47-55.1 Starting issue

[Matt_50]

1950 with a 350 motor. 4 bbl carb.

Haven't ran the truck much the last couple of years. We had a baby and moved.


Just got it in the garage to finally finish a few things but it has trouble starting. Having to use starting fluid to get it started. Rev it up a few minutes and then I'm good to go. Turn off and on just fine for next hour or so. Wait a few hours and I have to use starting fluid again.

What should I do?

[mr48chev]

It sounds like the gas is bleeding out of the bowl in the carb when it sits or the fuel pump may be getting tired.

If you have a quadrajet with the long paper filter, the filters that have the check valves on the inlet end help hold gas in the carb and even fuel in the line.

My 77 C30 has to have bit of starter fluid help once in a while if it sits too long and that one neverleaves the yard unless it has an actual job to do. At 8200 lbs empty it sucks gas like crazy.

I'd very honestly change any and all rubber gas lines in the fuel system and use the new hose that is rated for today's gas.

[Matt_50]

I'll double check but I'm pretty sure it has a new fuel pump. 4 years ago it got all new fuel lines ran to carb. Carb is a few years old. Carb is an edelbrock 1403.

[dsraven]

if you wanna check to see if it is fuel bleeding off and siphoning the float bowls empty just try putting a line clamp on the soft rubber fuel line after you run it and turn it off.let it sit for however long it usually takes for it not to start, then try to start it. if it starts like it should then it is siphoning likely. another way to quickly check is to let it sit for the normal time it takea to not start, then take off the air filter and look down inside the throat of the carb while you pump the throttle. you should see fuel squirting out of the accelerator pump nozzles.
I have had many brand new orr rebuilt mechanical fuel pumps over the years and some will have the valves stick open or closed so no fuel is allowed to pump. theoretically the valves in the pump should not allow fuel to run back to tank but we have all seen it not be so.I have had more issues with the three line pumps than the two line ones.
I have seen some cars/trucks where guys have used an electric pump, run in parallel with the mechanical pump, so they can prime the system before attempting to start the engine. it would be on a switch so you would knowingly have to turn it on or off.

[dsraven]

another thing that is common is that the hot engine will boil the fuel in the carb after you shut it off and walk away. it usually makes the thing smell like gas (and also the garage), but if you park outside and don't hang around the vehicle you may not notice. a thick fibre or phenolic spacer gasket under the carb usually helps insulate the carb aginst engine heat soaking it.
try the "look down the throat while pumping the gas" trick first. it's cheap and easy. try the clamp on the fuel line trick second. it's also pretty cheap and easy. for the heat soaking thing you gotta be hanging around after a "hot shut down" to smell under the hood for that raw gasoline smell. a fuel filter with the check valve is a great idea and may solve a siphoning issue. it's pretty easy to see if it is a siphoning or run back issue though

[Matt_50]

This is the most the truck has ran in forever. Each time I start it, it seems to do better and I can wait longer without an issue. Carb is just dirty?

This morning, first start up. Bowl was empty. Playing with throttle and no spray. Didn't want to start.

Started to loosen clamp on fuel line, started to drop immediately. Dripped from line and carb once I pulled it off. A little trickle for a sec from the line and I put it in top of carb. I figured there is no a tad bit of gas in the carb so let's try to start it. Started right up and I let it run a few minutes.

Turned it off. Clamped the line. Left for 45 min to an hour. Unclamped it and it started right up. Again ran it for a few minutes.

Left it again for about an hour. Without clamping the line. (Before it would empty in less than 30 min). Started right up.

In the next few hours I started it a time or two and let it run.



Seems to do better each time. Inside of carb looks dirty so I ordered a rebuild kit.

[dsraven]

you possibly have/had some leaky valves in the fuel pump which bled pressure back to tank and also allowed a siphon to start with that once the ball got rolling. with use maybe the valves are starting to loosen up and hold their pressure better.
if it were me i would yank the pump outlet line off at the carb and do a volume test to see if it is putting out what it should, then do a test to see what pressure it puts out, then see if it wil hold the pressure in the line when the pump is not working.
do you have a 2 line or a 3 line pump? got a pic?

[Matt_50]

2 lines off the pump. Haven't checked pressure after it has sat for a while. I know gas leaked out when removing the line, had some built up pressure.

[leegreen]

The empty float bowl seems definitive that this is a fuel supply problem.
The times it was hard to start, how did it shut down prior to that, did you turn it off or did it stall? In other words the float bowl would be empty if it had starved for fuel on the last run.

Tank, vent, lines, pump, filter, bad gas gumming something up, carb leaking.
Pump is the only thing with moving parts to go bad, and they are pretty cheap.
Each start being easier sounds like the system is washing itself out or a seal is swelling back up after drying out.

I suggest the carb rebuild / clean you already plan. Pull all the filters and either back flush to see what comes out or change them. Siphon some fuel from tank side of filter into a jar and see what it looks like. Check flow from pump.

[dsraven]

I'm with LG on his recomendations. see what you have coming to the fuel pump from the tank. is the tank in the cab or has it been upgraded to be outside the cab? if you get bad fuel (rusty, sludgy or poor flow) from the tank then obviously you gotta deal with that and then follow the line all the way to the pump, checking for anything that could cause a flow problem but also for the integrity of the parts. change out as required along with a new inline fuel filter somewhere before the pump. if it had one, replace it and cut the old one apart to see what it's been catching
check the fuel pump weep hole for any nice clean spots as those are where it has been leaking fuel. they only leak for a short time and then they start to spray down the side of the engine block with gas. sometimes that can cause a car fire thats pretty hard to put out without a good selection of extinguishers
check the carb for puddles of fuel under it or wet spopts around it after a hot shut down. leaking internally usually means fuel can dribble out into the carb throat and collect on top of the throttle plates which means it usually runs out the throttle shafts as well as down into the intake manifold. a leaky inlet valve in the bowls can also bleed off the fuel line pressure and cause the bowls to oveflow into the carb throat. anyway, a rebuild wouldn't hurt anything. also check all the parts when you take it apart to ensure it worth rebuilding. throttle shafts wear in the carb body and will only cause you grief when it comes time for set up. if you don't have a phenolic gasket under the carb that would be the time to install one to help keep the carb from getting too hot and boiling the fuel inside.

[dsraven]

one day when you have nothing else to do and wanna play with the truck you could look at shortening the lower rad hose so it doesn't rub on the fuel line as well.
as a mechanic I look for faults, sorry man, part of the training thats enbedded in the grey matter.

[Matt_50]

I'll check those things. Thank you.

Tank is in the back. Mustang tank. When I pulled off the line before the gas was clear.

I have a filter after the pump and before the carb. Should I move it or keep it where its at?


Thank you for the radiator hose suggestion. I didn't think of that at all. I had a hard time getting a hose to work there I think. Would it be just as easy to use a different fuel line? I saw some flexible stuff at the auto parts store the other day.

[dsraven]

probably easier to shorten the rad end of that hose, without seeing it that makes it harder to know.
stay with the steel line if you can, just my opinion.
keep the fuel filters, if they flow like they should then they shouldn't create a problem. one good filter before the pump somewhere is good enough and doesn't spill fuel on the engine if it leaks or when you change it though. go for a brand name filter that has a good micron rating and is the same size as the fuel lines at the pump, never smaller than that. remember rubber lines don't flow like a steel line does especially if the rubber line has a good bend in it, which tends to flatten the cross section of the line. reducing the size of the line a small bit, with a link or whatever, will have significant effect on fuel flow capability, so straight shots of line or slow bends are best with flexible line. steel line is less apt to restrict as long as the bends keep the line round and not starting to flatten out the shape of the line

[Matt_50]

That's good advice. Thank you again.

I would like to move my filter. Its just before the carb now and like you mentioned, it leaked when fuel I replaced it on the engine. I think I'll move it to the frame rail. This might be a dumb question... but does the fuel filter need to be mounted in anyway to keep it from rubbing on the frame rail?

I'm at work thinking about the radiator hose. I couldn't remember it touching. Went through my pictures and found when I installed it. Is this spacing acceptable?

Old picture. Brake and transmission lines are hooked up now.

[dsraven]

As long as nothing is rubbing anywhere then it's good.
If doing some new filters think about how the manufacturers placed them. Close to inlet of fuel pump works well if you have the room because you're likely under that end to change oil anyway so you have a drain pan and that end is up on stands. It also filters anything in the lines right at the pump instead of at the rear. Not that there should be much in the lines unless they are old and rusty.
If eliminating the filter near the carb maybe look at getting a new replacement steel line that's already bent and has the correct fittings installed. Unless the aftermarket carb has a different configuration.

[Matt_50]

Well now I'm on a new kick. I want a nicer cleaner look. A hard line or maybe braided all the way from pump to carb would look a lot better.

I'm seeing a lot of different options. Aluminum, steel, copper nickel... 3/8 line. And little kits that have a banjo bolt and short line from carb to connect to.

Any suggestions?

[dsraven]

fuel injection hose
https://www.napaonline.com/en/p/NBHH358A
fuel injection hose clamp
https://www.napaonline.com/en/p/BK_7051227
frame clamp
https://www.grote.com/electrical-con...-steel-clamps/

for a pre pump filter you will research and come up with a recomendation to go with something in the 100 micron area pre-pump and another post pump filter of the 40 micron rating. you gotta decide whats going to be needed for your set up. there are choices here for the type of fuel you use as far as what media is inside the filter. if reg pump gas is all, no ethanol added, then a plated steel housing is fine with paper media, with ethanol (E85 gas) in the fuel you will want to look at something with a stainless housing and steel mesh filter media. ethanol eats up the paper (cellulose) filter element and will send particles of that down the line to plug up your pump and/or your carb inlet. your off the shelf inline filter is prolly gonna be about a 10-15 micron filter, with paper media and a plated steel housing, just a heads up. cheap gas these days is often made with a lower grade of gasoline and then the octane level is brought up with some sort of alcohol, which isn't compaible with some fuel system components.