Died while running

[Supreme_Magnetic]

Hello Ratsun, 

 

Just got my 1978 Kingcab a few weeks ago. It has the stock L20B engine. I recently installed a new weber 32/36 dgv since the og carb was on its last legs. Everything was running great until yesterday when all of a sudden it just dies out on me as I am driving home. During the drive I had no issues and gas gauge was showing 1/4 of a tank. I pulled to the side of the road and tried a few things to get it to started again. It would crank over and start but immediately die out as if it needed gas. I checked the fuel filter and didn't see any issues. Also got some compressed air and blew it down the fuel line towards the filter to see if I can knock something out. No luck. The truck does have a electric fuel pump that was recently installed by the previous owner. I did just realize that I did not have a fuel pressure regulator for my electric fuel pump. Could that be the culprit? Any help would be much appreciated. 

 

 

 

 

 

[datzenmike]

Engine off look down the open carburetor and pump the throttle. What you should see is a squirt of fuel into the bore. No gas? find out why. Can you hear the pump working???

 

 

If there is gas, this isn't the problem..... for now.

 

Did you put a new fuel filter on when you changed the carb????

 

 

[Supreme_Magnetic]

Thanks for the help DatzenMike!

 

I looked down the carb and saw no gas come out when I pump the throttle. I went to the parts store this morning for a new fuel filter since I did not swap it out when I installed the new carburetor. Installed the new filter but no gas comes up to it when I try to start. Seem like the culprit could be the electric fuel pump. Looks new but maybe something clogged it? I believe my truck came stock with AC so it has always had a electric pump. Should I get a mechanical? 

 

Current fuel pump installed on the truck. 

[datzenmike]

21 hours ago, datzenmike said:

 Can you hear the pump working???

 

Just listening can tell you a lot.

Not working? Test for 12 v with key on. Still nothing, check that the ground is good.

 

There should be a filter between the tank and the pump. Sediment is not good for electric pumps.

[banzai510(hainz)]

Loosen the fuel hose on carb . Point in safe direction with no spark issue and gas should shoot OUT like a MOFO.

 

Hopefully he got a low pressure pump like under 4 pounds.

 

no gas squirting is the pump.if not the pump then the float bowl is emply  the needle valve is stuck closed (clogged?)

 

 

pour some a LITTLE gas down the carb and see if it fires off.  then you know you have spark.

 

 

PS nice truck its a keeper

Edited July 22, 2019 by banzai510(hainz)

[Supreme_Magnetic]

First of all thank you all for your help. It has definitely pointed me in the right the direction. Haven't solved the issue yet but getting close. Quick recap of todays effort. 

 

Added gas down the carb and fired right up. Confirmed I was getting good spark. Tested the voltage early this morning with a test light and was getting a positive read at the fuel pump wiring (BW wire). So my initial thought was the fuel pump was out. No power when key was on. Went to Napa and purchased a brand new Carter electric pump. Installed and still didn't turn on. After this I was pretty confused. Busted out the mutli-meter and started checking connections. Turns out I was only getting 1 volts at the fuel pump. 😞 chased the wires to the interior wires near the dash and found one wire to be loose. Plugged it back in and now I'm getting a full 12volts at the fuel pump. On start I can feel/hear it pumping. Only issue is nothing comes up to the fuel filter and still no gas coming up to the carb. Not sure if i missed anything. The lines do not seem to be clogged. I pushed some compressed air though the lines with no issues. Once again any help would be much appreciated. 

[datzenmike]

 Is the input and output on the pump reversed???

Put a hose on the output and direct it into a container and turn the pump on briefly.... got gas? Maybe pump is BIB bad in box.

[Supreme_Magnetic]

Bone head mistake of the year award goes to me! 💩 This morning I woke up early and was determined to get the truck running. After looking everything over I realized the gas cap wasn't all the way down and was causing the fuel pump to suck up air. Once I pushed it down I saw the fuel filter get nice and fuel. After that it started right back up light a champ! Moral of the story is to use a proper multi-meter and to double check all your wiring connections. Thanks again for all the help. This experience has sharpen my skills regarding electric fuel pumps. Looking into a mechanical pump moving forward. 

[datzenmike]

Can't see how the gas cap would change anything. Fuel level in the tank would not change. Maybe it just took a long time to prime.

[Stoffregen Motorsports]

Not likely the cap had anything to do with it. I think Mike is right about the prime. Maybe it drains back overnight and has to prime again. Some fuel pumps have a check valve in them just for this reason.

[distributorguy]

Make sure you're running a 4 psi pump, not 7.  All that fuel pressure can do 1 of 2 things:  blow fuel past the needle and seat fouling your plugs or lock the needle in place allowing no fuel at all as it slams closed.  The most common issue is debris (rust) in the tank caused from modern fuel getting into the pump.  Old or leaky lines are also a concern.  Make sure your pump is located at the tank, not up front, and it must be below the fuel level.    These pumps push, they don't pull well at all.  It should always be full of fuel via gravity.  Yours appears to be mounted above the tank which is BAD.  The tank outlet is down low in the side of the tank.  Mount the pump outside the frame rail, as low as you can.  Run a new line along the frame up to the carb.  

[Stoffregen Motorsports]

It looks like his pump is mounted under the tank. At least that's what I saw in the pic.

[Supreme_Magnetic]

On 7/22/2019 at 9:27 AM, distributorguy said:

Make sure you're running a 4 psi pump, not 7.  All that fuel pressure can do 1 of 2 things:  blow fuel past the needle and seat fouling your plugs or lock the needle in place allowing no fuel at all as it slams closed.  The most common issue is debris (rust) in the tank caused from modern fuel getting into the pump.  Old or leaky lines are also a concern.  Make sure your pump is located at the tank, not up front, and it must be below the fuel level.    These pumps push, they don't pull well at all.  It should always be full of fuel via gravity.  Yours appears to be mounted above the tank which is BAD.  The tank outlet is down low in the side of the tank.  Mount the pump outside the frame rail, as low as you can.  Run a new line along the frame up to the carb.  

Yes my pump is rated for 4psi but just recently got a regulator and a gauge so I can monitor the pressure properly. I know the weber carb wants 3psi tops of fuel pressure. After thinking about the whole process I do think that the pump just needed to be primed. The pump is located below the tank in the stock fuel pump bracket. Once again thank you all for the help. Looking forward to fixing the next set of issues that this 40 year old truck brings. 

[distributorguy]

The Weber will run up to 4.2 - 4.3 psi just fine.  The inexpensive regulators (under $100) can actually cause surging fuel pressure and more issues.  Your pump will be fine on its own.  The same thing can be said for cheap gauges, so unless you have a very good 15 psi gauge, it might not effectively read a precise 4 psi - just somewhere in the ballpark.  Expecting the 3 psi setting on a cheap regulator is accurate is a joke.  If anyone wants a box full of Holley low pressure regulators I'd send them to you, but I'm usually not that evil.  

 

If your pump is below the tank, you should be able to remove the output line from the pump and fuel will pour out on its own.  If not you can prime it from there.  Check fuel pump output with the pump powered up.  You should get close to 1/2 gallon per minute.  That verifies your pressure and volume are ok.  

[Supreme_Magnetic]

On 7/24/2019 at 5:19 AM, distributorguy said:

The Weber will run up to 4.2 - 4.3 psi just fine.  The inexpensive regulators (under $100) can actually cause surging fuel pressure and more issues.  Your pump will be fine on its own.  The same thing can be said for cheap gauges, so unless you have a very good 15 psi gauge, it might not effectively read a precise 4 psi - just somewhere in the ballpark.  Expecting the 3 psi setting on a cheap regulator is accurate is a joke.  If anyone wants a box full of Holley low pressure regulators I'd send them to you, but I'm usually not that evil.  

 

If your pump is below the tank, you should be able to remove the output line from the pump and fuel will pour out on its own.  If not you can prime it from there.  Check fuel pump output with the pump powered up.  You should get close to 1/2 gallon per minute.  That verifies your pressure and volume are ok.  

That's good to know that adding a regulator may not be a good idea at this point. So far I have been driving the truck all week and haven't had any more issues. So I just may leave the regulator off for now. Especially since I did end up ordering a cheap Summit regulator and gauge. 😂

 

Thanks again Ratsun for all your help.

[distributorguy]

The Summit gauge...  I have one on the race truck and we've been questioning it - we all think it reads low, the worst possible scenario.  I'd rather see it read high if you're going to have an error.  At least it has a glass lens so when fuel vapors sneak into it, it won't turn white and opaque like other cheap gauges.