Fuel Pressure Gauge Fluctuates

[rlane547]

Hey everyone.  I have a glowshift fuel pressure gauge on my 99 and it fluctuates a little intermittently. I run a FASS 150 and I also replaced the stock filter housing with a 2 micron spin on filter and located my sending unit in the output port of the housing.  Fuel pressure never drops below 15 at wot and never above 18.  It seems to only fluctuate at idle.  Also I removed the banjo line and replaced with 1/2 hose straight into the vp44. What can I do to stop the fluctuations and should I move the sender closer to the injection pump?

[mopartechnician]

You probably have a bad sender. I have replaced three on one pickup (glows&%#) . They sent out a new designed snubber with the last sender. Does it drop when the heaters are cycling? Why did you install a 2 micron filter when you can run a 2 mic on the fass?

Edited April 16, 2014 by mopartechnician

[mulcher812]

With the Glows#!% gauges I would say its the sender also...  they really dont have the best fuel gauges.

[dripley]

You could get a mechanical test gauge and double check your pressure and see if they both are fluctuating. My first FP gauge was a Glowshift and it worked fine for a while then start going crazy, but not just at idle. Do you have a needle valve or snubber or something protecting the sender from the VP pulses? The pulses will destroy the sender.

[Mopar1973Man]

Hey everyone.  I have a glowshift fuel pressure gauge on my 99 and it fluctuates a little intermittently. I run a FASS 150 and I also replaced the stock filter housing with a 2 micron spin on filter and located my sending unit in the output port of the housing.  Fuel pressure never drops below 15 at wot and never above 18.  It seems to only fluctuate at idle.  Also I removed the banjo line and replaced with 1/2 hose straight into the vp44. What can I do to stop the fluctuations and should I move the sender closer to the injection pump?

 

Correction... Move the sender FARTHER from the VP44. Closer you get the stronger the water hammer pulse are and the less time it takes to destroy a fuel pressure sender. What people don't under stand is there is roughly like 600 pulses a second coming from the VP44. In a mechanical gauge the pulse are very audible as a buzzing noise that changes with RPM's but with a electric sender the same buzzing noise can be heard over the clatter of the Cummins. But it still there eating away at the electric senders.

[rlane547]

Okay. Checked pressure with mechanical gauge and they're well within limits. Ordered a snubber valve and will relocate sender to firewall away from the engine. If it still doesn't work I'll do what I should have done in the first place and buy a better gauge. I knew better!

[rlane547]

You probably have a bad sender. I have replaced three on one pickup (glows&%#) . They sent out a new designed snubber with the last sender. Does it drop when the heaters are cycling? Why did you install a 2 micron filter when you can run a 2 mic on the fass?

Ignorance and availability. I didn't even check to see if they offered a 2 micron and I needed to replace cracked stock housing. I was a little wary of the FASS filter/separator and wanted a little extra insurance with filtration. Probably unwarranted.

[Yankneck696]

2 micron is NEVER unwarranted. It should come stock.

 

Ed

[mopartechnician]

Gotcha on the 2 micron. I run 2 mic on my airdog and 5 micron in stock housing. But your situation was different. The last pickup I put the banjo bolt in the bottom of the filter housing. Then ran a braided hose up to the sender with the new style snubber. We will see how long it lasts. Somebody could make a killing if the bought DiPricol. Hint hint ED