OK, here's the history. This is my '85 GS with the supercharged 13B in it. There have been three different symptoms, but I don't know if they are related, and I don't know for sure what to check first. Here are the symptoms:

1) Ever since I got it on the road, it has sputtered when I make slow right hand turns. It Would die if I let it, but I can keep it going until the corner is finished then it runs ok.

2) Last summer I let the fuel get really low and it sputtered badly, but I managed to get it to a gas station. But even after filling it sputtered for several miles.

3) Today it sputtered for a while, then completely died. I pulled it to the side of the road and tried to restart it, but it did not fire at all. I was close to work so I walked the rest of the way, then after work a friend took me to the car. It fired right up, but sputtered a little bit all the way home. This happened to me a week or so ago, but I managed to get it restarted before I came to a complete stop. Today's episode was on a full tank of gas.

Any ideas? I wonder if there is something in the tank that periodically covers the fuel pickup. Could it be an ignitor? But it'll still run if one ignitor is bad won't it? Any other ideas?

Thanks,
Rich

 

Fuel filter??

 

Ignitor, no, they are alive or dead.

You have all of the classic symptoms of debris in the fuel tank that's plugging either the screen at the bottom of the pickup tube, or the screen is split, (quite common), and debris is partially plugging the pickup tube, then falling back down once the engine/fuel pump is shut off.

Unfortunately, draining the fuel tank will not remove all of these little bits of debris because the threads that the drain plug screws into protrudes above the bottom of the tank.

Best option for repair is to drain the tank, remove it, then remove the pickup unit and clean out the tubes. If you're lucky and the debris is rust particles, use a long magnet to pick them out from the bottom of the tank. This is best done by removing the fuel level sender, as it will give you a straighter shot to the depression around the drain plug.

If the debris is more than rust, rinse out the tank with hot water and Dawn dish soap, a couple of times, then flush with cold water to remove the suds. Turn the tank upside down and drain the water out where the fuel pickup attaches.

If you have an old hair dryer, point it into the tank to dry it out, making sure there are absolutely no gas fumes left. If you don't have a hair dryer handy, add a couple of bottles of Heet to absorb any moisture left in the tank when refilling with fuel.

 

Check your timing to make sure your ignition is good. It sounds like a fuel problem. Replace your fuel filter and check your . I don't know much about Holley's......

 

Thanks guys. Trochoid, that's what I've been thinking ever since it sputtered when I ran the tank low, then it continued after filling. I've had the tank off before when I replaced the fuel lines, so I know how to do it and it isn't too difficult. The biggest problem is that the tank is within 2 gallons of being full, so I'll just keep it to short jaunts until the fuel level is more manageable.

Thanks,
Rich

 

Replace the filter first. See how clogged it is. Next, check the floats on the carb as well. What carb are you running??

 

Unfortunately running the tank low only seems to make any debris problem worse. I have seen the intank pickup tubes plug enough that the engine would only idle, yet the debris would not make it to the brand new fuel filter to show that that's what the problem was.

 

When you run it low again use compressed air and try to blow the lines coming from the tank to dislodge anything that might be in them.

 

its either what trochiod mentioned or it could be that your cat converter is clogged, cause i had this same problem with a truck that i was driving but most likely its your floats in the carb... that also might be a problem.

 

try cleaning the little filters on the banjo bolts on top of the carb where the fuel return and feed line connects to. my bros car did the same thing and found out these little buggers were dirty as hell. i blasted them with some carb cleaner and compressed air. try that and see if it helps any.

 

Could be that when you ran low on gas, you sucked something up and clogged the filter. I'd replace the filter before dropping the tank...

 

You don't run catalytic converters on Supercharged engines.

 

Sorry, but I have to revisit this. I dropped the tank, cleaned it out (didn't find anything serious...just a few rust flakes), reinstalled it, and changed the fuel filter. When I first drove it, it ran great and I thought I had it fixed, but then it started sputtering again. It seems like it runs ok when the engine has been off for several hours, but if I run it for awhile, stop and shut it off for 30 - 40 minutes, then restart it, it wants to sputter.

Any ideas?

Thanks,
Rich

 

fuel pump overheating? mine would do very similarly. Is fuel pressure stable?

 

I had a cracked fuel line sucking air one time that did this. It eventually split and started leaking. Have you tested the fuel pressure?

 

I had a fuel pump do the same thing... I used to smack it and it would "work" better for a little while lol.

 

The fuel pump (Mallory) was knew when I rebuilt the engine a year and a half ago, so it's doubtful that it's bad, but possible. I have a fuel pressure gauge and it flutters when the engine does, but is that a cause, or just a result of the engine not running?

Rich

 

Fuel pressure gauge fluttering might be a clue. Mine reads steady pressure even when I rev the engine. A cracked line sucking air sounds like a good bet, or maybe some type of blockage.

 

But why does it run ok when the engine is cold? I've just noticed the pattern, and haven't driven enough since I noticed to be able to say for certain, but so far it seems like it runs great unless it's been running, shut off, and restarted after sitting 30 - 40 minutes. That's when it wants to sputter.

Rich

 

It's a silly question but did you run new fuel lines for your mallory?

I made the mistake when I installed mine of using the stock fuel line setup, complete with check valve. The check valve provided enough resistance that I actually blew that pump inside a year. Once I bypassed the check valve and ran fuel hose directly from the pump to the metal hard line under the car it was much better. Fuel pressure improved and was much more stable.

Since you've cleaned out the tank, changed your filter, and we'll assume you've checked your fuel hoses, at this point it's either the fuel pump, carb, or ignition. Stumbling in corners has been pegged before as a carb issue, but general stumbling is often a fuel starvation issue. What kind of fuel gauge are you using, and what pressure do you have? How did you wire the mallory? (mine's fed off the stock wires, but I soldered them and used heat-shrink to ensure my connections were clean)

I don't know much about Holleys so unfortunately I can't suggest anything on the carb side.

Jon

 

Hey Jon -

Yes, I did replace all my fuel lines with 3/8" lines. I don't remember the brand of my gauges, but they're electric and not terribly accurate. The fuel pressure gauge reads 8 psi, but I checked it with a mechanical gauge a while back and it read 6 psi.

I used the existing wiring for the fuel pump and soldered my connections.

Thanks,
Rich

 

Hey, Rich.
What's your venting setup like?

 

I left the existing plumbing in place, but the hard line under the hood doesn't have anything on it...it's just open (I think). In the picture (taken before everything was hooked up), there is a hose coming from the vent line in the tank to the open hard line.

Rich

 

could something be wrong w/ the supercharger?

 

Sorry for the jack, but do you have a picture of the check valve by chance? that may be my problem. Is it the metal piece in the return line by the carb?