Evening Im new here we have a Pleasureway motorhome built on a 2000 Dodge 3500 Ram Van with a 5.9 gas engine. I tested the fuel pump pressure with a mechanical gauge yesterday and the pressure is good @ 49 but at a idle the needles vibrates about 2 back and forth. Accelerating the needle steadies and is smooth but when you take your foot off the engine rpm drop and the needle flutters not as fast as at idle but from about 40 to 50 a much wider range than the vibrating then it stops after a few seconds and goes back to vibrating until you accelerate again. Can anyone tell me what are some possible causes for this to happen. According to my big factory repair manual the pump and regulator and only filter are in the tank. Also i think i read where the regulator is not vaccume connected. I would appreciate any info Thanks Much.
Grumpy

 

That's just mechanical regulator flutter and is nothing to worry about. Mine has done this since I bought it over 4 years ago.

 

Are you saying the vibration or flutter or both are normal?? Thanks very much for the reply. Will that effect mpg any? cant seem to get any
Thanks
Grumpy

 

Yes it is normal when a mechanical regulator is used. This doesn't mean every single van will read this way, but if it does it is not a problem. It does not effect MPG at all.

 

So is 10 mpg normal for the 3500 with a 5.9 ?? I had older models same motorhome set up that got near steady 15 and this beast is doing real good to do 11 and it seems with or without a dingy behind it in town or highway makes little or no dif??? Im no mechanical genius but seems something is amiss?? Thanks so much for your reply.
Grumpy

 

It can be depending on how you drive. The terrain, highway or city driving, and the load in or being pulled behind are all factors. I have a V6 and with the weight of tools and materials that I haul around, I average 13 MPG highway and city.

 

I did forget one thing about the fuel and pressure gauge; actually the reason we started checking the pressure; after we had had the van for about 3 mo. we noticed a new noise, a humming kinda loud i guess since i wear hearing aids (big ones) and i could hear it. This humming is coming from what were sure is the fuel pump. I ran the tank down to about `1/4 tank and added a can of BG 44K and ran that then filled with prem. gas then when it got down to 1/4 tank agan we repeated. the noise seem to go away but it has came back so we thought the pressure test would tell if it was going out. Is this humm or loudning of the hum of the fuel pump indicate this??
And the weight of the vehicle on the mpg thing. it is a pleasureway motorhome on the 3500 van chasis 2000 year. I dont know the weight but it is not a power problem for the unit and we previously owned two others a 95 and 96 very simular units and both got 15mpg this 2000 is no where near that. Any thoughts on any of my babbling would be greatly appreciated.
Thanks, Grumpy

 

If you're getting 49 PSI then the fuel pump motor is working fine. The pumps do make a noise that can be heard outside. It's even louder if the gas cap is off with less than 1/2 a tank of fuel. My analysis is that the pump is fine and you have a very good hearing aid.

 

Thanks very much for all the help;
We will give it a good set of new plugs and call it good as it gets

Thanks
Grumpy