Airdog pump help wanted

[Mopar1973Man]

Ok Gang...

While I was out on my camping trip and hauling around my 31' Jayco Eagle Travel Trailer I had some weird fuel pressure problems occuring. Start up cold and get 17.5 just about 18 PSI at a idle and then pull the grade up to New Meadows, ID still holding 16 PSI which is normal and fine. But now as the day got hotter and we got down around Council, ID the pressure fell off to 12.5 at WOT and idled at 15 PSI. Hua??? While I was stopped the at one place I played with bumping the starter and you can see 17-18 PSI and then hear a change in pump pitch and the pressure fall again to 15 PSI. It's like the check ball is hanging up again. So I'm going to pull it back apart and double check again. So later on down the road I pick up fuel I figured I add a extra few ounce of 2 cycle oil than typical. Well the pressure went right back up to normal 17-18 PSI at idle and remain normal the rest of the day with no problems.

(Enjoying our camping)

Now hitched back up early morning and started my way back out of Lowman, ID and got good strong fuel pressure. But by the time I got to Banks, ID the fuel pressure was starting a to fall again. It went back down to the 12-15 PSI range again. On a few other stops I play again with bumping the start and sure enough yo can see 17 PSI for a burst of a second or two and then falls with change of pitch of the pump. I wondering if the fuel temperature is effecting the check ball and spring some how that its not working properly? Because with cold fuel its working fine but as a soon as the fuel warms up it sinks in pressure?

Yes... I got a fresh set of donaldson filters on my truck and no change with that...

 

[ramhunter9]

So what do you think it is ? Warm fuel or check ball ?

I would not say warm fuel as if that were the case you would hear about this more often .

 

[Mopar1973Man]

I'm leaning towards the check ball giving me hell now...

Just got done cleaning and re-installing my RV275 injectors and the fuel pressure was excellent right there at 17.5 no lower than 16...

Grrrr.... I guess its time to pull the AirDog and take a peek tonight...

 

[ramhunter9]

I would like to see this process

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[Mopar1973Man]

Your wish is my command...

Here we go... My AirDog Removed and laying on the workbench.

Here is the standard check ball and spring setup.

Here is my setup with 2 shiming washers to increase pressure.

Here is one washer laying on top of the fitting.

Here is the washer slid a little to show it.

Here is how I install the fitting and washers to keep them lined up.

With a little time and clean up... I'm back to 20 PSI idle and 18 PSI WOT...

To this day I don't know what causes this check ball to misaligned with the spring or jaming the check ball down into the coils of the spring but I know if I take the time and remove the check ball and blow the port out with compressed air it will work for many more months till one day the pressure falls off and a filter check doesn't fix it...

 

[ramhunter9]

Bad ass i am going to just add this to my maint list

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[Mopar1973Man]

Still holding up 20 PSI at idle and 18 at WOT...