Fuel Pump Failing/Failed?
02-16-2014, 01:00 PM
#1
Pro
Thread Starter
Fuel Pump Failing/Failed?
I believe I have a failing fuel pump on my 86 951...just looking for a little confirmation from the brain trust.
The car has consistently had the slightest of "bumpyness" when just getting into the boost. Enough to notice, but so minimal as to not convince me to really delve into it. Fast forward to a couple weeks ago.
Went to move the car out of the garage and was faced with a really hard start. When started, would only idle with a lot of pedal. Took it out for a drive and things seemed fine until I attempted hard acceleration in boost. Did pretty well until up to about 10 lbs, then loss of a lot of power. Same symptoms during numerous attempts at same scenario. Wasn't sure where to start looking until I noticed a whine coming from the rear of the car rolling back into the driveway. Closer inspection seemed to indicate the noise was coming from the fuel pump area.
Pending any additional direction from the group, plan is to replace the pump and screen.
Inputs? Concurrence?
Additionally, with my boost set at a conservative 12 lbs, it seemed to shoot up to 15lbs as the engine lost power. Could there be any correlation between fuel starvation and the spike in boost? No indication of any obvious failures such as leaks or disconnected vacuum lines.
Car is mostly stock with a Lindsey DP wastegate and manual boost controller.
Thanks all.
The car has consistently had the slightest of "bumpyness" when just getting into the boost. Enough to notice, but so minimal as to not convince me to really delve into it. Fast forward to a couple weeks ago.
Went to move the car out of the garage and was faced with a really hard start. When started, would only idle with a lot of pedal. Took it out for a drive and things seemed fine until I attempted hard acceleration in boost. Did pretty well until up to about 10 lbs, then loss of a lot of power. Same symptoms during numerous attempts at same scenario. Wasn't sure where to start looking until I noticed a whine coming from the rear of the car rolling back into the driveway. Closer inspection seemed to indicate the noise was coming from the fuel pump area.
Pending any additional direction from the group, plan is to replace the pump and screen.
Inputs? Concurrence?
Additionally, with my boost set at a conservative 12 lbs, it seemed to shoot up to 15lbs as the engine lost power. Could there be any correlation between fuel starvation and the spike in boost? No indication of any obvious failures such as leaks or disconnected vacuum lines.
Car is mostly stock with a Lindsey DP wastegate and manual boost controller.
Thanks all.
02-16-2014, 01:49 PM
#3
^^^ +1. Gauge test it 1st. Normal fuel pressure is 32/35 psi.
How old is the fuel filter?
Hook up a hose to the gauge / rail connector to a can / jar, jumper the fuel pump relay and chk for restricted fuel flow
A TPS unit will cause a stumble if it has moved or failed , chk to see that its clocked correctly and hasn't moved from its correct position .
How old is the fuel filter?
Hook up a hose to the gauge / rail connector to a can / jar, jumper the fuel pump relay and chk for restricted fuel flow
A TPS unit will cause a stumble if it has moved or failed , chk to see that its clocked correctly and hasn't moved from its correct position .
Last edited by spanky; 02-16-2014 at 02:04 PM.
03-14-2014, 04:19 PM
#5
Pro
Thread Starter
Finally got around to hooking up a pressure gauge and tested *per Clark's Garage.
Relay jumped, not running: holds a steady 41 PSI (* should read 36 +/- 3)
Replaced relay, started and idled: held at 40 for about 10 seconds, then pegged the gauge at 100 psi (* should read 29 +/- 3)
Engine off after 15 min: down to 0 psi (* should read 14.5 after 20 min)
Looking for direction... FPR? Damper? Fuel pump still suspect? Keep in mind that as I parked it last time, there was a definite whining coming from the fuel pump area...
Thanks for any inputs.
Relay jumped, not running: holds a steady 41 PSI (* should read 36 +/- 3)
Replaced relay, started and idled: held at 40 for about 10 seconds, then pegged the gauge at 100 psi (* should read 29 +/- 3)
Engine off after 15 min: down to 0 psi (* should read 14.5 after 20 min)
Looking for direction... FPR? Damper? Fuel pump still suspect? Keep in mind that as I parked it last time, there was a definite whining coming from the fuel pump area...
Thanks for any inputs.
03-14-2014, 09:54 PM
#6
Three Wheelin'
someone correct me if im wrong. psi jumping to 100 is a sign of a bad fpr. 0 psi after shut off is a sign of a bad check valve at the pump or a leak somewhere.
03-26-2014, 05:20 PM
#7
Pro
Thread Starter
Situation resolved!
Changed out the FPR, started the car and the pressure settled down to about 35 psi. Went out for a drive (cautiously) pushing the boost. Performed flawlessly. Thanks much to Lart for hooking me up with a quick FPR to get me back on the road!
Curiosity question... As indicated in the OP, when the engine started faltering, I noticed a boost spike. After replacing the FPR, I got on her pretty hard, and the boost stayed right where I had it set with the MBC. What could the correlation be between a failed FPR and the boost spike?
Changed out the FPR, started the car and the pressure settled down to about 35 psi. Went out for a drive (cautiously) pushing the boost. Performed flawlessly. Thanks much to Lart for hooking me up with a quick FPR to get me back on the road!
Curiosity question... As indicated in the OP, when the engine started faltering, I noticed a boost spike. After replacing the FPR, I got on her pretty hard, and the boost stayed right where I had it set with the MBC. What could the correlation be between a failed FPR and the boost spike?