AMC 360 Trouble Starting After Sitting

[AeroMoto]

Has an Edelbrock 8867 Carb on it.

...and by after sitting, I mean as little as a day. It'll crank and crank all day, but won't turn over. My "magic" trick is to use a little Vitamin E, starting fluid. Spray that in there and it'll start right up. I'm able to start it after several hours, haven't exactly tested the time.

So I'm thinking it's a gas problem. It's got a DUI ignition less than 6 months old. The accelerator pump is working when I twist the throttle at the carb. So that tells me either that there's gas in the bowl or there's gas in the fuel line (not sure where the accelerator pump gets the gas from).

I'm a newbie on Jeep carbs, but I've messed with motorcycle cars. So where should I start? TIA

 

[dabbrowne]

Hello Aero

I had the same problem. Installed a see through gas filter between pump and carb. Then you can see what is going on. I also had to replace the hose between the pump and the carb(small leak) and this fixed the problem and I stopped the vitamin E shots.

 

[IrishCJ6]

I had the same problem, I've tried everything, new hoses, pump, filters carb rebuild, etc etc and it still does it. I use to use starter fluid but its a pain in the arse and is very tough of valve train. So I've rigged up an electric pump in parallel that I have switched through a momentary switch on the dash, I can now prime the engine (5sec burst) and then start first time every time without hassle. It will double as an emergency backup if the mechanical pump ever packed up on trail. I decided to go down this route instead of ditching the mechanical pump solely for the electric to remove some of the known electrical pump faults (over pumping, too much pressure, faliures etc). To stop back-feeding I do use a couple of one way valves.

 

[ThisGuyUKnow]

So when you put starting fluid directly into the intake it doesn't start? When you say it doesn't turn over I assume you mean that it isn't combustion in the cylinder, not turning over would imply to me that the engine isn't spinning at all ie bad starter.

If you are not getting at least a rumble when you put starting fluid in the intake my first suspicion would be timing.

 

[AeroMoto]

I meant that it won't start. It turns over just fine. I can crank all day, great starter and battery. When I spray starting fluid into the carb it starts just fine...I'm just tired of carrying a can with me and taking the air cleaner off just to start it. I can pump the gas several times and see the accelerator pump squirt fuel in there, but it still won't start without Vitamin E.

 

[Old Dog]

Is your choke working?

 

[IrishCJ6]

I put mine down to either a pin hole in the fuel bowl on the carb allowing soakaway over extended periods or fuel vaporization from heat soak.

 

[AeroMoto]

I'm not sure if the choke is working or not. I would lean to it not working. I can pull the knob out and the baffle moves but it doesnt move back when I push the knob back in. I'm curious as to what affect the choke has on this problem.

 

[IrishCJ6]

I have a manual choke on mine too, to be honest I don't even use it and it gets dam cold here too. I find normally 4 pumps on the gas (once primed) and then she fires up, it might stall on the first tick over but then seems to catch itself and idles perfectly and I don't use the fast choke setting either as I found as soon as I went to restart it after it dying the first time cancelled the choke setting anyway. I too thought it could be the choke but to me it makes no difference.

 

[Torxhead]

If it starts with a shot of starting fluid( I like the Vitamin E shot comment), It usually means a gas issue. Starting with a complete fuel line inspection and making sure there is enough fuel pressure from the pump. A clog in the fuel filter will be an issue, Those see thru type units are a great visual indicator but only keep out the larger items and can leak easily. The fuel pick up sock in the gas tank is another culprit. Warm fuel in the carb can easily evaporate out thru excessive venting.

 

[Old Dog]

I'm curious as to what affect the choke has on this problem.

You made it sound as if it wouldn't start when cold but would if it only sat a little while, as in still warm

I have a manual choke on mine too, to be honest I don't even use it and it gets dam cold here too. I find normally 4 pumps on the gas (once primed) and then she fires up, it might stall on the first tick

You never said how many times you pump it but with the choke working it should be once, without the choke working try what Irish said.

 

[AeroMoto]

I've pumped it 3-5 times and it won't start. Which is weird because I can see the gas spraying down into the intake from the accelerator pump. I don't think the fuel is evaporating from heat because I haven't started it in several weeks and it just cranks and cranks. So the gas is probably escaping the carb, but I'm not sure how. Is there some kind of check valve in the fuel pump/line to prevent this?

I've also got what looks to be an inline filter of some sort after the fuel pump (engine-driven fuel pump). It's not see thru and I haven't taken it off yet. I'll try to take that off tonight and see if it's clogged. I can't help but think that the fuel pump isn't putting out enough gas until the engine is actually started, hence the need for starting fluid.

Thanks for all the help so far.

 

[ThisGuyUKnow]

The gas could be evaporating from the bowl when it's sitting but then I don't think you'd be getting a spray when you work the throttle.

When you pump the gas and see it spray out the carb or put starting fluid/gas directly in the throttle, are you getting ignition the cylinders? Or is it doing nothing?

 

[AeroMoto]

I'm getting her to fire up and run after I spray starting fluid, but not after just using the accelerator pump. I have to keep giving it a little gas to keep from stumbling and dying for up to a minute when it's super cold out (single digits and below), but after at most a minute it idles just fine. I agree that I shouldn't be getting a spray from the accelerator pump if the gas has evaporated from the bowl. Which is why I was asking where the accelerator pump gets its gas from. If it's straight from the fuel line then I could see it squirting. But if it gets the gas from the bowl, then how is it not starting?

I've dealt with motorcycle carbs, but nothing really with a fuel pump. So I'm stumped here.

 

[rufus1138]

im subscribing to watch the fix on this, ive gotta replace my fuel filter i know and the line needs a standoff bracket made but other than this im in the same position as you, sits overnight then hard to start.

 

[Torxhead]

The fuel in the accelerator pump usually fills from the bottom of the float bowl. If you think that the fuel pump could be an issue, a fuel pressure check with a gauge can be done.

 

[AeroMoto]

Is that gauge something that I can rent from the auto parts store perhaps? Do you just hook it inline?

I just found that it has a Napa Gold 3033 inline fuel filter between the pump and carb. Not sure if that has anything to do with it but I'll probably pick up a new one for piece of mind

 

[Torxhead]

Check fuel pressure gauges online, it should be installed at a location between the fuel filter and the carb inlet. Look for about 4 psi, this will just let you know if you have the correct pressure going into the carb. On my rig, I have a brass tee installed for installing a gauge for checking fuel pressure.

 

[hdgapeach]

I imagine it is a fuel supply problem. I say that because I have my father's old '68 Chevy C10 with the same issue. I initially believed it to be caused by the fuel pump but now think it's a combination of problems with the whole fuel system.

I replaced the fuel pump and continue to experience the same problem. What I have determined: After sitting for a few days without running, the truck will not start until what seems like forever cranking the starter and pumping the throttle pedal. Once I manage to get it started, it'll re-start problem free so long as I don't let it sit for a couple of days. If it sits for any great length of time it repeats the problem.

Being the '68 has a behind the seat fuel tank with the filler neck right behind the outside door handle, I tried taking the cap off of the filler neck and pressurizing the tank by sealing my mouth over the spout and blowing into the half filled tank. Held pressure till I was nearly blue, then released the pressure and put the cap back on. Hopped in the cab, turned the key and it started almost instantly. I know it's a pretty stupid method of bypassing the actual problem, but it suffices until I can get done with a couple of other vehicles to allow me the space in the shop to further diagnose and repair the cause.

I installed a clear inline filter and noticed hardly any fuel in it after a couple of days. After pressurizing the tank, the filter is half full which is all it will fill due to the horizontal position of the filter. I'm thinking the problem is due to fuel draining back toward the tank, maybe similar to a siphon effect. I intend to replace all the rubber fuel lines and rebuild the dirty Edlebrock 1405 carburetor. I'll bet I also have an evaporation problem with the carb. A new vented gas cap is also on the list. I've already removed the tank and cleaned it a couple of years ago.

I don't know if any of this is relevant to your condition but I'll post my success or failure if I get done with mine before you get yours figured out. Maybe it'll help if it's a success.

 

[mtnwhlr]

I imagine it is a fuel supply problem. I say that because I have my father's old '68 Chevy C10 with the same issue. I initially believed it to be caused by the fuel pump but now think it's a combination of problems with the whole fuel system.

I replaced the fuel pump and continue to experience the same problem. What I have determined: After sitting for a few days without running, the truck will not start until what seems like forever cranking the starter and pumping the throttle pedal. Once I manage to get it started, it'll re-start problem free so long as I don't let it sit for a couple of days. If it sits for any great length of time it repeats the problem.

Being the '68 has a behind the seat fuel tank with the filler neck right behind the outside door handle, I tried taking the cap off of the filler neck and pressurizing the tank by sealing my mouth over the spout and blowing into the half filled tank. Held pressure till I was nearly blue, then released the pressure and put the cap back on. Hopped in the cab, turned the key and it started almost instantly. I know it's a pretty stupid method of bypassing the actual problem, but it suffices until I can get done with a couple of other vehicles to allow me the space in the shop to further diagnose and repair the cause.

I installed a clear inline filter and noticed hardly any fuel in it after a couple of days. After pressurizing the tank, the filter is half full which is all it will fill due to the horizontal position of the filter. I'm thinking the problem is due to fuel draining back toward the tank, maybe similar to a siphon effect. I intend to replace all the rubber fuel lines and rebuild the dirty Edlebrock 1405 carburetor. I'll bet I also have an evaporation problem with the carb. A new vented gas cap is also on the list. I've already removed the tank and cleaned it a couple of years ago.

I don't know if any of this is relevant to your condition but I'll post my success or failure if I get done with mine before you get yours figured out. Maybe it'll help if it's a success.

If it has a quadrajet carb like most Chevys did they had a problem with plugs in the bottem of the bowls that leak so when it sets for a little while the gas leaks out leaving the carb dry so to fix this when you do a rebuild you have to epoxy them underneath the bowls to fix it. I don't know if the Edelbrock carbs have the same design.