Fuel issues
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Freshman User
Joined: Nov 2020
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Fuel issues
I have an 86 with a naturally aspirated 460. It hasn’t been driven in 14 years, so I’m sure it has plenty of varnish and gunk in it. Every once in a while it’ll start and move for a while and then die. It seems to idle well most of the time, but sometimes it won’t go above idle and dies as soon as you hit the pedal. I’m trying to trace down what the issue is. I think it’s just a sticky float, but not positive. Don’t have a ton of experience with gas/carbureted engines. Anybody have some good recommendations for freeing it up without rebuilding it? It has a holly E5HD-ED on it currently.
Fleet Mechanic
Joined: Jul 2013
Posts: 1,997
Likes: 237
From: NE Ohio
Nothing I list below is going to help 14 years of varnish, it's really best to clean it all out, off the vehicle.
Anything you use including below will probably make it worst honestly.
I think what will happen is that hard varnish will get loosened up from the use of additives.
The sludgier varnish that wasn't going anywhere will get broke down into smaller globules and proceed to clog everything up that isn't yet.
There are a lot of different additives out there to help and everyone has their favorite.
Seafoam, I'll say it before anyone else does, a ton of people love that stuff. I'm not against it but...
I like to use MMO regularly. I always try and add it to at least one of my tanks.
There is something called mechanic in a bottle to help clean up gunk in fuel systems.
You can also try one of the other fuel system cleaners, techrons is pretty good stuff. Just make sure it says it is ok for carbs.
I think techron sells one for each, FI and carbs.
As I stated at the start of post, It's probably going to need cleaned on the bench though when it gets to that point. Nothing helps.
Anything you use including below will probably make it worst honestly.
I think what will happen is that hard varnish will get loosened up from the use of additives.
The sludgier varnish that wasn't going anywhere will get broke down into smaller globules and proceed to clog everything up that isn't yet.
There are a lot of different additives out there to help and everyone has their favorite.
Seafoam, I'll say it before anyone else does, a ton of people love that stuff. I'm not against it but...
I like to use MMO regularly. I always try and add it to at least one of my tanks.
There is something called mechanic in a bottle to help clean up gunk in fuel systems.
You can also try one of the other fuel system cleaners, techrons is pretty good stuff. Just make sure it says it is ok for carbs.
I think techron sells one for each, FI and carbs.
As I stated at the start of post, It's probably going to need cleaned on the bench though when it gets to that point. Nothing helps.
New User
Joined: Sep 2020
Posts: 21
Likes: 0
Nothing I list below is going to help 14 years of varnish, it's really best to clean it all out, off the vehicle.
Anything you use including below will probably make it worst honestly.
I think what will happen is that hard varnish will get loosened up from the use of additives.
The sludgier varnish that wasn't going anywhere will get broke down into smaller globules and proceed to clog everything up that isn't yet.
There are a lot of different additives out there to help and everyone has their favorite.
Seafoam, I'll say it before anyone else does, a ton of people love that stuff. I'm not against it but...
I like to use MMO regularly. I always try and add it to at least one of my tanks.
There is something called mechanic in a bottle to help clean up gunk in fuel systems.
You can also try one of the other fuel system cleaners, techrons is pretty good stuff. Just make sure it says it is ok for carbs.
I think techron sells one for each, FI and carbs.
As I stated at the start of post, It's probably going to need cleaned on the bench though when it gets to that point. Nothing helps.
Anything you use including below will probably make it worst honestly.
I think what will happen is that hard varnish will get loosened up from the use of additives.
The sludgier varnish that wasn't going anywhere will get broke down into smaller globules and proceed to clog everything up that isn't yet.
There are a lot of different additives out there to help and everyone has their favorite.
Seafoam, I'll say it before anyone else does, a ton of people love that stuff. I'm not against it but...
I like to use MMO regularly. I always try and add it to at least one of my tanks.
There is something called mechanic in a bottle to help clean up gunk in fuel systems.
You can also try one of the other fuel system cleaners, techrons is pretty good stuff. Just make sure it says it is ok for carbs.
I think techron sells one for each, FI and carbs.
As I stated at the start of post, It's probably going to need cleaned on the bench though when it gets to that point. Nothing helps.
FTE Legend
Joined: Nov 2015
Posts: 30,855
Likes: 4,105
From: Angier, NC
If the tanks have had fuel sit in them for 14 years I would **** can them and get new ones along with the senders.
Pull and rebuild the carb, run a filter before the rebuilt carb with a little cleaner and you should be good.
If you don't get the tanks clean you will just keep pushing the crap into the carb.
Dave ----
Pull and rebuild the carb, run a filter before the rebuilt carb with a little cleaner and you should be good.
If you don't get the tanks clean you will just keep pushing the crap into the carb.
Dave ----
Moderator
Joined: Jan 2001
Posts: 56,964
Likes: 2,725
From: Virginia
If you don't want to put much time in it, sea foam will help it, might even fix it. If you can get it in the system at about 50% mix. You can't use a lawnmower fuel can on your truck, I am pretty sure you have electric pumps in the tanks. But if you don't have much fuel in it and pour the whole can of sea foam in it, it might clear up. You will have to get it running and let it run for about 20-30 miinutes to let it eat the gunk out.
Tuned
Joined: Apr 2008
Posts: 331
Likes: 9
I have an 86 with a naturally aspirated 460. It hasn’t been driven in 14 years, so I’m sure it has plenty of varnish and gunk in it. Every once in a while it’ll start and move for a while and then die. It seems to idle well most of the time, but sometimes it won’t go above idle and dies as soon as you hit the pedal. I’m trying to trace down what the issue is. I think it’s just a sticky float, but not positive. Don’t have a ton of experience with gas/carbureted engines. Anybody have some good recommendations for freeing it up without rebuilding it? It has a holly E5HD-ED on it currently.
One thing to consider is try to avoid running ethanol fuel if you can help it. These old gaskets dont really like it, and plus if your truck sits for a month the ethanol will separate and and continue to rust your fuel tank. My truck sat for 15 years (4.9 L6) and after running seafoam, new inline fuel filter and a new one at the carb it runs just fine - didnt have to pull the carb or anything like that. I ended up running seafoam from the tank as well as shooting carb cleaner down the carb itself. I did end up upgrading my rear tank to a 38 gallon one, so I dont have any of the rust issues to deal with anymore and I just dont use the front tank (until I get it replaced) I've been daily driving it since then for 2 years.
New User
Joined: Sep 2020
Posts: 21
Likes: 0
I’m short on time and haven’t gotten the truck licensed yet, but I ran some seafoam in the tank and it cleared it up pretty well after letting idle for twenty minutes or so. Planning on cleaning the carb and fixing gaskets when I get around to it.
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Tuned
Joined: Apr 2008
Posts: 331
Likes: 9
you can remove the air cleaner, start the truck and shoot some carb cleaner right down the butterflies (I did anyways) and that seemed to help my situation. I replaced all the fuel filters every time I did an oil change (until I replaced the old tank with a new bigger one) and After I did all that mine has run like a champ. I never did have to remove the carb at all. So when I first started working on my truck, it did the same thing as yours. In my case the carb was starving for fuel because the lines and filters were so clogged with particles coming from rusty fuel tank.
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New User
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you can remove the air cleaner, start the truck and shoot some carb cleaner right down the butterflies (I did anyways) and that seemed to help my situation. I replaced all the fuel filters every time I did an oil change (until I replaced the old tank with a new bigger one) and After I did all that mine has run like a champ. I never did have to remove the carb at all. So when I first started working on my truck, it did the same thing as yours. In my case the carb was starving for fuel because the lines and filters were so clogged with particles coming from rusty fuel tank.
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