Fuel delivery problem on my S5 Turbo
#1
Fuel delivery problem on my S5 Turbo
Hey guys... so I've run into a problem with my car recently. As most of us know, when you turn the key to the on position (not cranking) you'll hear your fuel pump prime and buzz to its little motor heart's content and then proceed to start the engine. My fuel pump is not doing that anymore and not allowing the engine to start up.
It happened out of nowhere, I drove the car earlier the day that it happened with no issues, boosting around and all... went back in, cranked it up, didn't make it out of my driveway when it just shut off.
I checked for power going to my fuel pump, and I'm getting around 5 volts at the relay under the steering wheel, and at the plug for the fuel pump when the key is in the on position. I've replaced the relay in hopes that may have been the problem along with the fuel pump and still no luck.
I have tried hard wiring the fuel pump straight to the battery to see if the pump turns on, and it does. However it doesn't build up more than 10psi of pressure according to the gauge on my FPR.
I'm running a microtech ltx8 ecu, Aeromotive afpr, and a Walbro 255lph. I'm stumped on what else it could be...
It happened out of nowhere, I drove the car earlier the day that it happened with no issues, boosting around and all... went back in, cranked it up, didn't make it out of my driveway when it just shut off.
I checked for power going to my fuel pump, and I'm getting around 5 volts at the relay under the steering wheel, and at the plug for the fuel pump when the key is in the on position. I've replaced the relay in hopes that may have been the problem along with the fuel pump and still no luck.
I have tried hard wiring the fuel pump straight to the battery to see if the pump turns on, and it does. However it doesn't build up more than 10psi of pressure according to the gauge on my FPR.
I'm running a microtech ltx8 ecu, Aeromotive afpr, and a Walbro 255lph. I'm stumped on what else it could be...
#2
Retired Moderator, RIP
iTrader: (142)
Join Date: Sep 2005
Location: Smiths Falls.(near Ottawa!.Mapquest IT!)
Posts: 25,581
Likes: 0
Received 131 Likes
on
114 Posts
I am sure that the pump doesn't turn on until you go to Start..then the AFM kicks the relay to keep the pump running.
Have you checked the pressure while jumping the fuel connector?
Is the stock fuel supply still wired as stock?
Have you checked the pressure while jumping the fuel connector?
Is the stock fuel supply still wired as stock?
#5
Rotary Freak
iTrader: (10)
Originally Posted by 88fc3sT2
Not running an AFM. And yes, when I turn the key, pump goes on. Happened every single time. All the wiring looks stock to me.Weird though because the fuel pump is brand new.
Trending Topics
#11
So I went back in the car to test the relay on the steering column, and used a separate ground to test for power and got 11.xx volts on two pins. Now, what I'm thinking is that maybe the ground for the relay is no good. Does that sound like a possible cause for this lack of delivery in voltage?
#12
Moderator
iTrader: (1)
Are you testing w/key to start and which wires have power. You're being ambiguous and it's hard to get a handle of what you are doing. Top left has voltage w/key to start. Top center has voltage w/key to on. Top right wire (remember, that Blue wire) has power w/key to start and key to on if the fuel check connector is jumpered. Bottom left wire is the constant ground.
#13
Are you testing w/key to start and which wires have power. You're being ambiguous and it's hard to get a handle of what you are doing. Top left has voltage w/key to start. Top center has voltage w/key to on. Top right wire (remember, that Blue wire) has power w/key to start and key to on if the fuel check connector is jumpered. Bottom left wire is the constant ground.
Went ahead and replaced the fuel filter because the pump wasn't producing enough fuel pressure, but that didn't clear my problem. I'm narrowing this down to my fuel pressure regulator. Gonna check in a bit to see if that is my problem.
#16
Moderator
iTrader: (1)
The Brown wire is a temporary ground and only grounds when the car is running . The top center wire should be 12 volts w/key to on and it should be Black/White. The B/R wire should be at the top left position and has voltage only w/key to start. When the B/R wire has power w/key to start then the Blue wire should have voltage as it powers the fuel pump. Does the Blue wire have power or not w/key to start? If the bottom two wires (Black and the Brown wire) are jumpered then the B/W wire (again, top row center position) and Blue wire should have voltage w/key to on. Does it? This will tell you if the relay is good or not and takes but a couple of minutes to doi.
#19
So I'm getting power to all the right connections. Everything works as it used to. Was able to pump out 42psi of fuel and got the car running for maybe 5 seconds. Then lost fuel pressure again. Since then, I haven't been able to figure out why my pump isn't putting out the necessary pressure. It primes and everything but only to 10psi. I checked the connection for the signal wire that goes from the plug on the pump to the relay for my microtech and it seems fine. I cleaned the contacts and put some electrical grease to help the connection but still nothing. Even went and got a new battery. I'm lost lol
#20
Moderator
iTrader: (1)
Jumper the bottom two wires of the circuit opening relay and see if this helps. Also, the car has an additional fuel relay under the AFM which could be problematic. If you jumper both Blue/Red wires at this relay it will bypass it.
And if the car starts and cuts out then leave the key to the on position and look for the Green check connector with 3 wires near the lead coil and make sure the Black/White wire has 12 volts. If it does not then the relay is shutting off (this would kill the engine).
And if the car starts and cuts out then leave the key to the on position and look for the Green check connector with 3 wires near the lead coil and make sure the Black/White wire has 12 volts. If it does not then the relay is shutting off (this would kill the engine).
Last edited by satch; 09-02-16 at 09:10 PM.
Thread
Thread Starter
Forum
Replies
Last Post
chuyler1
1st Generation Specific (1979-1985)
10
03-16-16 04:49 PM