I think I need a new fuel pump....

F

Fitman

Member
Joined
Jul 14, 2014
Hello everyone,
I have done about every bolt on performance aid to my '87 GN and it STILL will not do better than a 12.50 ET
A few people told me to check my fuel pump. A friend let me use his extended hose fuel psi gauge to view outside of the hood while driving.
Anyways, I've been told by everyone that it should read 1-to-1 psi to at boost. With vacuum line off of fuel regulator it reads 43 psi. At WOT with 28-psi (yes you read that correctly 28-psi) it, the fuel psi gauge, reads 63 psi. So to my understanding it should be around 71psi. With this test results, should I get a new fuel pump now? If so, will this improve my performance that much?
I attempted to attach a couple PL file's from last night runs. Hopefully I did it correctly.
Any help would be greatly appreciated, thanks all in advance!
 

Attachments

  • fri3.dat
    402.5 KB · Views: 54
  • fri1.dat
    377.3 KB · Views: 36
Fitman said:
Hello everyone,
I have done about every bolt on performance aid to my '87 GN and it STILL will not do better than a 12.50 ET
A few people told me to check my fuel pump. A friend let me use his extended hose fuel psi gauge to view outside of the hood while driving.
Anyways, I've been told by everyone that it should read 1-to-1 psi to at boost. With vacuum line off of fuel regulator it reads 43 psi. At WOT with 28-psi (yes you read that correctly 28-psi) it, the fuel psi gauge, reads 63 psi. So to my understanding it should be around 71psi. With this test results, should I get a new fuel pump now? If so, will this improve my performance that much?
I attempted to attach a couple PL file's from last night runs. Hopefully I did it correctly.
Any help would be greatly appreciated, thanks all in advance!
Click to expand...
Yes idealy you should be seeing 71 psi. Usually when a fuel system cannot keep up the pressure will start of closer to the target pressure and will drop as rpms and injector duty cycle % goes up......as the system cant supply the required volume to maintain the pressure target. .....Now if your pressure is a rock steady 63 psi i would first look at the boost reference signal going to the regulator ......although rare i have Seen this signal pressure not matching the boost pressure due to a blocked line a cracked rubber hose or other issue......you should also check the voltage drop at the fuel pump with the pump operating at the 71 psi target pressure....you need a compressed air source and a adjustable regulator to do this......you need toturn your boost down until you get this sorted out or you will be putting head gaskates on it very soon......
 
Your TPS voltage @ WOT is low ( 4.0 v & under ) , only once did it hit 4.3 v just before shut down . Is your TPS set right ?? Or is the floor mat stuck under the gas peddle ( had it happen to me ). Also post up your mods in your signature . Sam
 
Fitman said:
I have done about every bolt on performance aid to my '87 GN and it STILL will not do better than a 12.50 ET
Click to expand...
et is about how the car works.a good 44 car will 60ft in the 1.5 range, trap in the high 1 tens low 120 s,while going mid to low 11s.at 28 psi you should should be making solid 11 sec passes if the car is leaving good and making power.
 
Fitman said:
Hello everyone,
I have done about every bolt on performance aid to my '87 GN and it STILL will not do better than a 12.50 ET
A few people told me to check my fuel pump. A friend let me use his extended hose fuel psi gauge to view outside of the hood while driving.
Anyways, I've been told by everyone that it should read 1-to-1 psi to at boost. With vacuum line off of fuel regulator it reads 43 psi. At WOT with 28-psi (yes you read that correctly 28-psi) it, the fuel psi gauge, reads 63 psi. So to my understanding it should be around 71psi. With this test results, should I get a new fuel pump now? If so, will this improve my performance that much?
I attempted to attach a couple PL file's from last night runs. Hopefully I did it correctly.
Any help would be greatly appreciated, thanks all in advance!
Click to expand...


Definitely something a miss, I ran an 11.88 with a TE44 at 113. I didn't have a PL when I made my passes, but I did have a program called WinALDL and I was able to collect data on my passes. My turbo spooled to 24psi, no problem, but by the time I trapped my boost was 17-18psi. Later found a small leak in my cross over pipe. I would expect you to be running in 11s.
What fuel pump do you have now? I had two fail on me.
 
stock pump now
but ordered a 255lph Walbro & intermediate wiring from Full Throttle friday night
 
Fitman said:
stock pump now
but ordered a 255lph Walbro & intermediate wiring from Full Throttle friday night
Click to expand...

stock pump won't support the mods you have even with a hotwire and volt booster and the kitchen sink thrown at it .. the 255 will wake the car up

only thing saving you was the ALKY and VP you had in it
 
that's what I've been thinking as well. it's probably whats been keeping me from breaking into the 11's huh?!
btw,,, i checked my voltage to pump and i'm getting 13.7 volts
thanks for your input
 
Fitman said:
that's what I've been thinking as well. it's probably whats been keeping me from breaking into the 11's huh?!
btw,,, i checked my voltage to pump and i'm getting 13.7 volts
thanks for your input
Click to expand...

not sure about the 11's ... ET isn't at all important to me as it doesn't tell me much about what the car is doing .. now if you posted the mph both in the 1/8 and 1/4 ... I could give you an idea if its in the ballpark :)
 
Fitman said:
12.50's @ 110 mph all night long
Click to expand...

yupp mph is LOW for the parts you have and boost your running ... should be upper teens if not 120 ... start with the pump .. datalogg and re post files ... make sure it pulls clean to 5200

stock valve springs ?
 
Not to sound like a dick, but the fuel pump should have been your very first mod. ;) I've never seen such a built car without such a key component. Your car car is going to fly after you get that sorted out!! Good luck.
 
Also, there isn't a mention of the timing chain condition or mileage on the one that's in there. Getting my timing chain done was a night and day difference for my. The stock one had run its course.
 
phil_jordan said:
Not to sound like a dick, but the fuel pump should have been your very first mod. ;) I've never seen such a built car without such a key component. Your car car is going to fly after you get that sorted out!! Good luck.
Click to expand...

Good thing you dont wrench on these things fulltime... You wouldnt believe all the BS and misinfo on these cars .. Yea im sure the car will respond when he gets it upto par
 
Phil, No offense taken. LOL Since I just recently bought the car about a year ago and truly it has been a learning experience. Never had turbo car before, but I DO LOVE IT!
My car only has 33k miles.
Thanks for all your responses
 
Fitman said:
Phil, No offense taken. LOL Since I just recently bought the car about a year ago and truly it has been a learning experience. Never had turbo car before, but I DO LOVE IT!
My car only has 33k miles.
Thanks for all your responses
Click to expand...
That's really low mileage! Sounds like an awesome car. I suspect the timing chain hasn't been done yet?
 
You must log in or register to reply here.

Similar threads

spaceturbo
fuel Pump advice
Replies
4
Views
635
626gn
626gn
Toddmc66
Fuel pressure too high. Cut off the end of the return lin.
Replies
8
Views
436
dynoman
dynoman
C
No fuel
Replies
5
Views
519
hensleyt
hensleyt
8
looking for proper fuel pressure setting for the carbed turbo setup
Replies
3
Views
577
81LimitedT
8
S
Need help
Replies
4
Views
667
SuperStud28
S
Top