The Stovebolt Site Forums The Shop Area Engine Shop Won't start. Lost fuel???

The '78 250 in my 58 Suburban has recently developed a starting problem.

It has spark and cranks quickly like it should. It just won't catch or start. It acts like it ran out of gas. In order to start it, I have to pull the lid and filter and pour a about 2 tablespoons of gas down the carb. After that, it fires right up and runs normally. There are no issues with driving. It accelerates fine and performs well. After a quick stop it will fire right back up upon restart. The problem occurs after it sits overnight or longer.

I replaced the fuel pump about 3 months ago. I had a persistent fuel smell when driving. I found that that the pump had a leak. After replacement, the smell went away. I don't have any fuel smell now, so I don't think the fuel is leaking out.

In the past I would depress the gas pedal once to set the idle cam and then it would start right up.

I'm a bit baffled. Right now it's just annoying to have to grab the gas can every time I want to start the truck. I want to make sure there isn't any safety concern. I don't want the tuck bursting into flame on me.

Sounds like your choke either needs adjustment or eplaced.

I might add that if your carb has a worn needle valve at the float arm, it could be seeping back down and the line loseing it's prime possibly. I have that happen on one of my older cars.

look for a loose fitting on the newly installed Fuel pump. it may not leak fuel however leak air into the system on shut down causing the fuel to drain back to the tank. My suggestion.

Gary/Mike/Volf;

Thanks for the tips. That raises a question. Are you suppose to put any kind of sealer (teflon tape, locktite etc.) on the fittings on the fuel pump. There wasn't any kind of o-ring that I remember and I didn't put any kind of sealer on the fittings. I tightened them down, but I remember being concerned about overtightening/breaking them off.

I was able to start the truck the last two morning without having to prime the carb with a gas can. It took repeated pumping of the gas peddle and cranking the engine. After about 30-45 seconds of pumping and on again off again cranking it sputtered to life. Does that help clarify the problem at all??

Gary;

One other question. What would be the telltale sign of the worn needle valve? I rebuilt the carb about a year ago and I'm pretty sure I put a new needle valve in. If I pull the top off the carb would the fuel bowl be empty if the valve was no good?

Just want to know what I'm looking for.

if your needle valve is worn, you would most likely have gas pouring out all over the exhaust. You would get no benefit from pumping the gas pedal if there is no fuel in the carburetor. If you don't have sufficient fuel to start after 2 or 3 pumps of the pedal there would be no reason to continue for 30 seconds. (just look down the carburetor throat while actuating the linkage and you should see a stream of fuel coming out, if not you have no fuel in the carb or the accelerator pump isn't working) The needle valve may be STICKING in the closed position, and not allowing fuel into the carb, but there should be some left from the day before, although on hot days, combined with engine heat, it could evaporate pretty quickly. You don't use thread sealer on double flare fittings, that is what the flare is for. There is also the possibility you have something stuck in the valves of the fuel pump, it only takes a piece of rust the size of the period at the end of this sentence to shut you down. Then there is the ever present possibility you got a bad pump, there was one fella recently that went through 3 out of the box pumps before he got a good one. I can't believe you still think you would actually get what you are paying an outrageous price for in this day and age. One last thing, did it start immediately after the pump change?

Good info brokenhead. I am mentioning what I did because I had this issue on a 2bbl. on one of my 83 Eagles. The seat of the needle valve was bad and would let fuel go back down to the pump and into the tank after sitting for a few days.This was because mainly the carb is generally higher than the fuel tank and fuel tended to run that way rather than into and flood the carb.But like said, there should be some fuel left in the bowl.I could see that a couple of pumps on he pedal and crank overs could use that right up before it catches up with itself and pushes more in from the pump.Like brokenhead said, check the fuel pump, pull the line and use a can or soemthing to see if it is actually pumping fuel out satisfactorily. good luck.( by needle vavle I mean the one that works off the tang on the float and lets fuel in when it drops or blocks it off when the vowl is full )

Yep, needle & seat or center carb gasket. I am having the same problem with the carb. loosing its supply of gas after a week or two. But if I start it every 3 days or so, it starts instantly.

The check valve in the fuel pump is bad. Put a new pump on.

Mine has a new fuel pump, but the carb gets wet on the outside, like its leaking out of the carb ?? I did have the carb apart for cleaning, but didn't have a new gasket for the 2 halves. I did notice the gasket was torn in a small spot. I just put it back on until I could get a kit.
Mine may be a different carb from the one posted. Its on the 58 GMC 370 6cyl. 270 engine.

I was able to start the truck this morning. It takes about 1-2 minutes of pumping and cranking the engine before it will start. When I first crank the motor over, it catches and starts for just a second and then dies. It happens every time. There is no way to keep it running. It take all the pumping and cranking to get it started again.

How about I go back out to the garage in the morning before I do anything. I'll pull the top off the carb and see what it looks like in the fuel bowl. If its empty that should tell me something. I'll check the state of the gaskets while I'm at it. Is there anyway to tell if the needle valve is functional just be looking at it??

Larry, That would be a good idea to check bowl for gas and maybe adjust float level and drop but you really, really need a rebuild kit. Possibilities include (some have been stated already) Your bowl is emptying, accel pump bad, needle valve problem, too much fuel pressure (wrong pump), clogged filter, dirt in system/tank which keeps clogging somewhere, fuel lines, (rubber or steel) are sucking air, tank vent blocked, gas cap seal... Remedy: 1. Do a standard fuel pump supply/volume test (and also observe container for dirt). 2. Rebuild carb. 3. Change fuel filters. It will then start right up. A brand new or rebuilt carb would be great if you can afford, but screwing around with trying to figure out what part(s) inside carb is bad is a big waste of time! Usually if the engine will actually start and run up and down hills and under load and so on and the fuel pump does not leak, it is NOT the fuel pump. When you "break the seal" at where the fuel line attaches to carb and it visibly squirts out, the diaphragm in pump is good. Keep us "posted".

did you check the paper fuel filter in the carb inlet?it has a checkvalve in it to prevent fuel from draining back

I'm revisiting this issue again. My problem has changed somewhat, but I'm still having a persistent carb/fuel issue.

Now that it has gotten colder, the truck actually starts up just fine. I did discover a few days ago that the electric feed to the electric choke had gone dead. I sorted that out and the choke works correctly now.

Here is my current problem. The truck starts fine and runs pretty well for a short period of time. Then it sputters like its running out of gas. The vehicle will buck wildly as it tries to run without enough fuel. With some mad pumping of the gas peddle I can usually keep it from stalling but that is about it. When/if it finally dies. I have to sit for a minute or two and then it will start back up. It will run OK for a couple of minutes and then the same issue starts again.

It actually died on me in the middle of an intersection with the wife in the truck the other day. First time I've gotten her out for a ride in forever and the stupid thing quits on a busy street. Ugghh!! Luckily a friend happened along and helped us get out of the intersection. I had the tool box in the back and decided to monkey around with the carb a bit. I took the top off. The fuel bowl was about 3/4-7/8 full. I "pumped" the float up and down a few time, pumped the accelerator pump a few times and pumped/pushed the needle valve up and down against the spring a few times. That was about the limit of my expertise. All that took about 10-15 minutes. After I put the carb back together, the truck started and ran fine for about 4-5 miles of stop and go traffic and then started sputtering again. Luckily I was able to limp it home with it dieing on my again.

I tried driving it down the hill to work on Tuesday. It's about a 1.5 mile commute from my house to my office on the plant. It made it down to work ok but starting sputtering and quitting on the way home for lunch.

Now it sits in the garage. What puzzles me is that it will start again after sitting for a few minutes. Its like there is a line clogged that prevents enought fuel from getting into/through the carb. Once I burn through all the fuel in the bowl it can't keep up with the demand. There is still pressure in the lines and eventually enough fuel seeps into the carb again to allow the motor to start and run for a short period of time. Once demand passes supply again, it sputters and quits again. Any ideas on this.

I'm going to NAPA on Friday to see if I can get a rebuilt kit for it. I'll also double check the fuel pump. I just replaced the filter with a clear unit so I can see the clarity of the fuel. There is always fuel in the filter and it looks clean. I loosened the inlet fitting on the carb a bit and fuel squirted out so I'm pretty sure the pump is good. I will try a volume test to see if its putting out enough. Is there a way to look up the correct volume of fuel from the pump? Should it produce a cup of fuel in 10 seconds or something? I just don't know what right looks like for fuel pump function.

Anyway, I'm open to new suggestions.

Do you have spark when it quits and won't restart?

I kept having these weird fuel issues (I thought) and changed carbs and symptoms would seem better for short while, etc. Symptoms kinda changing, ended up being my coil. I'd always heard they went bad when hot, but mine seemed very intermittant.

also, check your oil level on crankcase, is it rising? Is the oil thin and runny and smells strongly of gas? I would have bet money my issues were carb related and chased my tail alot before dropping $20 on a coil. Mine was stalling and all kinds of crazy intermittant stuff (this was my 390 Galaxy).

The first thing you should have done was pull the spark plugs as soon as the problem starts to show up. They will tell you everything you need to know. If they are excessively wet with gas, you have a carb issue. Gas is coming from somewhere that it shouldn't. If they are dry, you have a fuel delivery problem upstream of the carb. Just for giggles, feel the coil to see if it hot.
Carl

Don/Carl:

I haven't checked the plug issue yet. I must add that it is on a 78-79 250 with an HEI distributor. The coil issue shouldn't apply. I ordered a rebuilt kit from NAPA this afternoon. It should be here in the morning. I plan on taking the carb off and trying to clean it out and readjust it.

I'll keep you posted.

stop! all of your symptoms suggest the fuel pump is sucking air. Seal the inlet fitting and or CHECK the line tightness. New feed line to tank or used? If used when you installed the pump you may have cracked the line. Did you shut off the tank with the petcock. Did you open the petcock all the way? You should check the fuel pump pressure and delivery/flow. I hope this helps.

I think you asked a question about the fuel pump fittings. Where the fitting threads into the pump body it is a pipe thread. The male part is tapered. So they should be turned in until they present some resistance. You don't want to really tighten them all the way. If they leak, try another turn or so. The lines attach to the fitting with a flare. Those should be done up good and tight.

Problem solved. I did a few things so I can't be sure exactly what the problem was.

The short rubber fuel line between the filter and the pump looked pretty ratty so I replaced it with new line. It may have been cracked and admitting some air.

I pulled all the plugs. They looked pretty good. Minor discoloration and a tiny boot of soot/carbon. I cleaned them up and validated the gaps.

I went to pull the carb off to do a rebuild and notice that the nuts holding the carb on weren't tight. For whatever reason, there weren't any lock washers on the bolts. Could have been sucking all kinds of air in through there.

I got the carb on the bench and I'm pretty sure the accelorator pump was shot. When I pushed the plunger up and down with fuel in the bowl, nothing happened. I used the rebuild kit that I got from Napa and went through a rebuild.

I got the carb back on the truck and it started right up. After about 20 secondsI had fuel geysering out the top of the carb. Long story short, the float was sticking. The rebuild kit I got had a tiny little wire clip the attached to the top of the float valve and hooked over the end of the float lever. I guess it was supposed to insure that when the float fell it would pull the valve open. Having the clip on the end of the float was jamming the valve open. After three times mounting the carb only to have fuel spray everywhere, I just scrapped the clip.

Finally, the truck started right up and didn't gush any fuel. It purrs like a kitten. The driving is much better. It doesn't sputter under acceleration and seems to have a lot more giddy up. I took it for a nice long test drive without issue. Although it was very frustrating to have to mount the carb 4 times, it was exciting to be able to figure out and solve the problem.

Thanks everyone for all the suggestions and help.

Thanks for the update, glad to hear you got it sorted out.