looking for help with fuel - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70Custom10Nut · 01-23-2010, 09:53 AM

Not sure exactly where to post this question. I posted my question in the engine forum, so I won't go into great detail. My truck is hesitating at hiway speeds, amongst other things. I'm just asking for advice on what to look for. thanks, Cnut

71meangreenc10 · 01-23-2010, 10:22 AM

If your going to check the fuel
1. see if trash (rust) is getting up to your carb.
2. check the condition of the carb, if its 40 years old, probably way past its time for a rebuild.
3. Whats the condition of the fuel pump?
4. Any vaccum leaks?

Dont forget to check the ignition system, are you running points or HEI? How old are the plug wires?

Smitty

fdbdw · 01-23-2010, 04:38 PM

X2 with 71 meengreen,

also check the fuel pick up sock, they get brittle and break up with age then the little pieces of sock get pulled into the fuel line
Also if you have an adjustable vac can on your dizzy make sure its adjusted right,
There are alot of things that can cause hesitations, always check the cheap and easy ones first, good luck and keep us posted

gonzo6869 · 01-23-2010, 10:58 PM

Had a similar problem. I changed the fuel sending unit sock, did not change a thing, but was old and needed to be replaced anyways. Next I checked the plug wires. One of them was laying on my headers, it was burnt, changed them, it was a little better but still had problems. To keep it short, due to a surplus of cash at the time, I bought a new carb, help a lot but still had issues. Got pissed and decided to throw parts at it. I ended up changing the vacuum lines, fuel pump, and plugs. The plugs I pulled out were not that bad, but were put in before an HEI was installed. They were gaped at .35 so with the new ones I changed it to .45, also, the plugs for number 5 and 7 cylinders were very loose, I could turn them by hand. Anyways, after all this the truck was running tits.

I would suggest changing your vacuum lines, if you got a TH350, that one too. Change your plugs and wires. Rebuild or buy a new carb(if needed). And a fuel pump. Of course you will do all this after checking your timing. O yeah, change your fuel filter(s).

suprachrgd82 · 01-25-2010, 12:49 PM

Newer fuels have increasingly higher ethanol content. Ethanol is has a tendency to degrade rubber fuel lines, allowing the fuel line particles to accumulate in "bottle necks" and fuel filters. It is quite possible that this a contributor to the condition.

01-23-2010, 09:53 AM	#1
70Custom10Nut Registered User Join Date: Sep 2007 Location: Vilseck Germany (currently) Posts: 317	looking for help with fuel Not sure exactly where to post this question. I posted my question in the engine forum, so I won't go into great detail. My truck is hesitating at hiway speeds, amongst other things. I'm just asking for advice on what to look for. thanks, Cnut

01-23-2010, 10:22 AM	#2
71meangreenc10 Its a Truck Thing...... Join Date: Dec 2004 Location: Sierra Vista, Arizona Posts: 3,159	Re: looking for help with fuel If your going to check the fuel 1. see if trash (rust) is getting up to your carb. 2. check the condition of the carb, if its 40 years old, probably way past its time for a rebuild. 3. Whats the condition of the fuel pump? 4. Any vaccum leaks? Dont forget to check the ignition system, are you running points or HEI? How old are the plug wires? Smitty __________________ 71 C10 283/3SPD Full Resto 71 GMC 1500 Sierra Grande http://67-72chevytrucks.com/vboard/s...d.php?t=518599 70 C10 Suburban Former military GSA truck. 72 Chevy Blazer 4X4, Sloppy Jo, Mountain Climber. Wife says no more trucks. http://67-72chevytrucks.com/vboard/s...d.php?t=707378 72 GMC 1 Ton Motor Home, wife said no more trucks until she saw this one. Gen 3 6.0/4L80E 4.10 http://67-72chevytrucks.com/vboard/s...d.php?t=761110 68 GMC Suburban was 3/4 ton, now 1/2.Wife shook her head 71 C30 Wrecker 71 C20 Scott-Bilt As weird as it gets..BB Cheyenne AC Truck 68 GMC Long Stepside. They keep following me home 71 C20 Longhorn/Ole Yellor 69 C30 Former Motor Home, Flat Bed time Last edited by 71meangreenc10; 01-23-2010 at 10:22 AM.

01-23-2010, 04:38 PM	#3
fdbdw Registered User Join Date: Jan 2009 Location: colorado springs Posts: 479	Re: looking for help with fuel X2 with 71 meengreen, also check the fuel pick up sock, they get brittle and break up with age then the little pieces of sock get pulled into the fuel line Also if you have an adjustable vac can on your dizzy make sure its adjusted right, There are alot of things that can cause hesitations, always check the cheap and easy ones first, good luck and keep us posted

01-23-2010, 10:58 PM	#4
gonzo6869 Cops, ha, catch me if you can! Join Date: Jun 2009 Location: Santa Barbara, CA. Posts: 271	Re: looking for help with fuel Had a similar problem. I changed the fuel sending unit sock, did not change a thing, but was old and needed to be replaced anyways. Next I checked the plug wires. One of them was laying on my headers, it was burnt, changed them, it was a little better but still had problems. To keep it short, due to a surplus of cash at the time, I bought a new carb, help a lot but still had issues. Got pissed and decided to throw parts at it. I ended up changing the vacuum lines, fuel pump, and plugs. The plugs I pulled out were not that bad, but were put in before an HEI was installed. They were gaped at .35 so with the new ones I changed it to .45, also, the plugs for number 5 and 7 cylinders were very loose, I could turn them by hand. Anyways, after all this the truck was running tits. I would suggest changing your vacuum lines, if you got a TH350, that one too. Change your plugs and wires. Rebuild or buy a new carb(if needed). And a fuel pump. Of course you will do all this after checking your timing. O yeah, change your fuel filter(s). __________________ 72 C-10 Stepper 350/TH350 3.73 in the back Edelbrock intake and Carb Hooker Comp Headers 275/60R15 on Rallies

01-25-2010, 12:49 PM	#5
suprachrgd82 Farmtruck desciple Join Date: May 2009 Location: 90605 Posts: 158	Re: looking for help with fuel Newer fuels have increasingly higher ethanol content. Ethanol is has a tendency to degrade rubber fuel lines, allowing the fuel line particles to accumulate in "bottle necks" and fuel filters. It is quite possible that this a contributor to the condition.



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