Fuel pres. jiggles too much -- any help?

[Kyle]

I've got dual AutoMeter fuel pressure senders (before/after filter). The needle on the gauge vibrates too much for my taste. Plus these senders are pretty expensive so I'd like to protect them as best I can.



Does anyone out there know of a "restrictor" or something I can put upstream of the sender to settle the needle down?????



Any help would be much appreciated.



Thanks,

Kyle

 

[CumminsAholic]

Good idea. I've got a mechanical gauge and it rarely moved before I put in the new pump. Now sometimes it'll move a half pound up and down. I dunno why it didn't do it before, maybe this pump needs to get broken in. Or maybe that's why everyone's having so many problems with the electric gauge senders, because the pump "pulses" so much. I'd think that by running a smaller size hose it'd cut down on the pulses, but they'd still be there. It'd just cut back on the volume of fuel that's pressing on the sender. It may help though. It'd be easy and cheap to try, just get a smaller i. d. hose. I'll stick to my mechanical gauge with a -4an line running to it.

Corey

 

[Deezul1]

If its possible mount an inline gasser fuel filter before the sender. It will act as a accumulator tank and dampen the impulses

 

[Joe G.]

Kyle,



Is your truck a 12 or 24 valve? Big difference in fuel pressure behavior.

 

[illflem]

Here are the devices you need that are made for the job, I prefer the needle valves 5WL12, they're cheap http://www.grainger.com/images/catalog/1421.GIF lower left corner. If you run a fuel pressure gauge on a 12 valve without a snubber it won't last a month, mechanical or electrical.



For some reason the page I linked to goes small after loading, if you right click on it an icon with arrows coming out of the corners appears in the lower right corner to enlarge the page.

 

[Kyle]

Deezul,

Now there's an idea I never would have thought of! I was thinking about a plug with a tiny hole through it to restrict the flow (even though there's not really any "flow").



You're saying put a "chamber" in between. I guess I just don't know enough about fluid dynamics.



I was also thinking about a softer hose in between. Let the rubber expand to take some of the bite out of the pressure change. Hhhhmmmmmmmmmmmmm

 

[Kyle]

Oops, didn't see the other replys come in.



Joe, it's a 24-valve - any advice?



Illflem (illflem?), That's exactly what I was looking for. Didn't think of a needle valve. I've got a few of those laying around and they're 1/8-inch -- just the right size. I think I may need to do a little experimenting this weekend. How far do you open the valve? How do you keep it at the right setting?

 

[Joe G.]

Kyle,



I have a 12 valve, but the needle valve should work about the same way. Just fool around with it until you get the vibration damped out without slowing the response too much. The problem is a LOT worse on the 12 valve with the pressure spikes from the mechanical lift pump. Not only will the spikes thrash a gauge shortly but the gauge is noisy before it quits.

 

[illflem]

Kyle, it's a two person job to adjust the needle valve, one to turn the valve and one to watch the gauge. Just crank it down till the pulsations stop. The Grainger valves have a lock nut to hold the adjustment. It's best to install the needle valve close to the source of your pressure rather than in the hose. This prevents the hose from pulsing which can chafe the hose. The inline fuel filter method will also work until the filter fills with fuel. What happens is air, which compresses, absorbs the pulse. It doesn't take long for it to fill with fuel and pulse, but works great for a temporary non-mounted gauge.

 

[Kyle]

Thanks guys for a simple, cheap solution.



After you get the valve set the way you like, how do you keep it from moving on you (opening up from the vibrations)? Maybe there's enough friction that they don't open up. I could crank down on the packing or thread the shaft and install a little lock nut. I don't want to go to a bunch of trouble trying to prevent a problem I wouldn't have had anyway. Have yours ever moved on you?

 

[illflem]

I have only had to readjust mine twice in 3 years. Tightening the packing nut down will work fine. Another trick is to use a rubber grease gun hose for jumpers, they have 1/8" NPT male fittings, are rated for 15k psi and are cheap to come by. Great for relocating a sender away from the engine vibrations.

 

[Kyle]

Thanks again,



That'll get me going...