Motor lugs and cuts out in 4th gear under load. *Update* Fixed, Problem solved

[Madgyver]

This thing can't climb hills now in 4th gear around 2000rpm.
It feel like it runs out of fuel as I press on the throttle, I need to let off slowly to keep it running and by then I'm moving like 40mph.

Carb problem? Or ignition?

 

[broncnaz]

I'd say ignition but it could be either.

 

[RT]

The gas filter is clean ,,,,right ??

Even if it's not that old , I'd check on it .

 

[bmc69]

which engine..what setup are ya talking about here, Mad?

 

[Madgyver]

which engine..what setup are ya talking about here, Mad?

351W, .030 over, Crower Baja Beast cam, '69 heads, Edelbrock performer intake, BC Broncos remand Quadrajet (earlier one), NP435, D20, 4.11 9" rear gear, 37" MTRs.

I'm on crunch time to figure this out.....

Fuel filter on the Quadrajet inlet cleaned out, Found crap in it.

Could the trash in the fuel lines screw up the mech. fuel pump?

I've switched carbs with a Holley DP and still got the same problem which got me looking into ignition problems or fuel delivery problem.

 

[wildbill]

%) %) %) Bad plug wires can do that under load. I had it happen to a new set of the nice yellow ones took a wile to fine as was the last place I went good luck.%) %) %) Bill %) ;D

 

[bmc69]

Could the trash in the fuel lines screw up the mech. fuel pump?

my word yes..lost two pumps in rapid succesion on a recent Scout job due to that. Ran great..then just sort of fade away to nuthin. Gets all stuck up in the checl valve on the suction side of the pump. I run a suction filter on all my own rigs..and a nice big ole Sierra Marine spin-on filter/separator after the pump.

 

[broncnaz]

What igntion does it have?

 

[cbford]

This is going to sound wierd (hehe), but I once had a muffler's guts rot out and block off the exit pipe partially and it did the same thing. I cursed that poor carb, fuel pump and dizzy for a week before I found it by accident.

 

[Madgyver]

What ignition does it have?

Stock type Ford module. Brand new.

 

[Broncobowsher]

OK, try this...
Get it up to the 40 MPH choke point.
Back off a little until it runs good then back off some more. Wait a few seconds and try again.
What I am trying to determin is if the fuel bowls are running dry. By backing off a little it gives them a chance to refill. If the power comes back then falls off, I would be checking fuel delivery.

Any chance of putting a pressure gauge after the filter that you can monitor while driving?

 

[Madgyver]

It was a bad mechanical fuel pump. I found a NIB Carter electric among my parts and hooked it up, Bypassed the mech pump with a new hardline.