engine and drivetrain Bad Mechanical Fuel Pump?

[car_cursed]

So a week ago my car stuttered and died, took 10 minutes of cranking to get it started again. I thought ignition, I tested the coil, put on a new cap and rotor and the problem remains. The car starts and idles fine, I can rev it in park, but if I put it I will gear it bogs down and dies. I replaced the fuel filter, and when I pulled line off the pump to the pressure regulator and cranked the engine barely a trickle came out. Anyone else have this problem?

Car is a 74 automatic base with a 2bbl solex.

[Dev02]

I JUST had nearly this same issue. Car wouldn't start, took the line off the carb and put it in a jar, cranked the car and a few small spurts came out but that was it.

 

Like you I also thought it might be something else, the fuel pump is too simple to break! I tried a squirt of gas directly in the carb; car started. Hooked it back up to the carb and put the line, pre pump, into a small glass of gas and nothing. Figured it had to be the pump.

 

So I contacted Blunt and ordered a new pump (mine is the longer one and not the short one listed on his site), and while I was at it did all new lines (using his recomendations) from the tank to the carb, and a new filter.

 

After installing the parts, and cranking the car for-eveeeeer, she started up and has been great since.

 

One thing I wish I'd thought of is getting new gaskets for the pump spacer at the same time as everything so I wouldn't need to take it all back apart.

 

Hope this helps the curse.

 

-Dev

[car_cursed]

What were his recommendations? Just new lines or something more. I think I might put new lines in since the car sat for 10 years.

['76mintgrün'02]

I have read on here that the diaphragm in the pump goes bad if it sits.  Sounds like this is what happened to yours.  You could do a test with a two bottles, or cans and see if it pumps fuel from one to the other.  Be CAREFUL and have a fire extinguisher on hand.  It is possible that the screen on the intake in the tank is clogged and the pump cannot get gas.  There is a plastic sleeve on the outlet of the tank and it can crack and allow air into the line as well.  If the flexible lines after the tank are cloth covered, they are likely original and should be replaced.  The cloth can hide cracked rubber.  

 

My money is on the pump itself having given up the ghost.  Some models have a removable top and you can replace the diaphragm, but others are crimped together and are not serviceable.  If you get a pump through Blunt, be sure to specify that you want the 'long-neck' version, not the one on his automated site.  (as noted above)  That unit is shorter and interferes with the coolant line that runs under the pump.

Edited July 31, 2014 by '76Mintgrun'02

[Hans]

If it sat for 10 yrs,

I'd be checking in the tank for crud.

[Buckeye]

I have one spare one for sale If you found out fuel pump is the culprit and want original replacement for it

http://www.bmw2002faq.com/classifieds/item/3549-fuel-pump-pierburg-oem/'%20title='Fuel%20Pump_Pierburg%20(Oem)

[Dev02]

What were his recommendations? Just new lines or something more. I think I might put new lines in since the car sat for 10 years.

 

His recomendation was safety line through the cabin (this line seals closed when heated, like in a fire) and some specific sized ruber lines in the engine bay and trunk. He knew the 2 sizes I needed... but I THINK it was 6mm connection to the safety line, then something larger connected to the pump (the pump has 2 different sized connections) and Weber.

 

I have no idea if you need to change your lines, others here will have much better advice on that. I just did it because I am slowely trying to change everything and every time I do something I try to put all new parts in.

 

Mintgruns' idea is almost exactly what I did and worked very well for me (and nothing blew up!).

[Arizona02]

Check fuel flow out of the pump before the regulator.

 To Test fuel pump, use a vacuum gauge on inlet to test suction then connect on the outlet to test psi.

 

[Mike Self]

two more things to check:

 

1.  air leaks upstream from the pump.  A mechanical pump simply won't pump gas if air can get into the lines--and those OEM cloth-covered fuel lines are notorious for age cracking under the cloth.  Air can then get into the fuel line.  And it can happen suddenly, as I found out on a two mile trip to the library--had to do some jury rigging in the library parking lot. 

 

2.  Check both the push rod end for wear (it should be square on the end, not beveled) and on the fuel pump pad that the push rod bears against.  I"ve had the pad wear to the point where the push rod wasn't giving the pump a full-length stroke.

 

You can test both by removing the pump from the car and operating it manually with a screwdriver, pulling gas or kerosene from one container to another.  Might save you the price of a new fuel pump.

 

cheers

mike

 

PS  I've had pumps sit for several years and still function properly once primed with a little gas...