Hey guys, I've got a small problem. I just put on a re-manufactured 1bbl Holley carb on my truck. When I start it, I usually let the oil pressure go up for about 20-25 seconds, then I take off slowly. Well ever since this new carb I step on the gas to go and it just hesitates and tries to die. It will rev to about 1200 rpm, then after that it'll start to cough and die. You can get it past that if you really mash the gas hard, but I don't really like doing that. I've tried to tinker around with all of the screws to no avail. It's becoming a real hazard, I think it probably takes my truck atleast 10 seconds to get to 40 mph. Now count that aloud using the 'one one thousand' method... thats SLOW!
So what do you guys think it is? could it be timing? Occasionally it'll try to deisel after the engine is really warm. The fuel mileage has been pretty crappy too, it was at approx 10-12 this week.

Thanks in advance...

Chris
1982 F100 Flareside
300HD I-6
SROD 4speed
Blue & Silver

 

It sounds as if the choke is not functioning properly . When you touch the gas pedal on a cold engine , first start of the day , the choke should fully close . After the engine starts , the choke should open slightly & continue to slowly open until the engine reaches normal operating temp . The dieseling problem can usually be associated with the fast idle cam , its likely keeping the idle higher than it should be for your engine . Since the problems started after the Holley installation , Id focus on adjusting it properly before you suspect other problems .

 

Check the needle valve/float for sticking or mis-adjustment on carb. Sounds as if you have a major "flat spot" upon acceleration. Your timing shouldn't be suspected at all. Seems to be all fuel related since adding the Holley. Visually go over the carb installation. Don't neglect to check the air cleaner/snorkel heat riser door. If the door is open on a cold engine it will give you poor acceleration/hesitation, if the door stays closed on a hot engine it will give you poor gas mileage and crappy pickup. This is controlled by the air temp sensor inside the air cleaner. Two vacuum lines run to it. There should be vacuum on the line that runs to the snorkel door on a cold engine. Also check your choke circuit (butterfly on top of carb) to make sure it is fully opening on a hot engine.
Good luck.

81 F-150 8' Styleside
4.9 1 BBL Carb
C6 auto trans
187,700 miles

 

Chris, try backing the choke off so that it won't come on, sounds like it's staying on too long, I'll bet you have some nice black smoke coming out of the exhaust too... I don't have a working choke or air cleaner door(I don't have anything to hook it too anyway) and mine starts and runs fine, just give it a few pumps when I go to start it up, let it warm up for a while(~3 min, gotta scrape the windows and such) then drop it in low and put it crossways going out of the driveway, drop it in second and wind it out to 4200(40), then do the same in third(80) then I drop it in high and cruise at 60(I think I've developed a bad habit, but, I love the sound...)
Evan MacDonald
82 F100 FlareSide
HD 300-6, 240 head
Hedman Hedder
NP435(6.69 low)
2.73 Geared 9"
Blue & Silver

 

Thanks alot guys, i'll try that tonight and will post back later. The term "flat spot" REALLY describes it best!

Chris
1982 F100 Flareside
300HD I-6
SROD 4speed
Blue & Silver

 

Hello. Had the same problem with my truck and new carb. It was the choke. Backed it off a little and it runs great now. Greg.



1985 F-150, Black with black fiberglass cap. 300 6. Aluminum mag wheels, BF goodrich tires.