Engine "Sputtering"....
 

Soo...I just recently started having this problem that im hoping somebody can help me out with...This past weekend I took '69 C/10 out for a drive and opened it up for the hell of it on the highway...I hit about 80-85 mph and the engine started "sputtering"...It was almost like a speed governor kicked in on it...I took it out again today to drive it to work since its nice outside and once I got on the highway it started doing the same thing again...but this time it started "sputtering" at only 65-70 mph and kept doing it till I reduced my speed to about 50 mph...and I accelerated and it did it again!

The truck starts fine, idles good, and accelerates great up to highway speeds, then this issue comes about once I get above 65 mph. As far as I know, quadrajets and TH350's dont have speed governors, so what could cause this problem? And why would it happen at 85 mph, then again at 65 mph a different day? Any ideas....cause I got none lol

Re: Engine "Sputtering"....
 

The condition you describe would lead me to the fuel pump. Sounds like it's weak and getting weaker. Sometimes a fuel pump that is going bad will not be able to keep up with demand at highway speeds. Another possibility is a restriction some where that is preventing the fuel system from keeping up with demand.
Just my .02.

Re: Engine "Sputtering"....
 

That was kinda what I was thinking, a restriction in my fuel line or the pump was starting to go...thanks for your input...ill check it out! :)

Re: Engine "Sputtering"....
 

i'd replace the fuel filter(s) before jumping to the pump

Re: Engine "Sputtering"....
 

Agreed. I had this problem a couple weeks ago and I thought of everything else before this. Glad I just replaced the fuel filter. That turned out being it and it has ran great ever since.

Re: Engine "Sputtering"....
 

For only $30 to replace the pump/filter from NAPA....id rather just do both....besides I cleaned my fuel filter this spring before I put the '69 back on the road....which leads me to believe it is the pump going


I picked em up today, with my work discount, so ill be swapping the pump & filter tonight with the new parts, hopefully it'll fix my issue :rolleyes:

If they dont...ill be doing a lotta this :barn: :alky: lol

Re: Engine "Sputtering"....
 

you're forgetting that your new pump just may be made in Chin, or some other craptastic place.
If your old pump is fine, then it is possibly better than new. Kinda like brake rotors, battery cables or just about any other thing these days.

Re: Engine "Sputtering"....
 

Well...I replaced the fuel pump and fuel filter last night...it started fine, idle was good, and took it for a drive. It seemed like the problem was fixed, driving around the country roads, I even took it up to 100 MPH on the empty highway with no issues!! So I thought it was fixed.....

But then this morning when I took my '69 out to go to work, it started acting up the same as before on the highway. It was cutting out above 60 MPH and reduced my speed down to 50 MPH, then 40 MPH, but if I tried giving it gas all I could hear was the quadrajet sucking air but it seemed like it wasnt getting ANY gas. Then on the range road, after I turned around to come back home, it stalled out on me. I got it started again without any real issues, but it kept "sputtering" all the way home any time I tried to give it gas above 40 MPH.

My only other ideas that could be causing this problem im suddenly having, but NEVER have come across before, is possibly bad gas or water in my fuel tank or maybe a vacuum hose on my carburetor cracked or came loose or my carburetor is gummed up....

I may pick up some octane booster and water remover and try pouring them both into my gas tank. Maybe pick up some carb cleaner too, spray my quadrajet inside and out. And inspect all my vacuum lines/hoses tonight. Hopefully that will fix my problem....*knock on wood*

Re: Engine "Sputtering"....
 

my second thought after a clogged fuel filter is sediment in the carb, or the floats not adjusted properly.

Re: Engine "Sputtering"....
 

I did some more searching and found this link too:

http://67-72chevytrucks.com/vboard/s....php?p=4229022

I found a crimped rubber fuel line im gonna replace. That looks like it should be the culprit restricting my fuel flow to my carb when I get on it! Im gonna blow out my hard line running from my tank to my pump while im at it too. On a side note, spraying a can of carb cleaner inside and out sure did wonders to my carburetor, its soooo much cleaner now! lol...I just removed all the lines & connections & sprayed the carb cleaner in every nook & cranny I could get it into!

Re: Engine "Sputtering"....
 

post ou the results... im having the same issue but diferent vehicule.

Re: Engine "Sputtering"....
 

Well...I got 'er done! :) I dunno what ACTUALLY was causing my problems, but replacing a crimped fuel line, a (possible) worn out fuel pump, the fuel filter, and carb cleaning my quadrajet ended up doing the trick. In the end my truck now starts, idles, and runs alot better now and it all costed me about $50 and a few hours worth of work.

Re: Engine "Sputtering"....
 

I'm gonna have to give those a try. My 307 spits, sputters, pops, and bangs whenever I get into it....or when I shift to 3rd. The 3rd gear thing has me stumped though. While I can prevent the symptoms in the first 2 gears by taking it easy, that doesn't help once I'm in 3rd. It's almost like once I'm running in 3rd, its not running on all cylinders.