No fuel entering carb, new fuel pump did not fix problem.

[kbanjo]

Hello all,

 

For a couple months I needed to pump the gas around 25 times to start the car. I tried putting a new fuel pump in and it didn’t help.

 

Now there is no fuel entering the carb whatsoever.

 

What’s my next step? I am very novice with car work but wanting to learn.

 

Also worth noting, I know one of cylinders is firing with low pressure (60 psi). It may be worse since it was measured. Someone told me it sounded like I was running on 3 cylinders not long before it stopped running. I have someone to help me with this problem, which I understand is probably a major issue.

[mataku527]

sounds like your fuel line has a crack in it.  If you want to test it, get a vacuum tester, plug up one side and see if it will hold any pressure.

 

 

[worzella]

If you are very careful, you could get a length of fuel hose and connect one side to the input end of the fuel pump and put the other end in a 5 gallon container of gas

 

This removes the real fuel line, sender and tank from the equation. If you get gas then something aft of the pump is bad

 

When you put new pump on did you have the plastic alignment grommets in the pump base holes? These align the pump and if missing your driving shaft off cam might not be engaging the pump mechanism properly

 

If not rearward problem and pump is pumping then carb float bowl or needles might be toast

[kbanjo]

Thank you both! 

 

One of the plastic grommets was missing when I removed the old pump, but I found a similar part and cut it to size. I think I got it pretty darn close. 

 

I'll try your fuel pump test, that sounds like a good idea. 

[Hodgepodge]

Was the replacement pump an exact match?  Did the pushrod fit correctly?    The only way to be sure is to do what Worzella suggested.   There is a long thread on here calle how to eliminate hard start/fumes in trunk that might have something useful.      

 

https://www.bmw2002faq.com/forums/topic/207789-how-to-eliminate-hard-startfumes-in-trunk/

[Dudeland]

You didn't say what carb you have but In the Weber carb there is a filter,  It is the large bolt on the bottom of the housing where the fuel line goes in.  Take it off and there should be a filter.  It can be plugged. 

 

If you take off the line going to the carb, does it squirt out fuel when it turns over?

[Mike Self]

Couple more things to check if the above suggestions don't work:

1.  If you have any remaining original cloth-covered fuel line between the fuel pump and the gas tank, replace it with modern rubber fuel hose, clamped in place.  Those old cloth-covered lines will crack and allow air to enter the line, and you won't see the cracks because of the cloth covering.  That pump would much rather suck air than fuel...and it will if there's a leak in the line.

 

2.  The two fuel pump styles ("take apart"--with screws holding the upper and lower halves together, and the crimped over body) use different length pushrods.  If your new pump doesn't look like the old one, chance are you're using the wrong pushrod.

 

3.  Did you check the filter screen at the bottom of the fuel pickup/gas gauge sender unit in the gas tank?  An old, never cleaned out tank may have enough crud in it to plug that screen solidly.

 

Let us know whatcha find

mike

[kbanjo]

I pulled the fuel line off the carb and carefully directed it into a bottle (so fuel line went from pump to bottle). No fuel entered the bottle when turning ignition / pumping accelerator.

 

Fuel pump looked identical to the old one. When I replaced it, the car behaved exactly as it did before (ran okay, but had to pump gas 25+ times before it would start). 

 

I am going to try to figure out how to check the filter in the gas tank, and see what's going on with the fuel lines! Time is limited, but I will report back ASAP. 

 

Thanks again everyone!

 

 

[mataku527]

I think you already had an idea that your carb wasn't getting fuel, rather you want to see if the pump is working. As other have suggested, take the line from the firewall to pump and place that in a container with gasoline.  

 

You can then run the starter as you did or just take the pump off and manually actuate it. If fuel moves, you at least know the pump is decent. 

 

Having gone through the exercise, I do think the plastic fuel line is likely a problem and will need to be replaced anyways if it is original 

[kbanjo]

Hi All - I got it up and running (sort of). 

 

I tested the pump by isolating it, and it was working. I traced the fuel line back to the tank and did not see any cracks - it doesn't look like it's the original. 

 

I took out the part that comes out of fuel tank and feeds the fuel line and cleaned the mesh filter on the bottom. After doing so, I was able to start the car!

 

Now I am back to my original problem from this winter, which is needing to pump the gas 25+ times to start it cold. Once it warms up it seems to run okay (aside from the fact that one cylinder isn't firing). 

 

Any theories?

[worzella]

I believe (always my novice disclaimer) that each pump of the pedal should squirt gas into carb primary barrel. Sounds like this is not happening. Can you have a friend pump pedal as you stare down throat to see if it is squirting?

[worzella]

Or put another way. If you pour a bit of gas down pprimary and crank does she start up just fine. At least for a few secs?

[kbanjo]

Will give it a try!

[Mike Self]

1 hour ago, kbanjo said:

Now I am back to my original problem from this winter, which is needing to pump the gas 25+ times to start it cold.   Presuming it's an automatic choke...is the choke setting when you pump the accelerator a couple of times when the engine is cold--(i.e. are the choke flaps closing and staying closed).  Or if it's a manual choke, are you pulling the choke knob out all the way to close the choke flaps?  And is the accelerator pump giving a good, healthy squirt when you work the accelerator linkage.  Squirt, not dribble...

 

mike

[kbanjo]

It is an automatic choke. Flaps are closed when cold and do open up when it warms up. I will work the accelerator linkage and report back!