I don't know. Mine does. Thats what I been asking about. It chatters three or four times. I was hoping when I quit using the heater relay and put a nother on there it would be less sensitive to the pulses. It has not worked for me.

A friend of a friend ahd an issue with a '99 and took it to the dealer and they changed the ECU. I'm curious if the ECU is designed to lower the V and not cut it. If those of use who have issues with may have issues with the LP control portion of the ECU.

Randy

 

I have a wire tapped in so that i can unplug it that is run off of a constant 13.3 volts ignition wire. It delivers this voltage constantly. I have experienced no problems running it all the time. It does help when Comp is on 5 & foot is on Floor. I have a quick connectcrimped for it. I leave it unhooked most of the time.

 

The driver in the engine processor might be causing alot of problems with the lift pumps.Might be a good idea to drive around with a volt meter on this wire.To check on its normal habits,might even learn about its logic.

 

On my truck today,on a normal startup, with a lab scope.As soon as the ignition awoke the processor,the fuel pump control, read full battery voltage12.6v-12.7v .As I cranked the engine it continued to read 11v to11.5 never ever varying no pulsation at all as it started it jumped to 13.8 to 14v again, it never varied at all.The pump control on my truck seems to run the pump with full battery voltage.Or in my case the fuel pump relay always stays on.In my particular case I do not have my heater grid hooked up.That is probably why I'm not seeing a pulse.You guys may be reading the heater grids dropping the voltage as a pulse.

 

It is 100 degrees here. No heaters turning on. That and one of my grids are unhooked. I used one of the relays to begin with then I thought I fried the control side (trying to explain the pulse). With my Fluke 89 I get 0v with key off. .29~v key on, pump off. 12.5v with pump running. And with initial key on it pulses faster then the meter can handle but I believe it is going to 0v. I started another thread asking about it and post more details there. Before I replaced the fuel sys. there were times the LP did not run on intial key on until I bumped the key. I think this may be a driver issue.

Randy

 

or just your volt meter with no load. Then watch the voltage,It may be a case of a failing driver,causing pulsation when the load excedes the abilities of the driver.

 

The pulses were meter only (and the pump). I've been thinking about a CAP and Diode in the + of the control to artifically extend the T/C of the relay and carry over the pulses but haven't do it yet.

Randy

 

That my signal is straight and solid and yours is a pulse.

 

Maybe the behaviour of the ECM regarding LP supply was changed over the years. I've put mine on an oscilloscope (sp?) and saw the pulses there. (Sorry, not a digital version so no printouts).
Might be just a freak occurrance that my PCM s doing it. I did find that the starting current of my Holley blue in winter is around 19A. Since then I've replaced the relays with a 30A class A transistor. I also made a wire with a switch under the hood to turn on the LP without bumping the key. Helps a lot when changing the filter. (My pump ressure relief is set to 17 psi, with the engine at standstill it will force the overflow valve of the VP44 open, and purge tha air from the system. )

AlpineRAM

 

Maybe the there was a change in the logic for model or a plain software upgrade. I'll try to get some more solid info from my friend about this truck. Maybe I can get them to put a meter on it.

Randy