930 Fuel Pump Question
05-30-2009, 01:21 AM
#1
Rennlist Member
Thread Starter
930 Fuel Pump Question
Hi:
I have a unique 911 Turbo. It started life as a 1977 Targa that was converted to a 911 Turbo based on an early 1980's 3.2 SC case. It has a CIS injection system with stock ignition. It runs 0.8 bar boost and I imagine is putting out somewhere around 350 HP (it is very quick).
The motor was built by David Hart of Prototech. The car was also converted to a Strosek body by Bob Aziano of Bad Boy Cars. The point I am making is that it is an amalgamation of various components but is a beautiful car and despite the lack of having a stock pedigree has worked flawlessly since I bought it a few years ago with 6000 miles on it. It now has 18,000 miles. I have performed all regular maintenance on the car including replacing cap, rotor, wires, plugs, adjusted valves, etc..
This year I took it out of winter storage, started her up and it ran great. Then one day after running about 1/2 of a tank after winter storage it just started running very rough. One minute it was running great then it just started running worse and worse over a period of about 5 minutes. Thereafter, it would start fine, idle fine but with any throttle application would run very rough (cough, sputter, etc.). It is undriveable. The fuel pump (rear one as far as I could tell) was also making quite a bit of racket (squeeling, it had never done this before).
In an effort to troubleshoot it thinking maybe I had some bad fuel I drained the tank by removing the fuel level sender and looked inside the tank (it looked fine), I removed the strainer from the bottom of the tank (it too looked clean with no evidence of rust, scale, etc). I replaced the fuel filter in the engine compartment and the spark plugs. I looked for cracked or leaking vacuum lines, etc but found none. I also replaced the transmission ground strap since it was old and ratty looking. I put in some fresh gas and started it up. No improvement and the fuel pump was still squeeling so I decided to replace the fuel pumps thinking that they might be the problem.
I ordered what I thought were the correct Bosch pumps (0 580 254 979 front, 0580 254 984 rear). Well when I got the pumps out what I found was that the front pump was a Bosch 0 580 254 967 rated at 165 l/hr @ 5 bar, the rear pump was a 0 580 254 979 also rated at 165 l/hr @ 5 bar. So it looks like what I thought was supposed to be the front pump was actually what was in the rear (which makes sense since the fittings are correct) and the 0 580 254 984 has the correct fittings for the front ... sort of. It has a molded hose barb but the outlet has a longer "stem" than the 0 580 254 967 than was in the car. Also the 0 580 254 984 is rated at 228 l/h @ 5 bar.
My questions are:
1) Is there any problem with running a 228 l/hr Front pump (0 580 254 984) with a 165 l/hr rear pump (0 580 254 979)? Will that upset the system, cause any problems, etc?
2) If 1) is no problem can I simply remove the fitting from the old 967 front pump (which has a check valve in it) and install it on the 984 pump (the fuel line is long enough to reach)? It appears that the 984 pump may already have a check valve built in, would that potentially cause a problem? I can also buy a banjo fitting that does not have a check valve if that is the case.
3) I am hoping that the fuel pump(s) turn out to be the culprit but if not are there any other ideas (I am concerned that it might not be the fuel pumps since when I applied 12v to the terminals both pumps seemed to spin fine without making any noise)? I am really hoping it's not in the fuel distributor or something like that.
If anyone has expertise in this area I could use some advise.
Thanks in advance!
Tom
I have a unique 911 Turbo. It started life as a 1977 Targa that was converted to a 911 Turbo based on an early 1980's 3.2 SC case. It has a CIS injection system with stock ignition. It runs 0.8 bar boost and I imagine is putting out somewhere around 350 HP (it is very quick).
The motor was built by David Hart of Prototech. The car was also converted to a Strosek body by Bob Aziano of Bad Boy Cars. The point I am making is that it is an amalgamation of various components but is a beautiful car and despite the lack of having a stock pedigree has worked flawlessly since I bought it a few years ago with 6000 miles on it. It now has 18,000 miles. I have performed all regular maintenance on the car including replacing cap, rotor, wires, plugs, adjusted valves, etc..
This year I took it out of winter storage, started her up and it ran great. Then one day after running about 1/2 of a tank after winter storage it just started running very rough. One minute it was running great then it just started running worse and worse over a period of about 5 minutes. Thereafter, it would start fine, idle fine but with any throttle application would run very rough (cough, sputter, etc.). It is undriveable. The fuel pump (rear one as far as I could tell) was also making quite a bit of racket (squeeling, it had never done this before).
In an effort to troubleshoot it thinking maybe I had some bad fuel I drained the tank by removing the fuel level sender and looked inside the tank (it looked fine), I removed the strainer from the bottom of the tank (it too looked clean with no evidence of rust, scale, etc). I replaced the fuel filter in the engine compartment and the spark plugs. I looked for cracked or leaking vacuum lines, etc but found none. I also replaced the transmission ground strap since it was old and ratty looking. I put in some fresh gas and started it up. No improvement and the fuel pump was still squeeling so I decided to replace the fuel pumps thinking that they might be the problem.
I ordered what I thought were the correct Bosch pumps (0 580 254 979 front, 0580 254 984 rear). Well when I got the pumps out what I found was that the front pump was a Bosch 0 580 254 967 rated at 165 l/hr @ 5 bar, the rear pump was a 0 580 254 979 also rated at 165 l/hr @ 5 bar. So it looks like what I thought was supposed to be the front pump was actually what was in the rear (which makes sense since the fittings are correct) and the 0 580 254 984 has the correct fittings for the front ... sort of. It has a molded hose barb but the outlet has a longer "stem" than the 0 580 254 967 than was in the car. Also the 0 580 254 984 is rated at 228 l/h @ 5 bar.
My questions are:
1) Is there any problem with running a 228 l/hr Front pump (0 580 254 984) with a 165 l/hr rear pump (0 580 254 979)? Will that upset the system, cause any problems, etc?
2) If 1) is no problem can I simply remove the fitting from the old 967 front pump (which has a check valve in it) and install it on the 984 pump (the fuel line is long enough to reach)? It appears that the 984 pump may already have a check valve built in, would that potentially cause a problem? I can also buy a banjo fitting that does not have a check valve if that is the case.
3) I am hoping that the fuel pump(s) turn out to be the culprit but if not are there any other ideas (I am concerned that it might not be the fuel pumps since when I applied 12v to the terminals both pumps seemed to spin fine without making any noise)? I am really hoping it's not in the fuel distributor or something like that.
If anyone has expertise in this area I could use some advise.
Thanks in advance!
Tom
05-31-2009, 08:11 PM
#2
Nordschleife Master
Join Date: Oct 2001
Location: Mount Pleasant, South Carolina
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No info on the pumps and squaling usually means a failing pump. Since it seems to sputter, it must be getting fire or some fire at least.
I would try a few things as well:
Is your CDI box whinning when the car is turned on?
Jump the red fuel pump relays to get fuel.
Jump the yellow relay in back to get fuel.
Pull the blue electrical connection off the back of the metering plate to get fuel to get fuel.
Ground the overboost switch wire (white wire) to get fuel.
Clean all your electrical connections and fuses, including the big red wires at the starter.
I would try a few things as well:
Is your CDI box whinning when the car is turned on?
Jump the red fuel pump relays to get fuel.
Jump the yellow relay in back to get fuel.
Pull the blue electrical connection off the back of the metering plate to get fuel to get fuel.
Ground the overboost switch wire (white wire) to get fuel.
Clean all your electrical connections and fuses, including the big red wires at the starter.
05-31-2009, 10:38 PM
#3
Rennlist Member
Thread Starter
Thanks for the suggestions
It is getting spark for sure since it starts and idles. I'll try those things and see what happens.
Any thoughts about increasing the front pump to 28 l/hr from 165 l/hr while sticking with the 165 l/hr secondary (rear) pump? I don't want to create another problem since my original front pump was a 165 l/hr.
Thanks!
Any thoughts about increasing the front pump to 28 l/hr from 165 l/hr while sticking with the 165 l/hr secondary (rear) pump? I don't want to create another problem since my original front pump was a 165 l/hr.
Thanks!
