massive hesitation when accelerating.

[EldarO]

try running 95.. it may actually run better if its currently rich

when you drop the boot on her it may just be dumping a heap of fuel in it, does it bog down if you progressively apply throttle before opening it all the way?

yeah it bogs down at any throttle, then as it stumbles through, if i hold it midrange it keeps stumbling, clearing itself eventually, but if i floor it, all good.

i think it is overfuelling, as its using more fuelt han usual, im just not sure why.

[Shakotan_Aaron]

could be partially blocked jets possibly? did you end up pulling it apart and cleaning it?

bit of shit could have got past the filter...

[EldarO]

read the plugs, none are sooty, all a light brown colour, no pre-ignition or otherwise.

i had a play with the timing and got it moderately bareable, but its still a fucking pain in the ass.

the accel pump is working, as in, it sprays in fuel, is it possible though that it could spray in too much?

[The Last Streetfighter]

If it is a points ignition car I'd say there was a problem with the points. My N10 used to do that when the points were shagged.How's the rest of the spark system?

[MWP]

carby is a few weeks old...

What carb is it?

Ive had the same thing happen on two occasions, from two different problems:
#1 - Carb was oversized for the engine: there wasnt enough vac to pull fuel in at low revs.
#2 - Dead carb accel pump: it pumps extra fuel into the engine when accelerating.

[WiLo]

Check plugs to see if they are fouled or not. Dark black plugs indicate running rich. May help you in some way.

i was having similar problems and the plugs were showing that it was running rich, it was rich on idle but lean under acceleration.

id try richen the mixture a bit and see how it goes

[sleeektoy]

Have you thought to check all the leads, distributor etc.

Only reason is - i had the same issue and it turned out to be the points gap closed up to nearly nothing in the dizzy. lack of decent spark = unburnt fuel = running rich.

no idea if they still had points then but a check/clean and poss replacement of cap/rotor/leads can make a big difference.

[WiLo]

Have you thought to check all the leads, distributor etc.

Only reason is - i had the same issue and it turned out to be the points gap closed up to nearly nothing in the dizzy. lack of decent spark = unburnt fuel = running rich.

no idea if they still had points then but a check/clean and poss replacement of cap/rotor/leads can make a big difference.

thats the first thing i did when i was having problem, spent over $100 replacing parts when all it needed was the float adjusted

[EldarO]

spark system is mint, overhauled everything when i got it.

carb is, once again, a standard carby, and everything is properly sized.

could be accel pump, MWP, you just answered my above question

it is a brand new standard carb.
secondly, THE CAR RAN PERFECT until this shit (6-7weeks)

third, i got pissed off today and reved it right out to redline (just before the red bit on the tacho) and its righted itself once again, prob is still there, but what was a bucking/jerking nightmare is now a minor flatspot.

ill take it to me carb dude sometime this week, see what he reckons.

this accel pump a pain in the ass to replace?

[matt86sx]

Not really familiar with Sierras, does it have a brake booster with a vacuum line running to the intake manifold?

I had a problem similar to what you were describing with my Valiant (245 Hemi 6 motor in this case) that I owned many years ago. Spent years trying to work the problem out and just driving around it in the meantime....changed virtually every part of the ignition, had the carb rebuilt, jets cleaned,etc, etc....

Turned out that there was a small leak in the brake booster diaphragm that nobody ever picked up......once we put a new booster in the problem was completely cured! Couldn't believe it was something so simple and that I had been looking in the wrong places the whole time trying to fix it.

Probably a VERY long shot that your car has the same issue, but thought I might throw it out there just in case. Sounds like you've tried everything else so you just never know......

Best of luck with it.

Matt

[EldarO]

brake fluid is low, ill top it up and see if theres any diff.

its fucking strange, its so intermittant, sometimes it will do it, sometimes it wont.

had to fucken work overtime today, so tomorrow ill refresh the parts of the ignition system i havent so far (points, and thats about it)

then ill start fucking with the carb, although im certain that isnt the issue, unless its the fucking accel pump.

[RO11LR]

Have you checked your fuel filter , might be a little blocked up ?

[thechuckster]

... i got pissed off today and reved it right out to redline (just before the red bit on the tacho) and its righted itself once again, prob is still there, but what was a bucking/jerking nightmare is now a minor flatspot.

crap/crud in the carbi - time to replace fuel filter and give the carbi bowls and float needles a good clean.

[EldarO]

fuel filter was replaced when i first got it, as the carby sucked balls, so i did all the cheap shit first, before deciding carby was definately the issue.

its not more than 2000k's old.

ill replace it again and blow the lines out.