Truck feeling like it is under load?

[Eastonfrench]

LSXCHEVY:
I don't know what the fuel pressure is, how can I check that?
Also, what is "ping"? I set the timing at the degree it calls for on the sticker under the hood. When you say pings under load, what do you mean? I don't have a tach, so it's hard to set anything at designated RPMs.

I am very handy, but very inexperienced with these older trucks. I suspected the fuel pressure, which is why I put the new fuel pump on.


Another thought, could it be spark plug gap? Anyone know what gap I should run? I just set them on what autozone told me at the time. What should they be?

[Eastonfrench]

Update: I ran it really hard and got her up to temperature and now it won't do it at all! Maybe that has something to do with it? What would cause these issues only until the truck is hot? I let it warm up 5 minutes before I dive it in the mornings and its 80 degrees here

[bd]

A slightly low float level can cause it, as well as choke adjustment, adjustment of the secondary air valve spring, and/or the secondary lock-out.  There could also be an anemic accelerator pump shot due to a stiff rubber pump cup that bypasses fuel when it's cold.

[Irish_Alley]

im going to add to what these guys said by what i just did to my truck to get it ready for the mud bog where you need all your power on the take off to get your wheels spinning and i had stumble on acceleration for the longest time.
 
first: floats in the carb bowls had to be adjusted to the right level

second: timing set at 15° with the vacuum advance unhooked and plugged. came out to something like 35° total

third: hooked vacuum advance up to the manifold vacuum instead of ported. (make sure you vacuum advance is working)

just by these three things i dont think my truck ever ran so good now i might need a new clutch lol

[LSXCHEVY]

 fuel pressure is, how can I check that

I have a fuel pressure gauge on the fuel line near the carb...electric pump with regulator makes it easier. if you have a mechanical pump, its a little more involved.

Also, what is "ping"? I set the timing at the degree it calls for on the sticker under the hood. When you say pings under load, what do you mean?

someone with more experience than me can chime in but I believe that the timing should change over time cause of drivetrain parts wearing out, sticker from 1980 might not be as relevant. advance the timing until you drive it under a load and will hear slight "pinging" or like a metal can sound type at high load or high rpm

I also would try the things mention by Irish, good info.. best thing I did for my carb was buy a wideband AF meter to take all of the guess work out of it...

[Irish_Alley]

ping or knock

Knock

Occurs when part of the air-fuel mixture in the combustion chamber away from the spark plug is spontaneously ignited by the pressure from a flame front originating from the spark plug.  The two colliding flame fronts contribute to the “knocking” sound.

Knock occurs more frequently when using low octane fuel.  Low octane fuel has a low resistance to knock (low resistance to ignition)

Knock is related to ignition timing.  (Knock is sometimes referred to as “Spark-knock”.)  Retarding the ignition timing will reduce knock.

Heavy knock often leads to pre-ignition.

Heavy knock can cause breakage and/or erosion of combustion chamber components.
Knock is sometimes referred to as “ping” or “detonation”.

[blazer74]

Did this problem just start one day or was something done that possibly caused this to happen. A little more history if possible.

First thing on my mind is fuel supply for falling on its face.


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[rich weyand]

Some more: Clogged fuel filter, or bad rubber line from the tank to the steel line, or from the steel line to the pump.

Another could be the choke set too lean.  It comes off too soon, giving you a period when you are running lean until the truck warms up.  Will run fine stone cold, will run fine hot, goes through a period when it is so-so.

[Eastonfrench]

Hey guys. I think my truck is not getting enough fuel at WOT, and as a result stutters/bogs for a second. I've got a two dollar fuel filter in the Quadrajet fuel inlet. Has anyone ever tried removing that and maybe installing an inline filter somewhere else in the line? I know autozone sells generic performance fuel filters. just wondering if anyone has done this or knows if it could help with fuel starvation when I gun it. I have a brand new fuel pump, and have done my best to make sure lines are tight and that there's no air getting in the system.

[enaberif]

I always pull the filter from inside the carb and then cut the steel line and put a filter in with soft lines.

[bd]

Locate a new in-line fuel filter in a convenient and easily accessible spot between the fuel pump and the carburetor, so the filter is always pressurized by the pump.

If the engine bogs just for a second at WOT, it sounds more like an issue with a lean accelerator pump shot, secondary air valve adjustment, power circuit timing, or vacuum advance issue.  Actual fuel starvation resulting from poor fuel delivery up to the carburetor, or an excessively low float setting, generally will manifest more as an overall loss of engine power with increasing throttle demand.

[Eastonfrench]

enaberif- So you just cut the hard line, and hose clamp soft line section in, with a fuel filter?

bd- I also think I have a generally low amount of HP. I've adjusted the secondary air valves, put a new accelerator pump in (though if there is a way to adjust it, I have no idea how). And I have verified that the timing and advanced mechanisms are in order.

[enaberif]

enaberif- So you just cut the hard line, and hose clamp soft line section in, with a fuel filter?

bd- I also think I have a generally low amount of HP. I've adjusted the secondary air valves, put a new accelerator pump in (though if there is a way to adjust it, I have no idea how). And I have verified that the timing and advanced mechanisms are in order.

Yup! I tucked it down near the frame rail out of the way of anything dangerous. In the new year I'll be redoing the hardline from the carb to the pump so there is less soft line than I have now.

[philo_beddoe]

May i also ask, i have the standard carb filter AND an in-line. Is that ok? Should i only have one?

[bd]

There's nothing wrong with that, but you are not really gaining anything.  Just don't forget to replace the filter in the carb, occasionally - lol.  Or, remove it completely and rely on the in-line filter.