Driving along I am getting fluctuating readings from my fuel pressure gauge, anything from 0psi to the normal 18psi. I have had the walbro Glacier system for less than 2 years and the fuel pressure gauge is the Westach Electric. How do i know if the pump is going bad or if it is the gauge? Can I use an ohmmeter to check the resistance in the pump or the sending unit? If so what is the setting for checking both? I am confident that if I loosen anything to check if fuel is coming out it will, because the pressure gauge fluctuates. Just trying to check otherwise.

Funny thing is that is seems to hold the pressure better when I am under 1500 rpm. but on the highway it reads very low. Under 1500 rpm or 45mph and below it seems to hold the pressure better...as I let off the fuel it goes down and then catches itself, or when I accelerate again it goes back to pressue and then starts to fluctuate again. Any ideas?? Thanks, Eric

 

Well, an ohmmeter on the fuel sender isn't going to tell you anything different than the pressure gauge.

I'd recommend connecting your DVOM to the pump as an ammeter and see if the current fluctuates when you are having pressure problems.

The other option is to temporarily install a mechanical gauge to see if you get the same fluctuations.

 

Thanks Dave...I am rather clueless as to how I should set the multi meter. Do I use DCV or ACV or another setting? What should it be reading at the pump??

 

First make sure the meter can handle a 10 amp load, most can. Usually you have to move the red lead to another socket on the meter. Then set the meter to amps. Connect it in series with either the positive or negative lead on the pump. Series meaning disconnect the pump and run the power or ground through the meter.

The pump ought to draw about the same amount of current all the time. If the current is stable like it ought to be, you have a flaky gauge or something wrong in the regulator. If the current is jumping around, then the pump is dying.