94 - Hesitation problem still with me.
05-15-2015, 03:55 PM
#1
Le Mans Master
Thread Starter
94 - Hesitation problem still with me.
Had this for a while now and I am on the verge of replacing the pump. It's basically a hesitation off the line, sometimes, and varies to the amount of hesitation at times.
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
05-15-2015, 05:21 PM
#2
Safety Car
From another CF thread.... (just guessing):
"A wideband sensor would tell a lot. And you should be able to duplicate this on a dyno. I would think it would show a sag in the torque curve."
"A wideband sensor would tell a lot. And you should be able to duplicate this on a dyno. I would think it would show a sag in the torque curve."
05-15-2015, 07:04 PM
#3
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Member Since: Jun 2008
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went through this with my '94 last year... i went nuts though, decided to get it over with..
complete fuel sender assembly, filter, pressure regulator and new bosch type 3 injectors... between the sock on the pump and the filter i have now idea how it even ran
she runs flawless...
complete fuel sender assembly, filter, pressure regulator and new bosch type 3 injectors... between the sock on the pump and the filter i have now idea how it even ran
she runs flawless...
05-15-2015, 08:12 PM
#4
Le Mans Master
Thread Starter
went through this with my '94 last year... i went nuts though, decided to get it over with..
complete fuel sender assembly, filter, pressure regulator and new bosch type 3 injectors... between the sock on the pump and the filter i have now idea how it even ran
she runs flawless...
complete fuel sender assembly, filter, pressure regulator and new bosch type 3 injectors... between the sock on the pump and the filter i have now idea how it even ran
she runs flawless...
Seabright - My Tech 1 gives it a good bill of health. O2 swings are good and fast, and my fuel trim numbers are right in the zone, 128 +/- a point or two.
06-02-2015, 03:43 PM
#5
Le Mans Master
Thread Starter
I have now replaced the sock and still seems to do the same thing. So now I have ordered a GM pump and I guess we will see where this takes me. The only other thing to check is the pulsator and other than blowing thru it I don’t know or any other way of getting a feel if the flow is restrictive thru it. I guess I will do this when I have the old pump out first.
06-02-2015, 05:36 PM
#6
Interesting you brought up the fuel sock. I had the fuel pump assembly out a few months back checking the tank for any debris and stuff and did check and clean the sock. It did not look bad but I did get another one which is sitting in my garage at this time. I did not have the new sock at that time.
Seabright - My Tech 1 gives it a good bill of health. O2 swings are good and fast, and my fuel trim numbers are right in the zone, 128 +/- a point or two.
Seabright - My Tech 1 gives it a good bill of health. O2 swings are good and fast, and my fuel trim numbers are right in the zone, 128 +/- a point or two.
06-02-2015, 08:05 PM
#7
Instructor
I have now replaced the sock and still seems to do the same thing. So now I have ordered a GM pump and I guess we will see where this takes me. The only other thing to check is the pulsator and other than blowing thru it I don’t know or any other way of getting a feel if the flow is restrictive thru it. I guess I will do this when I have the old pump out first.
06-02-2015, 10:17 PM
#8
i have the same thing in a 85.
different motor but ill sub and see what your solution is.
06-02-2015, 10:21 PM
#9
Le Mans Master
Thread Starter
The O2s might be original.
But after testing and checking everything, the only thing that gave any indication to a clue of the problem was a instantaneous drop or delay in fuel pressure as I step on the gas looking at a fuel pressure gauge on the hood. Just a momentary hold back on light acceleration usually when taking off.
I am familiar with a piece of hose replacing the pulsator. Seems like it was in there for a reason and if it is good I would like to leave it in.
But after testing and checking everything, the only thing that gave any indication to a clue of the problem was a instantaneous drop or delay in fuel pressure as I step on the gas looking at a fuel pressure gauge on the hood. Just a momentary hold back on light acceleration usually when taking off.
I am familiar with a piece of hose replacing the pulsator. Seems like it was in there for a reason and if it is good I would like to leave it in.
06-02-2015, 10:29 PM
#10
The O2s might be original.
But after testing and checking everything, the only thing that gave any indication to a clue of the problem was a instantaneous drop or delay in fuel pressure as I step on the gas looking at a fuel pressure gauge on the hood. Just a momentary hold back on light acceleration usually when taking off.
I am familiar with a piece of hose replacing the pulsator. Seems like it was in there for a reason and if it is good I would like to leave it in.
But after testing and checking everything, the only thing that gave any indication to a clue of the problem was a instantaneous drop or delay in fuel pressure as I step on the gas looking at a fuel pressure gauge on the hood. Just a momentary hold back on light acceleration usually when taking off.
I am familiar with a piece of hose replacing the pulsator. Seems like it was in there for a reason and if it is good I would like to leave it in.
06-02-2015, 11:22 PM
#11
Le Mans Master
Thread Starter
06-25-2015, 04:57 PM
#12
Instructor
Had this for a while now and I am on the verge of replacing the pump. It's basically a hesitation off the line, sometimes, and varies to the amount of hesitation at times.
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
I also am getting feedback through the gas pedal when it hesitates. It feels like something is pushing back against the pedal. If I let up for an instant and then push on the gas pedal again the car will take off. Someone suggested I try it with the traction control turned off. I haven't tried that yet.
Have you experienced a similar condition?
07-03-2015, 04:47 PM
#13
Had this for a while now and I am on the verge of replacing the pump. It's basically a hesitation off the line, sometimes, and varies to the amount of hesitation at times.
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
FPR and fuel filter has been replaced. Fuel pressure good. Drive with a fuel pressure gauge (on windshield) for a while and it seemed when the hesitating occurred, the pressure dropped few pounds for a sec. Engine runs well, ignition OK, no high speed or acceleration problem while up at highway speeds that is apparent.
So my thinking is the pump is getting tired after 22 years. But just wondering if pulsator could be possibly restricting the flow of fuel off the line (normal driving).
I don’t know if taking it all apart to look at it is a worthwhile thing to do as the problem is a subtle one and it seems like pump replacement might be the direct course of action. The pulsator things just bugs me as I know there is no real check for it.
Other than leaking, can the pulsator restrict flow?
So check all around: top cover torx screws, four 10mm bolts, IAC and TPS torx, if they are not well tighted can make an hole for vacuum leaks,