Can't figure out if fuel pump is the problem

Slampiece · 03-16-2012, 03:38 PM

My 4000cs won't start so I pulled the line off the fuel pump and cranked it over and gas comes out while it's priming, but not while it cranks, then when I turn the ignition off it squirts some more out. Any help would be much appreciated

Rogviler · 03-16-2012, 05:12 PM

Have you checked to see if the fuel pump relay is clicking on while you crank? It could be a bad relay (cracked solder joints), but the fact that it primes leads me away from that. The next suspect would be the hall sender inside the distributor. If it's bad it won't give the "engine is cranking/running" signal to the relay, but the relay itself would still prime.

It could be the fuel pump, but the fact that it primes is again unusual if that's what it is.

Unfortunately the only thing you can do with the hall sender is to rule everything else out and then replace it. Replacing it is the only diagnosis for it that I know of. If you replace it, just get the whole distributor as it's not much more than the sender by itself.

-Rog

westco4K · 03-17-2012, 07:13 AM

How does the fuel pump sound when its running? A nice even hum? or a squealing pig on its last leg? CIS requires alot of fuel pressure to operate properly and if it never reaches that mark there is a good chance the injectors arent even opening. Just something else to consider.

Slampiece · 03-18-2012, 02:19 AM

I don't feel the smartest but I am relieved. Thanks for the help guys. It wasn't squirting fuel while it was cranking cuz the battery was pretty drained. after spending quite some time on it I noticed my clamp holding the intake boot on was loose, so there was a small opening at the seal. That was my problem. This car makes me miss working on my Japanese cars but damn it looks good.

Rogviler · 03-18-2012, 09:43 AM

That's good! Always nice when it's something simple.

Yeah, you'll come to realize just how sensitive they are to vacuum leaks and other seemingly minor things. The funny thing is, you'll probably love it more the more you have to work on it. That's what happened to me and now I have a whole collection.

-Rog

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03-16-2012, 05:12 PM	#2
Rogviler AudiWorld Senior Member Garage is empty, add now Join Date: May 2010 Location: Colorado Posts: 748	Have you checked to see if the fuel pump relay is clicking on while you crank? It could be a bad relay (cracked solder joints), but the fact that it primes leads me away from that. The next suspect would be the hall sender inside the distributor. If it's bad it won't give the "engine is cranking/running" signal to the relay, but the relay itself would still prime. It could be the fuel pump, but the fact that it primes is again unusual if that's what it is. Unfortunately the only thing you can do with the hall sender is to rule everything else out and then replace it. Replacing it is the only diagnosis for it that I know of. If you replace it, just get the whole distributor as it's not much more than the sender by itself. -Rog

03-17-2012, 07:13 AM	#3
westco4K AudiWorld Member 1987 Audi 4000 Join Date: Dec 2011 Location: gj, co Posts: 101	How does the fuel pump sound when its running? A nice even hum? or a squealing pig on its last leg? CIS requires alot of fuel pressure to operate properly and if it never reaches that mark there is a good chance the injectors arent even opening. Just something else to consider.

03-18-2012, 02:19 AM	#4
Slampiece AudiWorld Newcomer Garage is empty, add now Join Date: Mar 2012 Posts: 2	I don't feel the smartest but I am relieved. Thanks for the help guys. It wasn't squirting fuel while it was cranking cuz the battery was pretty drained. after spending quite some time on it I noticed my clamp holding the intake boot on was loose, so there was a small opening at the seal. That was my problem. This car makes me miss working on my Japanese cars but damn it looks good.

03-18-2012, 09:43 AM	#5
Rogviler AudiWorld Senior Member Garage is empty, add now Join Date: May 2010 Location: Colorado Posts: 748	That's good! Always nice when it's something simple. Yeah, you'll come to realize just how sensitive they are to vacuum leaks and other seemingly minor things. The funny thing is, you'll probably love it more the more you have to work on it. That's what happened to me and now I have a whole collection. -Rog