454 falls on its face at 2500+ rpm

[obijuan]

my trucks got a carbed 454 and when im at highway speeds around 2500 rpm it just sputters and acts like its running out of fuel or getting too much or something. and its intermittent every other second it falls on its face untill i let off the gas and go back to around 2450. i cant go up hills or over 55 if i wanted to, its rather irritating.


it has a full tank of gas and a new fuel pump, also i zip tied the choke down cause its so damn hot here anyways. it can run smooth as butter all day long. but until i get on the highway and go up the first hill i get to about 2 miles down the highway it acts up. for 5-10 minutes before that it is less than 45mph.

ive never had this kind of problem and would appreciate it if yall gave me a place to start. im gonna go out there and start jackin with it to see if i find anything, i didnt see anythough out of the ordinary after work though.

 

[76zimmer]

Starting ideas: plugged cat conv. coil going bad, bad plug wires.

 

[buffblazer]

what carb ya got

i put a holley truck advenger on my 350 and it did the exact same thing at that rpm

found out it was the vac secondarys and its like a 5 min fix with a dif spring.

 

[obijuan]

its a stock qjet, all the vacuum lines seem to be going to the right places and the plug wires arent arcing out and are in the right order lol. how can i open up the cap and actually tell the coil is bad? is it just a replace and hope type thing?

 

[Merv]

its a stock qjet, all the vacuum lines seem to be going to the right places and the plug wires arent arcing out and are in the right order lol. how can i open up the cap and actually tell the coil is bad? is it just a replace and hope type thing?

Where i would start. Replace the cheaper stuff. Simple tuning on the carb. Good place to start.

 

[ZukiJohn]

Same problem..

I've had that same problem before,, it was in my dist cap.. the wires to the coil were shorting out and it took for ever to find... replaced coil and that black control module in dist. and all was well...

 

[resurrected_jimmy]

tape fuel pressure and vaccum gauges to the windshield and go for a drive to rule out fuel and bad tuning

 

[Kenny78]

Is the vacuum can for secondary lockout adjusable on your carb?

 

[80' 427]

I see you said new pump but what about the filter?

 

[obijuan]

ding ding ding!! got some time to really get into it and fixed some other things.
while i was in there i found this. im pretty impressed at the capacity.

 

[76zimmer]

holy crap, I've never seen one with that much in it.

 

[Kenny78]

I hope youre going to disassemble the carb, those filters will unseat if clogged so it will still run but push that junk in your carb.

 

[kitimatdude]

I just read this, I was going to suggest fuel filter but you already caught it. I had the same thing happen to me. I would just put in a new filter and run it, if goes great just leave it as is.

 

[mr.smartass]

Wow that's a lot of sand.

Ever thought of dropping your tank? Seeing that filter plus a new fuel pump makes me think your tank could use a good cleaning.

 

[Big Ray]

Wow that's a lot of sand.

Ever thought of dropping your tank? Seeing that filter plus a new fuel pump makes me think your tank could use a good cleaning.

+1

 

[chulisohombre]

hats crazy.how long was that filter on there?doesnt look good.there should never be that much crud runnin through there.no wonder your engine was choked

 

[Chaddy]

Wow that's a lot of sand.

Ever thought of dropping your tank? Seeing that filter plus a new fuel pump makes me think your tank could use a good cleaning.

X2

 

[1-ton]

You need to run another fuel filter inline on the fuel line as well. The carb fuel filter is a weak filter to be used as the only filter. You must also have some contaminates in your fuel tank as well, in order to have that much debri end up in the fuel filter.

If you do not already have one, get an inline fuel pressure regulator as well. Carbs really need them, in order to run smoothly. Inertia from hard turns, stops, and acceleration causes fuel pressure to be eradict on a carburator. Mr, Gasket or Summit Racing sell reasonably priced ones starting at about $30.

 

[obijuan]

good tips guys, i just got this truck basically right off the ranch in the strawberry feilds here. i wouldnt doubt its the OE filter. mihgt just ditch the saddles and go a big tank in the bed or something.