piperca

I posted a couple of weeks back regarding my campaign pump taking a dive after 1K. I replaced it with another pump I knew was good. Well, this afternoon I took a run to the hardware store and noticed my fuel pressure, that was 13psi when I left, was now 8psi. This is the same symptom I saw with the other pump. I'm now convinced it's something other than the pump ... any ideas?

Something else that's odd is the fuel pressure increases when I brake.

I'm leaning towards the fuel pickup. Bummer is I just filled up!

davemac

Something else that's odd is the fuel pressure increases when I brake.

Mine does the same thing, I think it`s something electrical. Sitting in the carport I can raise the fuel pressure from 13# to 15# by turning on the headlights, applying the brake (brake lights) & turning on the O/R lights. I`d be interested to know if yours does the same thing.

hotdram

Stupid question for the both of ya'll, but are your FP gauges mechanical or electrical?

~Rob

davemac

Mine`s electric, Westach.
Judging by piperca`s signature, his is too.

piperca

That is correct. I was suspecting the gauge, but this morning the pressure droped to 0psi and jumped up again. I let the truck idle and watched the pressure gauge. Each time the pressure dropped I could hear the pump change tone, it sounded like it was cavitating. I'm going to need to pull the tank module and check it.

Silverjay

I have a Westach and mine does the same thing. 13 with lights off and 15 with lights on.

duner

seems to me if you load the electrical system the regulator should increase the voltage thereby increasing the potential to the pump. just a thought

ratsun

Could it have something to do with the voltage the PCM is sending to the LP?
Perhaps try sending the LP 12v and see if it changes while driving and braking?

piperca

Mine doesn't do that. I suspect you may have tapped into the light fuse?

davemac

Nope, direct to the battery, fused o`course. I tend to go with duner on this one. Not gonna worry about it, as long as I got the fuel pressure...

piperca

The increase I see is when I am braking, the needle climbs 1-2lbs, but when I come to a stop the needle returns to normal, even with my foot on the brake ... strange!

davemac

Could the negative G forces caused by braking react on the fuel in the lines and cause an increase in pressure at the sonsor?

piperca

You may have something there, but I still think it's odd.

This weekend I'm going to R&R the fuel tank module with a new, larger, pick-up ... I really hope it works. I'm finally going to break down and buy a Walbro and regulator. I think some TLC on the fuel system and I'll be back in business.

I've got a job interview tomorrow. I hope she doesn't leave me stranded on the way!

davemac

Good luck with it. Let us know if it works.

Cmonroe

It is normal for fuel pressure to go up as you let off of the throttle and apply the brake. When then engine is under load the pressure will drop and then return as the load drops off. A 24v stock lift pump gives 14 to 15 psi without a load, under normal load mine drops to 8 to 9 with the box off, under fuel throttle and the box on the new Edge will drop your stock pusher pump to 3psi.