Carb Backfire: Only AFTER Warm???
Thread Starter
|
Tuned
Joined: Jan 2009
Posts: 457
Likes: 7
From: Decatur, AL
Carb Backfire: Only AFTER Warm???
Truck starts and runs great until warm. I mean it truly runs great and then, when warm...it just refuses to idle at all, and carb backfires. I am fighting an overheating problem at this time as well and think i have made some real progress there getting the radiator cleaned out etc. I cant get the truck to idle while warm to really get a good time set on it tho.
i am thinking bent pushrod, burnt valve, etc.
Going to start with compression test today. Need to do that just for reference anyway.
Any thoughts?
i am thinking bent pushrod, burnt valve, etc.
Going to start with compression test today. Need to do that just for reference anyway.
Any thoughts?
Fleet Mechanic
Joined: Feb 2007
Posts: 1,326
Likes: 48
From: Middle TN
You are running way too lean. Need to check your carb for dirt, sticking float, fuel filters and rubber lines. This is most probably why it is running hot. Need to fix this soon before engine damage.
Hotshot
Joined: Aug 2006
Posts: 10,764
Likes: 39
My truck had an Plate under the carb when I got it , It more or less had rotted (aluminum) ...while its running , spray some carb cleaner around the engine hoses , listen for the idle to increase...It will help find any leaks ...
Posting Guru
Joined: Nov 2008
Posts: 1,937
Likes: 2
From: wyoming
compression test?
Once your engine warms up you might have a valve sucking up into head. Have to pull rockerarms and measure with dial calipers once rocker arms off and piston at tdc at cylinder. Compression test will help alot on proving this troubleshooting procedure. Carb backfire is a valve staying open at intake or possible lean condition like the other guys spoke of. things to check???
Thread Starter
|
Tuned
Joined: Jan 2009
Posts: 457
Likes: 7
From: Decatur, AL
All of this followed right after an intake r&r for an oil leak. i have a 360 so i had to take the rocker assemblies off and the pushrods out too. i will check the pushrods, rockers, and the carb float too.
Thread Starter
|
Tuned
Joined: Jan 2009
Posts: 457
Likes: 7
From: Decatur, AL
ok, did all the above, rebuilt the carb again, several times, all to no avail. no fluctuation in vacuum at all. just will not idle after warm. starts like a champ cold. runs like a champ cold. but as soon as the choke goes vertical, the truck backfires thru the carb and dies. do all i can, it will not idle warm. had several professional mechanics look at it and they all say like yall, it is a lean run condition.
the assumption now is that the carb had a terminal warp/crack somewhere inside. i am now looking for a new carb to rebuild. the truck was doing so well until just now too but the lean run condition was there since i bought it 7-3-10.
the assumption now is that the carb had a terminal warp/crack somewhere inside. i am now looking for a new carb to rebuild. the truck was doing so well until just now too but the lean run condition was there since i bought it 7-3-10.
Thread
Thread Starter
Forum
Replies
Last Post
Cedarghost
1973 - 1979 F-100 & Larger F-Series Trucks
8
Mar 26, 2016 08:13 PM
brokersteve
1973 - 1979 F-100 & Larger F-Series Trucks
9
Dec 11, 2012 04:35 PM
LIF150
335 Series- 5.8/351M, 6.6/400, 351 Cleveland
26
Dec 20, 2011 12:00 PM
LIF150
1973 - 1979 F-100 & Larger F-Series Trucks
9
Sep 12, 2011 03:59 PM
