fuel pressure drop

[racer5252]

i am having problems with knock and think i have it narrowed down to the fuel pump. i have around 40psi fuel pressure and as soon as i get on it the pressure rises to 55 or so then as it starts boosting the pressure falls back to 40 and stays. it is a walbro 169 pump that is 1 1/2 years old.Also has the hotwire kit. Could it be something else besides the pump?? Thanks

 

[bmackinnon]

i am having problems with knock and think i have it narrowed down to the fuel pump. i have around 40psi fuel pressure and as soon as i get on it the pressure rises to 55 or so then as it starts boosting the pressure falls back to 40 and stays. it is a walbro 169 pump that is 1 1/2 years old.Also has the hotwire kit. Could it be something else besides the pump?? Thanks

Classic sign/symptom of dying fuel pump.... replace it.... and don't get into the boost until you do.... !!!! :wink:

 

[philosobrad]

i am having problems with knock and think i have it narrowed down to the fuel pump. i have around 40psi fuel pressure and as soon as i get on it the pressure rises to 55 or so then as it starts boosting the pressure falls back to 40 and stays. it is a walbro 169 pump that is 1 1/2 years old.Also has the hotwire kit. Could it be something else besides the pump?? Thanks

Follow up on this if you don't mind.....mine has been having same symptoms for the last few days. Then today it left me stranded. I can let it set for a little bit, start it and have great fuel pressure, then watch the pressure slowly drop to zero and dies. I'm GUESSING fuel pump as well.

 

[racer5252]

i think im going to order a walbro from racetronix.They seem to have a good reputation on the board.

 

[GNVYUS 1]

Really, all these Walbro fuel pump issues and everyone keeps rebuying them??

There are other pumps that won't die or cause pressure issues up top, if you want quality then look elsewhere.

 

[racer5252]

The wabro ****169 pump seems to be the one giving everyone the problems. Racetronix sells GSS340M pump that they machine in house. I dont believe there has been any problems with these. Someone please chime in if im wrong.

 

[Racetronix]

The wabro ****169 pump seems to be the one giving everyone the problems. Racetronix sells GSS340M pump that they machine in house. I dont believe there has been any problems with these. Someone please chime in if im wrong.

[FONT=&quot]There were no chronic problems with the GSS340M pump like there was with the F20000169 pump.

Just as with any other DIY HP product there have been some isolated problems with a small handful of customers. Reported issues with Walbro pumps still accounts for less than 0.5% of the pumps sold here. The GSS340M is a pretty safe bet at a good price.[/FONT]

 

[philosobrad]

I had the car towed the few miles it died from the house yesterday evening. Started it in the driveway and let it idle for 20 minutes.......and it did fine.

Not sure now what direction to head.

How does one determine for certain that the fuel pump is sketchy?

 

[philosobrad]

Bump

 

[87GN_70GS]

Loosen the fuel return line, have it dump into a calibrated bucket. Using a stop watch and various fuel pressure settings (50 psi, 60, 70 etc) , measure fuel flow rate (fuel amount divided by time) with the engine off (helps to add a batt charger). Compare the numbers you get with the readily avaible pump performance numbers (can get them off a graph). More than likely, if the pump is bad, performance will fall off at the higher pressures. But, there may be an intermittant failure mode for the pump where the performance checks fine but it just craps out at odd times.

 

[Racetronix]

I had the car towed the few miles it died from the house yesterday evening. Started it in the driveway and let it idle for 20 minutes.......and it did fine.

Not sure now what direction to head.

How does one determine for certain that the fuel pump is sketchy?

You can use a scope to see if there is a problem with the pump's motor. A good tech should have and know how to use one to do this.

 

[SS_Sean]

Oscilliscope? How is a tech going to determine if it's bad if he doesn't have test signal parameters?

 

[Racetronix]

Oscilliscope? How is a tech going to determine if it's bad if he doesn't have test signal parameters?

Test signal parameters?

All one would look for is an even smooth signal pattern if the armature contacts and brushes are OK. If they are not the signal would be noisy and uneven. Auto techs are trained to know what to look for.

 

[philosobrad]

You can use a scope to see if there is a problem with the pump's motor. A good tech should have and know how to use one to do this.

It's strange, I started her up again last Thursday and she idled and revved in neutral fine........even took it for a short ride and back with no issues.......but I DID notice that the typical loud fuel pump whine that it's had since the rebuild was almost inaudible now.......strange stuff.


I got lazy and just ordered a Racetronix Walbro on Friday:biggrin:

I noticed the sock on this year old Walbro was mighty nasty........anyway, we'll see. I'm wondering if the E85 cleaned the varnish out of this factory fuel tank to the detriment of the not that old pump?

Will report back as soon as I have some solid information, and an honest appraisal of the Racetronix product!

 

[Racetronix]

It's strange, I started her up again last Thursday and she idled and revved in neutral fine........even took it for a short ride and back with no issues.......but I DID notice that the typical loud fuel pump whine that it's had since the rebuild was almost inaudible now.......strange stuff.


I got lazy and just ordered a Racetronix Walbro on Friday:biggrin:

I noticed the sock on this year old Walbro was mighty nasty........anyway, we'll see. I'm wondering if the E85 cleaned the varnish out of this factory fuel tank to the detriment of the not that old pump?

Will report back as soon as I have some solid information, and an honest appraisal of the Racetronix product!

You should rinse the tank out a few times before putting in the new pump.

 

[philosobrad]

You should rinse the tank out a few times before putting in the new pump.

Thanks........Dropped it off this morning at a friend's radiator shop this morning for a colonic cleanse.

 

[Racetronix]

Thanks........Dropped it off this morning at a friend's radiator shop this morning for a colonic cleanse.

Check to make sure your yellow bulkhead connector is not corroded and that the tin plating on the terminals is in good shape.

 

[philosobrad]

The fuel pump completely solved the "lean at 15lbs or over boost condition".

The car has never performed better!

Thanks!!

 

[Racetronix]

The fuel pump completely solved the "lean at 15lbs or over boost condition".

The car has never performed better!

Thanks!!

Cool !