No Gas in Carb.

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  #1  
Old 10-13-10, 07:25 AM
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No Gas in Carb.

I have a 1988 Jeep Wrangler. If I don't start it every day the car will not start unless I pour gas into the carb. Before pouring the gas into the carb I can pump the accerlerator and looking into the throat of the carb I can see there is no gas being pushed down into the manifold. I replaced the fuel pump and the fuel filter. This did not solve the problem. What could be wrong?
 
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  #2  
Old 10-13-10, 12:04 PM
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No Gas in Carb.

Lorenzo,

Since you didn’t post an engine size, I feel that I should make you aware of few details that you may have overlooked.

You are aware that the 2.5 is a TBI, and the 4.2 is a 2BL right?

You do know the difference between both right?

Just checking. Don’t get insulted. You’d be surprised to know how many folks refer to a TBI as 2BL.

BTW, What was the outcome with the "HEI"?
 
  #3  
Old 10-13-10, 01:52 PM
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The engine is a 4.2. A 2BL carb is the same as the industry has always had. A TBI is designed for fuel efficiency by squirting gas into the manifold. I'm not very knowledgeable on TBI's but according to you mine is a 2BL since the engine is a 4.2 thus knowledge of TBI's is not required today. So how does this cause the carb to not have fuel when it sits for two days?

I posted my reply on the HEI. Just in case the HEI was defective (I bought it at a junk yard.) I'm going to install a new one. However, finances being what they are, I have to wait until next month to buy one. Thanks for all the advice.
 
  #4  
Old 10-13-10, 02:30 PM
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Lorenzo,

It’s a vapor lock issue. Right now I have an appointment, and don’t have time to write something on vapor lock.

For now:

Confirm a good gas cap seal. The cap should release vacuum when opened.

It’s possible for fuel lines to have small cracks or splits that don’t leak fuel, but do leak vacuum, so check the lines. If the lines look worn or if you’re not sure of their condition, change them.

Check back at about 11 PM tonight for additional information.
 
  #5  
Old 10-13-10, 04:29 PM
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For people that really do have a carburetor with said problem, most likely cause is needle is not making good enough seal with the seat. Then gas runs back toward tank and float drops. Mechanical fuel pump then also loses it's prime, because an open needle/seat lets air get behind the fuel, to let it backdrain.

You can confirm this scenario by carefully adding some gas to the vent tube of the carburetor, with say an eyedropper. But do not pour any down the throat of the carb as this will skewer the test. By adding fuel this way to the bowl, you bring up the fuel level to the point that the engine can once again suck it out of the carb.

It is a relatively easy job to remove the top half of the carb (called an air horn) in order to replace the usually dried out needle. Or you could have some sediment stuck on the needle tip, causing this also. You do have to be real careful though with the little wire piece that holds the needle in place. Carefully observe how that is hooked!

[When working with gas and carbs, and trying to start the engine, it is wise to have some damp rags to smother out a backfire, and fire extinguisher at your side also.]
 
  #6  
Old 10-14-10, 03:16 AM
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Lorenzo,

Sorry this arrived late.

Vapor lock doesn’t take place between the fuel pump and carburetor. Vapor lock occurs between the fuel pump and fuel tank. The suction of the fuel pump lowers the pressure in the fuel line, while at the same time the evaporation point of the fuel is lowered. If there is a restriction (aka hot spot) in the fuel line the fuel will evaporate before it reaches the fuel pump. The fuel pump is not designed to pump fuel vapors, so the engine stalls, starts with difficulty, or doesn’t start at all. Check the areas of the fuel line that run close to the exhaust system or downstream from any exhaust heat. Drive the Jeep for about an hour. Next get it on a lift and up in the air. Run your hand along the fuel line feeling for hot spots. If you find any hot spots, either re-route the fuel line away from the heat, or wrap the line with the “Thermo Tec” product in the link at the end of this page. Also check the rubber fuel line hoses that connect to the fuel tank. If they look smashed, cracked or split change them. If you unsure of their condition, then just change them. Now I hate to be the one to tell you this, but the new fuel pump you installed could be the problem, especially if the pump is aftermarket. On a “Jeep” an “OE” fuel pump (mechanical or electric) should only be used. The fuel pressure psi for your Jeep should be:

4-5 PSI
At Idle
At normal operating temperature

Using a fuel pressure gauge confirm the above PSI and post back the results.

There were two fuel system related recalls on Wranglers. One for fuel pumps, and the other for fuel tanks. Did you ever do them? If not check with your dealer, to see if your Wrangler was included in the recalls. Recall numbers appear below.



NHTSA CAMPAIGN ID Number: 07E064000

NHTSA CAMPAIGN ID Number: 94V106000

Click on the link below

Thermo Tec Thermo-Shield, Thermo Sleeve, Express Sleeve, & Silicon-Coated Heat Sleeve: JSC Speed
 
  #7  
Old 10-14-10, 07:26 AM
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Vapor Lock in 88 Jeep

Thanks all for the infomation. I will inspect the gas line from the tank to the carb. I will check for recall information at my local Jeep dealer. This may take a couple of days.
 
  #8  
Old 10-14-10, 08:19 AM
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fuel problems

Another test I would do is a fuel delivery test. Disconnect the line from the pump to the carb, stick it in a container and crank the engine. A rough guide is a pint of gas in 30 seconds. You can have pressure and not delivery.
 
  #9  
Old 10-14-10, 08:56 AM
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I once had a big block mopar with a thirsty Thermo Quad that had two opposite problems going on at the same time. A heavy gas saturated plastic float that would cause erratic flooding, and a sometime needle issue that would drain the bowl from time to time that made me then need to do a 20 step tap dance on the gas just to get it to fire. When I changed out the float the flooding stopped, but the sometime hard cold starting didn't until I put in a new needle and seat as Ecman51 said. Of course that was also after I wasted my time changing out the fuel pump first.
 
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Old 10-15-10, 04:34 AM
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Lorenzo,

Just for laughs and giggles, make sure you didn’t install the fuel filter upside down. The filter has two outlets. The outlet at the center goes to the carburetor. The outlet on top goes to the return fuel line. If the return isn’t on top, gas will siphon back into the tank when the Jeep is sitting motionless, thus causing a loss of residual fuel line pressure. I realize you had this problem before, and you changed the filter and pump in an effort to resolve the problem, but if you installed the fuel filter upside down, it would produce the same problem you had originally, and you wouldn’t realize it.
 
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Old 10-15-10, 07:16 AM
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Originally Posted by equinox View Post
I once had a big block mopar with a thirsty Thermo Quad that had two opposite problems going on at the same time. A heavy gas saturated plastic float that would cause erratic flooding, and a sometime needle issue that would drain the bowl from time to time that made me then need to do a 20 step tap dance on the gas just to get it to fire. When I changed out the float the flooding stopped, but the sometime hard cold starting didn't until I put in a new needle and seat as Ecman51 said. Of course that was also after I wasted my time changing out the fuel pump first.
You're right about the float issue. I forgot about that. It must be 30 years ago I last monkeyed with taking carbs apart! Yes, sometimes the float gets saturated and sinks and causes the needle to drop, letting the gas out of the bowl!
 
  #12  
Old 10-15-10, 07:40 AM
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88 Carb

I went to the local Jeep dealer and they looked up the recall data. My Jeep has not been fixed as per the recall. I will take it this Monday and they will do the repairs. I don't know if this will take care of the problem but I'll see what happens.
 
  #13  
Old 10-15-10, 09:38 AM
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No Gas in Carb

The gas line runs from the tank on the driver's side of the vehicle. The exhaust pipe runs on the passenger's side. There is nothing to heat the gas line. The line is secured to the engine on the driver's side with a bolt and runs under the engine to the fuel pump. The pump has two equal towers on top. The tower on the passenger's side has the fuel line from the tank. The tower on the driver's side goes to the carb. The line coming from the tank is secured with a clamp. The line going to the carb is secured by a bolt. There is no way to mix the lines. The insulation on the gas line under the engine is frayed. I'll replace that to protect the line from engine heat.
 
  #14  
Old 10-15-10, 12:37 PM
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Lorenzo,

You’re doing the right thing by addressing the recalls first. Successful auto repair is simple common sense and logic. The difference between a mechanic and a great mechanic, Is that a great mechanic will apply common sense and logic first. The great mechanic knows that addressing TSB’s and recalls is the first step in troubleshooting, and ruling out the basics. Look at it this way. Again it’s nothing more than simple common sense and logic.

1997 Grand Cherokee. Various and occasional cylinder misfires at cylinders 1, 3, and 7, however cylinders 5 and 8 misfire more frequently than 1, 3, and 7.

Well, the wanna be or amateur mechanic will

While the great mechanic will look for TSB’s or recalls first.

While the great one is looking, he finds TSB # 18-48-98


(Quote) I'll replace that to protect the line from engine heat.

JUST MAKE SURE THAT BOTH RECALLS ARE DONE. THE COMMON SENSE AND LOGIC HERE ARE THAT EITHER OR BOTH RECALLS COULD ACCOUNT FOR THE LOSS OF FUEL PRESSURE/VACUUM.
 
  #15  
Old 10-30-10, 08:00 AM
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88 Carb

I took out the carb and cleaned it. I bought a kit and replaced all the parts in the kit. The Jeep started just fine. I tried it a bit later and same old same old. The engine just goes round and round. There is an electrical switch at the back of the carb. I did nothing with it since there was nothing in the kit to replace parts. What is the function of that rear switch?
 
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Old 10-30-10, 08:26 AM
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Not sure on the wires. Can't remember if for choke adjustment or other.

You say after your rebuild that it started right away. But it didn't use to, did it? Your present problem and old problem may not be related.

Then you went to try it later. HOW much later? And when it did not start, did you remove air cleaner to see how the choke position was, and if it would have been right for the temp of the engine at the time you tried to restart it?
 
  #17  
Old 11-01-10, 07:13 AM
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88 Carb

The car has always started if you leave it overnight. But, it doesn't stay running. This just started about a month ago. The car ran just fine before then. So, in the last month something has happened to the car. I'm pretty sure it's the carb but can't seem to identify the problem to fix it. The car has spark and fuel and now the carb is clean. Yet, it still doesn't run the way it should.
 
  #18  
Old 11-01-10, 03:30 PM
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So it starts okay, after it sits? Except it just don't stay running? If so, does it suddenly up and die, or does it peter out instead? How long does it run for - and when it is running, is it running good, then quits? - or runs badly, then finally quits?

Could you answer my question about the choke, from my last post?
 
  #19  
Old 11-01-10, 05:26 PM
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Hi Lorenzo,

In the face frustration it’s common for an individual to loose sight of the oblivious….Just as a reminder Lorenzo....We’re doing online auto repair here....As a master mechanic, and speaking for my colleagues….We can only help you based upon your answers and feedback….Again for the simple (common sense and logical reason) that we don’t have your Wrangler in front of us.

Lorenzo, there are (virtually countless) un-answered questions. For that reason, and that reason alone your Wrangler continues to go unrepaired. The following is a basic, simple and fundamental test. You should have posted the results of this test weeks ago. Had you done so, your Wrangler could have been running by now. It’s in your own best interest to do this simple test and post the results.

Your last post tells me that it’s time for a NEW carburetor. However before replacing the carburetor, I would like you to do this, SIMPLE, OBIVIOUS, and BASIC test and post the results.

Let your Wrangler sit for at least 5 days without being started.

Remove the fuel line connection at the carburetor.

Insert the fuel line into a clear one quart container.

Get into the wrangler, and place an egg timer that is set on zero on
the dashboard.

Now have a second person hold the disconnected fuel line into the container.

Now crank the engine, and start the egg timer.

The goal here is to see if the fuel pump can fill the quart container in less than 30 seconds.


Posting the results is in your own best interest

Best Regards
Sam
 
  #20  
Old 11-02-10, 12:13 PM
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88 Carb

ASE, I will do as you suggest.

ecman51 - When the car starts it runs fine. Sometimes it runs for 5 minutes or more without problems. Then it just dies. It doesn't sputter, it just dies. When I drove it to the dealer I drove it for almost a mile before it died. The car will start if you pour a little gas into the carb the next day. Remember, the car ran just fine until this problem started.

I was not working during the summer. Now I work nights so I don't have as much time to work on it as I used to.
 
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Old 11-02-10, 04:07 PM
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Per your last post. Whenever you have some sort of mechanical problem, and you think you honed in on the problem by doing something (in your case, adding gas) you always have to rule out coincidence . In your case, you could rule that out if say you first tried to start the car several times, unsuccessfully, in the morning -THEN add the gas, and see if it only starts then. If you just go out there and add gas, you can't be certain it would not have started if you did NOT add the gas. Just thought I'd throw that out there. Nevermind, if you DID do the procedure I mentioned.

The way you put things chronologically in your post, makes it difficult for us to know exactly what is happening. For example, you do not specifically say in your last post if when it starts and runs fine for 5 minutes or one mile, if that is after you had to add gas or not. This could be very important to know this so maybe we don't all go down the wrong path. I am frankly intrigued how the car just dies without stumbling first, if there is only some gas issue here. The more specific your statements are about what the vehicle does, the quicker perhaps days can be shaved off what you need to be looking for. ASE alluded to this as well.

You said you rebuilt the carb with the whole kit. Did you put in a new needle and seat and a new float, and get the gas/float level right, ourt of curiousity? And have you ever done anything like this before?
 
  #22  
Old 11-03-10, 05:15 AM
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Lorenzo,

(QUOTE) It doesn't sputter, it just dies.

(Quote) When I drove it to the dealer I drove it for almost a mile before it died.


Ok, that day going to the dealer, when it stalled, did it restart by you just turning the key, or do you have to pour fuel into the carburetor again to get it started?

(Quote) The car will start if you pour a little gas into the carb the next day.

This tells me that the float bowl is losing fuel. Reasons for this appear below:

Fuel pump issue (Doesn’t matter that pump was just changed). Could still be defective.

Gas cap issue.
Float issue
Acceralator pump issue
Needle and seat issue
Cracked carburetor casing


The next time it stalls, do nothing to restart it. While the carburetor is still attached to the manifold, remove just the top of the carburetor, and let us know if there is fuel in the bowl.

Next reinstall the carburetor top. Now remove the fuel line from the carburetor and place the line into a container. Now simply turn the key and crank the engine. Let us know if the container fills with fuel. Loss of fuel in float bowl, and stall while in motion, sounds like two different issues to me.
 
  #23  
Old 11-03-10, 09:32 AM
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Finding out if there is fuel in the bowl will help eliminate the possibility of stalling/hard starting caused by a bad pump, a sticking float/needle, cracked/leaking bowl etc. It does sound like there is something else going on as Sam said, and perhaps there is something intermittant with the ignition as well. In the good old days I had a bad distributor pickup coil that ran on again, off again, and took me more than a few days to find. I was changing the fuel pump, and even the ballast resistor to no avail. It was a Mopar. Just wondering when it starts after pouring gas down the carb after sitting overnight whether you have tried to start it just before pouring in the gas only to confirm the assumption that adding the gas is doing something.
 
  #24  
Old 11-03-10, 09:43 AM
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Gas cap issue.
Float issue
Acceralator pump issue
Needle and seat issue
Cracked carburetor casing
Next time you park for the night.....Take the fuel cap off and toss it on the back seat. Try starting it in a day or two.

The "Supply side " of the pump is Suction......Which means for any fuel that leaves the tank, an equivalent amount of air must be drawn in to compensate for the missing volume of fuel. A plugged Vent Line, or an INCORRECT fuel cap (or worn out for that matter) will leave a "Vacuum" in the tank that sucks the fuel back when you shut the truck off.

It is also possible that "Sock" in the tank is partially plugged, producing the same effect, except the suction would be trapped in the supply lines and not in the tank.

If this is a GM style carburetor, with the fuel filter inside the "Inlet Nut", make sure the check valve is in the end of the filter.... (Us old guys remember the difference between 470 and 471 Dont we????)
 
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