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#1 |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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truck fires but wont idle
The trucks been sitting awhile for close to a year, truck will crank over but wont idle and Im stumped. Heres the setup 1970 C10 sbc( not stock) with an electric external fuel pump mounted on the frame, coming from an in cab tank, to a 600 Edelbrock carb. No fuel pressure regulator. When I turn the ignition the fuel pump starts humming and shows 6.5 psi on the gauge in the fuel line, then I crank it fires right up but you have to keep your foot tapping the pedal to keep it running. I noticed the fuel filter by the carb does not fill up. As I mentioned the truck has sat for awhile but I since then have replaced the carb with a brand new one, and drained out all the old fuel from the entire fuel system. I even blew the metal line and fuel pump with compressed air. I feel like Im missing something, but dont know what else to look for. This is my current fuel system. Any imput?
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#2 |
Registered User
Join Date: Mar 2018
Location: Texas
Posts: 51
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Re: truck fires but wont idle
The the fuel line off the carb and see how much it flows. You should rewire that pump. solder the connection or at least get the butt splices with the heat shrink. If your 12+ wire is smaller than the lead coming out of the pump it should be replaced with at least the same gauge.
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#3 |
Registered User
Join Date: Jan 2018
Location: TN
Posts: 104
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Re: truck fires but wont idle
Idle jets are probably gummed up.
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1969 C10 Suburban Custom (Factory 396/TH400, survivor with no rust) |
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#4 |
Registered User
![]() Join Date: Oct 2011
Location: Victoria, B.C
Posts: 3,794
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Re: truck fires but wont idle
So hang on a second.....
The fuel filter that does not fill up....is not by the carb based on the pics, its down in front of the block right? Now, the pressure gauge which Is by the carb ends up showing 6.5 psi right? Try disconnecting the fuel line from the upper gauge (near the carb) and run this into a bucket or gas can and see if the pump starts to fill it up and how consistent the flow is. I would start with that.....simply troubleshooting. My two bits. Coley
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....for some men, there is experience, skill and effort....for the others...there is visa and UPS LOL 1966 Chevy 1/2 ton (Florida- Red/white) 1972 Chevy 1/2 ton (California- Blue/white) 2005 Chevy Silverado HD2500/Duramax 2000 Dodge Ram 1500 |
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#5 | |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
Quote:
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#6 |
Registered User
Join Date: May 2013
Location: Post Falls, ID
Posts: 889
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Re: truck fires but wont idle
Check for vacuum leaks?
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#7 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: truck fires but wont idle
Too much fuel pressure. Very common prob on edelbrock and brought up here last month.
Get pressure regulator and reduce to 5 psi. I'd bet that fixes it. Mark
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#8 |
Senior Member
![]() Join Date: Dec 2006
Location: Studio City, Calif.
Posts: 2,873
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Re: truck fires but wont idle
I'll tell you one thing. If you ever have that v-belt break, there is a good chance that that little plastic see-through filter will be shattered and you will have a major problem. I once bought a car with this set-up and about a month later the belt snapped and broke the filter and my car became a freeway fireball. If they had YouTube back then I'm sure I would have been a star. -BA
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'69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme. |
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#9 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: truck fires but wont idle
Read this thread. Same prob you have
Many didn't believe that it was a fuel pressure problem but that's exactly what it was 6.5 is too much pressure even though edelbrock specs say 6.5 is max. http://67-72chevytrucks.com/vboard/s...d.php?t=759963
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My build page http://67-72chevytrucks.com/vboard/s...d.php?t=764662 My cabinet building site http://www.cbcabinets.com Last edited by rockyrivermark; 04-18-2018 at 08:47 PM. |
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#10 |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
Ok update I relocated the fuel filter out of harms way added a fuel pressure regulator and for some reason it does not change the pressure shown on the gauge. The gauge is steady at 6.5psi even adjusting the allen screw up or down while the fuel pump is on priming. I can't get the motor to stay on to adjust the regulator at idle. Also as I try and keep the motor running it will die and spit fuel out of the top of the carb. WTF!
Last edited by VOoDoO70; 04-20-2018 at 03:16 PM. |
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#11 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: truck fires but wont idle
Definitely have to get the pressure down
When at idle do you see gas flooding in the carb?
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#12 |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
I took the carb apart checked the floats they are good, cleaned the screens behind the needle and seats everything is good. The carb was actually clean since its brand new. No flooding in the carb just cant get it to run on its own.
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#13 | |
Registered User
Join Date: Mar 2018
Location: Kuna, Idaho
Posts: 117
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Re: truck fires but wont idle
Quote:
If you rev the motor up off idle and hold throttle position will it stay running at sat 1800 rpm?
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Forgive my typos, big fingers and little Android digital keyboard....what a mess ![]() 06 GMC Sierra crew cab Z71 DD leveling kit, 34's, bumper, LED lighting. Still doing stuff to it. 67 El Camino Custom 300 Deluxe. In progress. 55 GMC 371 2 1/2 ton. Upcoming project. |
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#14 |
Registered User
Join Date: Oct 2017
Location: Manitoba, Canada
Posts: 141
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Re: truck fires but wont idle
This is old school... so check the following:
1) Choke not closing properly. Adjust choke if necessary. 2) Big vacuum leak on engine somewhere. Use vacuum gauge to check. Fix the leak. You may have put the base gasket on wrong or it is the wrong one for this carb & engine combination. 3) Choke pull off setting incorrect. Adjust to factory specs. Carb can get bumped in shipping or transportation and can accidentally change the setting. 4) Fast idle RPM set too slow. Adjust to recommended RPM. 5)Low fuel delivery. Correct delivery to carb. Usually it is a plugged up filter. 6) Electrical or compression problems on the engine. Do complete tune up & diagnosis to correct the problem. 7) Float level set very low. Check & adjust the float level to factory specs. 8) No voltage/ground to the idle solenoid (if equipped). Check for power & ground. Repair the problem as required. 9) Defective idle solenoid. Replace/repair problem as required.
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#15 |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
If I start the engine and throttle the pedal to hold the rpms it will stay running. Once I let off the pedal it dies. Aberdare, Im not sure what steps 3 4 8 and 9 actually mean as far as checking them on my setup to see if they are properly set.
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#16 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: truck fires but wont idle
Get that fuel pressure down first.
Can't stress enough how edelbrock carbs are funny about fuel pressure.
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#17 | |
Registered User
Join Date: Mar 2018
Location: Kuna, Idaho
Posts: 117
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Re: truck fires but wont idle
Quote:
Dan
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Forgive my typos, big fingers and little Android digital keyboard....what a mess ![]() 06 GMC Sierra crew cab Z71 DD leveling kit, 34's, bumper, LED lighting. Still doing stuff to it. 67 El Camino Custom 300 Deluxe. In progress. 55 GMC 371 2 1/2 ton. Upcoming project. |
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#18 | |
Registered User
Join Date: Oct 2017
Location: Manitoba, Canada
Posts: 141
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Re: truck fires but wont idle
Quote:
From personal experience I would say that #2 is your most likely culprit.
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**RED SEAL CERTIFIED JOURNEYMAN SINCE 1993** My 1966 GMC Value Van Project 1951 GMC 9430 1-Ton I'm just going to put an OUT-OF-ORDER sign on my forehead... and call it a day. |
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#19 |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
I went out and bought another fuel pressure regulator as the one I installed previously had no effect on the fuel pressure, Im installing it as we speak. So going down the checklist I starting messing with the choke and discovered if I close the choke and clamp it down the truck will idle! Sounds right too. Once I hit the throttle it will die. Do I need to adust my fast idle screw? The cam and screw are currently not touching unless I manually close the choke by hand. I never have the choke closed but once I did so it actually stayed on. Ive never messed with the fast idle screw how is it supposed to be set?
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#20 | |
Registered User
Join Date: Oct 2017
Location: Manitoba, Canada
Posts: 141
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Re: truck fires but wont idle
Quote:
... with the choke is closed, the engine idles... what does this tell us? I know what it tells me. -- less air -- same amount of fuel... therefore; idle mixture is incorrect... but WHY is the idle mixture incorrect? Wrong setting? Idle speed? Fast idle? Vac Leak? Mhmmm... sounds to me like a vacuum leak is your culprit - Item #2.
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**RED SEAL CERTIFIED JOURNEYMAN SINCE 1993** My 1966 GMC Value Van Project 1951 GMC 9430 1-Ton I'm just going to put an OUT-OF-ORDER sign on my forehead... and call it a day. |
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#21 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: truck fires but wont idle
I've been away, just got back, haven't read thread through, but saw the title and first thread. I'm sure there have been many helpful suggestions but let's get our terminology straight for now and all future issues. If people want good help and get straight to the issue, I suggest knowing the difference between cranking over, firing, and running.
From what little I have read here I see your truck cranks over, fires, and starts, but the issue in not idling. *Cranking over means battery and engine will turn engine. No spark and/or no fuel * Firing means you at least get some spark and some fuel. No start * Starting means just that. It's running. If it doesn't, look back to other two * Idling means sit there and run w/o giving gas Just trying to help people help themselves with giving correct information to start things in the right direction and get straight to the issue.
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#22 | |
Registered User
![]() Join Date: Jan 2011
Location: Chattanooga TN
Posts: 6,208
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Re: truck fires but wont idle
Quote:
If you read up more on that carb, it will also tell you you'll need a carb spacer or the heat will radiate up through the body of the carb itself and cause vapor lock (fuel is boiling in the bowls) Not only that, Edelbrock recommends their $100+ fuel pump for it. A stock mechanical fuel pump is too much for a 1406 / 1407. I can only imagine what kind of pressure the electric pump is pushing to it. I see two options for you my friend -- change to a Holley, or a fuel pressure regulator ( a good one) which negates the benefits you'll see from the electric pump.
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#23 |
Registered User
Join Date: Apr 2011
Location: Fairview Park, Ohio
Posts: 1,031
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Re: truck fires but wont idle
Yep. I put a 1/2" spacer. Cheap. $25. Funny thing I have phenolic at my shop, could have made us easily. Works well.
I have a stock mechanical pump but gauge reads 5 psi so good. Get the pressure down and report back of that helps. Mark
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#24 | |
Registered User
Join Date: Mar 2018
Location: TEXAS
Posts: 25
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Re: truck fires but wont idle
Quote:
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