poston fuel pump problem!

[buickpower]

My car has been leaning out pretty bad, like 730mv on 15psi! I am running a poston fuel pump which is apparently a modded syclone pump, and is essentially new. I also run 37lbers and fp of 47 line off (new accufab). I had tried a bit lower pressure ~45 with the same end result. My translator is also on the max rich WOT setting, 14%. But still the fuel pressure gauge does not even go as high as it should (62) it hits mid 50's, and decreases from there! I have verified that the pump is getting good voltage 13.9 at the back of the car where the pump plugs in, and that the alternator is getting good voltage during the run. I even tried changing the fuel sock and filter up front, to no avail.

My question is, has any one else had similar problems with this pump? It was supposedly rated at 4-600hp . Also, would dropping the fp down to the recommended 42 line off allow the pump to deliver any more volume because of the lower pressure, or should I just trash this pump like i am thinking?

 

[suicide six]

Try a fuel filter first if you havent already, You may be getting 13.9 volts at pump during idle but not at wot. Has the car had a hot wire kit done yet? Check for leaks at vaccum lines as well as hard lines.Pump may be on its way out but check the easy things before dropping tank. your 02 numbers are semi close it maybe just some restriction or a leak.

 

[buickpower]

yeah, i think you may be right. i did the in tank filter today, and i did the inline one a couple of weeks ago, but that was before i started driving the car again so i will probably do it once more for peace of mind.

I also got thinking...I have an oil leak at the front crank seal, I wonder if the oil is slinging out under boost and coating the crank sensor, making it read poorly. And since there is an RPM based fuel trim, could that have some affect? I only consider that because my Maf sensor is 230 and climbing before I let off, and i don't have the fast update burned into the chip for the scanmaster, so it may be pegging.

Any thoughts on this?

Also, the fact that i have to add the max amount of fuel with the translator at WOT worries me. Does the ecm need to be reset everytime you move the switch on the translator or??

 

[suicide six]

47lbs on fp reg seems high to me, but i guess every car is somewhat unique.What kinda knock readings are you getting at wot.How old is o2 sensor?Too much leaded fuel will shorten the life.Maybe all you have is aloose grd for o2 sensor.Check passenger side of motor rear head,this is viewed from under car looking up.If its tight,check for good connection to terimal ends.My 87was doing this last month and like you adding fuel had no effeect to 02 readings. but what concerns me is your fuel pressure readings.

 

[buickpower]

usually there is very little knock, although a couple of times it has registered about 7 degrees. Then other times the o2 millivolts go as low as 695! and there is no knock? at least that is registering on the scanmaster....needless to say i don't stay in it for very long.

I haven't run any leaded gas on this 02 sensor, and it seems to be active, but i may just turn it in under warranty.

Just for the sake of it, here are my scanmaster numbers in park at warm idle:

o2-roaming actively
af: 05
L8: 39
bat: 13.9
Int: 128
Blm: 123
clt: 162
ats: 107
rpm: 775-800
tps: .44
Iac: 09
cc: cycling through 255 actively

 

[buickpower]

ttt

 

[Black Car]

Connect a know accurate mechanical with hose and place it where you can read the gauge while you are under WOT.
That way you can see exactly what WOT pressure you have.
Could be FP regualator(sp) isn't doing its job.

Another thing to check is remove the scheider valve from the fuel rail and connect (push on) a rubber hose and run it into a container. Use the fp test connection (behine alt- Black single wire connector) to run the fuel pump for one minute. Measure the amount of fuel that the pump delivered in one minute. Should be right at 1 gal if the fuel lines, filter and pump are doing their job.

Gary

 

[buickpower]

The pressure gauge is one mounted by my wiper, and i am watching it drop. good idea on the flow test. Does that still work even though the pump doesn't have to deliver that volume under the normal operating pressure?

 

[Black Car]

The pressure gauge is one mounted by my wiper, and i am watching it drop. good idea on the flow test. Does that still work even though the pump doesn't have to deliver that volume under the normal operating pressure?

Yes, you are just looking for volumn not pressure.
Another thing to do, run the fuel pump and squeeze closed the rubber return line (near the frame) closed to see what pressure the pump can do dead headed.
I won't keep it closed for more than 30 seconds, just in case if the internal pressure relief on the pump doesn't work.

 

[buickpower]

i'll try that tomorrow. somebody (a mechanic of all people) that i should squeeze it closed and drive around like that. i didn't think that was a good idea because of the pressure... anyways thanks for more tips.

 

[buickpower]

aargh

well, just swapped out the poston pump for a walbro 340. no change... still leans out to high 600's and cuts right out, not sure if this is the computer pulling radical amounts of timing that don't show on the scanmaster, or the car is just plain running out of fuel. i am getting close to my wits end, does anyone have any suggestions?

 

[WH1]

I'm experiencing close to the same problem, O2's between 690 to 750 with alky and hardly any or no knock. Walbro 340 hotwired with less than 300 miles on it and fuel pressure set at 45 psi and double checked with 2 different gauges. Swapped out regulators with no difference. I have noticed that my Scan Master altenator readings are from 11.9's to 13. So before swapping fuel pumps, I'm going to put on a volt booster and see if that helps. Keep me posted so I can see what works for you.

 

[buickpower]

i will keep you posted, and i may end up going to a volt booster as well after reading another active thread with a similar leaning out problem. how do the boosters work anyway?

 

[WH1]

All I know is they provide constant 14 to 15 volts to the fuel components. If you look at my parts wanted thread of "volt booster" 67 Turbo Camaro has offered me one for $50 that I don't need as I have one on the way. He and his brother are stand up people if you choose to buy it from him. HTH.

 

[buickpower]

thanks for the heads up.