help! 72 302 wont idle more than 10 seconds

[TheRktmn]

I've seen people install an inline fuel filter backwards. It would allow fuel through slowly so the carb would get gas when off, then use it up faster than it could flow when running. Your filter should have an arrow designating direction of flow to carb on it.

 

[JimNiki]

I'd also check the balancer as a priority... It's not unusual for an old one to have the rubber damper perish causing your timing marks to be out.

Check all the basics like you're installing a new engine for the first time..

 

[rutkak]

Concur with Rocketman Bob on the filter direction. I'd then check your float levels.

I'd seriously drop that timing down though - even without the car running it back her down a bit. You mentioned your vac advanced with capped so 30 is your timing without vac advance - that's crazy talk. I'd also recheck your firing order on your plugs - 15426378.

Just throwing this out there, probably not the case, but what kind of fuel pressure does that Holley need? I'm assuming it's low (<6 psi) and your fuel pump "should" put out at least that. If you don't have a vac gauge, get one. You can use it to tune your carb and check your fuel pressure. Your probably fine, but it can't hurt checking if you already own one.

 

[mcampbell26915]

alright so I cant believe I did this but I had the fuel filter on backwards when I installed a new one, just flipped it around and it works better but it still doesn't stay running. I can start it and it runs well and I can even have the choke open a little bit without it dying. when I start it, it goes and then after a few seconds starts to die if i have the choke like a little tiny bit open, and when i close the choke all the way the rpms kick back up and it stays alive, for another few seconds then it eventually just dies. not sure why, both air mixture screws at 1.5 turns out, idk about idle. any ideas?

 

[TheRktmn]

It does sound like a severe vacuum leak.

What are you using for a gasket between the carb and intake? I have never had good luck with the thin paper ones and always use the thicker ones.

I would disconnect every vacuum line; brake booster, AT, PCV valve, AC etc. and plug all the ports. If the problem goes away reconnect one at a time...

 

[Wasagachris]

You definately have a run lean condition caused either by a massive vacuum leak or a fuel supply issue. You need to start at the beginning and check everything in the supply side of things first.

Did you follow the wisdom of 72Hcode and check for fuel supply to the carb?

"one way to test the fuel getting to the carb is disconnect the hose to the carb and install a long hose and put it in a bucket, then disconnect the coil and crank the engine over with the starter.

there should be a good amount of fuel going into the bucket. that would tell you the pump and lines are working and not clogged."

If you have a good supply of fuel to the carb the follow his suggestions on the carb.

If not hook up the input line at the fuel pump to a plastic gas can and try to run the car using a supply of fuel from the can. If it runs well off the can you have a problem with the lines or in the tank itself.

How old is the fuel in the tank? How full is the tank?

 

[rutkak]

It does sound like a severe vacuum leak.

What are you using for a gasket between the carb and intake? I have never had good luck with the thin paper ones and always use the thicker ones.

I would disconnect every vacuum line; brake booster, AT, PCV valve, AC etc. and plug all the ports. If the problem goes away reconnect one at a time...

Take pictures of your setup. Include multiple angles on the engine. Heed Rocketman Bob's note.

 

[72HCODE]

ok try this,, real quick..

go to the back of the car, remove the fuel cap,

start engine....

if it runs right, your tank is forming a vacuum because the fuel vapor system is clogged up.

if there is no improvement then you should still see how much fuel the pump is generating out with a manual cranking of the starter.

and hunt for a vacuum leak to rule it out.

the engine is starving for fuel, the question is still why and you need to keep ruling things out.

try the cap removal.

 

[mcampbell26915]

Alright so I tried the gas cap thing and it didn't work, it has gas, at least a gallon for sure. The gas is maybe a month old high octane ( the more exorcise type ) so I think the gas is good. I tried the fuel pressure check thing, I put a peoce of hose at the end of the fuel line and routed it into a plastic bag and then cranked it over. Not much came out , I don't think , I took a picture of what came out. The picture is what came out after 2 cranks each about 4 seconds long. Im not sure if that's the right amount or not, you guys tell me haha. Also the gas looks more yellow than it's supposed too... Idk what that is about but whatever. Also , does the AC draw vacuum? Because I just took out the AC but I couldn't get any of the cables or tubes or whatever out, so they are just sitting there not going to anything. I taped off the end of the AC cables with electric tape just in case. I used the thin paper gasket for the carb to manifold, and I used a thicker one for the carb to spacer. I'm not sure what you guys mean by " cranking it with the starter" ... Does that just mean start it with the key ? Thank you guys. I will add a couple more pictures to this to show you guys my set up


I'm not sure if I'm uploading these pictures right , let me know if they are showing up because I am new to this, here is a video of me trying to start it, hopefully this works. This video is me starting it, and then trying to keep it alive with starter fluid. This isn't a very good example, usually I can keep it alive as long as I spray starter fluid in it , but you can see that it idles good and then just dies randomly, also you can see the choke is almost all the way closed and still runs. Hope this helps, thank you guys

 

[72HCODE]

cranking the engine with the starter either means using the key and cranking the engine that way or using a remote starter.

you crank the engine for 10-30 seconds with the coil disconnected. 2 cranks 4 seconds long isn't long enough to determine anything other then the pump is pumping fuel.

problem can still be, fuel, vacuum, or electrical.

try getting the engine to run as long as possible with the choke closed, disconnect the electric choke if you have one.

then cover the top of the carb with your hands and see if that kills the motor if it keeps running vaccuum leak from somewhere.

when you disconnected all the vacuum lines did you check the rear vacuum tree on the intake manifold to make sure those are capped off.

try disconnecting the vaccum booster if you have one and cap the line off the manifold as well.

if you have a PCV is it functioning correctly, you can cap that off as a possible vacuum leak source.

the idea is cap all vacuum accessories off the intake manifold for testing.

you may have a massive leak through the manifold base.

 

[mcampbell26915]

alright ill disconnect the coil and try again, and ill also cover up the choke and try. im not exactly sure what all has vacuum, i think i know what the vacuum tree it, but it has 3 separate tubes going to it and none of them are cracked, im not sure what the vac booster is, and im not sure what line you are refering to off the manifold. is there some sort of diagram to show me what all has vacuum? im sorry im still new to this stuff, thank you. also did the pictures get uploaded? i cant tell

 

[rutkak]

alright ill disconnect the coil and try again, and ill also cover up the choke and try. im not exactly sure what all has vacuum, i think i know what the vacuum tree it, but it has 3 separate tubes going to it and none of them are cracked, im not sure what the vac booster is, and im not sure what line you are refering to off the manifold. is there some sort of diagram to show me what all has vacuum? im sorry im still new to this stuff, thank you. also did the pictures get uploaded? i cant tell

The video didn't post but just take several pictures and upload them. Obviously fuel is the main issue since it runs with starter fluid but I'm confident there is some type of vac issue. I think you mentioned that you pulled the manifold, you should have used RTV sealant on the front and back of the intake manifold or at worst the crappy little cork gaskets. If not, you have a massive air leak in there.

 

[mcampbell26915]

hmm... did the pictures upload? i know the video didn't but i cant tell if the pictures went up either. if not, then i am not sure how to do it.

i used RTV sealant, however i re used the same gasket. when i took it out the first time, i scraped everything off with razor, putty knife, carb cleaner, the works. once i got it all clean i put the rtv on all the correct spots and laid brand new gaskets down and put everything back together. when i fired it up, it ran great except there was a huuuuuuge oil leak ( oil squirting out so fast it reached 1 foot away from the car) because i didnt put the right amount of sealant on the front and back of the valley, where the crappy cork ones would go if i had put them there. so i had to take everything apart again. so i took everything apart, re-scraped everything clean, and then re aplied the RTV only this time using the correct amount of sealant. however, i re used the same gasket that i used last time. it still looked relatively new, because it was only in the car for about a day. however i have been told ex-post-facto that i should never re-use gaskets, i just thought i would because they were really expensive and i didn't want to buy more. oil stopped leaking by the way, but now it could have a vacuum leak. but I am not sure why the vacuum leak would be causeing the much of a problem now, because it was running the other day, after the intake manifold swap. so im just confused as to what changed from a week or 2 ago to now, a week ago it was idleing ok, and just needed to be adjusted to be able to be driven, but now it wont even idle. the only thing i changed since then was the alternator, because it was a bad alternator and needed to be fixed because i couldnt troubleshoot my car because the battery kept dying before i could test anything. hopefully this information helps. thank you very much.

 

[rutkak]

I wouldn't reuse the gaskets but they shouldn't be causing THAT much of a problem. Check one of my earlier posts about what should have line running to it to check. I wouldn't be checking without at least 5 gallons of gas. As far as the yellow colored gas, you probably have some rust in the fuel tank. I'd make a few trips to give her at least 5 gallons before going through anything else.

No pictures uploaded. Make sure you click to "Insert in post"

 

[Don C]

The vacuum booster is the large diameter can the brake master cylinder attaches to, provides the power brakes, and has the large hose running from the vacuum tree at the back of the manifold. It would probably take a vacuum leak that big to make it stall.

The wrong carb spacer, say one for an EGR and you don't have an EGR valve, will cause a huge leak. The PCV line and valve is also a potential source for a large leak, if not properly connected.

The other vacuum lines run to the vacuum advance on the distributor, the vacuum modulator for an automatic transmission, and to a vacuum reservoir if you have an air conditioner. I don't believe any of these are large enough to cause a leak big enough to kill the engine that fast.

 

[JimNiki]

If you want to be a real bush mechanic, just get someone to hold a piece of carboard so the air from the motor's fan won't interfere and just light a smoke and move it around slowly around the manifold... You'll soon see the smoke being sucked in if you have a leak...

Do the whole manifold and then also do all the other fittings connected to the manifold if you don't want to unplug stuff...

 

[mcampbell26915]

Hi everyone , I took several videos and I have been trying to upload them and I cant seem to figure it out, when I try to post them it says that the attachment isn't allowed... im not sure why. anyway, if someone could help me figure out how to post the videos that would be good because I took videos of me trying to start it and a walkthrough of my engine and everything so that everyone could see what I was working with and hear what it sounds like.

anyway, I tried the idea of masking off the top of the carb with duct tape to keep any air from going inside of it at all, and it didn't run, or even start. so I need to have at least a small amount of air going through the choke in order for it to start, which means vacuum leak is less of a suspect. once I took the duct tape off and opened the choke about a 1/10 inch then it fired up and ran for about 40 seconds, then eventually died randomly. to keep it alive for those 40 seconds, I had to mess around with the choke. when it was loosing RPM I closed the choke more and it picked back up, and eventually after about 40 seconds of that it died. I checked some of the vacuum lines, the big drum looking think that the master cylinder attatches too ( I think it might be called the vacuum booster or some thing) and the line was good. the grommet that connects that tube to the drum think was cracked, but it was still air tight I believe, because when I removed the hose to check if it made a difference, it didn't run for more then 2 seconds. so that tells me that that hose is ok, and there are 2 more hoses other than that one , on the vacuum tree. both of those hoses I looked at and there are no cracks in them either, and there is a 3rd nozzle on the vacuum tree that is capped off. all together on the vacuum tree there are 4 nozzles, 1 is the vacuum booster ( the big circular drum thing) and 2 others go to different things that I am not sure what the name is, and the 4th nozzle is capped off. it ran before without that one connected to anything, so I doubt that's a problem , im just telling everything I know. I checked the pcv tubes, one is good and the other pcv thing I switched out for a breather so its not a tube anymore, so that's good also. I sprayed starter fluid around base of carb while it was running and I didn't notice any dramatic change in rpm, I might have heard a small amount but it could have been just in my head. I switched around the carb spacer thinking I could have had it on backwards, so i flipped it around and put it back on and now i think it is definitely on wrong because i am unable to push the throttle cable back. so i will flip that back around, and while i am at it i will replace the gasket. how would i know if i have the wrong spacer? it fits exactly right and looks exactly right. alright let me know what you guys think, thank you so much for all your guys help!

 

[JimNiki]

Try disengaging the choke completely, maybe even fully closed, it is not allowing the carby to close properly among other things.

 

[rutkak]

I'd say not worry about the video, just post pictures. I'd sure move that timing down a good bit as well.

 

[Wasagachris]

Have you confirmed that you are getting a proper amount of fuel to the carb? That should be your first job.

You stated that you put 1 gal of fuel in the tank and that the fuel that came out of the pump into the plastic bag looked " too yellow".

Follow the recomendations that several people have posted and confirm that you are getting enough fuel to the carb.

I would try running the car off a 5 gal can connected to the fuel pump and see what happens. Then you know you have 1) enough fuel to start with and 2) clean uncontaminated fuel.

Then you can start looking for vacuum leaks and/or timing issues.