About 6 months ago I installed a Walbro fuel pump and it has been working perfectly up until thursday. I have it set right now to idle between 18-20 and rarely drops below 14 or so unless I have the comp on 5x5. Well, as of lately, my guage will go from 20, give it a little throttle(and I mean a little), and it will drop down to 3-5 psi, bounce around there for a minute, sometimes drop to 0 if you are on the gas at all, then, 30 seconds later go back up to 15-20 like normal gain. It is kind of intermittent, as in stop and go traffic, it will only do that say 1 out of 5 times taking off from a stop light. Autometer electric gauge that is only 6 months old mounted off of the schraider valve with a rubber hose and sending unit is on the fender, with a needle valve almost all the way closed. Think the sending unit is bad already? I first changed the filter and cleaned the filter that is pre-walbro that came with the kit, both looked good and did not fix the problem. The pump sounds like it is operating normally, ie, no surging or anything. Drop the bucks on a mechanical gauge before coming to any conclusions? What is your guy's take on this?

Thanks

 

I had some pressure issues and found air in the filter canister. loose fitting in the input side of the lift pump.

 

I'ed bet it's the sending unit. I don't have an electronic gauge but all my fuel pressure problems to date have been gauge/isolator related. It drove me crazy for a while but once it was fixed fuel pressures have been rock steady.
If you can get your hands on a machanical gauge for a few hours just by-pass your current system and see what it's doing.
Mike

 

I just got my walbro on and had terrible fuel pressure drop. I have a big truck fuel filter on the draw side so I pulled the stock fuel filter out after driveing it about 15 miles. Cured the problem, pressure won't drop below 14 with comp on 4x4. The stock filter was almost new with about 1000 miles on it.