn & wrap it around the pump & see if that works. If it starts to get fuel right away you know it's a heat sink problem.
BTW, don't let the wife/ mom/ girl friend know your stealing food from the freezer to test your fuel system! And don't eat them when you're done either!
 
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